Compact monitor

[sebackman]

Hi all,

What do you think about combining the new M2 waveguide driven by a 4" driver with a 2206 for a compact monitor type DYI speaker? An updated Array 1200...

It would probably have to be active to take advantage of the waveguide.

Maybe there will be a need for a UHF unit as the 2430k probably goes higher than the 2447/245x drivers.

64892

Kind regards
//RoB

[Horn Fanatic]

Hi all,

What do you think about combining the new M2 waveguide driven by a 4" driver with a 2206 for a compact monitor type DYI speaker? An updated Array 1200...

It would probably have to be active to take advantage of the waveguide.

Maybe there will be a need for a UHF unit as the 2430k probably goes higher than the 2447/245x drivers.

64892

Kind regards
//RoB

The 2206 is an awesome driver for a two way system. A large format compression driver won't give you the sizzle of a tweeter. Can't see that you have room for a tweeter anyway. Isn't the 2430K used in a three way configuration? What is your application?

[sebackman]

Hi,

The intention is to build a small "monitor type" HiFi speaker for home use. I don't have space for large floorstanding units so these would would be as close as I can get I guess. They will be supported by two SUB1500 subs in closed cabinets.

I have a few 2206's so I plan to find a matched pair.

If there is a need for a UHF unit I think there is space to mount someting at the bottom of the waveguide . I will check clearence over the weekend.

Kind regards
//RoB

[pos]

AFAIK that horn cannot be obtained as a part...

[Horn Fanatic]

AFAIK that horn cannot be obtained as a part...

Yes, that would preclude any design plans. All I can suggest, is to refrain from using a constant directivity wave guide for HiFi. By their very design they are a high frequency killer, and subject to phase incoherency issues.

[spkrman57]

I'm liking the resurgence of 2206 2-way designs.

Ron

[sebackman]

The plan is to use 2451Be's and if they do not go all the way, to use 045Ti's.

[John W]

Your design looks very similar to this pair I have, but with the newer horn. These were built by the JBL Custom shop and originally installed at the Experience Music Project in Seattle.
The custom shop designed an internal, passive crossover that gives them a nice flat response from about 75hz to 18k. I haven't sketched out the component values, but they would probably be somewhat different for the other horn.

Drivers are 2206 and 2450.

I really enjoy the sound of these, the are super detailed and dynamic.
I had them setup outside last summer on top of a pair of 2241 woofer cabinets for my daughters 16th birthday party. Wow, given some space and some wattage even better.

[sebackman]

Cool!

I have never seen those. What horn is that? Is it a JBL horn? Do they have a JBL type number?

That layout is very close to what I want to do. I bet they sound fantastic. Is it a 2" or 1,5" driver, ie 2450 or 2450SL?

I will try to keep mine as compact as possible as they will be wall mount.

I'm using 2451 drivers.

All the best

//RoB

[John W]

These horns came from the JBL Custom Shop. I assume they were one-offs, since they don't have any numbers on them

The motors are 2450, but the horn has an integral housing that fits over the driver. My guess is that they pulled the covers off the 2450 and bolted horns over the top. The diaphragms are the ribbed 2450 version

[sebackman]

That was neat. I have not seen them before. Is the 2450 without the snout identical to a 2450SL, except for the dia? Do you have any measures on the horns/box. Pretty cool that the horn cover the driver. –Learning every day.

I built a similar speaker using a SR4722X cabinets with 2206 and 2450SL on 2332. I had to make distance rings to the 2206 and add some acoustic foam to the sides to mitigate the standing waves from the recessed baffle. Maybe yours are better and it is not a problem.
http://www.audioheritage.org/vbulletin/showthread.php?35293-1kHz-suck-out-from-2206H-in-SR4722X-cabinet-ideas&highlight=suck

Well, I need to manufacture adapters as the 2451 has a wider bold circle than the D2. I had hoped to have them this weekend but I won't get them until next week. I will post some measures then. Same with the VTX F12 horn, uses the smaller bolt circle. I’m making an adapter for them too. Please see picture.



All the best
//RoB

[John W]

That was neat. I have not seen them before. Is the 2450 without the snout identical to a 2450SL, except for the dia? Do you have any measures on the horns/box. Pretty cool that the horn cover the driver. –Learning every day.



Here are some measurements I took a while ago.

The first is with both the 2206 and the horn together.

The second is cut off at 200hz for some reason, but includes a small inductor I added to try and bring down the bump at 12k.

[sebackman]

John W, that is very good measurement results. I hope to get near that with my small project.

Ok, here is some update on the Compact Monitor project progress.

We are planning to use the 2206 beneath the M2 waveguide in an active setup. Driver will be a 2451Be and/or 2451Ti. I have looked at other 12” but it seem like the improvement, except possible for the fantastic 1200Fe, is not really that big when used with subs (80Hz) and crossed into the M2 waveguide at 800-ish Hz. I don’t really have room for a 15” in this system, so a 12 will have to do. 2006 should do a good job there. Comments or suggestions?

I have tried the M2 waveguide with the 2451Ti’s and that resulted in some interesting measures. It appears that the 2451 Ti is a bit sensitive to this horn, albeit nice and predictable. The picture shows two different drivers in the same graph just for a sanity check. Please disregard the black line which is the sum of them. The differences are close enough to be the result of position in my improvised measuring setup. I normally do measures out door and will do that here also later.

65078

Attached is a picture of the M2 from the front and rear side.

65079

They do not come with a driver mount and as far as I know the original is not available, so I had to make some of my own. Even if they were available they are designed for the D2 with a smaller nose that the 245x / 476 4” drivers. The larger bold circle of the 2451 is almost as bid as the mount circle on the horn. I had some adapters made by aircraft quality aluminium and drilled them for both the large and small JBL bolt circle. I also made some adapters for the VTXF12 horn to accept the larger bolt patter of the 2451. Please see picture.

650806508165082


I will revert with more info as we progress. Please come with suggestions and comments on the project.

All the best
//RoB

[sebackman]

Some additional info

The new VTX F12 horn seems good and attached is a picture of that beside the M2. -Pretty big difference size wise.

65084

Even the VTX F12 horn seems to be an improvement over the older PT-F95HT. It is being offered by JBL in the new VTX series with the D2 and in the STX with the 2453 so it should be ok with booth. Attached is a measure with two 2451H Ti drivers. Please disregards the black line.

65085

It appears that the Ti drivers may not reach all the way with the M2 waveguides but maybe the Be’s can. However there is room to introduce a 045 in the bottom of the M2 waveguide. Pls see picture. Let's see what happens with some EQ applied to those curves

65086



All the best
//RoB

[4313B]

We are planning to use the 2206 beneath the M2 waveguide in an active setup. Driver will be a 2451Be and/or 2451Ti. I have looked at other 12” but it seem like the improvement, except possible for the fantastic 1200Fe, is not really that big when used with subs (80Hz) and crossed into the M2 waveguide at 800-ish Hz. I don’t really have room for a 15” in this system, so a 12 will have to do. 2006 should do a good job there. Comments or suggestions?Compared to the 1200FE, the 2206H has the large four-inch voice coil and increased sensitivity.

[macaroonie]

Thanks for posting the pics of the M2 throat. For some reason I reckoned they were moulded in 4 parts with the joins along the diagonals. Seems not.
It would be fun to carve those from wood.

BTW you are not messing around here , some good engineering going on , nice.

[ivica]

I have tried the M2 waveguide with the 2451Ti’s and that resulted in some interesting measures. It appears that the 2451 Ti is a bit sensitive to this horn, albeit nice and predictable. The picture shows two different drivers in the same graph just for a sanity check. Please disregard the black line which is the sum of them. The differences are close enough to be the result of position in my improvised measuring setup. I normally do measures out door and will do that here also later.



All the best
//RoB

Hi RoB,

Interestingly that the response is almost flat, not as expected CD horn behavior.

regards
ivica

[sebackman]

JBL 2451J Be on JBL M2. Pretty nice.




Kind regards
//RoB

[sebackman]

Some additional data

Test JBL M2 / 2451H Be 2015 04 03

Indoor workshop lower floor, upward on work bench.

LSPCad 60 (latest update), M-Audio Fast Track Pro, Samson Servo 200, Earthworks M30 (calibrated), 33mf in series,
2-Channel measurement, 48kHz, 512 buff, 65536 MLS, 1/24 smooth offset 64 cm, range 40db, window 4ms (OBS short window only high frequency usable), approx 86db SP level. No EQ or PEQ.

Kind regards
//RoB

[baldrick]

An impressions how the m2 waveguide sound compared to other horns?? Are the M2 waveguid really that good or is it more the DSP and D2 driver makes the difference in M2?

Kind of surprised to see the measurment with 2451 dropping so much downto the 800hz crossing point, I would expect the D2 driver to drop even more than 2451!?

[sebackman]

Baldrick,

As you can read the the time window is very short, ie no usable data that low. I will post data from outdoor measurements later.

Kind regards
//RoB

[baldrick]

Sorry, didn't see that until now :)

[4313B]

An impressions how the m2 waveguide sound compared to other horns?? Are the M2 waveguid really that good or is it more the DSP and D2 driver makes the difference in M2?It is a combination of all three working together. I do know that all the previous waveguides JBL had didn't do what they needed the M2 waveguide to do in this specific instance, so there's that.

[ivica]

Baldrick,

As you can read the the time window is very short, ie no usable data that low. I will post data from outdoor measurements later.

Kind regards
//RoB

Hi sebackman,

Using 4ms windows, I would expect that the frequencies under 500Hz, can be much influenced, but not 1.5kHz.
As I have said, before, I believe that the lower frequency "loading" of the M2 horn, as seems to me as "fast flaring wall type horn", is not so good as can be expected due to its large mouth format. Almost the same as OSWG type of horns.

For D2430K driver, may be that is not a problem, due to its membranes, but for the old JBL 4-inch dome type diaphragms with metal-made suspension, large diaphragm displacement (at lower frequency) can be fatal. (especially 2441AL, and 476Be). Here using Truextent Be, or Radian 4-inch diaphragm,
with a polymer suspension would be less sensitive.

Am I right, we would see one day when our honorable member 4313B, would make THD measurements of his 476Be with M2 horn.

regards
ivica

[4313B]

For D2430K driver, may be that is not a problem, due to its membranes, but for the old JBL 4-inch dome type diaphragms with metal-made suspension, large diaphragm displacement (at lower frequency) can be fatal. (especially 2441AL, and 476Be). Here using Truextent Be, or Radian 4-inch diaphragm,
with a polymer suspension would be less sensitive.Are you taking into consideration just how loud these things are? Especially in a home environment? Are you guys using the recommended 6 to 10 dB resistor pad between the c.d. and the amp? Protection caps?

I agree that the polymer suspensions are less prone to fatigue but I don't think it is an issue here. Doug Button, Greg Timbers and I have talked about these suspensions and c.d. excursion.

I will confess my real concern - that foam in the back can... it turns to tar over time and, quite frankly, I'll be replacing that junk with felt as soon as I get around to it. The 476's are chock full of that stuff and it has to go.


Am I right, we would see one day when our honorable member 4313B, would make THD measurements of his 476Be with M2 horn.The thought has never even occurred to me. I suppose if I was hearing a bunch of junk I might be inclined to investigate the cause but given that they are so insanely clean sounding I probably won't bother. :o:

[ivica]

Are you taking into consideration just how loud these things are? Especially in a home environment? Are you guys using the recommended 6 to 10 dB resistor pad between the c.d. and the amp? Protection caps?

I agree that the polymer suspensions are less prone to fatigue but I don't think it is an issue here. Doug Button, Greg Timbers and I have talked about these suspensions and c.d. excursion.

................

The thought has never even occurred to me. I suppose if I was hearing a bunch of junk I might be inclined to investigate the cause but given that they are so insanely clean sounding I probably won't bother. :o:

Hi 4313B,

Have You tried 476Be with M2?
I am sure (if not yet) that one day You will inform us about that [476Be & M2], and after that some of us can decide whether or not to make DIY M2 ("inspired") horn, and what would be lower frequency that such 244x/5x combo with M2 that can be applied to them. I believe that something around 800Hz, using sharp (say 18~24dB/oct) filtering would be good protection for the driver suspension.
Neglecting the possible problems about LF loading of the driver, on-axis response shown here (almost FLAT up to 15kHz), push me to believe that such combo (244x/5x & M2) is not so wide dispersive as it has been said in some M2 presentations. I would expect a kind of CD-horn behavior (-6dB/oct roll-off, over say 3kHz), but here I can to see.

regards
ivica

[4313B]

Hi 4313B,

Have You tried 476Be with M2?No, not yet. Just on the older 100x100 and 90x40 waveguides.

[ivica]

No, not yet. Just on the older 100x100 and 90x40 waveguides.

Hi 4313B,

Can You show on 90x40 WG (may be PT-H95HF)

regards
ivica

[4313B]

Hi 4313B,

Can You show on 90x40 WG (may be PT-H95HF)

regards
ivicaNot anymore. The 476Be's are bolted to H4338 horns. I'll be bolting the 476Mg's to the M2 waveguides.

[sebackman]

Hi,

Thank you for feedback on the 2206 vs other 12”. Not needing the lowest octave when running subs (SUB1500’s) it sounds like 2206 may be a good choice, even if 1200FE takes it one step further.

I normally mount an attenuator to reduce sensitivity 5-10db as suggested, at least on the drivers with more exotic diaphragms and I always mount a protection capacitor. I have no idea if it has any sonic effect but I have always used a large and a small capacitor in parallel, as in the M2.

When testing here I use a 33mf Audyn cap to protect the driver. Normally I also set the MLS sweep to start at maybe 4- 500Hz to reduce any strain on the dia. I agree that at normal listening levels at home it feels less likely that the suspension would harden and give up.

4313b, what kind of felt do you use to replace the foam. In one of my spare drivers the rot has started… Suggestions much appreciated.

I will do some measures outdoors next weekend and also some on and off axis and publish. I also have a pair of almost new 2450SL’s to test. -Later I will throw in the DSP settings in one of the BSS units to see what happens. 

I also agree that other JBL driver/horns can probably be “DSP tuned” to deliver equally solid sonic results, or at least almost. But having toyed with DSP filters for quite a few years I know that getting good results with them goes beyond setting PEQ’s to flatten the curve.

My guess is that if the raw data curve from D2 on M2 waveguide would be given to a bunch of different people to equalize, their respective DSP settings would be different but the final measure may very well be rather similar. There is just way to many parameters to tweak and let alone combinations of them. In the newer DSP units there is virtually “no limit” to EQ/PEQ settings. The BSS units can do both IRR and FIR filters and even combinations of them.

The settings for M2 kindly posted by 4313b leads me to think that JBL has a computer algorithm to calculate several different combinations of EQ/PEQ/phase/delay with an acceptable final curve. Then they listen to each different combination to verify that a given combination of DSP settings indeed sounds good. That is why I think the M2 is getting so fantastic reviews. They have spent the time needed, they have the HW needed, they have a large anechoic chamber and they have the skills to find the right HW / DSP combination.

I think it will be difficult to privately find “the combination” to make other horn combination to sound equally good. If JBL at some point in time would to publish full DSP settings for K2 / 43XX horns that may well prove to be equally good or even better for home use.

This is also why I have chosen to limit myself to use the 2332 horn for a number of years. With my drivers (2451Be) they produce a nice curve that is easier to “straighten” than some of the other horns I have tested. Albeit that the other horns may very well sound significantly better with passive filters or other active settings I have not been able to get them to the same level as the 2332 with my DSP settings (to my ears). I do have pretty decent measuring equipment but it may very well be the lack of knowledge and/or experience preventing other horn/driver combinations to deliver their native superiority at my place. 

The interesting thing from my point of view is that we do have the M2 DSP setup from which we can do tweaks to adjust for other woofers, other cabinets and potentially other drivers. That base is very important because we do know that the DSP settings with the original HW sound really good. We cannot expect to get to the level of M2 system quality, but I do think we can get acceptable close with that as a starting point. Without access to the DSP settings I would probably not have dared to take on this project, just too many unknowns. :-)

I know that Mr Timbers have posted some DSP suggestions for other JBL speakers and that may very well be equally good or better. For some people the original JBL speakers will always be the preferred sound, for some people adding DSP processing and/or other tweaks may make their clock tick. And then there are lunatics like me who attempts to create our own combinations and accepting that they are not JBL speakers but DYI bastards. Albeit good sounding bastards.

The real M2 real game changer to me is that JBL created a system where components and SW is integrated into one function, producing accurate sound.

More data will come soon.

Kind regards
//RoB

[4313B]

4313b, what kind of felt do you use to replace the foam. In one of my spare drivers the rot has started… Suggestions much appreciated.http://www.mcmaster.com/#f13-felt/=wnjab6

Courtesy of our member badman. http://www.audioheritage.org/vbulletin/showthread.php?26757-foam-or-felt-in-the-cover&p=268321&viewfull=1#post268321

I've used the 1/2" stuff in the past but the 476's are loaded with two of the foam pads instead of just the usual one.

[pos]

4313b, what kind of felt do you use to replace the foam. In one of my spare drivers the rot has started… Suggestions much appreciated.
If you want to stick with foam you can try these, readily available in Europe :
http://www.ebay.fr/itm/PANNELLI-FONOASSORBENTI-PER-MOTORI-COMPRESSORI-10mm-/320767492106?pt=LH_DefaultDomain_101&hash=item4aaf3b800a
http://www.ebay.fr/itm/PANNELLO-ADESIVO-10mm-ANTIVIBRAZIONE-PER-SUBWOOFER-/321653900645?pt=LH_DefaultDomain_101&hash=item4ae4110565
(with or without adhesive backing)
You can also try their melamine foam (basotect), which is supposed to be more efficient in absorbing waves...


The settings for M2 kindly posted by 4313b leads me to think that JBL has a computer algorithm to calculate several different combinations of EQ/PEQ/phase/delay with an acceptable final curve. Then they listen to each different combination to verify that a given combination of DSP settings indeed sounds good. That is why I think the M2 is getting so fantastic reviews. They have spent the time needed, they have the HW needed, they have a large anechoic chamber and they have the skills to find the right HW / DSP combination.
I don't think the EQ was done automatically on the M2: this type of EQ is easy to do manually (I did something similar on some 2344), the hard part is to get a meaningful (set of) measurement(s).

This is where JBL's infrastructure and (LSR) measurement technique is invaluable: being able to automatically take several hundreds of measurements and deduce 30°/10° averaged curves as well as first reflexions and sound power all in once is great for evaluating and EQing a loudspeaker.
But now that we know that the M2 *is* well behaved the "only" thing that you would need is a 30°/10° averaged measurement to be used as your EQ target, and (manually) EQ that flat as JBL did for the D2+M2 waveguide.

Here is what I did for the 2344:
I mounted the 2344 on a PA loudspeaker pole so that the rotation angle was at the horn slot.
I then set the MLS length to something like 20sec, and slooooowly/smoooothly rotated the pole while taking the measurement, up to around 15°.
This gives a usable 30° horizontal average measurement (+/-15°, the horn being symmetric) that retains phase information (because the slot-mic distance is constant) and can be windowed to exclude reflexions.
I don't think the 10° vertical measurement is that important given the small angle (+/- 5°), but you can obtain it by rotating the horn on the pole so that the verticals become the horizontals... (you can also of course do the diagonals that way)

+/-15° horizontal averaged measurement (caution: the 2426J used was probably somewhat out of spec...) :
65097

EQ curve (~15 manual EQ and filter points) :
65098

final +/-15° horizontal averaged measurement (900Hz LR 36dB/oct target) :
65099

[ivica]

I.......
Here is what I did for the 2344:
I mounted the 2344 on a PA loudspeaker pole so that the rotation angle was at the horn slot.
I then set the MLS length to something like 20sec, and slooooowly/smoooothly rotated the pole while taking the measurement, up to around 15°.
This gives a usable 30° horizontal average measurement that retains phase information (because the slot-mic distance is constant) and can be windowed to exclude reflexions.
I don't think the 10° vertical measurement is that important given the small angle (+/- 5°), but you can obtain it by rotating the horn on the pole so that the verticals become the horizontals... (you can also of course do the diagonals that way)

30° horizontal averaged measurement (caution: the 2426J used was probably somewhat out of spec...) :
......

final 30° horizontal averaged measurement (900Hz LR 36dB/oct target) :
....]

Hi POS,

How that "averaged measurements" differs from the:
(a) on axis response;
(b) is there any off-axis response ( say -15deg off axis) that is almost identical to the averaged response?

regards
ivica

[pos]

Here is the on-axis response:
65100

I don't have any single point off-axis response measurement to show (did not keep them, sorry).

If you open both the 30° averaged and the on-axis response in two tabs of your browser and alternatively switch from one to the other, you will see that the on-axis response has a small and low Q depression around 8kHz that is not there in the averaged measurement.
In fact the response is hotter 15° off-axis than on-axis at these frequencies, which seems to be a common trend in many biradial horns....

[pos]

For reference, here is the on-axis response measurement of a 2426H on the 2344, taken from the brochure:
65101

As you can see the depression around 8kHz is clearly visible here (and you can also guess that the 2426J I was using was probably not up to spec...)

[Mr. Widget]

Here is what I did for the 2344:
I mounted the 2344 on a PA loudspeaker pole so that the rotation angle was at the horn slot.Very nice work!

I'm not sure if you took this into account or not, but did you use a baffle? I have never taken measurements of the 2344, but most of the horns I have measured, measure differently when in a baffle than when freestanding. I'm not sure if a baffle the size of your final speaker would markedly change your results, but it might.


Widget

[ivica]

Here is the on-axis response:
65100

I don't have any single point off-axis response measurement to show (did not keep them, sorry).

If you open both the 30° averaged and the on-axis response in two tabs of your browser and alternatively switch from one to the other, you will see that the on-axis response has a small and low Q depression around 8kHz that is not there in the averaged measurement.
In fact the response is hotter 15° off-axis than on-axis at these frequencies, which seems to be a common trend in many biradial horns....

Hi POS,

So averaged and on-axis on the same graph.
so the differences are not so much, may be the response on the half of the off-axis response angle would better match, but the differences are not so much as can be expected, may be as 2344 horn is quite wide dispersion angle over +/- 45 deg off axis (horizontal)

regards
ivica

[sebackman]

Hi,

Excellent data. I can try to do replicate that for the M2/2451Ti (without baffle) over the weekend if time permits. How far out did you measure? I will measure outdoors to use a long time window and long sweep.

I have some on and of axis measurements from last week. I will see if I can find them and post here. They are with a out of spec driver but gives a picture of what happens.

Do you have any suggestion for a European felt supplier as I would be preferred felt over foam? I have checked here but they only offer thin felt. If not, I will follow Badman’s link and order from the US.

Regarding DSP settings, I think you can get to the same final correction curve using different combinations of DSP settings as they interact with one another. Whether the different combinations sound different is a different story. The M2 settings are rendered good by many so I will try to keep as close to them as possible.

What I can say is that the same DSP parameter settings do sound different in different brand DSP units. I have not tested if they indeed measure different (with the same settings) and if corrected to the exact same output would sound the same. My guess has always been that they use slightly different algorithms to treat the sound so even if a PEQ is set to the same exact parameters they do not do exactly the same thing. -And that the implementation of the A/D converters is different. That is why I feed my BSS digital signal.

Maybe 4313b or someone else on this excellent forum can shed some light on how the JBL DSP setting process works.

Kind regards

//RoB

[pos]

Very nice work!

I'm not sure if you took this into account or not, but did you use a baffle? I have never taken measurements of the 2344, but most of the horns I have measured, measure differently when in a baffle than when freestanding. I'm not sure if a baffle the size of your final speaker would markedly change your results, but it might.

Thanks Widget

There was no baffle but I figured it would not change the response that much: the butt cheeks are off the baffle anyway, and in a 4430/35 only the lower lips would have some sort of baffle support. Maybe I was wrong and as it could possibly change the response down low though.
This was more of a test, as obviously the driver I had at hand was not good. I'd love to get a proven 2426H/J to test though, and publish the EQ for anyone to use.
In this case this baffle thing would have to be addressed.
Another question is driver to driver variation: would a precise EQ be worth it with driver that can vary in their response from one (good) unit to another (good) as much as the 2426 can (even new ones). I think the D2 is much more consistent in this regard (similar to BMS driver maybe), as among the 3 I had, all measured almost exactly the same, even those that had distortion problems...

Obviously to make precise EQ usable you need a horn that has an even reponse over a wide angle *and* a driver that has a good unit to unit consistency...

[pos]

Hi POS,

So averaged and on-axis on the same graph.
so the differences are not so much, may be the response on the half of the off-axis response angle would better match, but the differences are not so much as can be expected, may be as 2344 horn is quite wide dispersion angle over +/- 45 deg off axis (horizontal)

regards
ivica

What this tells you is that the off axis response around 8kHz gets significantly louder than the on axis one a certain angles.

[pos]

Excellent data. I can try to do replicate that for the M2/2451Ti (without baffle) over the weekend if time permits. How far out did you measure? I will measure outdoors to use a long time window and long sweep.Not sure about the distance. It was indoor (more of a test than anything serious...) and the mic was probably 1.5m away from the horn...
If you want to rotate the horn during measurement you have to use an MLS signal.


Do you have any suggestion for a European felt supplier as I would be preferred felt over foam? I have checked here but they only offer thin felt. If not, I will follow Badman’s link and order from the US.Maybe something like that?
http://www.audiophonics.fr/fr/traitement-acoustique-absorbants/pinta-resobson-fu1220-absorbant-textile-feutre-auto-adhesif-400x500mm-p-5410.html
What thickness are you looking for?


Regarding DSP settings, I think you can get to the same final correction curve using different combinations of DSP settings as they interact with one another. Whether the different combinations sound different is a different story. The M2 settings are rendered good by many so I will try to keep as close to them as possible.Any minimum phase correction leading to the same amplitude curve should give you the exact same result, regarless of the actual number of EQ points and type used underneath.


What I can say is that the same DSP parameter settings do sound different in different brand DSP units. I have not tested if they indeed measure different (with the same settings) and if corrected to the exact same output would sound the same. My guess has always been that they use slightly different algorithms to treat the sound so even if a PEQ is set to the same exact parameters they do not do exactly the same thing. -And that the implementation of the A/D converters is different. That is why I feed my BSS digital signal.
There are many variations in EQ types and interpretations from one unit to another: constant Q vs proportional Q EQs, Fc position of a shelving filter, Bessel Fc interpretation, etc...
This can really be a source of problems and a major cause of sonic differences when going from one unit to another.
This is something I tried to address in my M2 settings analysis document: https://docs.google.com/document/d/1bzJyui75ZG_-wjV95dqKSbFs1Xh87bk2qlc-qS7Kk_Y/edit?usp=sharing&rm=demo

The best way to avoid compatibility problems is to avoid shelvings and bessel filters when designing your EQ. Then you only have to deal with constant vs proportional Q... (easy enough)

[1audiohack]

....Here is what I did for the 2344:
I mounted the 2344 on a PA loudspeaker pole so that the rotation angle was at the horn slot.
I then set the MLS length to something like 20sec, and slooooowly/smoooothly rotated the pole while taking the measurement, up to around 15°.
This gives a usable 30° horizontal average measurement (+/-15°, the horn being symmetric) that retains phase information (because the slot-mic distance is constant) and can be windowed to exclude reflexions.
I don't think the 10° vertical measurement is that important given the small angle (+/- 5°), but you can obtain it by rotating the horn on the pole so that the verticals become the horizontals... (you can also of course do the diagonals that way)


Very clever Thomas!

Barry.

[ivica]

Any minimum phase correction leading to the same amplitude curve should give you the exact same result, regarless of the actual number of EQ points and type used underneath.


There are many variations in EQ types and interpretations from one unit to another: constant Q vs proportional Q EQs, Fc position of a shelving filter, Bessel Fc interpretation, etc...
This can really be a source of problems and a major cause of sonic differences when going from one unit to another.
This is something I tried to address in my M2 settings analysis document: https://docs.google.com/document/d/1bzJyui75ZG_-wjV95dqKSbFs1Xh87bk2qlc-qS7Kk_Y/edit?usp=sharing&rm=demo

The best way to avoid compatibility problems is to avoid shelvings and bessel filters when designing your EQ. Then you only have to deal with constant vs proportional Q... (easy enough)

Hi POS,

Very nice work about M2 equalization You have shown us in the mentioned link.
So if I have understood your work 'inverse' response would be M2 & D2430K FR response.
I have done that from your figures and attached here where the mentioned response of M2 with D2430K is shown as red line.

regards
ivica

[pos]

Hi Ivica,
Yes more or less, but taking into account the passive network and 800Hz LR 36dB/oct acoustical high-pass target (flat otherwise, with no attenuation up high as shown in the LSR measurement set, but is it true?...), the listening window averaged response of the D2/M2 waveguide with no filter should look like that:

http://www.audioheritage.org/vbulletin/showthread.php?33972-JBL-Master-Reference-Monitor&p=373835&viewfull=1#post373835
http://www.audioheritage.org/vbulletin/attachment.php?attachmentid=65046&d=1428085817

[ivica]

Hi Ivica,
Yes more or less, but taking into account the passive network and 800Hz LR 36dB/oct acoustical high-pass target (flat otherwise, with no attenuation up high as shown in the LSR measurement set, but is it true?...), the listening window averaged response of the D2/M2 waveguide with no filter should look like that:

http://www.audioheritage.org/vbulletin/showthread.php?33972-JBL-Master-Reference-Monitor&p=373835&viewfull=1#post373835
http://www.audioheritage.org/vbulletin/attachment.php?attachmentid=65046&d=1428085817

Hi POS,

Very interesting behavior over 8kHz (neglecting about 10dB lower then mid frequency range)
If such response can be get from the measurements of the driver and horn combo, they behave as two drivers are in the combo, one VHF connected to CD horn and UHF driver with diffraction slot (such as 2405). Interesting....(almost unbelievable - for me)....

regards
ivica

[sebackman]

POS, Ivica and other good members,

Can you please explain to me how the M2 combination of passive electric -6db/oct, DSP electric -6db/oct and acoustic filters -24db/oct (horn/mouth and driver/back cap) interact to protect the D2 driver and get to a 36db/oct LR filter slope.

The JBL 2430K seem to be 20 ohms impedance and the resistor attenuator in the M2 cabinet reduces sensitivity -9db. The values match exactly (13ohms/11ohms) and also seem to match the system sensitivity taking the DSP settings into account. Also the designation “K” indicates that it should be higher than “J” = 16 ohms following the old JBL nomenclature.

If that is a correct assumption, the 38mf (33,3+4,7) capacitor in line with 20ohms corresponds to a first order 6db/oct slope with -3db at approximately 209Hz. I addition there is a DSP filter of first order 6db/oct Butterworth with -3db at 782Hz.

The DSP PEQ settings of -4,3 db @ 760Hz and -5,6db @ 3,3kHz seem to have too narrow Q to help much. And the system input EQ at +1.1db at 500 does not help either…

Is the horn loading the driver harder below a certain frequency or is it the back cap reducing the diaphragms movement. For the mechanical amplitude of the driver diaphragm to be reduced below a certain frequency, given fixed voltage across the range, the electric impedance in the driver below a certain level would have to increase to reduce current trough it?? -And when the impedance falls again further down in frequency the idea is that the electric filters shall have reduced the voltage level to un-harmful levels??

From the available JBL impedance curves for the 244X/245X drivers it appears that the impedance peak at about the double on nominal impedance, dependant on horn. Is that alone enough to save a D2 when receiving several hundreds of system watts and only 12db/oct electric protection?? -Or will it indeed give large dome/ring movements but that they are not fatal to the D2 driver??

The combination of Butterworth and LR is interesting and I assume that the combination of passive XO -6db/oct Butterworth, DSP XO -6db/oct Butterworth and acoustic XO –24 db/oct sums up to a 36db LR slope to give a perfect summation.

Still learning.

Kind regards
//RoB

[sebackman]

Or….

Is it a game of sensitivity? The 2215ND has a sensitivity of about 95db 1w/1m @ 8 ohms from data in the tech section. System sensitivity of M2 is 92 db. If D2 is 110db @ 20 ohms, as the other JBL large format drivers, that would give a sensitivity difference of about 15db. The resistor attenuator in the cabinet is -9db = voltage gain 0,355

50V signal applied to each driver would be
2216Nd = 8ohm = 312W
2234K= 20ohm = 125W

Add the – 9db resistor attenuator to the driver would reduce voltage to 50V*0,355 = 17,74V = 15,7W over 20 ohms

And if impedance increases to 40ohm (double impedance at lower frequency resonance point) the power would be only 7,87W at the resonance max.

So even if the system get’s 500W RMS the D2 would only see a fraction of that at lower frequencies and maybe that is ok for the drivers and the diaphragm movement when combined with passive crossover @ DSP 6 + passive 6 db/oct ?

Or am I getting it all wrong here??

If this is correct, why have many of the other JBL designs had much steeper crossover slopes if it is not really needed?

Kind regards
//RoB

[pos]

Hi Robert

I don't know the ins and outs of JBL's choices here. The S9800 is similar in this regard (6dB/oct HP filter, basically a cap with some resistors...).
Earl Geddes also uses a similar topology in his passive Summa system (single cap with a knee around 10kHz IIRC).
The key here is to add a zobel to avoid having an amplitude peak at the impedance peaks down low.

[macaroonie]

Since there is a fair likelyhood of many DiY systems along these lines I was having these very naughty thoughts.
The 2206 is pretty much the go to driver for this application but it is really a mid bass driver in it's normal use.
For domestic home brew systems where the power handling available is not required is there any mileage in replacing the pleated surround with an M roll or regular foam ? Perhaps add a little mass ?
Obviously the T/S parameters will change but given that this driver is good to almost 2kHz and normally will be used with a horn from 800Hz then a little of the top end and power handling could be sacrificed to gain some extension at the bottom.
Anyone done this ?

M

[ivica]

Or….

Is it a game of sensitivity? The 2215ND has a sensitivity of about 95db 1w/1m @ 8 ohms from data in the tech section. System sensitivity of M2 is 92 db. If D2 is 110db @ 20 ohms, as the other JBL large format drivers, that would give a sensitivity difference of about 15db. The resistor attenuator in the cabinet is -9db = voltage gain 0,355

50V signal applied to each driver would be
2216Nd = 8ohm = 312W
2234K= 20ohm = 125W

Add the – 9db resistor attenuator to the driver would reduce voltage to 50V*0,355 = 17,74V = 15,7W over 20 ohms

And if impedance increases to 40ohm (double impedance at lower frequency resonance point) the power would be only 7,87W at the resonance max.

So even if the system get’s 500W RMS the D2 would only see a fraction of that at lower frequencies and maybe that is ok for the drivers and the diaphragm movement when combined with passive crossover @ DSP 6 + passive 6 db/oct ?

Or am I getting it all wrong here??

If this is correct, why have many of the other JBL designs had much steeper crossover slopes if it is not really needed?

Kind regards
//RoB

Hi RoB,

There are three electrical protection of the drivers membrane:

1. capacitor in-series with the rest of the drivers circuitry
2. Hi pas filter of the DSP crossover
3. sensitivity reduction resistors 13 and 11 Ohms

Depending of the horn loading the driver, maximum diaphragm displacements would occur, but using some simulation programs such as Hornresp,
it can be seen that around 300Hz~400Hz would be the most critical frequency region (without the DSP influence), with DSP HP would shit such region up say somewhere about 500Hz, (but making driver better protected).
regards
ivica

[sebackman]

I’m still curious how the passive, active and acoustic crossover interact in the JBL M2, so if anyone can shed some light on that I would be grateful.

This upcoming weekend we will be playing around with some drivers and horn and I will post measurements next week. We will be testing 2450SL, 2451Ti and 2451Be on the 2332, M2 and the new VTX F12 horns.

-And here is some additional info on mounting.

The M2 waveguide has 8 plastic pre drilled fasteners to mount a driver adapter. The plastic material is actually pretty good. To use a recessed plastic or wood screw proved difficult so I actually tapered the holes for a M6 machine bolt. The holes are about 50 mm deep so I had to make a tap that was long enough, so now each hole accepts M6 bolts. It turned out to be very strong and can easily hold a 245x driver. I will later add some LockTite on final assembly just in case....

The adapter is made out of aircraft quality aluminum and designed to let the snout of the horn attach to the driver with only 0,5mm distance.

The M6 bolts are completely recessed and hence will let me mount whatever driver I want as I drilled for both bolt patterns. Even a 2430k will fit. Please PM for a drawing.


I have settled for the 2206 for now and will be drawing some cabinets in the near future. The plan is to get something up running this summer in a 5.2 system using my Crown CTS amps and the BSS BLU800 as DSP.

More info next week.

Kind regards

//RoB

6525765262652596526065261

[pos]

Hi Robert

I’m still curious how the passive, active and acoustic crossover interact in the JBL M2, so if anyone can shed some light on that I would be grateful.
I don't think there is anything fancy here: the passive network is just a lpad to reduce hiss and a cap to protect the driver from hardware or user error. It is set sufficiently low to only play a minor role in the final acoustical response.


The M2 waveguide has 8 plastic pre drilled fasteners to mount a driver adapter. The plastic material is actually pretty good. To use a recessed plastic or wood screw proved difficult so I actually tapered the holes for a M6 machine bolt. The holes are about 50 mm deep so I had to make a tap that was long enough, so now each hole accepts M6 bolts. It turned out to be very strong and can easily hold a 245x driver. I will later add some LockTite on final assembly just in case....
Very nice!


The adapter is made out of aircraft quality aluminum and designed to let the snout of the horn attach to the driver with only 0,5mm distance.
So there is a 0.5mm air gap between the driver and horn throat?
That could potentially cause problems in the UHF. Maybe you could fill that gap with cork or other material?

[sebackman]

Hi POS

It is the same with the JBL original adapter and in reality there is no gap as the gasket on the front of the 245x driver will compress slightly and fill the gap. 0,5 mm is not much...

I can try to make a detailed picture over the weekend. A gap is at least not visible to the eye on close inspection.

Also, the initial 2451Be measurements does not show a problem. I'm not shure my spare 2451Ti are up to spec... Need to take them apart and clean/align.

Kind regards
//RoB

[ivica]

I’m still curious how the passive, active and acoustic crossover interact in the JBL M2, so if anyone can shed some light on that I would be grateful.

This upcoming weekend we will be playing around with some drivers and horn and I will post measurements next week. We will be testing 2450SL, 2451Ti and 2451Be on the 2332, M2 and the new VTX F12 horns.

-And here is some additional info on mounting.

............

More info next week.

Kind regards

//RoB



Hi
Hi sebackman ,

If we are talking about the acoustical response of the compression driver with the horn mounted, it seems to me that that the total behavior is almost the same as closed box response of the speaker. Theoretically, that response behaves as high-pass filter of the second order (slope -12dB/oct, or 40dB/dec), introducing a kid of delay depending of the applied frequencies. Such delay diminish as frequency rises. It can be equivalent as distance delay but depending of the applied frequency. A kind of measure of such delay usually called "group delay" .
Applying any type of the filter (analog, digital, passive or active) would add its group delay to the reproduced wave front.
Applied horns has "horn length" of several cm, but it can be much more, say 20cm or more. If it is assumed that 1kHz wave length is about 34cm. If a kind of addition of the acoustic wave front from two drivers is the listener perception of the speaker response, say mid-bass driver and the horn driver their mutual positions between the drivers, can make large influences to the total frequency response of such two driver response. If we have two drivers near one the other reproducing the same frequency sound, total level would be twice larger, or +6dB, so if the two drivers using the same type of network (but one high-pass an the other low-pass), and if they have the same efficiency, and the used frequency is in the pass-band of the driver, in order not to produce over or under shoot, in the response at the crossover frequency networks transfer faction have to be designed in the way that at the crossover frequency on each of the driver the leveled of the applied voltage has to be ½=0.5 of the level in the pass band or -6dB. But another important thing has to be satisfied that at that frequency total delay of the wave fronts from either drivers has to be the same.
Some time is not easy to get such equal delay, as may be the compression driver mounted on the horn, due to the horn length, and even the cross over network have been designed correct, the response is not flat as expected. A kind of "comb filter effect" can be get dye to the differential delay of the reproduced wave fronts from each of the drivers.
It is known that depending on the horn type, depending on its cross-section surface flare, depending of any kind of "obstacles" that can be find in the horn throat (as can be seen on M2 too) in order to enhance diffraction to "widen" horizontal dispersion, or horn mouth is abruptly finish (to baffle), so more or less reflection would be generated, if passive network is used then there is large influence of the driver&horn impedance influence to the total responses (as in the region of several hundreds Hz up to several kHz, depending of the used horn driver electrical impedance can change its value). All that can make large "bouncing" in the driver&horn response, so the behavior of the predicted the 2-nd order high-pass response can differ much.
On the following figure it can be seen the different response using the same driver but applying horn with different horn flare surface walls. The calculation has been done using HORNRESP software.
Horn length (depth) is about 17cm, while horn mouth of 900cm2, while horn throat is 1.5inch diameter driver.
OSWG- Oblate Spheroid (Hyperbolic)
EXP -Exponential
Cos-Hyperbolic
LeCleach
From the attached figure it can be seen that if we want to apply crossover at 800Hz the response would be very different, even ideal (mid)-bass driver is used. Not to mention that 17cm length is almost half of the 1000Hz frequency wave length, so the relative position of the horn (relative to the (mod)-bass cone surface would be important too.

[sebackman]

Dear all,

Thank you Ivica for the info. Without seeing the impedance curve to verify that a specific driver/horn combo increases the impedance below XO point to protect the diaphragm I’m still a bit nervous to go 790Hz @ 6db/oct on the 2451Be’s.

The series capacitor JBL added in M2 seem to be tuned much lower XO in being 38mf @ 20 ohms (-3db at about 205Hz). If there is not a significant increase in electric impedance towards the amplifier as a result of the acoustic and electric characteristics of the driver/horn combo, what protect the diaphragm from dangerous excursions?

Anyway, we have had a completely wild weekend with a 4" driver / waveguide shootout.

We tested 2450Ti, 2450SL and 2451Be (Truextent) on the 2332, the new VTX F-series waveguide and the famous M2 waveguide. Only 4” drivers so far but a kind Forum member has offered to measure on his 2435’s and that will happen in a few weeks. -By me or him  .

I thought I would sum up some impressions and observations. All of the combinations do sound really good compared with most other speakers from my horizon. We have used 2332 for years and in a DSP environment and with some correction they sound nice and are well behaved. However when comparing to the new VTX waveguide it is clear that development has not stood still.

We did MLS measures on all combinations of drivers and horns at 0, 30, 60 and 90 degrees angle. The setup was outdoors on a 2,2m high tripod and I general as described by member POS above. The small “table” on top of the tripod with the driver/horn was rotated and the microphone was kept stationary. The turning circle was not geometrically correct so the phase is off a bit but the SPL should be reasonable correct.

For interested members please PM for measuring data.

Listening was conducted in a normal living room in a fully 3-way active setup with 2206 below the driver/horn and SUB1500 subbs.

As can be expected they all measured good but the SL and the Be diaphragm’s shows less break-up and are more stable over the higher frequency range. Albeit there is a significant difference in the visible curve shape from the measurements, it was not perceived to be that great in reality when listening. No doubt the SL and Be was an improvement but Ti was certainly no slouch.

We decided to minimize confusion by focusing on one driver type to test all horns in sequence. We chose the standard 2451Ti as that is what most people would have and that was good it is likely that the others diaphragms perform better. The 2332 we know well and we have used them with 2451 (Ti/SL/Be) for many years. Given some DSP “help” they are sharp and detailed. Maybe not the best coverage and a bit narrow at the top but still very enjoyable. -To my ears, even better than some horns perceived by others to be superior. They do what they do and our test setup verified that.

Then we moved to the VTX waveguide and now the sound opened up and felt more “alive”. It is difficult to point out exactly a particular field of improvement but we all thought that definition and precision was improved. This even if the 2332 had reasonable accurate DSP settings but the VTX did not. Clearly this is a better and more modern horn. I started a thread some time ago asking if the older PT-F95HF would be an improvement over 2332 and I still cannot answer that question, but the VTX waveguide certainly is an improvement. They are not very expensive, so I would recommend users of the older compact horns to get a pair of VTX and try them out. The have the same footprint as the 2332 and PF waveguide and should be a direct drop in. Even if being all plastic they are sturdy enough to hold any of the Neodym drivers but if used with a 244X ferrite driver I would make a support bracket. Worth mentioning is that they are only drilled for the small bolt circle and if used with the 2451 with the larger pattern, an adapter is needed.

We were all quite happy with the improvement in the perceived sound quality of the VTX when we turned to the M2 waveguide. First of all, the instruments and details in the M2 are not very unlike the VTX, so from that aspect they are both an improvement compared 2332. But the way it delivers the sound is completely different. It is kind of hard to describe but some reviewers has described it as moving into the music instead of being in front of it. The sound is delivered with complete ease, more like a silk dome than a driver/horn combo. Voices come closer but keep the “room” is intact. -A bit weird actually. It is a dramatic difference.

We all liked the sound of the VTX but the M2 is something different. Given the time constraints we did only rather crude DSP settings so there is still much ground to cover.

I did see a comparison between the 2451 (I think) and the 2430k on a PT-F95HF a while back and as I remember the curves they were really not that different in that combo. So we dialed in the original M2 DSP settings just to try. And to our surprise it worked significantly better than we expected. It sounded really good. From memory better than most other systems I can remember. -Accurate and clear as a driver/horn combo but delivered smooth as a soft dome unit. We used 790Hz HP XO with B12 slope since there was no capacitor in series.

Our setup was a three way system so we could add UHF trough the DSP as we wanted but with the original M2 DSP settings none of us felt the need for it. Not even with the Ti diaphragm. The M2 waveguide is so smooth and effortless so a pure two-way with 4” drivers will be just fine for most people. With a 476Mg it would probably be a killer…

All in all, the VTX shows that almost 15 years of development really imply improvements. The DMS-1, from where the 2332 came from, was designed in the late 90-‘s. The VTX came to market 2014. Not that 2332 is bad, but the VTX horn just does it all better. And it measures better too.

Now M2 is something different. Even with crude DSP settings a big smile was seen on all of us as we flipped through different CD’s. Clearly the original JBL M2 system is even better since it was designed as a system. However, after this weekend I think that a reasonable portion of the well-deserved M2 praise may very well come from the waveguide performance alone. The 1500Nd is of course a gem in its own right and the combination must be fantastic.

Not having tried the 2430k and understanding that it may well be even better still, I think my original thought to combine a 2206 with a 2451Be or a 2450SL on the M2 may well be the end of the search for me.

Having established that the M2 waveguide is a keeper and is by far “good enough” even with the older 4” drivers, the question is should we build 2 Compact monitors or 3 to the HT…

Sorry for the lengthy post…

Kind regards
//RoB

[cooky1257]

Dear all,


Not having tried the 2430k and understanding that it may well be even better still, I think my original thought to combine a 2206 with a 2451Be or a 2450SL on the M2 may well be the end of the search for me.

Having established that the M2 waveguide is a keeper and is by far “good enough” even with the older 4” drivers, the question is should we build 2 Compact monitors or 3 to the HT…

Sorry for the lengthy post…

Kind regards
//RoB

Thanks for a great write up.

[4313B]

Having established that the M2 waveguide is a keeper and is by far “good enough” even with the older 4” drivers, the question is should we build 2 Compact monitors or 3 to the HT…
LCR

Yeah, the M2 waveguide is pretty sweet. Interesting that it went from a closely guarded device to an over the counter device. JBL was downright militant when it first came out. NO! NO! NO! :rotfl:

I took mine into work yesterday and one of the machinists countersunk the flange holes for me so I can bolt 476Mg's to them.

Great write up, thank you for taking the time.

[Earl K]

Wonderful review !

Thanks a lot <> :)

[sebackman]

I just got some additional guides. That is good news. For those looking to embark on the M2 DYI journey you could try to get them from reconingspeakers.com and ask for Randall. Part no is # 5025594. They also seem carry the mounting flange (# 5025224) which was not available when I got mine. Please remember that the original flange only accepts the narrower nose drivers like 243x and smaller JBL driver mount bolt circle.

You can mount the adapter plate using screws for plastic and potentially recess them in the adapter plate like 4313b mentions. But I opted for making my own adapter plate with dual bolt patterns and cutting M6 threads in the waveguide.

When cutting threads in plastic I recommend doing this in steps not to get the plastic “floating”. I used a pre, mid and end tap and only cut about 1-2 cm at a time before cleaning out the hole and continuing. The 8 holes in the waveguide are deeper than a standard tap so I got a “long” tap and grinded down almost the entire shaft to be able to thread deeper as a final cut. It went very well and I believe the adapter plate easily can hold any 245x driver and even potentially a 2447 (subject to baffle sterngth).

Kind regards
//RoB

[4313B]

What studs did you use to mount the c.d.'s?

Did you use any goop to hold the studs in to the c.d.'s?

[Don C]

I was looking at some long set-screws. Like Mcmaster 94355A548 (http://www.mcmaster.com/#94355A548)
Seems like the hex would make them easy to install. But I haven't tried them.

[4313B]

I was thinking the same thing. :) Thanks!

[sebackman]

Hi

For the adapter plate I used 8 pcs M6 machine screws MF6S M6x45mm. These are normally hex socket but mine were Philips. They are countersunk 90 degrees and with flat head.

http://nfgab.se/en/fasteners/2_socket-head-screws/200_socket-head-screws/1218_hex-socket-flat-countersunk-head-screws-iso-10642/

For the driver I bought a 3 fot long 1/4" threaded rod and just saw off the studs I needed with a bow saw. The JBL standard driver studs are too long. I measured the depth of the thread in the driver, added thickness of the adapter plate and added about the thickness of a nut and a washer + 5mm.

65363

I made a bunch of shorter studs while I was at it.

The old studs can be difficult to get out from the driver. Don’t use a screwdriver, it will only damage the stud. With the driver on its “back”, use two nuts and inter lock them at the top of the stud with two wrenches and with the upper nut locking the lower nut you can unscrew the stud using the lower nut.

Mount the new shorter studs in the same way but reversed order.

Kind regards
//RoB

[Mr. Widget]

I was looking at some long set-screws. Like Mcmaster 94355A548 (http://www.mcmaster.com/#94355A548)
Seems like the hex would make them easy to install. But I haven't tried them.I've been going that route with acorn nuts for years now... it is the simplest way to reach into the back of a cabinet and install a driver.


Widget

[grumpy]

Lots of interest here... Just ordered a pair of horn/flanges. Will likely try 1500al before deciding on obtaining 2216Nd (or subsequent versions thereof) :) Many thanks to those who continue to share their work and interest!

[4313B]

I was looking at some long set-screws. Like Mcmaster 94355A548 (http://www.mcmaster.com/#94355A548)
Seems like the hex would make them easy to install. But I haven't tried them.


I've been going that route with acorn nuts for years now... it is the simplest way to reach into the back of a cabinet and install a driver.


WidgetAfter checking the local hardware store I went ahead and ordered the set screws from McMaster. Thanks for that link!


I just got some additional guides. That is good news.After messing around with the stock M2 flanges I suspect that I would prefer your flanges. :yes:

[grumpy]

After messing around with the stock M2 flanges I suspect that I would prefer your flanges. :yes:

probably an improvement, and possibly less $$. Was easy (short term) to just click on the box...
oh well :)

[sebackman]

Hi,

I can probably have more made at a reasonable price. PM if of interest. They are alu so shipping cost are minimal.

Kiind regards

// RoB

[grumpy]

Thanks Rob!

[sebackman]

Always more fun with pictures...
6536965370

[sebackman]

Here is the adapter.
Kind regards
//RoB

65371

[pos]

Robert,

Thanks a lot for that picture!

It looks like there is just enough room to bolt the holes on the 114mm diameter circle.
What about the 82.5mm one?
It looks like the holes will be difficult to reach behind the adapter/horn holes, and the horn angle will not help.

http://www.audioheritage.org/vbulletin/attachment.php?attachmentid=65261&d=1429641211
http://www.audioheritage.org/vbulletin/attachment.php?attachmentid=65260&d=1429641133

[pos]

By the way, what is the use of that particular part of the waveguide here?
Why not just chop it off, as it was not part of your original adapter plate?
Is it there only to ensure correct positioning?

65405

[pos]

For the driver I bought a 3 fot long 1/4" threaded rod and just saw off the studs I needed with a bow saw. The JBL standard driver studs are too long. I measured the depth of the thread in the driver, added thickness of the adapter plate and added about the thickness of a nut and a washer + 5mm.


After checking the local hardware store I went ahead and ordered the set screws from McMaster. Thanks for that link!

What length did you order?

[4313B]

I ordered forty M5-0.8 x 40mm to mount the horns to the baffle and the adapter plates to the horns, a bit long for the adapter plates to the horns I suppose but as sebackman pointed out, those holes are ~ 50mm deep.

I also ordered ten 1/4-20 x 1" of the studs with the allen head drive.

I can see why G.T. didn't want to bother with bolting a 476 to one of these waveguides :p I did it but it took some jiggling of the nuts to get them on the studs through the narrow slots.

I left the plastic wrap on the waveguide until I get ready to bolt it to the baffle.

[pos]

I did it but it took some jiggling of the nuts to get them on the studs through the narrow slots.
On the original adapter these holes are centered between the adapter/horns holes:
http://reconingspeakers.com/product/jbl-m2-horn-flange-5026224/

Whereas on Robert's adapter these holes are partly behind them, and the 114mm ones are centered.

Based on your jiggling experience, do you think this would be more difficult in that case?

[pos]

I also ordered ten 1/4-20 x 1" of the studs with the allen head drive.
That is the one I am worried about: is 1" a good fit?
How deep is the thread on the 476?
I guess I will have to measure my 2450SL...

[ivica]

Robert, Thanks a lot for that picture! It looks like there is just enough room to bolt the holes on the 114mm diameter circle. What about the 82.5mm one? It looks like the holes will be difficult to reach behind the adapter/horn holes, and the horn angle will not help.

Hi POS,

It seems to me that the "interconnection plate" holes for 2450-1.5 [2450SL] or 2452, or 2431/35 drivers (positioned at 82.5.mm diameter) have to be offset-ed 67.5 degs (not 45 deg as shown), so a kind of nut can be mounted, not to be "covered" by the M2 horn mounting plastic stubs.. I think that 4313B has done in that way while using 476 driver.

regards
ivica

[sebackman]

Deal all,

-No need to worry. 

The studs I use are 27-28mm, a tad longer than an inch. I use them for 2450SL, 2451 and some other stuff I have lying around. One inch is probably as good even if a few extra threads won’t hurt. I bought a ¼” threaded rod and just saw the studs in the length I needed. -Cheap and effective.

The drawing is correct. The yellow holes are for mounting the adapter to the waveguide. The blue are for the large JBL bolt circle and the green for the small. As you can see all the JBL driver mount holes are geometrically in between the yellow holes so no waveguide boss should be in the way for mounting the nut on the studs from the driver. We have mounted both 2450SL’s (small circle) and 2451’s (large circle) on the adapter without any problem. If you start moving the holes you will wind up with some holes being covered by the bolts mounting the adapter plate to the waveguide. -Your call.

POS, I have no idea what the extra boss (9th) in the M2 waveguide is for. Maybe 4313b knows? It is not the same height as the other 8 mounting bosses so it cannot be used for mounting the adapter plate without milling to accommodate the extra height. Maybe JBL used it as a guide to get the adapter in the right place if mounting the driver in the cabinet after the waveguide was attached to the cabinet. –Just a guess.

I just forgot it in my drawing and initially planned to take it out but since I was unclear to its purpose I let it stay and made an additional hole in the adapter plate afterwards. I cannot see a need for it so on the rests of the waveguides coming in next week I will remove it.

Kind regards
//RoB

[ivica]

Deal all,

-No need to worry. 


The drawing is correct. The yellow holes are for mounting the adapter to the waveguide. The blue are for the large JBL bolt circle and the green for the small. As you can see all the JBL driver mount holes are geometrically in between the yellow holes so no waveguide boss should be in the way for mounting the nut on the studs from the driver. We have mounted both 2450SL’s (small circle) and 2451’s (large circle) on the adapter without any problem. If you start moving the holes you will wind up with some holes being covered by the bolts mounting the adapter plate to the waveguide. -Your call.



Kind regards
//RoB

Hi RoB,

As I have seen from Your figure green and yellow holes are "on the same radius", so after mounting the plate plastic horn studs would make a kind of difficulties to instal the nuts on the metal studs that were previously screwd into the driver body, so that is why I have suggested to make holes for the metal studs on 67.5 degs.
Unfortunately I have no M2 horn to confirm all that.

regards
Ivica

[sebackman]

Hi Ivica,

If you look at the right hand side of my ugly drawing you will see that the diameter is different for all circles. As the nuts will have to be mounted from the side once the adapter plate is attached to the waveguide and the driver is inserted into the adapter plate, the important issue is that nothing obscures the driver bolts from the side. –And with the suggested adapter it does not for any of the two bolt patterns. Both 4-bolt JBL patterns are 90 degrees split and drilled so the small circle goes geometrically in between 4 of the waveguide studs and the large bolt pattern in between the other 4. Please see the picture above.

Kind regards
//RoB

[pos]

Ok, that makes sense, thanks.

While I am ordering on mcmaster.com, wouldn't one of these make the job easier than a hex nut, together with the 1" stud?
http://www.mcmaster.com/#thumb-screw-nuts/=x2x9v0

[sebackman]

Hi,

Your call. Mounting with studs and nuts as described is really not any problem at all. It takes 2-4 minutes to bolt up any driver in a safe way.

Kind regards
//RoB

[ivica]

Hi Ivica,

If you look at the right hand side of my ugly drawing you will see that the diameter is different for all circles. As the nuts will have to be mounted from the side once the adapter plate is attached to the waveguide and the driver is inserted into the adapter plate, the important issue is that nothing obscures the driver bolts from the side. –And with the suggested adapter it does not for any of the two bolt patterns. Both 4-bolt JBL patterns are 90 degrees split and drilled so the small circle goes geometrically in between 4 of the waveguide studs and the large bolt pattern in between the other 4. Please see the picture above.

Kind regards
//RoB

HI RoB,

It is clear to me that the diameters of the circles are different, I want to say that the it would be better that relative angular positions of the for 2450sl stubs relative to the M2 horn stubs would be almost as the case for 2451
You have show on the:
http://www.audioheritage.org/vbulletin/attachment.php?attachmentid=65261&d=1429641211
But as I have said , I have no M2 horn to confirm that.

regards
ivica

[pos]

I just measured my drivers:
- the 2450SL has a 16mm long thread (0.63")
- the 2435HPL has a 7mm long thread (0.28")

Robert's plate is 5.5mm thick (0.22")

So, when used with a standard 7/32" nut (0.22"), the ideal stud would be 27mm long for the 2450SL, and 18mm long for the 2435HPL.
So 1" studs for the 2450SL and 3/4" studs for the 2435HPL would be good matches.

Thin 5/32" nuts would be the perfect match with the 1" stud for the 2450SL

[sebackman]

Dear all,

Sorry for the confusion on my adapter drawing. I uploaded an older design and failed to recognize that, hence the argue that it was correct. Sorry.

Of course members Ivica and POS was right the whole time!

The first set (pictures above) of adapter plates was drilled with the old design but the other sets used the design below.

Please see the correct drawing below. Sorry, my bad.

Kind regards
//RoB

65413

[pos]

Hi Robert,

Thanks again for your work on these, and sorry to kinda hijack your nice project thread with general M2 waveguide discussions...

Why not make the adapter 5mm instead of 5.5mm to avoid having a 0.5mm gap between the driver and the horn?
I understand that this gap is partially filled with the compressed gasket, but still wouldn't it be better if not gap existed at all, and the gasket would be homogeneously compressed on the plate and horn? :dont-know:

[cooky1257]

Do we have a Euro price for the M2 waveguides or is pay once in the US inc shipping, then again with 20% VAT and once more with customs import duty?

[sebackman]

Hi POS,

Agreed. However in reality there is no visible "gap", please see attached picture. Maybe my "0,5mm" really is less.

I did not want to take a chance that the driver would damage the "snout" when the bolts are drawn. In the best of worlds they would be completely flush mount when the driver is mounted and the bolts tightened and that seems to be the case from what I can see.

I paid USD on order and actually picked up the first set in the US and brought home. Talk to Randall at SE.com.

4313b, have you any chance to measure your fantastic 476Mg on the M2 waveguide?

Kind regards

//RoB

6541565416

[ivica]

4313b, have you any chance to measure your fantastic 476Mg on the M2 waveguide?

Kind regards

//RoB


Hi RoB,
That would be interesting to be seen, especially if off-axis measurements can be done too.

regards
ivica

[ivica]

I ordered forty M5-0.8 x 40mm to mount the horns to the baffle and the adapter plates to the horns, a bit long for the adapter plates to the horns I suppose but as sebackman pointed out, those holes are ~ 50mm deep.

I also ordered ten 1/4-20 x 1" of the studs with the allen head drive.

I can see why G.T. didn't want to bother with bolting a 476 to one of these waveguides :p I did it but it took some jiggling of the nuts to get them on the studs through the narrow slots.

I left the plastic wrap on the waveguide until I get ready to bolt it to the baffle.

Hi 4313B,

Any news about Your experiment with 476 & M2 horn?

Regards
ivcia

[ivica]

Hi POS, Agreed. However in reality there is no visible "gap", please see attached picture. Maybe my "0,5mm" really is less. I did not want to take a chance that the driver would damage the "snout" when the bolts are drawn. In the best of worlds they would be completely flush mount when the driver is mounted and the bolts tightened and that seems to be the case from what I can see. I paid USD on order and actually picked up the first set in the US and brought home. Talk to Randall at SE.com. 4313b, have you any chance to measure your fantastic 476Mg on the M2 waveguide? Kind regards //RoB 6541565416

Hi sebackman,

What is the size of the M2 throat in horizontal plane (Ht) and in vertical plane (Vt) from the driver surface, and what is the total M2 depth?

kind regards
ivica

[sebackman]

Hi,

I will meaure and revert later today.

Kind regards

//RoB

[4313B]

4313b, have you any chance to measure your fantastic 476Mg on the M2 waveguide?


Hi 4313B,

Any news about Your experiment with 476 & M2 horn?

Regards
ivciaHere is the current status of my waveguides. I was going to measure the mounting cutout and holes last night but didn't get to it.

[ivica]

Hi,

I will meaure and revert later today.

Kind regards

//RoB

Hi RoB,

Seems You have forgotten to measure...??

regards
ivica

[sebackman]

Hi Ivica

Sorry for the delay.

Both Ht and Vt are 40mm. They look to be different but they are not. I will post some pictures later in the week.

The depth is more difficult to measure as the WG is curved. If I put a ruler across the WG middle vertically it is 117mm deep. Will post picture later.

Kind regards
//RoB

[ivica]

Hi Ivica

Sorry for the delay.

Both Ht and Vt are 40mm. They look to be different but they are not. I will post some pictures later in the week.

The depth is more difficult to measure as the WG is curved. If I put a ruler across the WG middle vertically it is 117mm deep. Will post picture later.

Kind regards
//RoB

Hi sebackman,

Many thanks RoB for the info about the M2 dimensions.

Interestingly for me, that a kind of notches on the response M2 & 2541Be (You have shown us)
http://www.audioheritage.org/vbulletin/showthread.php?36789-Compact-monitor&p=373896&viewfull=1#post373896

are due to the horn throat reflection, (I can guess)
as it seems to be a kind of PIPE {J.E. Karlson may be} whose length is about 4cm ,
and 1/4 pipe reflection-cancellation would start at 345/0,16 = 2156Hz, (theoretically, but here it behaves as shorter pipe)
and would repeat periodically.

As You have said, total horn length (depth) is about 117mm, first maximum in the response would be expected at
345/(2x0.117)=1475 Hz, what is also shown, and as the horn is relatively SHORT, lower frequency response is 'problematic'
due to the not good driver loading. Due to that "fact" using JBL 476Be/Mg diaphragm ( our friend 4313B has)
with 'diamond-shape suspension' under 1kHz can be a (destructive) problem on high levels,
but for the D2430K, Radian-AL or Truextent-Be with a polymer suspension, I believe, would not be a problem.

Regards
ivica

[4313B]

Due to that "fact" using JBL 476Be/Mg diaphragm (our friend 4313B has) with 'diamond-shape suspension' under 1kHz can be a (destructive) problem on high levels, but for the D2430K, Radian-AL or Truextent-Be with a polymer suspension, I believe, would not be a problem.As far as I know, I am the only one foolish enough to use the 476Be or 476Mg on the M2 waveguide so the rest of you should be safe. ;)

[ivica]

As far as I know, I am the only one foolish enough to use the 476Be or 476Mg on the M2 waveguide so the rest of you should be safe. ;)


Hi 4313B,

Ha, ha, lucky You are, so can enjoy in the best CD-drivers (of mankind) ever.
It would be nice, one day when You can show us measurements data [FR, THD]...
May You can show us 10W behavior of the mentioned drivers loaded with M2 horn,
especially from 500~700Hz and up, so we can see that M2 is really masterpiece of
engineering....so may be DIY version can become a reality.

I am very curious to see the results.

Regards,
Ivica

[sebackman]

Santa comes early this year...

65651

[srm51555]

Back in stock.....Awesome Santa!

[sebackman]

Not sure they are back in stock. These have been in transit a while...

I hope that JBL will start shipping them again soon.

Kind regards
//RoB

[macaroonie]

That's quite a remarkable picture considering the history.

[sebackman]

Hi,

A bit of update.

I needed to finish up some other speakers for various rooms in the house and as usual it kind of got out of hand…

-Built 2 pairs of super compact boxes for the workshop and garage. I also did a fatter big brother for use without sub in the house.

The four “twin brothers” are both 2206 and one pair is 2450SL on VTX F12 waveguides and the other 2451H on VTX F12. Not much bass really but they will be run actively with a sub. Sound very nice though with the new waveguides. I guess that the smallish ports will be noisy at high levels but these won’t go PA so it should be less of a problem.

Their fatter brother is a pair of 2206 in rebuilt SR4722X cabinets with VTX F12 horns and a different brand 4” driver. The cabinets are reinforced and tuned to about 40Hz. The curve drops pretty steep from about 100Hz but some DSP here does wonders. Runs on a Driverack Studio on a Crown CTS4200. Decent bass acctually

Now some time for contemplation and to build some active XO amp cases. I have one built with a BSS Omnidrive and a Crown CTS4200 for one pair of the twins. A few more Crown CTS’s lying around but need to decide on XO. Stupidly I sold my BSS BLU16 units a while back. One should really never sell anything . I got a DCX somewhere but would like to keep reasonable the same gear for simplicity. I think the Driverack and DCX will have to leave space for some more Omnidrives. They were very pricey new but now one can find them at very reasonable prices and all SW are for free from BSS website. We’ll se
Once amps and XO’s are in order I will do some serious measurements on these using the M2 EQ structure and see how far I get. Should be pretty good. –Will revert.

On the M2’s compact monitors I do have the horns I need and I will run 3x M2’s in front and 2x VTX in rear due to size restrictions. All with god old 2206’s. I was planning on cabinets but kind of got stuck when I did not manage to decide whether to go for a 2-ay or a 3-way using the 045Ti’s.

Still not sure. The 2451Be’s fall off quicker than the 2450SL’s on the M2 but the curve can EQ’s easily with the DSP. Now if introducing the 045’s above 10k-ish a lot less EQ will be needed and maybe that would sound better. There is room for a 045 with a K2-9800 style horn in the M2 waveguide mould as per above.
http://www.audioheritage.org/vbulletin/showthread.php?36789-Compact-monitor&p=373885&viewfull=1#post373885

Any suggestions?

New adapter plates ordered and a test box will be built within a few weeks, time permitting.

How are the rest of people here that did get their hands on M2 guides doing?

Kind regards
//RoB


65754
65755
65756

[sebackman]

Dear all,

Time is really the most difficult component to track down in order to bring new DIY projects to life.

Finally the small 2-way monitors for the garage and the workshop is finished. -Both with 2206 and the new JBL F12 waveguide. One pair with 2450SL and one pair with 2451Ti. Small footprint is always nice and integrated pole mounts and fly mounts add to flexibility. 2226 subs to both pairs.

66131
66132

And a third pair of active XO SRX4722 on steroids for the “Sauna”… 2206 and the new JBL F12 waveguide and 4” driver.

The electronics for the M2 horn compact monitor is already in place with the existing system so the next step will be to draw cabinets for 2206 and the M2 horns. A bit like what Don is describing in a different thread.

I have finally decided to also mount the 045Ti’s with the K2-9800 horns in the M2 horns to have the option for a three-way if needed. I will be very compact. I hope to talk to the machine shop later this week to see if/how they can mill the plastic in the M2 horns to ´make space for the 045 horn where the label should be mounted. The horns are small and should fit nicely.

I’m playing with the thought to do a sealed box for the 2206 as they only go to 80Hz. What do you think about that? Or is the only way the ported way…

Good news that several members on the Forum now have received M2 horns, it’s always good to compare findings and learn from each other. I hope that all with back orders get theirs soon. I managed to get 8 horns so there should be hope for all.

More info as I go along

Kind regards
//RoB

[pos]

Those look tiny :p
(and very professional ;) )


I’m playing with the thought to do a sealed box for the 2206 as they only go to 80Hz. What do you think about that? Or is the only way the ported way…

If you can measure and correct the response (sorta like a Linkwitz Transform), and are planning a steep enough acoustical crossover slope (or a high enough crossover frequency) then a BR is often a better solution as it reduces excursion/distortion.

This can all be simulated using winISD pro (beware that the EQ implementation in this software is a proportional Q type, whereas your BSS uses constant Q...)

[ivica]

Hi,
A bit of update.

......

On the M2’s compact monitors I do have the horns I need and I will run 3x M2’s in front and 2x VTX in rear due to size restrictions. All with god old 2206’s. I was planning on cabinets but kind of got stuck when I did not manage to decide whether to go for a 2-ay or a 3-way using the 045Ti’s.

Still not sure. The 2451Be’s fall off quicker than the 2450SL’s on the M2 but the curve can EQ’s easily with the DSP. Now if introducing the 045’s above 10k-ish a lot less EQ will be needed and maybe that would sound better. There is room for a 045 with a K2-9800 style horn in the M2 waveguide mould as per above.
http://www.audioheritage.org/vbulletin/showthread.php?36789-Compact-monitor&p=373885&viewfull=1#post373885

Any suggestions?

Kind regards
//RoB

Hi sebackman,

Nice work indeed.
If You plan to arrange 2-way box, I would suggest You to try with JBL D16R2441 ALUMINUM diaphragm, as it seems to me the best compromise if it is planed to be use up to 20kHz. Even D16R2445 Ti (that has more ringing around 12~14kHz) behaves usable up to 20kHz.
I think 2206 using as mid-bass in the sealed box about 50Lit would be the best solution.

If 3-way network is of interest may be DBX DriveRack PA2 would be acceptable solution (amazon.com 320 U$D).

regards
ivica

[sebackman]

Thank you Pos and Ivica,

I guess I will have to build one of each to test. Cross over under the 2206 is planned at 80Hz-ish down to sealed SUB1500's.

For XO I only use BSS nowadays. I like them better than the DBX units. I do have a Driverack PA but a BSS Omnidrive with the newer FW sounds better IMHO.

updates to follow...

kind regards
//RoB

[macaroonie]

Nice work Rob.

Here , I posed this question on another thread re the 2206 .
Since it is the inexpensive go to Mid Bass for projects like yours the problem is that it runs out of steam at 80 Hz. Since you are unlikely to need to use the 600w power that is available pehaps an option would be to re surround with a more compliant foam rather that the stiff pleated surround.
Clearly this will change the free air resonance down the way. Prehaps even add a little mass. This is all from the JBL method that we have seen before ( 2234 / 2235 ) You have enough measurement gear to work it out from there.
Since the 2206 is pretty good all the way up to 2K ish you have frequency range in hand Vs the x/o frequency.
You should be able to get it down to 40-50 Hz. Of course power handling will drop but that should not be an issue in your application.

Cheers Mac

[sebackman]

Update,

Not much has happened. I have spent most of the summer time enjoying some time off. A few weeks in the US and some time at home.

The "muzak boxes" for the garage (2206/2450SL/VTXF12 horns) are all done as per above. Still too many drivers on the shelfs.... New projects.

Glad my little quest for M2 WG’s back in January has resulted in so many nice and talented people on this forum getting their own sets. It will be interesting comparing notes when some systems are up and running.

Three of the eight M2 WG’s I brought to the Nordics are shipped off to Gothenburg in Sweden and only five remaining here :-) .

Three of remaining five are shipped off to the guy who does the M2 adapter plates for me. He is going to mill away the edges on top and bottom so the WG will be even on all sides. That should make the cabinet structure easier without impairing the sound. I will post pictures when I get them back. He is also doing some additional adjustments, but more of that later.

Since I have some restrictions in size due to all speakers in my HT being wall hanged, to reduce the frontal acreage will be appreciated by others in the family. The M2 WG’s are not very discrete…

The last pair WG’s will probably go into a floor standing pair for 2-channel listening without sub, unless someone else needs them more than me. Probably with a good used pair LE14H-X or 1400PRO if I can find them. Only thing I have is a new pair of 2226 that may work. For the HT it will be 2206 to reduce size and there I do have subs.

Ideas much appreciated. Also hints on where to find a good pair of woofers.

-Probably getting the “treated” WG’s back within a few weeks.

Kind regards
//RoB

[sebackman]

Dear all,

Following some months of minimal action I hope to get some time over for building again.

Since there already is a thread dedicated to M2 clones and that is not what I’m attempting I will keep feeding into this thread.

After finishing the garage speakers as per above, the project has de-railed again and spun into two projects.

The first project will be a pair if stereo speakers for my overnighting apartment as I commute to work. They will be equipped with M2 “MkII” waveguides, 2450SL drivers and LE1400H woofers. No subs. I will try to put them in a pair of SP215-9 cabinets I have laying around. Please see picture with a 1400PRO for an idea. I’m going to use LE1400H’s (now getting new edges) and they are much smaller in diameter so they actually fit in the box whereas the 1400PRO does not. More pictures to follow.

The M2 is exactly as wide as the cabinet and it will be flush mount. I will add in a new baffle that will set the waveguide in level with the cabinet top. There will also be a new baffle for the woofer so that the woofer baffle and the front of the waveguide will be flush. Hopefully I get my LE1400’s with new edges within a few weeks and the fun begins.

I will use a Crown CTS4200 with a build-in BSS Omnidrive to drive them. 4 x 240W I plenty in an apartment  .

The sharp eye can see that the “MkII” (have to call it something, right?) designation of the waveguide means that is lower than the original. The original waveguide is 394mm high but mine are now only 352mm to reduce the frontal surface of the cabinet. –Amazing what can be achieved with a CNC machine and some brave decisions.


In the cabinet I will mount them upside down with the JBL badge on top to reduce the distance from the woofer to the driver. Anyone with ideas how to source a JBL badge that can fit except paying $50 for the original M2 badge?

The other set will 3 new fronts to the HT equipped with M2 “Mk II improved” waveguides, 2451Be, 045Ti-1, K2 9800SE horns and 1400PRO’s. The rears will be 2206 with VTX F12 waveguides and probably 2451Ti’s. Or if I can source 2450’s, take of the snout and use them. -Anyone having a set of 2450 with our without diaphragms for sale?

Attached picture is to give an idea of the plan. And also here M2 MkII will be used albeit in “Improved” version with a 045 horn recessed in the waveguide. What do you think of that?

The woofer will be mounted slightly off set to make space for a reflex port.

I think using Be diaphragms may call for a super tweeter, at least from my measurements.

Best regards

//RoB

6872368724

[sebackman]

Here are some additional pictures of the "Improved" version :-)

I also added a picture to show the difference between 1400PRO and LE1400H in size, the LE basket is much smaller (please note the favorite speaker building tool at the bottom of the picture...)

The 1400PRO is dia 362mm and the LE1400H is 355mm. The width is 343mm for the 1400PRO but only 325mm for the LE1400H.

I can't fit the 15"'s, so I have to make good with the 14"'s and/or 2206.

Best regards
//RoB

6872568726

68727

[pos]

In the cabinet I will mount them upside down with the JBL badge on top to reduce the distance from the woofer to the driver. Anyone with ideas how to source a JBL badge that can fit except paying $50 for the original M2 badge?
http://www.audioheritage.org/vbulletin/showthread.php?33972-JBL-Master-Reference-Monitor&p=375911&viewfull=1#post375911 :)


Are these mk2 versions entirely custom made with CNC, or are these originals with reduced lips?

[sebackman]

Hi POS,

These are the original JBL guides. My CNC man says it would be difficult to do clones cheaper than the originals.... We have not scanned them. Maybe Guido has a better “CNC handle”.

However one thing that we discovered is that the JBL forms are not very accurate... We built a jig to fix the guides when we run the CNC machine and my 5 guides seem to come from at least two different cast sessions as we had to re-align the CNC machine to get good results. The 5 axis CNC is VERY accurate.

The material is also odd. The outer form is plastic and that is fine to mill. The filler is odd and eats routers.... -Just turns into dust when milled.

Anyway, now sanded and clear for some paint.

Worth noting is that 3 of the guides has some residual from the cast in the throat and needed some additional work to get smooth. You can check yours by running your finger in the driver opening, they should be completely smooth with no edge. 3 of mine did so that has been sanded off.

Kind regards
//RoB

[pos]

Worth noting is that 3 of the guides has some residual from the cast in the throat and needed some additional work to get smooth. You can check yours by running your finger in the driver opening, they should be completely smooth with no edge. 3 of mine did so that has been sanded off.
Yep I can sense and see a small seam in mine, but it is so small that it cannot affect sound (™), and sanding it would probably require the entire horn to be repainted...

[1audiohack]

Hi POS,

The material is also odd. The outer form is plastic and that is fine to mill. The filler is odd and eats routers.... -Just turns into dust when milled.

Kind regards
//RoB

Mineral loaded usually means sand filled in the urethane world. Yahoo! Super destructive to cutting tools and absolute hell on pumps until they figured out how to carry that (mineral) into the product fluid stream post pump.

Barry.

[sebackman]

Hi

Makes sense that it contains some kind of mineral. Even sanding took some work.

When it comes to the “edge” in the mouth it is easy to remove with fine sandpaper (240). It is only in the inner mouth so it will be barely visible from the outside. And if you go after with (1500) sanding cloth it actually looks pretty much like before but without the “edge”. That is at least what I did.

I choose to believe that is an improvement ;-) . The first two guides from January did not have that edge…

I will have to repaint the upper and lower edges for sure, but I’m not planning to repaint the entire guides for the pair without the 045 horn.

I may have to repaint the whole of the 3 guides with the 045 horns as one of the guides needed some polishing after milling the 045 horn mount. -Why not in White….

Kind regards
//RoB

[srm51555]

Always an interesting project, glad to see it continue. Keep up the good work.

[sebackman]

Hi all,

Short update.

Too much food and “Christmas” have reduced time in the work shop. Small progress have been done and the all the M2 horn are back after treatment. 3pcs are milled for JBL 045Ti-1 horns and drivers and all 5 pcs are milled for reducing baffle area as mentioned above.

The material is difficult to work with and I will see if I can polish the end surfaces or if I have to repaint them. -More info next week.

Three of them are going into the HT as new builds and 2 are going into 2 channels speakers to my other system.

On the 2 channel system some progress has been made. As mentioned above I will use LE1400H woofers and they just came back with new surrounds. -Brilliant job from LN Högtalarservice, they are as new (well... they are new).

I decided to build them using a pair of old stock JBL SP215-9 cabs I had and have braced them and will add new baffles to them this week. There will be a new baffle for the M2 waveguide on the box in the Picture and an separate elevated baffle for the LE1400 to bring them into plain level (pics will follow). The M2 will not have any cover, but the LE1400's will have a steel mesh/foam cover.

I hindsight it would probably have been easier to build new ones… The cabs are built in plywood and now reinforced with bracing and additional improvements.

They are about 60 litres (about 2 Cu Feet) net which may prove a little short on the LE1400’s. I plan for two 3” ports at the bottom. –Have not had time to run numbers so far and it may prove that the ducts will be longer than the depth of the cabinet to get to Fs 27Hz…. Some damping will bring perceived volume up to maybe 70 litres. Inputs here are very much appreciated,

A "scilent" Crown CTS4200 amp with an built in BSS Omnidrive unit is prepared and is standing by to be engaged. An excellent amp and with built in full BSS capabilities, easily a match for the new HD series except for “sheer power”. I would even argue that the CTS series may be better that the HD series for HiFi use, as for the power it is not really needed in home Environment, the CTS crank out above 4x200w RMS.

More info will follow.

Kind regards and Happy New Year
//RoB

6905369054

[pos]

Can't wait to see the result! :)

[ivica]

Hi all,

.......
They are about 60 litres (about 2 Cu Feet) net which may prove a little short on the LE1400’s. I plan for two 3” ports at the bottom. –Have not had time to run numbers so far and it may prove that the ducts will be longer than the depth of the cabinet to get to Fs 27Hz…. Some damping will bring perceived volume up to maybe 70 litres. Inputs here are very much appreciated,

.......
Kind regards and Happy New Year
//RoB



Hi RoB,

Hmmm, ports length over 50cm, ...?
may be 30Hz and over that would be something that can be in the consideration...

regards
ivica

[sebackman]

Dear all,

I coulduse some help with my Compact Monitors. As mentioned I will use the LE1400Hwoofers in rebuilt SP215-9 cabinets.

Thecabinets are about 65 litres net and with some dampening I believe I will gain3-5 litres additional perceived volume. Anyway, let’s assume 67 litres.

Beloware the T&S parameters I have for the LE1400H. When I feed them into thecalculator weird numbers on port and length comes out. -And the response curve does not lookencouraging at all…

Are theseparameters completely wrong? What are the T&S for LE14H-3 or 4?

LE1400H:

Fs: 28,5
Qts: 0,22
Qms: 7,39
Qes: 0,23
Vas: 171,3
Re: 4,7
Le: 4,1
Sd: 670
BL: 20,3
Mms: 112,9
Za: 8
Zmin:6,8/150
Zo:155,6
Cc: 15
F:127
Rms:2,74
Cms:0,28
D: 29,2
Ref voltage sensitivity: 93,5



Allinput much appreciated.


Kindregards
//RoB

[JeffW]

LE14H-3

http://www.audioheritage.org/vbulletin/showthread.php?11317-LE14H-3

LE14H-4

http://www.audioheritage.org/vbulletin/showthread.php?21501-Le14h-4

[sebackman]

Thank you for the LE14H-X T&S. I will feed them into the calculator and see what comes out. The parameters do not seem to be miles off mine so there should be hope.

-But the SPL graph I got did not look pretty. What size cabinets and porting is recommended for the LE14H-3-4 drivers?

Mine is about 65 liters so it should play well with the LE1400H.

Slowly going forward inspired by the fantastic result by dprice and srm51555. These will be kept in black Duratec to keep the "road box" feeling.

I finally gave up on mounting the port on the front, there just is not enough room there… I plan to mount it in the back and have done some research on potential draw backs. The main reason not to have it in the back seems to be that you cannot place the speaker flat against a wall. I can live with that. Since the wavelength at the port f0 is rather long, placing the port within ¼ wavelength distance from the woofer should be acceptable. This will be shorter.

I’m planning to use only one 3” or 4” port. The 14” woofer won’t move the same amount of air as the 15” and I will use it in my flat… J Do you think one 3” port would be enough?

-Struggling a bit with mounting the M2 WG as the turned out to be not entirely parallel and the rear surface is not in the same plane. I will have to find a way to fit a gasket to compensate for that.

It will be very compact and the sides of the WG will be the sides of the box on top and below there will be a cover over the woofer, hence the sides are a little recessed on the side of the woofers.

Still some way to go, but at least progressing in the right direction.

Kind regards
//RoB

6920469205

[baldrick]

Why do you want to use Le1400 instead of 1400PRO in this application? I would imagine that 1400PRo might be better suited since you probably will need a sub anyway because of the small size.

As far as I remenber Le1400 was supposed to be used in the "new version of 250TI" but never made it to production? I therefor thought LE1400 was similar to LE14 and would like a similiar sized box as 250TI/Array1400?

[pos]

Very nice little monitors! The "squircle" 12' frame and reduced horn make for a very compact front baffle.

Regarding port diameter, it depends on the extension you are looking for: if crossed over to a sub the ports will probably not see much velocity.
This can all be simulated using winISD pro.

[JeffW]

The port on the 1400 Array is 4" ID x 9.5" Long. I think the volume is listed

http://www.audioheritage.org/vbulletin/showthread.php?10643-1400-Array

[sebackman]

Hi,

I opted for the LE1400H due to the very small basket width as a result of the squircle design, it is only 325 mm across. -And I hope it may have better bass extension than the 1400PRO due to foam edge, lower Fs and heavier cone with Aquaplas.

I can’t fit a 15” into such small box and LE14H-3’s or 4’s are very difficult to find over here as you know. The LE14H-3 would probably have been the best.

Below is a T&S summary of some of the 14” drivers. Pretty interesting. I made an extra column for my LE1400H as I suspect that some of the T&S data I have may be wrong. For instance I don’t think the cone is much lighter than the other 14”s. And I think the Le is off.

On the new drivers JBL uses MLSSA to measure T&S and instead of stating “good old Le” they state L1 and L2. Is it correct to assume that L1 = Le?

After some Internet digging today I decided to go with two flared rear firing 3” port and make them as long as physically possible in the smallish cabinet and see how low that is. According to WINISD it should be around 30-35-ish Hz.

I not planning to use a sub in this set up, I will use “the Force” being a BSS DSP and some Crown power to compensate for lack of cabinet volume. Drivers will be a fresh pair of 2450SL’s.

The other set in the HT will be 1400PRO’s and SUB1500’s below just as you point out.
These are just for my small “overnight” apartment. 

[sebackman]

Here is a short update.

It seems like everyone else is progressing much faster than me… Anyway, a little update so far.

I settled for using 2x3” ports with flares in both ends. My cabinets are small and the baffle does not leave room for ports, so these will have to be back firing. The rear is very narrow so I adopted the idea from srm51555 to use “inner” flares in both ends. It turned out to be an excellent fit. The port tubes in the picture will be cut to fit in the box. About 28 cm should give about 30Hz-ish in 70 litres box.

While I was at it with stealing other members good ideas I took POS advise in the M2 thread and ordered some JBL logos from the Bay and they turned out to be good quality and fit just fine.

The baffle for the woofer is in place and next step will be some sanding and putty before painting and doing the mesh in front of the woofer.

Please note that the M2 horns are a little warped from manufacture in the sense that they are not entirely flat from side to side in the rear. This may cause some concern for those planning to use the waveguide as sides in the front of the cabinet, as the original M2. I will try to lower the centre of the baffle behind the WG a little and make up for the rest with a flexible neoprene gasket. I will return with more pictures as I progress.

I have turned the WG upside down to minimize the frontal area. We did a quick and dirty laser scan and from what we can see it is completely symmetric so that should not be a problem.

Now there is only the rest left…

Have a good weekend.


6930869309

[sebackman]

6931169312

[srm51555]

..... to use “inner” flares in both ends.

While I was at it with stealing other members good ideas I took POS advise in the M2 thread and ordered some JBL logos from the Bay and they turned out to be good quality and fit just fine.

Please note that the M2 horns are a little warped from manufacture in the sense that they are not entirely flat from side to side in the rear. This may cause some concern for those planning to use the waveguide as sides in the front of the cabinet, as the original M2.



Looks like some real good progress Rob. I also want to add when I removed the horns to verify if mine were also warped I was left an imprint on exactly where the high spots are when the horn is mounted since I applied the foam gasket to the cabinet. Now what to do with those is a different story.

I think POS is the originator of using the inside port on the outside.

Thanks,
Scott

[sebackman]

Dear all,

It seems like I can find most things I need, except time.

Anyway, cabinets are all set and I will start mounting drivers next week.

The fact that the waveguides are not plane in the back and not parallel in the sides have made life a bit difficult. Last week I decided to mill down the sides a few millimeters to get flush mounting on the sides. In my cabinets the WG is visible from both sides and the top.

This also means that I will have to respray them after grinding down the lower part of the sides.

Attached is a picture of the cabinets and test mounted LE1400H. I like the “road/tour” look. What do you think?

The cabinets are 70 litres and my plan is to use dual 3” rear firing reflex pipes with an F0 somewhere in the 32-34Hz region. I just have to fine tune once the horns are there and I have included some internal damping.

The recessed part of the cabinet beside the woofer is for a recessed arced grill that will cover the woofer, following the curvature of the WG and be flush attached on the sides of the cabinet.

Tomorrow I will take the 2450SL’s apart to make certain that they are clean and aligned. They are almost new so they should be fine.

Soon it is time to start building the 3-way M2’s for the HT, with 1400PRO’s, 2451Be’s and 045’s .

Kind regards
//RoB

6980769808

[Earl K]

Fabulous !

:)

[1audiohack]

Fabulous !

:)

Ditto!

Barry.

[pos]

For some reason it reminds me of the DD55000

[bubbleboy76]

Very nice little speakers!
Would be fun to compare them against 4429 some time.
Do you know how the directivity will match in the crossover region? I read somewhere, that the same size of woofer and horn usually is good best-practise (from a directivity point of view). So maybe a 15" is a general better match to the M2 horn than a 12".

[sebackman]

Hi,

Maybe the pictures give that impression POS, but these are tiny compared to the DD55000. These would look like your average table top computer speakers if you would place them side by side :-) .

bubbleboy76, I was not aware that the physical width of the WG would influence directivity that much. The M2 WG is 100 by 100 degrees I think, so I hope that should be ok. Several of the JBL K2 series speakers do have much wider horns than their woofers so that gives at least some hope. I will just have to measure and listen when I get that far.

Anyway, LE1400H is a 14" woofer and a sibling to LE14H-3/4 but with a 1401Nd coated cone so the physical width difference compared to a 15" is not all that big.

I certainly hope that these will at least match 4429 given, the larger woofer (albeit that 1200FE is really good woofer), the small format driver in the 4429 compared to the large format SL driver here and that the M2 WG is a newer design. These will also be active with a BSS DSP like the original M2's so maybe that can help a little.

It may also be easier to succeed with a DIY 2-way design compared to a 3-way as the 4429. -Unless you are JBL with "unlimited" design and measuring capabilities. :-)

-More info to follow.

Kind regards and thank you for input.
//RoB

[pos]

The point of view make them look quite impressive, with the horn staring at you from above, like the DD55000 do.
Why not put the tweeter on the side like the DD55000? ;)

[sebackman]

Like this? :-)

69837

[sebackman]

Hi,

As mentioned above the M2 waveguides does not have entirely parallel sides, the guide is 4 millimetres wider in the top. Attached is a picture of how much I needed to mill down to fit into my cabinets.

In the original M2 cabinet the guide is flanked by the sides of the cabinets and they have rounded/angled edges. In my cabinet the guide forms part of the sides. Hence I decided to round of the edges with the router. I will have to respray them anyway . In the attached Picture it is not bolted to the cabinet, hence the gap.

Now it’s time for painting the guides and make grills in front of the woofers.

One step at a time

Kind regards
//RoB


6983869839

[pos]

Like this? :-)
No no, one the side like this :spin:
(just kidding, your implementation looks neat and sound!)

http://www.audioheritage.org/vbulletin/attachment.php?attachmentid=26782&d=1185406012

[srm51555]

Looks like some great progress on both the two way and the three way. Keep up the good work.

[baldrick]

Speakers are starting to look great!! They will be pretty cool when painted :applaud:

I've always been curious about those LE1400, are they any good? Didn't know until you wrote it was a 1401ND/LE14-3 mix :)

Let me know if you make adapters :bouncy:

[sebackman]

While I’m “post bombing” LHF tonight I might as well update progress on the Compact Monitor. I guess that I have to get used to that all my projects keeps going for years instead of months due to lack of time….

The waveguides are all set with parallel sides and all. I tried to paint them myself but with less than desired result :crying:. Now they are off to a “real” paint shop for some proper treatment and with additional charges to remove the remains of my futile attempts.

They will be kept black, it’s such a happy color :) . The WG for the upcoming 3-ways will be Anthracite Gray as per the older JBL horns.

Baldrick, I have no clue as to the performance of the LE1400’s. I plan to mount them next weekend and measure/adjust the porting to get somewhere in the region of 30-35Hz. They will probably be used in Oslo so maybe you can swing by if you find the time. I can post a measuring curve when I get around to do it.

70102

Cabinets are pretty much done and grills ready to mount. As you can see the curvature of the grill follows that of the WG when attached. I don’t think the “mesh” will affect the sound from the woofer and the WG will be open.

70101

I also got some new D8R475Nd diaphragms and mounted in my almost new 2450SL cores. The pair measured very close so I hope it will be good.

Having followed the “charge coupling threads” and being a firm believer I did some math and the size of the capacitors needed to make up a protection but without interfering with the XO was very large. Hence I decided to go without protection cap but with an -8db attenuator. I got some 50w alu housed resistors with low tolerance, in fact low everything  , and place my trust into the protection circuits of my beloved Crown CTS amps….

I first made an attenuator for the expected 8ohm diaphragms but when they arrived they were indeed 16ohm so I had to redo them again…

These won't have the 045Ti's , it was just for the Picture. They will go into the next Project.

70103

Getting there.

Kind regards
//RoB

[sebackman]

The Compact Monitor turned out to be too big for bookshelf and too short for floor standing so I made some stands that should bring them pretty much in M2 original height.

I will use them in an apartment so the stands would have to prevent bass vibrations to be shared with everyone else in the building.

I got some Oak and decided to make a stand that matched the speaker cabinet footprint at the top but was a little wider at the bottom.

70104

It has integrated anti vibration inserts on top and in the bottom of each the pillars and also very soft feet at the bottom. The picture shows the feet and mounts.

70105

I found these feet when looking for feet’s to my SUB1500 HT subs and stumbled on a company in France that does anti vibration mounts for helicopter dashboards. They have a very controlled function and are behave almost fluid but without losing their form.

I use them under my subs that are quite heavy 75kg each and they are completely still even at rather high excursions. But if you push the cabinet at the top it moves to the side. I hope it will work here also.

-A bit crude but I hope you like them.

70106

Kind regards
//RoB

[srm51555]

While I’m “post bombing” LHF tonight I might as well update progress on the Compact Monitor. I guess that I have to get used to that all my projects keeps going for years instead of months due to lack of time….



Great work like this always takes a little more time. Looking good.

[JuniorJBL]

Hey Rob, Those are looking really cool! Looking forward to your impressions. :)

[pos]

Always more fun with pictures...
6536965370
Hi Robert,

Nice work on the tap. I did not have the tool to reduce the diameter so I had to find a thin one, which proved difficult.
I currently have one horn tapped with M5 threads, but I will redo them with M6 now...
And the second one is still untouched.

Did you enlarge the hole from the original ~4.7mm to 5mm before tapping the M6 thread?

[johanwholst]

Intresting those damping "feet"
I have a couple of subs around 80kg each that needs something like those.
Where did you find them?

[pos]

Hi Johan

Not the exact same model, but you could use these: DVA.6-30-36 (http://www.audiophonics.fr/fr/pointes-absorbeurs-contrepointes-pieds/pied-conique-caoutchouc-amortissant-30x36mm-m8-unite-p-8954.html)
Conic feet tend to be better than straight ones (settling vs weight is not linear).
See attached pdf for calculations.

At 20kg per foot (4 feet for your 80kg sub) you would get a 8mm settling, which translates to a 6Hz resonance frequency.
The calculated reduction in vibration transmission would be as follow:

-6dB at 10Hz
-20dB at 20Hz
-40dB at 60Hz

I have been using these, as well as the smaller 20-24 version, but I will now try foam.

[johanwholst]

Thanks a lot again Pos!

Sorry for the off topic

[sebackman]

Dear all,

I think POS ideas should work very well.

I also received some questions on the anti-vibration feet.

I think the company I used to calculate has been sold and the site is downsince many years. However, I think this may be where they winded up.

http://www.hutchinsonai.com/company/index.cfm

Here is another company that should be able to help.

http://www.gmt-rubber.com/

I don't know who makes the ones I use, as I buy them locally and have actuallynever asked. They just happen to have dampeners with similar function as theones I calculated.

The ones I use are 50mm diameter, 36mm high and made with 40 shore rubber (soft). Theyhave a built in metallic plate covering one end and with a M10 bolt hole formounting. I typically bolt them to the speaker using a sheet of standard anti vibrationrubber mat in-between the foot and the speaker. The mat is thinner (6mm) and absorbs adifferent frequency spectrum.

I have read somewhere that the mounts recommended for aircraft, are all-attitude,with resonant frequencies of 15-30Hz, and 1:1 stiffness in alldirections. The mounts for helicopters are 7-10Hz, must be mountedhorizontal, and have stiffness ratios of around 4:1. They are much looserside to side than up and down.

So are my speakers. You can sit on the subs without problem but can also swaythem from side to side with only one finger. A bit odd but it works very goodindeed.


POS, no extra drilling. Just very slow turning the tapand empty the hole many times as you go to avoid loose plastics jamming the finished threads. I typically did 5-10 mm and the outwith the tap and clean the hole with compressed air. Takes a bit of time butthe threads are perfect and very sturdy. I did the threads all to the bottom in the holes.
You can borrow my extra long M6 tap if you want. Shall Isend it to you in an envelope?

Kind regards

//Robert

[pos]

POS, no extra drilling. Just very slow turning the tapand empty the hole many times as you go to avoid loose plastics jamming the finished threads. I typically did 5-10 mm and the outwith the tap and clean the hole with compressed air. Takes a bit of time butthe threads are perfect and very sturdy. I did the threads all to the bottom in the holes.
You can borrow my extra long M6 tap if you want. Shall Isend it to you in an envelope?

I did already tap one of the two horns my M5 taps, so it would probably be better to redrill it to 5mm to remove any trace of the old thread.
Or should I just retap it?

Thanks for the offer on the tap.
I had a lot of difficulties finding a long enough tap, or more precisely thin enough, because for some strange reason 99% of the taps out there have a rod that is larger than the internal part of the thread (and sometime even larger than the external one!), so you cannot go very deep.
The rod must not exceed 4.2mm for a M5 tap, and 5mm for a M6 one.
I finally found good/thin taps in a very specialized shop, so now I am all set :)

[pos]

So are my speakers. You can sit on the subs without problem but can also swaythem from side to side with only one finger. A bit odd but it works very goodindeed.
I tend to do the same thing, but this remark from GT (http://www.audioheritage.org/vbulletin/showthread.php?37662-JBL-4367-first-listen&p=386898&viewfull=1#post386898) got me worried lately :

The trick is to get something that doesn't rock or tip. You will eat the bass kick immediately if any enclosure movement is allowed. The woofer kicks really hard and if any energy is consumed moving (rocking) the enclosure due to it not being properly coupled to the floor, you will lose bass kick and impact. The proper use and need for spikes (or equivalent) is not BS. It is based in sound theory and is easily demonstrable.

[sebackman]

Hi,

Well, who am I to question the master. That is probably the norm and correct in an overwhelming majority of the cases.

But what I can say is that my subs are sealed 70 lite cabs (one SUB1500 driver in each cabinet fed by 1100W RMS each) with very thick walls and sturdy bracing and even if I play very loud they are completely still. No movement what so ever. But you can still move them with your finger. You can balance a quarter on the edge on them when playing "full throttle".

I have no idea why it works, but it does.

POS, I had to make a tap to get it long and thin as you mention. Good that you found a finished one, I never did.

Kind regards
//RoB

[sebackman]

I just got the WG's back from paint. A bit of a bumby ride, they had to redo them several times.... Now they are textured black (black is such a happy color) .

Tomorrow the will mate with a fresh pair of 2450SL/476Nd and go into the Compact Monitor.

Amps are also ready to go to work.

70407
70409
70408

Have a nice weekend

//RoB

[pos]

It looks really nice!
I prefer this texture to the original, and it is probably also more solid...

[bubbleboy76]

Nice!

I will not do any anatomical jokes on the M2-horn. I did it on the Buttcheek-horns, and on the Array-horns, but with the M2 it is not funny any more!!

[sebackman]

Dear all,

Slowly getting there. Mounted one WG today and it was quite difficult to adapt the gaskets to get a smooth surface. Tomorrow I will try to adjust the port lenght.

Kind regards

//RoB

704117041270413

[Odd]

Snyggt!

[sebackman]

 
Dear all,

The HW part of the project “Compact Monitor” is done. Did not really turn out exactely as planned, but close enough. Attached are some pictures on the final result.

There were some questions earlier on the LE1400H and I have not used them before. Attached is a measurement from them in the 75 litre “Compact Monitor” cabinets. They are ported at 30Hz (measured). The curve is a combination of the dual ports, near field and far filed. MLS measurement with calibrated mic and no smoothing! Look pretty darn good to me.

The waveguide is attached with M6 machine bolts from the inside. That was tricky. Sealing was crucial as the WG are not level in the back. There is a picture of the sealing and the result.

We also had a discussion on spikes or soft feet and just for the fun of it the last picture shows a coin balancing on top while playing some country music at roughly 200W peak. They are completely still.

Kind regards
//RoB

706607066170662

[sebackman]

70663
70664
70665

[sebackman]

70666

[sebackman]

Ok. The small VTX clones are done. The M2/LE1400H Compact Monitors are done.

Now I'm setting up amps and XO for them. Crowns and BSS as usual.

Next task will be the new HT speakers with modified M2 WG's. I have already milled out for the 045Ti-1 drivers and K2 9900 horns. The woofers will be1400PROS's and in order to reduce baffle width I decided to make them as narrow as I can. They will be wall mount and a small baffle will be more esthetically pleasing.

I was a bit worried to put the saw blade into them. To be sure they would not move I built a jig and built some support for my adjustable circle saw. Only the first one is done but it worked out just fine and I’m taking of 36mm on each side.

The material is a bitch, it is some kind of glass and just kills the blade. I’ve got a pretty decent machine but can just go 1-2 mm per pass to not get to hot so the plastic melts. I did a first try run to confirm and then took the plunge.

More info will follow.

Kind regards
//RoB

710887108971090

[pos]

Wow, very impressive as usual!
Looking forward to seeing the result! :bouncy:

[srm51555]

Wow, very impressive as usual!
Looking forward to seeing the result! :bouncy:

Me too!

[NWCgrad]

Very nice work, amazing to see someone taking a power saw to the M2 waveguide...but I can see why as its oddly shaped on the edges.

Can't wait to read the results and your thoughts!!!

[sebackman]

Hi,

Here is where the chainsaw massacre ended up. Albeit I used a circle saw :eek:.


First picture shows the difference in width between standard and my "Mk II's" :bouncy:.


The second shows the footprint of the baffle. -Looks pretty compact to me. No space for a port on the front so thay will have to go on the rear side. Or potentially keep them sealed and let the DSP do the rest. I've got plenty of power behind so for domestic use that may be an option. Anyone here used 1400PRO sealed? I’m using subs so I don’t need much below 50-60Hz.


The third picture is the L + C + R wave guides ready for paint. The intention is that they will be gray as the horn in the 4365/4367 or potentially a little lighter. I will mount the 045-ti-1 horns in the WG’s prior to paint so that is next. I also need to take out some material on the rear of the WG for the 045 driver to fit. That should be a straight forward router job.

Not really entirely happy that this will be a 4-way system but I guess that is the sacrifice to be made on the domestic alter to keep the peace. Floor standing speakers are banned in the living room. –Just have to push the DSP harder :blink:.


Kind regards
//RoB

711477114671148

[srm51555]

They look perfectly cut, nice work.

[sebackman]

Dear all,

Attached are some in room measurements (no smoothing) from the Compact Monitors. Crown CTS amps and BSS DSP as always.

M2 waveguide with 2451SL/475Nd 20ms XO 544Hz LR24 100cm out with crude light eq (12db HS). Not too shabby

72085

Woofer (LE1400H) 143 cm out, 150ms, no eq. The room is pretty forgiving it appears.

72086

XO will be around 800Hz but I need to figure out the slopes as these do not have the M2 capacitor network, only a 8,4db attenuator. The originals have 36LR and 6LR which would be 36LR and 12LR in my setup without the cap's. That feels a wee bit aggressive at 800Hz for the driver...

More info to follow.

Kind regards
//RoB

[sebackman]

2450SL / 475Nd / M2, no smoothing, 10ms MLS window, 113 cm out, XO 544Hz LR24, calibrated mic

72273

[Burman]

You are one mad scientist ;)

[Dagfinn]

Wow, makes me want to do this...
88144
Can I ask, what is the exact width of the WG after cutting?

[sebackman]

That should be a good combination with a D2 driver or a 2450SL/2451SL driver.

Huge upgrade compared to cone mid and a dome. That would bring you very close to M2 / K2 territory.

DSP is a must.

Go for it!!

//Rob

[macaroonie]

@Dagfinn

I was going to post a link to this thread to you but hey , you beat me to it.

Rob and Pos and Baldrick and Odd have trod the path for you. The only issue I would see here is if you went with the M2 waveguide you need to remember that the front edge is curved and it is bigger than the footprint of the standard grille.
A clever fellow like yourself should be able to develop something that would ' fit '
Glad to see you doing your homework. :)

Best regards Mac