Compact monitor

[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 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 Attachment 65415Attachment 65416

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
ivcia

Here 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/vbullet...l=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...

[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/vbullet...l=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

[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.




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