Greetings all,
it appears the the 4367 wave-guide is no longer available. Is thee any other one that would allow for a 600-700 Hz cross-over with 2450SL driver? I have the Aquaplassed diaphragm is it matters. I have build an enclosure for TAD 1601A and that is where it is crossed-over in the Exclusive models.
Kindest regards,
M
TAD TH-4003 clone will correspond to this. There is a good one manufactered in Hungary available through eBay.Originally Posted by mefisto
Look at the Joseph Crowe radial horns from Canada
He has measured these horns in his blogs. They are impressive!
https://josephcrowe.com/collections/see-all
https://josephcrowe.com/products/es-...d-horn-no-1978
He matches the horn throat to your driver and the crossover.
I think you will find this horn a better option than the 4003 which as specifically designed for the 4003. The throat sections of that horn maker were not acceptable. He may have improved since. The M2 wave guide is another consideration.
Hi mefisto,
I don't know what could work beyond the JBL M2, 4367 and the VTX wave guides. Sorry can't help there.
Do ask for specific measures with the 2450SL/2451SL on whatever horn you decide to use. The distance between the phasing plug and the mouth does matter. Horns that may look very similar may not always perform the same way.
I have tried many horns/wave guides but in reality few of the expensive and nice looking horns can match the rather simple and optically not convincing VTX horn. Even if the newer JBL horns are really made for the D2 they seem to love the 4" drivers.
I would ge a single of the el cheapo plastic VTX waveguides and compare to whatever else you find. Its only $50 in the US and bolts straight up to the 2450SL. Coat it on the outside with bitumen helps a bit with making it more "dead".
I have no idea on the horn recommended above and maybe they are just the ticket. But do buy a "wave guide" and as oppose to the older diffraction horns. For many of them there is a dramatic improvement for HiFi use. There are probably excellent diffraction horns for the 245X drivers, but he hassle to find them made me give up and use the proven combos.
Ian knows his stuff so maybe start there and I agree that the older TAD 4003 horn may or may not suit the JBL drivers. And they seem to have a diffraction mouth which would be a no-go for me. But they sure look nice. Each to their own.
If you need any driver horn data/measurements on the JBL wave guides just give me a shout
Kind regards
//Rob
The solution to the problem changes the problem.
-And always remember that all of your equipment was made by the lowest bidder
It's easier to demonstrate off axis using an RTA, a protractor, and piece of string. I was easily able to easily do 5 degree increments with mine:
https://youtu.be/pbbS0QYK2_o
Hi dn92,
thank you for your reply.
I know about Athos Audio, I even corresponded with a gentleman who was contemplating ordering from them, but the quoted price was beyond my means.
Hi Ian,
thank you for your reply.
As with the Athos Audio, I am aware of Mr. Crowe, but again the price is way beyond my means.
Hi Rob (sebackman),
thank you for your reply.
If I am misinterpreting your measurements from post 13 correctly, the VTX would not support 600 Hz cross-over, but the M2 might.
Regarding the measurements, I have a dim recollection that we corresponded about it, but I cannot find any such e-mail. So if you have a measurement of the 2450SL (Ti Aquaplassed diaphragm) on the M2 wave-guide and you think that it could be reasonably equalized to about 600-700 Hz, could you please e-mailed it to me?
Kindest regards,
M
Hi Rob,
I had some time to look closely at your measurements posted earlier in the thread.
A few thoughts for users at home contemplating these VTX wave-guides
Rob’s work here is an excellent foundation for a nice diy project.
The crossover point and crossover characteristics
Within reason l don’t see an issue with crossing the VTX wave guide over at 750-850 hertz with the named driver variants.
Attempting to go down to 700 hertz without a steep high pass filter is best avoided. In theory the match of the hortizonal and vertical low end pattern control is likely more audible. Wave guides unless large like the 4367 typically unload and loose pattern control below 750-850 hertz. Thats why they are wide. What’s needed is ideally a match in the pattern control with the woofer and the wave-guide and a smooth pattern control up the sensitive 2,000 hertz region. This is to avoid pinching the polar response from 100+ down to 80 or less too quickly. Those discontinuities are bad if you read the 4430-4435 white paper.
The woofer properties
A light cone at the apex of the dust cap (no mass ring) is important to the continuity of the woofer and the wave-guide. A crossover point going of hundred hertz is not going to change that with removal of the mass ring in the case of the 2235H. The 2234 in the 4435 has no problem keeping pace with the 2344 with a 12 db crossover. Removal of the mass ring is not that difficult (Google) in preference to shelling out on a pair of 2216nd which are more challenging to set up. It’s then a fairly inexpensive diy loudspeaker with cheap drivers and horns.
Aim for least a 24 db slope on the woofer. Like wise for the wave guide.
The details
The how part is the key for those at home.
The effect of a fixed L pad in preference to a protection cap? What to do?
Greg Timber’s advocated a 6 db pad when l last met him. With an active crossover Greg said 6 db was okay. I would even look at a 10 db pad too keep noise down if going active.
The effect of the changing phase response of the wave-guide needs to be accounted for in either FIR dsp or a passive crossover to ensure phase tracking.
The horn EQ
The challenge for those at home is defining the EQ for these wave guides either in DSP or a passive crossover. Then having a simple way of bending the high frequency (brilliance) to work with their preferences. The same with the 2,000 region (presence) which l traditionally found sensitive in setting up the 2344 100x100 wave guide You need to listen or measure because it’s quite sensitive in that region. Compare to a reference loudspeaker as Robert H suggested.
REW and your ears are your friend
A Simple Passive DIY M2 network.
A passive network is certainly a simple approach if it works correctly. A while ago l did a simple passive but very effective steep acoustic slope 2 way passive network that could be adapted to any of these M2 or VTX wave guides and drivers with adjustments.
The attached screen dumps are the on axis response, the simplified schematic and a graphical representation of my simple passive network for the M2 driver and horn components. The waveguide variable EQ shifter was recommended by Greg Timbers who said the M2 wave guide when flat can be too hot in some acoustic settings.
The response is not a magazine curve and the final response will need to be measured in free field conditions.
The aim was to develop a passive network for diy audio amateurs at low cost and complexity that effectively tracks the M2 active system response except for the low.
The network can be easily revised for other woofer and horn driver combinations including the VTX wave guides. A seperate active low frequency boost module will be developed for the diy audio amateur to emulate the M2 low frequency specifications.
To clear the aim here is not to clone an exact passive version of the M2 but to offer a working diy passive M2 monitor without all the dsp hubba and expense.
Once l have tested the network with some different drivers l will post an update and talk about the next steps.
I understand.
I have done a 700Hz crossover point in my DIY Passive "M2" I was pushing it a bit but I got the best summation @ 700 and was only about 50Hz lower than the 4700. My measurement is with a 476Mg but any of the 2450 series should be very similar as far as low end response on the waveguide. Look at the upper curve no EQ. You can see the step below 700 so 600??
Also attached is a measurement on the PTH1010 a 100x100 waveguide. Smaller but still loads well and is inexpensive compared to the M2. There is now a -1 version I don't have measurements on.
Rob
"I could be arguing in my spare time"
Hi Robh3606,
thank you for your reply.
As I am not as knowledgeable as the forum members (hence my search for a wave-guide/driver combination that is documented), can you explain the "I was pushing it a bit" because looking at your raw measurements, the 105 dB level is crossed as approximately 650 Hz, so why is the cross-over at 700 Hz "pushing it"?
Regarding the "best summation @ 700", are you talking about the pattern matching as mentioned by Ian?
I will read your thread.
Is there any other source for the M2 but Speaker Exchange?
Kindest regards,
M
mefisto, if you look at the data files (pls see below) you can see how low you can go with each driver on each horn. All the raw data is there. No caps to adjust for, just plain FR in different forms. Data can be imported to your favorite simulator SW.
The small VTX horn it is not the same as the older PT-XXXX. It is JBL part no #5006815. They look similar but they are not, the 6815 is a better waveguide. Albeit that the PT-series does exist in a 100x100 and the 6815 is 90x40, I think. Narrow dispersion vertically may not be a drawback as it reduces floor and ceiling bounces.
With DSP you can get away with XO very low with steep filters. In my findings I agree with Ian and if you have a decent woofer that can go up a bit it is easier to get the drivers to like each other.
IMHO 700Hz is borderline for M2 and would say closer to 800-850Hz is easier. But is surely can be done as Robh3606 clearly shows. I do 850HZ on my M2/476's from 1400PRO.
4367 can do 700Hz as it is wider but I understand that they are NLA, so that is may not be an option unless you find someone sitting on a pair. I will do 700LR24 DSP to 2216Nd-1 in my 4367 clones.
VTX is probably 875-1000Hz even if also they can be pushed down with DSP. I typically do 950-1000Hz in my builds.
Regarding passive XO's I'm the wrong guy to give any advise. Fortunately many others here can. :-)
For whoever may having a difficulty getting to sleep attached is a link to my Dropbox with all the shout-out data. I will leave the data there for a few weeks and then take it down, so download what you need.
Start with looking at the schedule in the Excel file to see the way the files are named. There you also can see which driver is which as I measured 9 drivers of different models.
Full set of data files for 50cm & 100cm distance for all drivers on all horns. 90, 60 and 30 degrees covered. In the PDF there are screen shoots of all measures. No smoothing except for a few added graphs and then noted in the text.
Impedance data for all combos done on a DATS3. SW free from Dayton even without the HW to view files.
"Naked" means no wave guide, nothing else...
https://www.dropbox.com/sh/57lpmq9og...sJaTowd_a?dl=0
Have fun.
The solution to the problem changes the problem.
-And always remember that all of your equipment was made by the lowest bidder
Hi Rob (sebackman),
thank you for your response and the link to the measurement data.
I will certainly look at the data, the problem is, I am not sure that I can interpret them correctly. To wit, see my response to Robh3606 who wrote that the 700 Hz was "pushing it", but my reading of the raw data was that 700 Hz could be comfortable.
Regarding your statement "Narrow dispersion vertically may not be a drawback as it reduces floor and ceiling bounces", my understanding is that the size of the wave-guide mouth determines the frequency range within which the pattern is controlled, cf. Keele. Thus, unless one crosses over below this frequency, no reduction of the bounces is achieved.
Regarding the "small VTX horn", I am confused; the JBL part no 5006815 shows as "Set up for 4 or 2 bolt pattern. 1”-1.3” throat"; the 2450 SL is 1.5" throat.
Kindest regards,
M
Hi mefisto,
Easy part first, the 5006815 is a 1,5" throat waveguide, so that is plain wrong. I have a bunch of them here. The bolt pattern on the flange is the small JBL 4" driver bolt pattern as 2450SL (4-bolt) and I think 2453. They will also take the D2 (aka 2430k, 2-bolt)) direct fit.
If you want to use 2451 or 2452 you need to either make an adapter or just use some spacers and large washers to bolt it down. I use an adapter. Look in the "compact monitor" thread that I did a few year ago, I think the drawing on the adapter plate is there.
On the lowest frequency that is determined by the acoustic load on the driver by the horn and is a function of the combination of the driver and the horn design. At a certain frequency the horn does not represent an acoustic "resistance" for the driver which means that the "controlled" function reduces quickly. It may well be that it can be used below this but many parameters will change and unless you have measuring capabilities and lots of time I would not recommend going below this point.
If you look at the impedance curves (DATS3) in my provided data you can see what happens when the acoustic "connection" between the drive and the horn gets lost.
I agree that the low frequency capabilities is to some extent directed by the throat but also the flare and the width of the horn (and many others). There are certainly others here that can lay out the technical specifics much better than I can.
Regarding dispersion the most important parameter is the physical shape of the flare/horn. A square horn will have a somewhat even dispersion horizontally and vertically while a rectangular horn will have different coverage pattern. A reduced vertical dispersion will reduce sound power going in that direction compared with straight and horizontal energy, which will inherently lower the amount of floor and ceiling bouncing energy. Somehow I don't think that was the question?
kind regards
//Rob
The solution to the problem changes the problem.
-And always remember that all of your equipment was made by the lowest bidder
Hi Rob (sebackman),
thank you for your response and specifically for confirmation that the 5006815 is a 1,5" throat wave-guide. And no, I will not use 2451 or 2452 as I do have the 2450SL.
I do not want to derail the thread too much, but my understanding is that the "reduced vertical dispersion will reduce sound power going in that direction" works only below a frequency controlled by the size of the mouth. Thus the cross-over must be below this frequency for this to work.
I had downloaded all the files, that is an enormous amount of work that you had done.
Kindest regards,
M
We appreciate you chiming in on your project. Detailed discussion of your project is best moved to a new thread.
Some measurements of the 2216nd and the M2 horn on and off axis with REW and some JBL tech sheet data of the 90 x 50 waveguide.
The FR reponse curves for illustration purposes only. The divisions are 5 db and smoothed 1/24 octave as l recall in a room.
The 90x50 waveguide power response
The response graph is a 2216nd and a M2 horn and an unknown driver?
Remember your crossover point will be -6 db so in practice this will look like the attached image (DD67000 horn and driver with crossover and EQ).
Using REW is actually quite straightforward with a Mac PowerBook as you only need the calibrated Minidsp mic with its calibration file. For diy this is more than adequate loudspeaker measurements. REW capabilities had been continuously improved and it now features a host of measurement types for loudspeaker measurements, impedance, voltage drivers with a Focusrite usb interface, RT60, curve averaging, curve smoothing and psycho acoustic curve filters for assessment of room acoustics and loudspeaker voicing.
How you approach this is entirely up to you.
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