Which horns for JBL 2451 Be drivers?

[Herman Chigrin]

Hello,

I now have some 2451h drivers with original diaphragms. My plan is to load them with Be diaphrams and try to make a nice 2-way monitor. 3-way is an option but I will barely manage making a 2-way. So here goes:


1. How do I chose between the 8ohm and 16ohm Be diaphragms (http://reconingspeakers.com)?


2. Which 1.5 horns would you recommend for 2451 with Be diaphragms?


Some options that I found:
Multi-cell horns like this: http://stereo-lab.de/produkt/klug-horn/
M2 waveguide
2384 waveguide
JBL 4367 horns -- are these even available?
Wooden radial a la TAD style (I think the TH4003 is 1.5" throat)


Just tryin to get the best perfomance (music only no movies) out of these 2451. Thanks in advance!!


Herman

[ivica]

Hello,

I now have some 2451h drivers with original diaphragms. My plan is to load them with Be diaphrams and try to make a nice 2-way monitor. 3-way is an option but I will barely manage making a 2-way. So here goes:


1. How do I chose between the 8ohm and 16ohm Be diaphragms (http://reconingspeakers.com)?


2. Which 1.5 horns would you recommend for 2451 with Be diaphragms?


Some options that I found:
Multi-cell horns like this: http://stereo-lab.de/produkt/klug-horn/
M2 waveguide
2384 waveguide
JBL 4367 horns -- are these even available?
Wooden radial a la TAD style (I think the TH4003 is 1.5" throat)


Just tryin to get the best perfomance (music only no movies) out of these 2451. Thanks in advance!!


Herman


Hi Hernan,

I think If You want 2-way system, I would suggest to use D16R2441 JBL AL diaphragm or may be even D16R2445. With Be(Trx) UHF driver would be "a must".
Concerning the 2-way system and FH dispersion I think that M2 horn would be the best, or may be You can make a 1.5-inc Yuichi large horn WITH FINS.
LF driver would be a 'problem' may be ?

regards
ivica

[pos]

Hello Herman,

This is a great driver choice!


1. How do I chose between the 8ohm and 16ohm Be diaphragms (http://reconingspeakers.com)?
Depends on your amp.
Noise (hiss) is the biggest issue with high sensitivity devices in an active system.
16 ohms will give you a 3dB advantage there, and also reduce amplifier distortion, but at the cost of 3dB reduction in max SPL capabilities (if the amp is the limiting factor).
That said some low power amplifiers with very low residual noise might be more at ease with a 8 ohms load, like the LPUHP amps, but this is a rare case.

IMHO 16 ohms nominal is generally the better choice there.
JBL even went to 32 ohms nominal with the D2 (dual 16 ohms coils in series), and only wire them as 8 ohms (coils in parallel) in passive PA speakers.


2. Which 1.5 horns would you recommend for 2451 with Be diaphragms?

I suppose you will not be using a tweeter, so constant directivity up high might be an interesting asset, leaving out tractrix horns
On the other end of the spctrum the size and low frequency cutoff that you should target will depend on the woofer and crossover frequency choices.
The come the issue of the throat size and bolt pattern.



Multi-cell horns like this: http://stereo-lab.de/produkt/klug-horn/No experience with these, but multicell horns generally need a tweeter up high where each cell starts to beam.
Stereolab does adapt to any existing throat size and bolt pattern in there resin tractrix horns, but I don't know is that is the case with those wooden horns.


M2 waveguidevery good choice, but you will need the adapter sebackman designed in order to plug the 2451 on it.


2384 waveguideno experience with that one, but it is said to be very good and it looks like it has both new (2435/2450SL/D2) and old (2451) bolt patterns.
Is it sturdy enough to handle a 2451 without specific bracing?


JBL 4367 horns -- are these even available?I think these can be obtained, but you might again have to use a specific adapter as these are designed for the D2 form factor.


Wooden radial a la TAD style (I think the TH4003 is 1.5" throat)
Memebr Woody designed a 1.5" version (3/4 scaled down) of the Arai 290 horns, and they seem to measure and sound pretty good!
TH4003 is not a good choice here: almost impossible to find and clones might not be accurate, narrow directivity up high, 39mm throat vs 38mm for the JBL...

Another candidate you should consider is the H9800.
I think Guido still does clones (in Germany), and can provide a 1.5" version with an adapter plate suitable for a 2451 driver.
I also know someone in France who might sell some in the near future.

If you plan on using a small woofer (12" max) or maybe include a midwoofer (10" would be ideal) then you can also consider the smaller JBL PT waveguides...

[pos]

With Be(Trx) UHF driver would be "a must".

Hi ivica,
Not in an active system IMHO, as the HF rolloff is relatively gentle and very well behaved.
That said in a passive system Ti SL diaphragms are easier to handle.

[baldrick]

Haven’t tried myself but several have compared 2384 to M2 and prefered 2384, I guess 2384 can also be used at lower freq.

I use 2451be in M2 and sounds good enough for me but lacks a litlte at the top Even with EQ.

[johanwholst]

For a two way system you cannot beat 2384 or M2
2384 is sturdy enough for 2451. Build quality is horrible, but they are readily available, cheap and sound great crossed at 700-800. Can easily be sanded down and painted and should definately be damped with bitumen or equivalent stuff. maintains directivity control beyond 10k with Be but I ended up with a tweeter

[Mitchco]

+1 to what @johanwholst said.

I use a JBL 2453h-SL CD on the 2384 waveguide, biamped JBL 4722 2-way. User notnyt on the AVSForum has many CD measures on this waveguide between pages 121 and 146 starting at: http://www.avsforum.com/forum/89-speakers/1925586-just-purchased-pair-jbl-4722n-speakers-121.html including a Be. I really like the sound of the 2453h-SL, but might consider Be...

I use a steep digital XO at 630Hz as recommended by JBL for this system and sounds excellent. I tried at higher frequency, like 750Hz and 800Hz with the steep XO and it shifted the image up more towards the waveguide. At 630 Hz it the two sections blend seamlessly.

Finally, if you use the 2384, you may have to shape the top a bit (10 to 20 kHz) due to increasing directivity because of its screen spreading compensation - i.e. designed for being behind a screen. See Zilch's measurements to get an idea: http://www.audioheritage.org/vbulletin/showthread.php?23546-Screen-Array&p=236160&viewfull=1#post236160

Personally, I have been very happy with the waveguide - very smooth response and directivity. It is a 90 x 50 pattern, whereas the M2 waveguide has a wider pattern both vertical and horizontal.

Kind regards, Mitch

[Herman Chigrin]

Guys, thanks for the excellent responces! I'm really amazed by the thoughtfulness and amount of good information to digest.


My first surprise, Ivica, is that the Be Trx 4" diaphram will need an UHF driver. This is the opposite of what I imagined, from my understanding that Be is the strongest material and I assumed it will play more highs than other materials and increase the breakup freq.
The stock diaphrams in my 2451 are ribbed titanium. They don't sound very pleasant. But from what I gather the 2451 Be is a good combo.


When you say UHF would be a must, is it because the Be lacks quantity or quality of highs? I'm NOT seeking to get flat to 20khz extension.


As far as LF driver, I do not know yet but my thoughts are light, hard, vintage sound drivers with low xmax that focus on mids and midbass. Maybe pair of 12" or pair of 15", like Tesla or Supravox.


The goal is to cross around 700hz to a fast, dynamic and tonally rich woofer(s). A sub may be an option later down the road but the key for me is a CD on a horn that does not have nastiness. That and a good midrange midbass woofer. No subass needed for now. Music only.

[ivica]

Guys, thanks for the excellent responces! I'm really amazed by the thoughtfulness and amount of good information to digest.


My first surprise, Ivica, is that the Be Trx 4" diaphram will need an UHF driver. This is the opposite of what I imagined, from my understanding that Be is the strongest material and I assumed it will play more highs than other materials and increase the breakup freq.
The stock diaphrams in my 2451 are ribbed titanium. They don't sound very pleasant. But from what I gather the 2451 Be is a good combo.


When you say UHF would be a must, is it because the Be lacks quantity or quality of highs? I'm NOT seeking to get flat to 20khz extension.


As far as LF driver, I do not know yet but my thoughts are light, hard, vintage sound drivers with low xmax that focus on mids and midbass. Maybe pair of 12" or pair of 15", like Tesla or Supravox.


The goal is to cross around 700hz to a fast, dynamic and tonally rich woofer(s). A sub may be an option later down the road but the key for me is a CD on a horn that does not have nastiness. That and a good midrange midbass woofer. No subass needed for now. Music only.


Hi Herman,

As You can see from the other member experience Be diaphragms would produce clear sound but over 10~12kHz UHV driver is needed, even EQ applied.
I believe that is because of the mambrane suspension as it is not made of Be, but a kind of plastic , If You can get JBL Be original diaphragm (for 476 driver) then may be it would be a different story, but AL (JBL d16r2441 may be would be a solution for the home listening ) or even d16r2445. each of them have a kind of unpleasant response over 12kHz, but not so large as d16r2446. some experiments can be made with d16r2451SL diaphragm, but I believe that the result would be the same as Be(Trx) applied.)
As You can see, some members are satisfied with 2384 horn too. May be 2381 or PT-H95HF, or PT-F95HF or STX825 are candidates too. Latter two are vary similar I think, but have to be used , I believe over 1.5kHz.

https://www.jblpro.com/ProductAttachments/tn_v1n31.pdf

some more results
http://www.audioheritage.org/vbulletin/showthread.php?36686-New-JBL-waveguides-5006812-90x50-vs-PT-F95HF&p=375519&viewfull=1#post375519


regards
ivica

[baldrick]

From What I’ve heard Truextent is the manufactur of JBL BE and My guess is that 476be are quite similar as the once being sold from Truextent. The 476 is a bit different than 2451 and is probably the reason for them producing more UHF than 2451!?

[johanwholst]

Ari and I tried 2450sl with TE and 476be in M2. The sensitivity in the uhf is practically identical with a slight nod to the 476be.
They also sound quite similar when eqed but 476be a tad more relaxed

Regarding beryllium, cd horns and uhf:
Implementing a tweeter is not easy!
There are a lot of advantages dropping it.
Added expense, comb filtering, loss of point source etc
2384 handles 16k superb alone.
I added tweeters, but ended up with costly 045be's
Tested 2404 and 077, but they were a terrible match...

[johanwholst]

Thanks for the inspiration for a lower xo with 2384
Dropped from 750 to 650 last night, and as you mentioned; it blends better with the midbasses even some additional distortion may be introduced


+1 to what @johanwholst said.

I use a JBL 2453h-SL CD on the 2384 waveguide, biamped JBL 4722 2-way. User notnyt on the AVSForum has many CD measures on this waveguide between pages 121 and 146 starting at: http://www.avsforum.com/forum/89-speakers/1925586-just-purchased-pair-jbl-4722n-speakers-121.html including a Be. I really like the sound of the 2453h-SL, but might consider Be...

I use a steep digital XO at 630Hz as recommended by JBL for this system and sounds excellent. I tried at higher frequency, like 750Hz and 800Hz with the steep XO and it shifted the image up more towards the waveguide. At 630 Hz it the two sections blend seamlessly.

Finally, if you use the 2384, you may have to shape the top a bit (10 to 20 kHz) due to increasing directivity because of its screen spreading compensation - i.e. designed for being behind a screen. See Zilch's measurements to get an idea: http://www.audioheritage.org/vbulletin/showthread.php?23546-Screen-Array&p=236160&viewfull=1#post236160

Personally, I have been very happy with the waveguide - very smooth response and directivity. It is a 90 x 50 pattern, whereas the M2 waveguide has a wider pattern both vertical and horizontal.

Kind regards, Mitch

[cooky1257]

Ari and I tried 2450sl with TE and 476be in M2. The sensitivity in the uhf is practically identical with a slight nod to the 476be.
They also sound quite similar when eqed but 476be a tad more relaxed

Regarding beryllium, cd horns and uhf:
Implementing a tweeter is not easy!
There are a lot of advantages dropping it.
Added expense, comb filtering, loss of point source etc
2384 handles 16k superb alone.
I added tweeters, but ended up with costly 045be's
Tested 2404 and 077, but they were a terrible match...
Agree 100%, in my experience pouring over graphs will only take you so far and you have to trust your ears. I’ve got both SAM1’s with 2435be and H9800 with 2452/be in both cases I decided I didn’t miss/ need any uhf and with some gentle eq just let both roll off gently above 14khz.i als use Tannoy HPD’s that have similar roll off characteristics.

[ivica]

From What I’ve heard Truextent is the manufacture of JBL BE and My guess is that 476be are quite similar as the once being sold from Truextent. The 476 is a bit different than 2451 and is probably the reason for them producing more UHF than 2451!?

Hi baldrick,

May be I AM WRONG, but I think that 476 JBL Be diaphragm has metal (Be) so called 'diamond-shape' suspension, while Truextent Be diaphragm suspension is made of polyester or some other 'synthetic' material, so a kind of UHF frequency emphasize is diminished.

http://www.audioheritage.org/vbulletin/attachment.php?attachmentid=57641&stc=1&d=1354807911

I think that in 476 driver, a kind of short copper ring is mounted in the magnetic circuit, but I am not sure.

regards
ivica

[Ian Mackenzie]

My comments is the limit (width) of the diffraction slot in the horn is possibly the issue . I

This can result in a pencil beam at frequency = or higher width of the slot
Btw l must re measure my Tad 4003s

If l lost sleep on it l might by a Scan BE tweeter and cross it over actively with a small Pass Aleph amp @20000 hz

[ivica]

My comments is the limit (width) of the diffraction slot in the horn is possibly the issue . I

This can result in a pencil beam at frequency = or higher width of the slot
Btw l must re measure my Tad 4003s

If l lost sleep on it l might by a Scan BE tweeter and cross it over actively with a small Pass Aleph amp @20000 hz

Hi Ian,

I will agree with You that is why on PT-H95HF and M2 horns such slot size is only 3/4-inch width somewhere in the throat part of the horn.
I think that using JBL D2430K, or BMS4592 would have a great problem to find proper horn that would be good for all applied frequencies
from the bottom to the top. May be 476Be would be "in" the same problem.

regards
ivica

[Mitchco]

Thanks for the inspiration for a lower xo with 2384
Dropped from 750 to 650 last night, and as you mentioned; it blends better with the midbasses even some additional distortion may be introduced

Cool, I really like this waveguide. For fun, here are the frequency and phase response and distortion measurements. This was with the mic 1 meter away on axis, in-room, no XO, 83 dB SPL ref and sweep from 600Hz on up:

7989079891

Personally, I don't think any UHF driver is needed, and depending on one's age, such as myself, likely never to hear it :-) The distortion is quite low, even at 600 Hz. I certainly could mate the driver better to the waveguide as evidenced by the notch at 12.7 kHz. However, I use DSP eq for constant directivity waveguide eq and it smooths it out nicely, with response to -3 dB at 19 kHz relative to a house curve target response. User notnyt got similar measurements to mine: http://www.avsforum.com/forum/89-speakers/1925586-just-purchased-pair-jbl-4722n-speakers-137.html#post42209001

Here is notnyt's measures of the 2452h-BeX4008 combo on the 2384: http://www.avsforum.com/forum/89-speakers/1925586-just-purchased-pair-jbl-4722n-speakers-130.html#post41972249

And JBL 2435HPL: http://www.avsforum.com/forum/89-speakers/1925586-just-purchased-pair-jbl-4722n-speakers-140.html#post42272969

[ivica]

Cool, I really like this waveguide. For fun, here are the frequency and phase response and distortion measurements. This was with the mic 1 meter away on axis, in-room, no XO, 83 dB SPL ref and sweep from 600Hz on up:

7989079891

Personally, I don't think any UHF driver is needed, and depending on one's age, such as myself, likely never to hear it :-) The distortion is quite low, even at 600 Hz. I certainly could mate the driver better to the waveguide as evidenced by the notch at 12.7 kHz. However, I use DSP eq for constant directivity waveguide eq and it smooths it out nicely, with response to -3 dB at 19 kHz relative to a house curve target response. User notnyt got similar measurements to mine: http://www.avsforum.com/forum/89-speakers/1925586-just-purchased-pair-jbl-4722n-speakers-137.html#post42209001

Here is notnyt's measures of the 2452h-BeX4008 combo on the 2384: http://www.avsforum.com/forum/89-speakers/1925586-just-purchased-pair-jbl-4722n-speakers-130.html#post41972249

And JBL 2435HPL: http://www.avsforum.com/forum/89-speakers/1925586-just-purchased-pair-jbl-4722n-speakers-140.html#post42272969


Hi Mitchco

I think the response round 10kHz is not good. May be some kind of strong reflection has happened.
Did You try the same driver with different horn?
I have seen such behaviors with 2441 drivers and some horns too, but with much narrower notch at 10kHz.

regards
ivica

[Mitchco]

Hi Mitchco

I think the response round 10kHz is not good. May be some kind of strong reflection has happened.
Did You try the same driver with different horn?
I have seen such behaviors with 2441 drivers and some horns too, but with much narrower notch at 10kHz.

regards
ivica

Hi ivica, yes, that measure was without a proper spacer between the driver and waveguide. With a 1/2" spacer:

79900

As mentioned, could be made better with sanding the waveguide's ridges where the CD mates to the waveguide. As johanwholst indicated, the build quality is not the greatest. But without sanding down, the eq'd response at the LP for the 2 way turned out ok:

79901

Kind regards, Mitch

[Herman Chigrin]

So far am leaning towards 2451be+2384 or Radial type horn.

Will I need a spacer between 2451 & 2384 horn combo?
What is the horn model no from JBL 4367? Is it the H9800?

Herman

[Ian Mackenzie]

Guys how big is the 2384? Not sure about the Waf?

I assume a Tad 4003 would work

[Mitchco]

AVSforum user notnyt shared this with me on his 2384 waveguide:

79929

Dimensions of the waveguide can be found in the JBL 4722 product sheet: https://www.jblpro.com/ProductAttachments/SS4722_0509.pdf Btw, the product photo is crap, the woofers are black.
It's 30" wide x 15" high x 15" deep, which includes the compression driver. More like 26" x 12" for the waveguide area that smoothly transitions to the flat front.

WAF - well, it depends, it is pretty big waveguide for sure. I count my lucky stars that my wife, who first noted when the 4722's showed up that they were bigger than her washer and dryer - lol! However, she loves the big sound. I sometimes review and measure speakers for computeraudiophile.com and they are all smaller and more expensive. My wife says the bass sound from those smaller speakers sounds like it is coming from a "milk carton". I made mention that I may get something smaller and she said absolutely not... haha - a dream come true! I can share a pic of them in a living room environment for waf, but I don't want to step on Hermans thread.

[Herman Chigrin]

Can you please provide more information on the needed spacer? I will use 2451 CD with 2384 waveguide.

thank you,
Herman

[Mitchco]

Spacer info with pics: http://www.avsforum.com/forum/89-speakers/1925586-just-purchased-pair-jbl-4722n-speakers-208.html#post49649681

Cheers!

[sebackman]

Dear Herman,

I concur with most points above.

Given a choice, get 16ohm dia’s.

If you do go Be you will want a UHF as also iterated by ivica, Baldrik and others. The Truextent’s falls off rather sharply above 12k. DSP EQ can compensate but does not sound as good as 3-way to my ears. I use a BSS BLU800 for DSP so I don’t think that is the limiting factor. I always ended up with JBL 045’s in my Be setups. JBL also always used UHF’s for all their Be K2’s.

I have built both 2-way and 3-way systems with these components and the best sounding system was using 2451 core with 475Nd dia’s on the M2 wave guide. The SL diaphragms can go all the way up and requires much less EQ. You will sacrifice some of the Be sound but there are so small differences and considering how much easier it is to get a 2-way to work compared with a 3-way it is an easy choice as johanwholst is pointing out. And they are much cheaper also. Knowing back then what I know today I would not have bought Be dia’s for M2 WG usage.

A note to Mitchco’s post, I do concur, but you seem to use SL dia’s which is fine. The curve would be different with 4” Be dia’s. Even if most of us cannot hear 15k let alone 20k the overall sound is much more pleasing with a speaker that does produce sound all the way up. At least to me. I can mute my 045’s and tune the 2451Be’s to give a reasonable curve but is does not sound the same. However, with the 2451/475Nd combo on M2’s there was no need at all for additional UHF.

I also do have access to a pair of D2’s and my personal choice is still the 4” drivers sound wise for DYI. But I respect that others may have an opposite view.

Maybe worth mentioning is that the M2/K2’s are “systems” that few of us can get close to even using top notch components unless we clone a JBL factory system of our liking. To get to 95% with DIY is achievable but to get to 100% without the resources and time put in by manufacturers like JBL is considerably much more difficult, even with knowledge and good measuring tools.

I have a few of the older horns and to my ears (and mic) they differ substantially from M2 (and probably 4367). Only your ears can decide. Mine like the M2’s. -And the small cheap plasticWG from the VTX F12/F15.

I have not been able to access the 4367 horns as a spare part but there is no reason to expect that they should not sound great. The 4365 horns do not have the same sound to my ears. Not worse or better, but different. You will have to judge by listening.

I would absolutely audition M2 and/or 4367 (WG’s DIY or JBL speakers) before settling on 2384. Or any other wg for that matter.

I can send measuring data on 2451 Ti, SL and Be on M2 if you want.

Kindregards
//Rob

[johanwholst]

Dear Rob
Great post, and i agree. Partially
A 4" driver with Be mounted to a modern CD does benefit from a tweeter with the following reservations:
-The tweeter is up for the job (forget about the old JBL tweeters and other ring radiators)
-The horn in front of the tweeter matches the horn in question
-A decent DSP solution us used
-The setup is measured with a prober calibrated mic and dialed to perfection.

To get this right is costly and hard work. I know only of two tweeters that í would use with the horns I prefer; 045be and tad 703. That means we are venturing into expensive territory for hopefully a slight improvement in sonics.
If this quest is worth it is must be highly individual. For me it was, but to be honest, the improvement is marginal, and I have used the M2 waveguide and 2384 for quite som time without the tweeter, and frankly; I did not really miss it. But the classical audiophile paradox, when it is there, I would not drop it.

Another intresting thing to consider, is that instead of uprgrading from SL to Be, maybe invest in a pair of tweeters? A pair of 045be´s does not cost much more than the TE diaphragms, and to my ears can be used as low as 10k.

[sebackman]

I totally agree with your points.

With SL diaphragms in a 2451 core on the M2 WG's there is, in my view, no need for UHF at all. My measurements also confirm this. I have used 475Nd diaphragms but I think they are the same as D16R2451SL. There are at least no visible differences except the markings. I'm loading a good pair of 2451's with brand new D16R2451SL diaphragms as we speak and will measure them tonight. I can revert if I find any outrageous differences compared to the 2451/475Nd pair lying next to them.

I have not had the same long experience with the 2384, so I leave any comments to you as I know you have done extensive listening to both.

Regarding 045Be's there is actually a 045Ti-1 that sounds equally good to my ears and are easy to obtain (and cheaper) as a spare part. I think it will be very difficult to hear difference between Ti and Be above 10-12k.

Regarding 045 XO I think JBL used passive 8k in Array 1400, so maybe it is the UHF horn setting the limits.

Kind regards
//Rob

[Ian Mackenzie]

Very informative

[ivica]

I totally agree with your points.

With SL diaphragms in a 2451 core on the M2 WG's there is, in my view, no need for UHF at all. My measurements also confirm this. I have used 475Nd diaphragms but I think they are the same as D16R2451SL. There are at least no visible differences except the markings. I'm loading a good pair of 2451's with brand new D16R2451SL diaphragms as we speak and will measure them tonight. I can revert if I find any outrageous differences compared to the 2451/475Nd pair lying next to them.

I have not had the same long experience with the 2384, so I leave any comments to you as I know you have done extensive listening to both.

Regarding 045Be's there is actually a 045Ti-1 that sounds equally good to my ears and are easy to obtain (and cheaper) as a spare part. I think it will be very difficult to hear difference between Ti and Be above 10-12k.

Regarding 045 XO I think JBL used passive 8k in Array 1400, so maybe it is the UHF horn setting the limits.

Kind regards
//Rob

i

Hi Bob,

about 20dB EQ ....????

regards
ivica
H

[Robh3606]

Don't forget the PTH1010 a poor mans M2. They work very well with the large format 1.5" drivers and are easy to EQ. Here are passive preliminary networks using a 476Mg. I use them with 2435's and they sound good and image very well. Also a much smaller alternative and very shallow depth wise so no significant delay issues at crossover.

Rob:)

[wrager]

This thread is gold! Couple quick questions: Is there a difference between the 2450-SL phragm and the 2451-SL?
Assumption: I can use an 8 ohm phragm in a 16 ohm body and it will operate as an 8 ohm driver (nominal).

[pos]

This thread is gold! Couple quick questions: Is there a difference between the 2450-SL phragm and the 2451-SL?Diaphragms are supposed to be the same, but you will sometimes see aquaplas on the surrounds and sometimes not....
There also was a latter 2450SL-A driver with a ribbed diaphragm.


Assumption: I can use an 8 ohm phragm in a 16 ohm body and it will operate as an 8 ohm driver (nominal).
Yes
(though I would personally always choose a 16 ohms diaphragm over an 8 ohms one when given the choice)

Note that the 476Be and 476Mg are 16 ohms nominal despite what their EDS says.

[wrager]

Yes
(though I would personally always choose a 16 ohms diaphragm over an 8 ohms one when given the choice)


Thank you POS, you are always a great help! Why would 16 ohm be a better choice? What am I giving up, 3dB?

[pos]

You're welcome :)

This was touched on in the third post of that thread:

Noise (hiss) is the biggest issue with high sensitivity devices in an active system.
16 ohms will give you a 3dB advantage there, and also reduce amplifier distortion, but at the cost of 3dB reduction in max SPL capabilities (if the amp is the limiting factor).
That said some low power amplifiers with very low residual noise might be more at ease with a 8 ohms load, like the LPUHP amps, but this is a rare case.

IMHO 16 ohms nominal is generally the better choice there.
JBL even went to 32 ohms nominal with the D2 (dual 16 ohms coils in series), and only wire them as 8 ohms (coils in parallel) in passive PA speakers.

16 or 32 ohms compression drivers will even let you use some top headphones amplifiers that no speaker amplifier can touch in term of residual noise and distortion: https://www.massdrop.com/buy/massdrop-x-thx-aaa-789-linear-amplifier

Another peculiar benefit of using a 16 ohms compression driver compared to an 8 one is that you will be able to use a smaller and cheaper protection cap ;)

[Dr.db]

Memebr Woody designed a 1.5" version (3/4 scaled down) of the Arai 290 horns, and they seem to measure and sound pretty good!


Can you share any measurements regarding this 1,5"-yuichi horn?

I was told simply scaling down a horn doesn´t really work, it rather has to be redesigned and the proportions adjusted...
So I´m really interested if this horn performs as good as the full-size yuichi a290 :)

[ivica]

Can you share any measurements regarding this 1,5"-yuichi horn?

I was told simply scaling down a horn doesn´t really work, it rather has to be redesigned and the proportions adjusted...
So I´m really interested if this horn performs as good as the full-size yuichi a290 :)

Hi Dr.db,

I do not think that 3/4 scaling down would be the best solution. As You know that all JBL 2-inc CD drivers has (almost conical or exponential) horn that 'convert' 1.5inch phase plug opening to 2inch driver mouth. Such horn length is about 6cm to 7cm, so such "transition small horn" can be made if You want A290 to connect with JBL 1.5inch driver.
Other solution can be done using Dr.Yuichi recalculation procedure but starting with 1.5inch driver mouth instead of 2inch. I do not think that it would differ much then previously mentioned adding small 'transition' horn.

I think that EQ 2451Be (if it is Trex-Be) would be greater problem, but if You are using JBL Be (476) diaphragm, then I believe that there would be no problem about EQ it.


regards
ivica

[Herman Chigrin]

I think that EQ 2451Be (if it is Trex-Be) would be greater problem, but if You are using JBL Be (476) diaphragm, then I believe that there would be no problem about EQ it.

regards
ivica

Ivica,

what is the problem with putting EQ on 2451Be (Trex-Be), as opposed to JBL Be (476)?

Herman

[ivica]

Ivica,

what is the problem with putting EQ on 2451Be (Trex-Be), as opposed to JBL Be (476)?

Herman

HI Herman,

I would expect that 4" Trex-Be would have large dropout over 10kHz compared to JBL 476-Be diaphragm, as 2440 vs 2441 diaphragms have.

regards
ivica

[richluvsound]

An interesting thread indeed !

I'm looking for a horn that behaves as close as possible to the TH4003 in its dispersion pattern . Talking to Ari about the M2 horn , 4367 but , I'd like to use 650htz as a the crossover point . That leaves the Autotech range or ...get the throat adapter and making a A290 . I have H9800 clones , but not convinced they'll come anywhere near in a 2-way set up .
I want to avoid DSP .... I'd rather take my time and go passive . This my first speaker design from scratch .... I have some very good people helping me and I'm not in a rush .... So here goes . I'll start a thread here and over on diyaudio.com

Parts: 2450SL /4016 BE
JBL 1500AL - 150 litre
Horn ?


Rich

[Ian Mackenzie]

Have a look at the Jbl 2384

It’s getting good feedback from diy

[richluvsound]

Have a look at the Jbl 2384

It’s getting good feedback from diy

Its huge Ian , and not the prettiest thing to look at . Have you tried any of the Tractix horns ? I can get the 4367 horn ,but I was really hoping to keep the baffle as narrow as possible .
The price of the 2384 is good , Scan it and CNC in wood .

http://www.diyaudio.com/forums/multi-way/302910-horn-450-2000hz-510-a-5.html


Rich

[1audiohack]

How about a pair of clone 4338’s with billet “aluminium” throats?

They are 20.25” X 8.625”

[1audiohack]

They are permanent mold cast from mineral loaded rigid urethane.

Barry.

[Ian Mackenzie]

Its huge Ian , and not the prettiest thing to look at . Have you tried any of the Tractix horns ? I can get the 4367 horn ,but I was really hoping to keep the baffle as narrow as possible .
The price of the 2384 is good , Scan it and CNC in wood .

http://www.diyaudio.com/forums/multi-way/302910-horn-450-2000hz-510-a-5.html


Rich

Hi Rich,

Not recently. Depending on your aesthetic needs the Le Cléac’h AH-340 (600mm) could be interesting?

If you are doing a passive crossover from scratch you really need a diy friendly horn

http://www.azurahorn.com


The 2384 is the only modern Jbl horn readily available that will do 650 hertz properly.

If you relax that criteria to 750-800 hertz you can accommodate a narrower baffle.

[Ian Mackenzie]

Hi Barry,

They are nice. I have heard the 4338 and it’s really nice.

[ivica]

How about a pair of clone 4338’s with billet “aluminium” throats?

They are 20.25” X 8.625”

Hi 1audiohack.
oho, what a nice work.
I have an idea about how complex surface curvature is to be realized in order to convert circular to rectangular horn cross section
regards
ivica

[1audiohack]

Thanks guys.

These were what I was to make for Project May. I was a year late and $10K short.

I made a made a dozen of them so now I just have to make something with them. They do sound great for sure.

Barry.

[Mr. Widget]

Damn Barry! That's gorgeous!
Now, how about banging out a new intake manifold for my VW? :bouncy:


Widget

[JeffW]

Doc Mark snapped some pics during the throat machining process when we were out there in November 2014. I don't think the final iteration of the molded parts were done for some time after that.

http://www.audioheritage.org/vbulletin/attachment.php?attachmentid=63628&d=1416334098

[dn92]

An interesting thread indeed !

I'm looking for a horn that behaves as close as possible to the TH4003 in its dispersion pattern . Talking to Ari about the M2 horn , 4367 but , I'd like to use 650htz as a the crossover point . That leaves the Autotech range or ...get the throat adapter and making a A290 . I have H9800 clones , but not convinced they'll come anywhere near in a 2-way set up .
I want to avoid DSP .... I'd rather take my time and go passive . This my first speaker design from scratch .... I have some very good people helping me and I'm not in a rush .... So here goes . I'll start a thread here and over on diyaudio.com

Parts: 2450SL /4016 BE
JBL 1500AL - 150 litre
Horn ?


Rich

Behaving like TH-4003 means no EQ needed.
There was someone in France (J.P. Voiturier (ARTEC company doing audio electronics products)) who studied a horn dedicated to TAD TD-4003, free to use for diy. May be pos knows how to find the corresponding information. If I remember well it was published in the former Revue du Son macazine.

[richluvsound]

Thanks guys.

These were what I was to make for Project May. I was a year late and $10K short.

I made a made a dozen of them so now I just have to make something with them. They do sound great for sure.

Barry.

Thats a wonderful project .... how did I miss that ? Are there any plots for the 4338 ? Is there a cad file for it ?
We've simulated the 1500 AL for the box tuning and size :

Rich.

[richluvsound]

Behaving like TH-4003 means no EQ needed.
There was someone in France (J.P. Voiturier (ARTEC company doing audio electronics products)) who studied a horn dedicated to TAD TD-4003, free to use for diy. May be pos knows how to find the corresponding information. If I remember well it was published in the former Revue du Son macazine.


Interesting , but my french is worse than my cantonese .... POS ?


Rich

[pos]

dn92也是法国人 ;)

Rich, do you have TD4003 drivers at hand?
That design, or the original TH4003 one, would require EQ with a JBL driver anyway.

If you are looking for a passive solution then the 4367 is probably one of the best possible choice today.
I think the horn itself is available (I know an individual who managed to get his hands on a pair), but the D2430K is expensive.

[richluvsound]

dn92也是法国人 ;)

Rich, do you have TD4003 drivers at hand?
That design, or the original TH4003 one, would require EQ with a JBL driver anyway.

If you are looking for a passive solution then the 4367 is probably one of the best possible choice today.
I think the horn itself is available (I know an individual who managed to get his hands on a pair), but the D2430K is expensive.


Hi Pos,

I think we'll end up designing a horn .... I can get the 4367 ,but I don't the cabinet that wide .... 120 litres looks very good for the 1500AL ,So keeping the dimensions is a must . Although , I'd think seriously about buying one 4367 ,scanning it and making a clone in wood . I have the TAD 2404 here, but I wont be messing around with them as far as taking them apart .Unless... someone wants the TH4003 cloned and wants to pay for it .

I have 2450sl and truextent here . I have a friend to help with the measurement and theory ( horn design ) I thought the 4367 sounded awful at Munich . Certainly wasn't inspired by the driver or the complete system .

Sorry , Herman , Widget ..... Can I take all my nonsense to another thread ? . I seem to have unwittingly taken over this ... sincere apologies .

Rich

[dn92]

As richluvsound mentionned that he plans to build another pair of eXclusive 2404, I expected a new pair of TD-4003 to be concerned. Of course with a JBL 2451, at least one high shelf will be needed with a TH-4003 or Voiturier's horn. No need with a a TD-4003 and I think probably also not with TD-4002z.

[richluvsound]

As richluvsound mentionned that he plans to build another pair of eXclusive 2404, I expected a new pair of TD-4003 to be concerned. Of course with a JBL 2451, at least one high shelf will be needed with a TH-4003 or Voiturier's horn. No need with a a TD-4003 and I think probably also not with TD-4002z.

I didn't like the TAD 4002z when I heard it .

This is not a 2404 .... was never meant to be . I have some expensive parts sitting here doing nothing .... I may as well build a speaker , sell it on ( already sold and thank fully not to the usual low-ballers) and put the proceeds toward keeping the 2404 sitting in my living room ;)

Hey , its all fun and it turns out there are some great choices for horns including designing a new one .... thanks for the PM's folks.

Rich

[Ian Mackenzie]

I didn't like the TAD 4002z when I heard it .

I have some expensive parts sitting here doing nothing.

Rich

I know that feeling...Lol

[richluvsound]

Hi Rich,

Not recently. Depending on your aesthetic needs the Le Cléac’h AH-340 (600mm) could be interesting?

If you are doing a passive crossover from scratch you really need a diy friendly horn

http://www.azurahorn.com


The 2384 is the only modern Jbl horn readily available that will do 650 hertz properly.

If you relax that criteria to 750-800 hertz you can accommodate a narrower baffle.

Hi Ian,

I'm not in the studio anymore .... or they'd be ideal . The baffle is 550 mm or 21 5/8 " . I could rotate it 90 degrees . Its gonna be great to catch up in september - something nice to look forward to .

Rich

[marco_gea]

Behaving like TH-4003 means no EQ needed.
There was someone in France (J.P. Voiturier (ARTEC company doing audio electronics products)) who studied a horn dedicated to TAD TD-4003, free to use for diy. May be pos knows how to find the corresponding information. If I remember well it was published in the former Revue du Son macazine.

I have that Revue du Son article. Here's a scan of the plans for that horn. It could be a good fit for the 2450SL too, I think.

[Herman Chigrin]

>>>I didn't like the TAD 4002z when I heard it .

Rich, I have the TAD 4002 and I don't really like it either. Too bright, like an arch welder. However, on the JBL 2384 horn, with the accompanying, HF rolloff, it sounded more balanced and quite acceptable. This combo is not bad but need careful EQ, one that will bring up the highs but not activate the shrillness and edginess of the TAD 4002.

[sebackman]

I would definitely look at a modern wave guide before going the diffraction slot horn-way. To me the M2, 4367 and even the el-cheapo VTX-F12 WG does sound better than many expensive horns with a diffraction slot.

It is a surprisingly small difference between the el-cheapo plastic JBL#506815 and M2 WG and in my world smaller than between the new generation WG’s in general compared to the older horns. Maybe that is just me.

Since the #506815 WG is so cheap I would at least give them a try before venture into more exotic (expensive) horns. The fact that is cheap, small, uggly and made in plastic does not change the fact that they sound and measure good.

Regarding 2450SL vs 2451 core I have always thought that they are identical. They are, as far as I can figure out, not. The phase plug is different and sits differently in the 2450SL. After having moved dia’s (Ti, SL, Be) around between them I have also come to the conclusion that they do measure and sound different. Differences are small but given a choice I would opt for 2451 core.

With a proper SL diaphragm (preferably D8R475Nd or D16R2451SL) they measure and sound wonderful on the waveguides mentioned above.

Be's are also fine, but as stated above, do benefit from an UHF unit as in all JBL K2 speakers.

My 25 cents.
//Rob

[engineerjoe]

I would definitely look at a modern wave guide before going the diffraction slot horn-way. To me the M2, 4367 and even the el-cheapo VTX-F12 WG does sound better than many expensive horns with a diffraction slot.

It is a surprisingly small difference between the el-cheapo plastic JBL#506815 and M2 WG and in my world smaller than between the new generation WG’s in general compared to the older horns. Maybe that is just me.

Since the #506815 WG is so cheap I would at least give them a try before venture into more exotic (expensive) horns. The fact that is cheap, small, uggly and made in plastic does not change the fact that they sound and measure good.

Regarding 2450SL vs 2451 core I have always thought that they are identical. They are, as far as I can figure out, not. The phase plug is different and sits differently in the 2450SL. After having moved dia’s (Ti, SL, Be) around between them I have also come to the conclusion that they do measure and sound different. Differences are small but given a choice I would opt for 2451 core.

With a proper SL diaphragm (preferably D8R475Nd or D16R2451SL) they measure and sound wonderful on the waveguides mentioned above.

Be's are also fine, but as stated above, do benefit from an UHF unit as in all JBL K2 speakers.

My 25 cents.
//Rob
Do you mean the 5006815? like this?
http://www.prosoundservice.com/m9/JBL%20Pro%20Parts%205006815--jbl-pro-parts-5006815-horn-90-x-50.html
or
https://reconingspeakers.com/product/jbl-horn-lens-5006815-stx825/

[sebackman]

Yes, that is the one.

Emotionally they are generally ruled out day one, due to looks and material, compared to other much more impressing packages.

But in reality, they perform very well with the 4" 2450SL/2451 cores. JBL uses them in their +$3k VTX F12 /F15 speakers together with D2 drivers.

I use them in several systems and today. My HT uses them with 2451Be’s and 045’s UHF on top.

-Even made a VTX F12 clone with 2206 woofers and 2451SL’s in these WG’s and they work just perfect.

The M2 WG is a step up no doubt, but bigger and more expensive. However, the step up is smaller than the eye would like us to believe. Only your ears and wallet can decide if it is worth it.

One must bear in mind that M2 is not a bunch of drivers it is an integrated system. If you take away or change a compenent it willl look the same but it's not an M2 system anymore.

I have both and enjoy them both. Where size and money matters the #5006815 can be an interesting choice. In an all-out high end alternative I would build an full and faithful M2 clone, unless you are willing to spend much time to measure and develop your own tunings with an alternative choice of cabinet and/or drivers.

DIY can take you quite far with a good choice of drivers and many hours, but you will most likely not touch M2 territory. For some, like me, that is fine as I prefer the 4” cores to the D2’s and understand that in using them I will sacrifice something else. Even my faithful M2 clones will be running 2451SL’s (D8R475Nd).

I’m only suggesting to try them. Someone here (LH) has tried them before and concluded that he preferred other horns. Your ears, your choice.

I also do have some brand new 2453SL’s and D2’s that I’m going to test (measure) in a few weeks on these WG’s and the M2 WG’s. I can post the finding here if of interest.

Kind regards
//Rob

[ivica]

Hi,

Some ideas can be seen here:
http://www.audioheritage.org/vbulletin/showthread.php?34275-h9800-and-476mg&p=346443&viewfull=1#post346443

If using up to 12kHz, may be JBL PT-H95HF , is something that has to be "investigated".
http://www.audioheritage.org/vbulletin/showthread.php?36528-Is-PT-F95HF-a-meaningful-sonic-upgrade-from-2332&p=371066&viewfull=1#post371066
(http://www.audioheritage.org/vbulletin/showthread.php?36528-Is-PT-F95HF-a-meaningful-sonic-upgrade-from-2332&p=371066&viewfull=1#post371066)
may be
JBL sn/o:443495-001 waveguide ( as used in AM7215/95 box) called PT-H95HF-1, expecting the unit
price round 100$ is OK too.

regards
ivica

[sebackman]

Hi Ivica,

Albeit looking similar I do think there is a real sonic difference between the older PT wave guides (PT-F95HF) and the VTX F12 #5006815. I have had both and the newer certainly sounds better to my ears.

They do look very similar but when put side by side there are differences. The audible differences are much bigger than the optical.

Here is some info.

http://www.audioheritage.org/vbulletin/showthread.php?36686-New-JBL-waveguides-5006812-90x50-vs-PT-F95HF&highlight=new+jbl+waveguides

Kind regards
//Rob

[engineerjoe]

I am interested in all the JBL drivers that have come out since my touring days. I just got a pair of the neodium 1.4" drivers and the magnets are deteriorated bad. I scraped out all the filings and wiped off the diaghrams and now they work very well. I'm interested in how long that will last? It is disappointing since I'm such a huge JBL fan. I hope it is a small sample of what's out there that's hopefully still working fine.
I also just got a 2450 driver to compare with the old heavy 2446 2" ones that I have. ( yes I am way behind here)
I am interested in high quality sound but for pro sound reinforcement where they need to perform for many people.
I toured with INXS in 86' and the RH horns and drivers were the weak point of the sound system to me. The Martin low and low mid cabs were excellent. I was happier with my small sound system at home with the old 2441 drivers than the large system on tour.
With all the advancements in tech, I fell way behind and now being bored, I am trying out stuff I've missed.
Thank you for the great info here so far!

[ivica]

Hi Ivica,

Albeit looking similar I do think there is a real sonic difference between the older PT wave guides (PT-F95HF) and the VTX F12 #5006815. I have had both and the newer certainly sounds better to my ears.

They do look very similar but when put side by side there are differences. The audible differences are much bigger than the optical.

Here is some info.

http://www.audioheritage.org/vbulletin/showthread.php?36686-New-JBL-waveguides-5006812-90x50-vs-PT-F95HF&highlight=new+jbl+waveguides

Kind regards
//Rob

Hi sebackman,

Thank You for the link. It would be interesting to be seen comparable measurements PT-F95 vs ST825.
But any of them has to be used say over 1.5kHz. But such frequency can be a dispersion problem for 15" drivers.

Not to mention M2 driver to be applied. But for home listening 4" drivers, I believe can be used, may be even on the lower cut-off region.

regards
ivica

[Mitchco]

Some measures of a JBL 2453H-SL on STX825 waveguide crossed at 800 Hz: https://www.avsforum.com/forum/155-diy-speakers-subs/2709033-2453h-sl-stx825-waveguide-over-2265g-1-center-channel.html
Further down in the thread also a measure using a 2452H-Be driver - looks really good too.