D2430K compression driver information?

[Dave Zan]

The new D2430K looks impressive but there is no real information on the JBL website or in earlier threads here.
Has anyone here seen the AES preprint number 8502 by Alex Voishvillo or tested this driver?
A response curve would be nice if the paper is not available.
Does anyone know the price in the USA?

Dave Zan

[ivica]

The new D2430K looks impressive but there is no real information on the JBL website or in earlier threads here.
Has anyone here seen the AES preprint number 8502 by Alex Voishvillo or tested this driver?
A response curve would be nice if the paper is not available.
Does anyone know the price in the USA?

Dave Zan

May be interesting reading:

http://www.google.com/patents/US20110085692

http://www.prosoundweb.com/article/print/designer_notebook_an_in-depth_look_at_the_new_jbl_vtx_series_line_array



Regards
Ivica

[Dave Zan]

Thank you for the reply.
I had read the patent but there is no real data - I want a response curve!
I hoped that some of the keen measurement experts would have compared it other JBL drivers.
Since I am not a member of the AES the $20 for one paper seems a bit expensive.
No members here who want to read about JBL's latest hot invention?

Best wishes
David

[Mike Caldwell]

I think there was some borrowing or sharing of design on the driver from the BMS coaxial drivers. The exploded views look very similar. In the past I think there has been a JBL BMS collaboration on some of the cone compression drivers used in the JBL AE series boxes.
http://bmsspeakers.com/index.php?id=693

[Dave Zan]

Yes it looks similar to the BMS idea, but the new patent application is by Harman and their employee Alex Voishvillo and the driver is Mexican built so it looks like they don't want to collaborate any more;)
But what does it cost and what's the response like?
If any AES member wants to read the paper and send me a copy then I will be happy to pay for it.

Best wishes
David

[ivica]

Yes it looks similar to the BMS idea, but the new patent application is by Harman and their employee Alex Voishvillo and the driver is Mexican built so it looks like they don't want to collaborate any more;)
But what does it cost and what's the response like?
If any AES member wants to read the paper and send me a copy then I will be happy to pay for it.

Best wishes
David

It seems to me that on D2430 two diaphragms per driver (totally 4 ) are applied in some kind of 'push-pull' or compound construction while on BMS there are 'single' diaphragm per driver (totally 2)

Regards
Ivica

[Dave Zan]

It seems to me that on D2430 two diaphragms per driver (totally 4 ) are applied in some kind of 'push-pull' or compound construction while on BMS there are 'single' diaphragm per driver (totally 2)

Regards
Ivica

The JBL driver is actually very similar to some parts of the BMS patent - 2 voice coils per D2430K. They have separate connections but there are not 2 separate drivers each with 2 voice coils. I notice that JBL does not have a patent yet, just an application. I wonder if it will be successful.
What is unusual is that the cross-section of a BMS co-axial driver does not look like the BMS patent. Or not the cross-section I checked at least.
I don't know the explanation for this difference.
This explains why some people say the JBL is quite different from the BMS. They must have compared a BMS driver and not the BMS patent.

Now would someone in the USA please tell me the local cost?
They won't talk to "for'ners"

Best wishes
David

[Mike Caldwell]

I'm going to guess that it will never be offered as an off the shelf component part , none of the JBL dual coil differential drive cone speakers are. Through a JBL service center maybe, at what cost I could only imagine!

[more10]

I talked to the Swedish BMS representative today. JBL has "refined" an old BMS patent.

[4313B]

It was suggested that this transducer really isn't for hi-fi use although it does have some interesting qualities. I was all set to order a pair just for fun and was talked out of it. Definitely an upgrade from a 2431 but probably hard pressed to beat a 2435 (for home hi-fi use).

[ivica]

It was suggested that this transducer really isn't for hi-fi use although it does have some interesting qualities. I was all set to order a pair just for fun and was talked out of it. Definitely an upgrade from a 2431 but probably hard pressed to beat a 2435 (for home hi-fi use).

I wonder why low distortion, flat frequency response, high efficiency ,...etc, would not be applicable for "hi-fi". Owing to the published data and applied patents, especially complicated and 'usually shape' phase plugs, I believe that such driver would become very high quality sound 'transducer'. I only wonder what kind of horn would be applicable to such kind of (expecting) ultra wide frequency driver, especially be aware of the BMS4590/4592 horn application problems.

Regards
ivica

[4313B]

They are sound reinforcement ring radiators designed for maximum output with very low distortion.

I have no doubt whatsoever that they would do just fine for those who like such things.

They are quite expensive, a third more than anything else JBL Pro makes. That said, they are nowhere near as expensive as a 476Be.

[macaroonie]

There was a thread running here that was blocked for no given reason. I guess that the collective enquiring mind was probing a little too deeply in the midst of a patent app.
So most of what you need to know as to how it works is on this page.

http://www.prosoundweb.com/article/designer_notebook_an_in-depth_look_at_the_new_jbl_vtx_series_line_array/P2/

Bump up the images and you will see what is going on.

Very clever left field engineering going on here IMO , it has taken a completely different slant on how to achieve the workings of a comp driver and apparently with some success.
It runs out to 30 K ish without compensation , minimal power compression , high spl / powerhandling .
Great work whoever did it congrats.

The BMS does not work the same way at all. The dias in the JBL work like a bellows , both pushing / pulling at the same time. The BMS is a 2 way coax with a X/O requirement.

I fully expect to see this technology trickle down.

[4313B]

Thgere was a thread running here that was blocked for no given reason.If you are talking about the new studio monitor thread, it was removed at the request of JBL Pro. Once the scheduled release date has passed there should be no problem.

We've gone through this several times with Harman Japan too. They announce something before Northridge announces it and all hell breaks loose at Northridge.

[macaroonie]

I get that in spades. One point as ever WRT Harman marketing , as an international, sorry, worldwide presence in Pro Audio you would think that they could perhaps get their timing organised. There are a lot of people within that organisation getting paid a lot of dosh to get things right.
Seems that they collectively couldn't run a bath.

My comments come from having dealt with Harman professionally way back when , it was the same then.

Absolutely no reflection on the clearly ground breaking work that comes from the engineering side.

[pos]

It runs out to 30 K ish without compensation
Are you sure about that? I am sure the mass breakpoint is very high in frequency, but there will always be one, and much lower than 30khz I guess. So ultimately compensation will always be needed when used on a constant directivity horn, at some frequency...

[macaroonie]

Pos , I did a LOT of digging on this driver and the info is there if you care to look. Chase down VTX boxes and you will find all you need to know. I'm pretty certain it's 30K ( might be - 6 or -10 in fairness ) The main thing is that the driver seems to play well beyond ' normal' mass break points. Remember the dias are very small by comparison with conventional types and I suspect they have achieved very high compression ratios.
Read more my friend , its fascinating. :applaud:

[pos]

Yes I have read the articles linked in the other thread, but nowhere have I found any tube measurements for example (VTX box measurements account for EQ that compensate the rolloff).
So it is is difficult to assert any mass breakpoint before Techbot gives us the EDS :p

I have some 2407 ring radiators (direct BMS knockoffs), and even with the tiny radiating surface and ridiculous MMS it still has a mass breakpoint, and not that higher than other drivers...
So far the 2435 (without aquaplas) is the driver with the highest mass breakpoint that I know of (excluding supertweeters), and it is still nowhere near 30khz, nor 10khz.

[macaroonie]

As I said , somewhere in the online info , including You Tube , there is mention of the driver extending out to 30K
Clearly absolute tech info will be kept under wraps till the patents are granted.
I don't blame them , this would seem to be cutting edge innovation. Thats probably why they gave the nice Russian gentleman a job.
I can readily see this driver format becoming much more familiar in the future. The current offering is operating at the extremes of the parameters , power etc. The compliance will need to be on the stiff side to cope with the incoming signal. Come back down to domestic and or small ' studio ' requirements and a lot of mechanical aspects can be smoothed ,softened or refined.
4313 is correct in that this is a working tool meant to get very loud , all day , every day.
Not necessarily ideal for domestic use.

[pos]

there is mention of the driver extending out to 30KOk, but that does not say anything about the need (or lack of) to use compensation (EQ) to reach that point.

[macaroonie]

http://www.youtube.com/watch?NR=1&v=1JWg1icrqn0

Mark Gander at 1m50s Admitedly unqualified statement

[pos]

He talks about a smooth response without breakups (thanks to the small mylar ring diaphragm), nothing about mass breakpoint or compensation EQ

[ivica]

He talks about a smooth response without breakups (thanks to the small mylar ring diaphragm), nothing about mass breakpoint or compensation EQ

Hi,

May be attached figure can explain all the words about the F-R.

http://www.diyaudio.com/forums/attachments/multi-way/299053d1346475366-jbl-d2430k-compression-driver-aesp8502f17.pdf

It seems to me that at LF section Xmax limitation make D2430K less efficient but on the HF section it outperforms 'dome' model. Unfortunately the distortions were not shown.

Very nice technical explanation can be find in :

http://www.google.com/patents/US20110085692

http://www.google.com/patents/US8280091

regards
Ivica

[pos]

It seems to me that at LF section Xmax limitation make D2430K less efficient but on the HF section it outperforms 'dome'
Interesting measurement, thanks.
(1, red) is the dual driver. It peaks in midband, then rolls-off earlier than the dome metal, and then goes up and extends a bit further after 20khz (but the horn is not CD anymore at those frequencies).
Looking at those measurements it *looks like* the D2430K mass breakpoint is in fact lower in frequency than the one of a titanium dome compression driver:blink:

My 2407 exhibits a similar behavior in the UHF, and published curves are similar: JBL (http://www.audioheritage.org/vbulletin/showthread.php?21754-2407h), BMS (http://bmsspeakers.com/index.php?id=4540nd_curves).
Distortion measurements of the D2430K would be interesting indeed, but one can expect the 2nd order distortion to be lower than single ring radiator drivers thanks to the dual push pull diaphragms (even order distortion cancellation...)

[pos]

Here are the crossection settings from the M2 preset for the D2430K on the M2 waveguide, published by 4313B:

http://www.audioheritage.org/vbulletin/attachment.php?attachmentid=59016&stc=1&d=1369326015

and together with the (1st order electrical!) crossover and global EQ:
http://www.audioheritage.org/vbulletin/attachment.php?attachmentid=59019&stc=1&d=1369326357

So obviously it *needs* EQ to reach UHF on a constant directivity device: around 10dB between 2kHz and 9kHz. Above 9kHz it seems to keep its level up to 20kHz (and maybe above), which is a phenomenon that already partially appears on the 2407H and other BMS designs.

Lets wait for distortion measurements now, to see the effect of that push pull design on 2nd order distortion! (which was the big drawbacks of BMS designs...)

[ivica]

Here are the crossection settings from the M2 preset for the D2430K on the M2 waveguide, published by 4313B:

http://www.audioheritage.org/vbulletin/attachment.php?attachmentid=59016&stc=1&d=1369326015

and together with the (1st order electrical!) crossover and global EQ:
http://www.audioheritage.org/vbulletin/attachment.php?attachmentid=59019&stc=1&d=1369326357

So obviously it *needs* EQ to reach UHF on a constant directivity device: around 10dB between 2kHz and 9kHz. Above 9kHz it seems to keep its level up to 20kHz (and maybe above), which is a phenomenon that already partially appears on the 2407H and other BMS designs.

Lets wait for distortion measurements now, to see the effect of that push pull design on 2nd order distortion! (which was the big drawbacks of BMS designs...)

Hi pos,

It is interesting that only several dBs compensation is really needed ( points 6. , 7. and 8.) to compensate almost much deeper ( over 10dB) notches on the driver 'alone' response. May be some improvements have been done after serial production established.

Regards
ivica

[4313B]

So obviously it *needs* EQ to reach UHF

Not really any different than the 476Mg on the H9800 horn or the PT waveguides. If I remember correctly, a 6 dB shelf above 6 kHz in those instances.

Of course the 476Mg is, for all intent and purpose, unobtainable.

JBL is also nit picking with respect to the M2, obviously they wanted that curve as flat as possible to wow the graphophiles. The K2 and E2 have only a few notches amongst them. They could be cleaned up significantly if desired.

[ivica]

Hi,

May be attached figure can explain all the words about the F-R.

http://www.diyaudio.com/forums/attachments/multi-way/299053d1346475366-jbl-d2430k-compression-driver-aesp8502f17.pdf

It seems to me that at LF section Xmax limitation make D2430K less efficient but on the HF section it outperforms 'dome' model. Unfortunately the distortions were not shown.

Very nice technical explanation can be find in :

http://www.google.com/patents/US20110085692

http://www.google.com/patents/US8280091

regards
Ivica

Some additional information can be find:

http://www.fohonline.com/images/stories/12/02/current/30.200.1202.pdf

measurements done with 1.5-inch plane wave tube.

[macaroonie]

http://www.google.co.uk/url?sa=t&rct=j&q=&esrc=s&source=web&cd=13&ved=0CIQBEBYwDA&url=http%3A%2F%2Fwww.hifisentralen.no%2Fforumet%2F attachments%2Fvennetra-der-hifimerker%2F177064d1358245173-na-r-bare-12-eller-sta-rre-er-nok-tra-den-jbl-fans-16028.pdf0_o_l.pdf&ei=_NQxUu3VMMnT7AbYroHoAg&usg=AFQjCNF9_SDC6VXmOh0ADt_dtYgY0sfpIg&bvm=bv.52109249,d.ZGU

Download the pdf.

One snippet it directly describes and has a diagram for a 1.5" coil version :)

[pos]

Interesting thanks!

10 pages left to find :D

[ivica]

http://www.google.co.uk/url?sa=t&rct=j&q=&esrc=s&source=web&cd=13&ved=0CIQBEBYwDA&url=http%3A%2F%2Fwww.hifisentralen.no%2Fforumet%2F attachments%2Fvennetra-der-hifimerker%2F177064d1358245173-na-r-bare-12-eller-sta-rre-er-nok-tra-den-jbl-fans-16028.pdf0_o_l.pdf&ei=_NQxUu3VMMnT7AbYroHoAg&usg=AFQjCNF9_SDC6VXmOh0ADt_dtYgY0sfpIg&bvm=bv.52109249,d.ZGU

Download the pdf.

One snippet it directly describes and has a diagram for a 1.5" coil version :)

Hi pos and macaroonie,

Thanks for the link and the file. In any case it would be interesting when ONE DAY some of our AH-forum member would make "independent" measurements with real available 1.5"-throat horns, either on axis and off axis, THD..... etc.
For me personally, comparison with 2" BMS 4590 or 4592ND especially with 'new-comer' 1.5" BMS 4595ND would be interesting...(745 U$D http://www.usspeaker.com/bms%204595nd-1.htm )

Regards
Ivica

[pos]

Here are some measurements comparing the D2 driver with a 2435 and a 2450SL equipped with Truextent Be diaphragms.

- PT-F95HF horn, laying on the floor, upward-facing
- dayton mic (calibration not loaded!)
- ~50cm distance from the horn mouth (not precisely matched between drivers of different depth...)
- 4th order HP filter at 800Hz using Hypex AS100D plate amp
- no EQ
- all drivers are coming from ebay, but the Truextent Be diaphragm is new

The noise floor was pretty high, with hiss coming from the amp (no lpad or autoformer was used, and this of course impacts the lower impedance drivers more...).
Output level were adjusted in the filter to compensate for differences in nominal impedance.


D2430K vs 2435HPL
62343


D2430K vs 2450SL-Be
62344

[ivica]

Here are some measurements comparing the D2 driver with a 2435 and a 2450SL equipped with Truextent Be diaphragms.

- PT-F95HF horn, laying on the floor, upward-facing
- dayton mic (calibration from cross-spectrum)
- ~50cm distance from the horn mouth (not precisely matched between drivers of different depth...)
- 4th order HP filter at 800Hz using Hypex AS100D plate amp
- no EQ
- all drivers are coming from ebay, but the Truextent Be diaphragm is new

The noise floor was pretty high, with hiss coming from the amp (no lpad or autoformer was used, and this of course impacts the lower impedance drivers more...).
Output level were adjusted in the filter to compensate for differences in nominal impedance.



Hi POS,

Thanks for the measurements You have sent us.
Interesting that on the measurements fro the D2430K there are no deeps around 9.3kHz, 11kHZ, and 16kHz as with M2 horn

( look at the )
http://www.audioheritage.org/vbulletin/showthread.php?33972-JBL-Master-Reference-Monitor&p=354296&viewfull=1#post354296
http://www.audioheritage.org/vbulletin/attachment.php?attachmentid=60494&stc=1&d=1383303224

I wonder what would be the drivers behavior with PT-H95 horn.

regards
ivica

[1audiohack]

Hi Thomas;

Well it certainly looks like the D2 will be nice to work with on the DIY side.

What is the lower trace on the scale? Does your test rig generate a phase response?

I will get back to you on your PM to me today.

Thanks for sharing!

Best,
Barry.

[Earl K]

Yes,

Thanks POS !

<> Earl

[4313B]

Yes, thank you very much for the post pos. I'm still not going to give up my 4-inch coils ( it's a legacy JBL thing ;) ), but these things are considerably more reasonable in the price department. G.T. did mention a distortion issue with the D2, I think it was around 1 kHz, but I can't remember the gory details. And it sounds damn good in the M2.

[ivica]

Yes, thank you very much for the post pos. I'm still not going to give up my 4-inch coils ( it's a legacy JBL thing ;) ), but these things are considerably more reasonable in the price department. G.T. did mention a distortion issue with the D2, I think it was around 1 kHz, but I can't remember the gory details. And it sounds damn good in the M2.
Hi 4313B,

May be LF ( <1kHz) distortion of D2 is involved by the M2 horn. It seems to me that M2 is a kind of compromise HF bandwidth and HF dispersion. It would be interesting to get some more data about D2 with the PT-H95 horn. I believe that LF distortion would be reduced, but HF section would lost bandwidth and dispersion.

regards
ivica

[pos]

What is the lower trace on the scale? Does your test rig generate a phase response?
Hi Barry

The lower trace is the 3rd order distortion.
The noise floor was pretty high, and the mic I used is also not ideal for distortion measurement (internal 2nd order is always higher than the measured driver for example...).
I should redo this with proper gain structure (an autoformer between the amp and driver) and a beefier mic (1/2" capsule), but I don"t think I will have the opportunity to do this anytime soon...

Regarding phase, it looks like all the drivers exhibit pretty much a perfect minimum-phase behavior over there bandwidth, so no surprise there.


Thanks for sharing!
my pleasure

[pos]

Yes, thank you very much for the post pos. I'm still not going to give up my 4-inch coils ( it's a legacy JBL thing ;) ), but these things are considerably more reasonable in the price department. G.T. did mention a distortion issue with the D2, I think it was around 1 kHz, but I can't remember the gory details. And it sounds damn good in the M2.

Distortion seems to rise pretty quick under 1kHz (and level drops down), maybe that is the issue GT talked about?

[pos]

Hi 4313B,

May be LF ( <1kHz) distortion of D2 is involved by the M2 horn. It seems to me that M2 is a kind of compromise HF bandwidth and HF dispersion. It would be interesting to get some more data about D2 with the PT-H95 horn. I believe that LF distortion would be reduced, but HF section would lost bandwidth and dispersion.

regards
ivica
I think the horizontal HF beamwidth will be better with the PT-H than with th PT-F, thanks to the diffraction devices.

David Smith did an interesting comment about the M2 horn somewhere on the diyaudio forum (and I posted it here also).
He said something along the same lines as you: compared to a 2344 this new waveguide favors off-axis smoothness (relative to on-axis at least) over absolute directivity control.
Certainly a worthwhile compromise.

[pos]

Some random thoughts:

- I did some listening tests comparing the D2430K and 2450SL-Be with careful EQ, and they sounded more alike than different I would say... Almost impossible to distinguish. That said, it was restricted to the 1.2kHz-18kHz range, with no other drivers, and with the horns laying on the floor: not an ideal situation, and quite fatiguing.

- The truextent Be diaphragm has a major breakup above 20kHz that should be attenuated with EQ or it will trigger any preringing nastiness the DAC might have (if not a 96kHz DAC that is), as can be seen in the impulse measurement (preringing just before the impulse)

- The 2435HPL is truly an impressive small driver, with the highest mass break point frequency I have ever measured in a driver. Its phasing plug does not play well with that particular horn though, as we all know, and that ~13kHz hole cannot (and should not) be addressed with EQ (it moves off axis!). The 2432 phasing plug would probably be worth trying : 2432 front cap with 2435 back cap and diaphragm...

- The D2430K has a really smooth response up high with no apparent breakup or resonnace. This reminds me the 2450SL (Ti SL diaphragm) a lot : the mylar ring is probably very well dampened. It also have the same rise in the UHF that can be found on many other ring radiators, like the 2407H.

- The fact that the D2430K is a 32ohms driver (in 16//16 position) is a really nice feature as it will reduce the hiss (and distortion) coming from the amp (-3dB compared to a 16ohms driver, and -6dB compared to a 8ohms drivers). I wish more compressions drivers would be 32 or even 64 ohms devices, especially when used with active filtering: no more lpad or autoformer would be needed with most amplifiers (but it looks like the crown XTI is still not silent enough for this...)

[pos]

Here are some additional distortion measurements with a better noise floor (mic with a 1/2" capsule, and an autoformer to reduce hiss and distortion from the amp), comparing the aforementioned 3 drivers.
Each graph shows a different harmonic distortion order as the lower traces.
The mic is not calibrated, so disregard the (heavily smoothed) upper curve.
The drivers where grossly EQed for CD compensation and midband matching.

blue curve is 2450SL-Be
red curve is 2435HPL
green curve is D2430K

2nd order
62350


3rd order
62351


4th order
62352


5th order
62353


6th order
62354

[ivica]

Here are some additional distortion measurements with a better noise floor (mic with a 1/2" capsule, and an autoformer to reduce hiss and distortion from the amp), comparing the aforementioned 3 drivers.
Each graph shows a different harmonic distortion order as the lower traces.
The mic is not calibrated, so disregard the (heavily smoothed) upper curve.
The drivers where grossly EQed for CD compensation and midband matching.

blue curve is 2450SL-Be
red curve is 2435HPL
green curve is D2430K

2nd order
62350


Hi POS,

Thanks for the THD data You have done.
On the 2nd distortion curve it is 'visible' that D2430K driver is NOT so good for the lower frequency range ( under 2kHz), as 2435 or 2450. I can expect that the reason is much smaller diaphragms (two) total surface ( I can guess the surface is about 60% of the 2450 diaphragm). So I would expect that the larger horn would help there, but then, the problem can arise in the high frequency response.

regards
ivica

[pos]

Yes, maybe that is the issue 4313B talked about.
On the other hand it might also be a problem with that particular driver (from ebay), but I guess it would had showed also with other harmonic orders in that case...
I got a pair and the one you see here measured is the best one of the two: the other one had markedly more distortion, especially around 2kHz for even order harmonics :
https://www.dropbox.com/s/nwbce5k9mbdyfj7/D2430K.zip

Probably a misaligned VC, but I don't want to open that driver :D
I will get another one as a replacement from the seller and we will see what happens...

According to the AES paper the total radiation area of the two 3" ring (extending inside and outside of the VC) should be similar to a single 3" dome.
And the push-push orientation should reduce even order distortion....

[ivica]

Yes, maybe that is the issue 4313B talked about.
On the other hand it might also be a problem with that particular driver (from ebay), but I guess it would had showed also with other harmonic orders in that case...
I got a pair and the one you see here measured is the best one of the two: the other one had markedly more distortion, especially around 2kHz for even order harmonics :
https://www.dropbox.com/s/nwbce5k9mbdyfj7/D2430K.zip

Probably a misaligned VC, but I don't want to open that driver :D
I will get another one as a replacement from the seller and we will see what happens...

According to the AES paper the total radiation area of the two 3" ring (extending inside and outside of the VC) should be similar to a single 3" dome.
And the push-push orientation should reduce even order distortion....

Hi POS,

May be some diaphragm destruction....

I do not know the 3" dome exact data, but it seems that two 3"rings would have the same surface as 3" dome,
if 4"dome to be in comparison, then I would expect that for 4" dome surface would be about 85cm2, comparing to about 49cm2 for 3"dome.


regards
ivica

[Mostlydiy]

Thanks for sharing this pos, its really interesting stuff. Similar measurements with the 476Be/Mg would be a real treat but I know they are hard to come by.

/Mostly

[Dave Zan]

- The fact that the D2430K is a 32ohms driver (in 16//16 position) is a really nice feature as it will reduce the hiss (and distortion) coming from the amp (-3dB compared to a 16ohms driver, and -6dB compared to a 8ohms drivers). I wish more compressions drivers would be 32 or even 64 ohms devices, especially when used with active ...

Thanks for the measurements. Did you pick these up from Ebay in USA? I had my eye on a pair!
The 32 ohms may actually be a problem if the amp is specifically optimised for low noise.
Have you made any measurements with the VCs in parallel rather than series?

Best wishes
David

[pos]

Yes these come from ebay.
I did not try the 8ohms setup, but I'd expect the measurements too look the same, once the noise floor of the amp has be taken off the equation (by the use of an lpad or an autoformer)

What amp are you thinking of?

[Dave Zan]

Yes these come from ebay.

Lucky I did not bid and raise your cost. Must check here next time I want a pair.;)


I did not try the 8ohms setup, but I'd expect the measurements too look the same

I think there is a coupled mode that can exist when the VCs are in parallel, that does not exist for series connection.
Ideally the two sides are perfectly equal and there will be no excitation of that mode, the measurements will be the same.
I wondered about the difference in reality. Would be an informative test, if the results are the same then the driver is close to theory.


What amp...?

I plan a dedicated compression driver amp of ultra low noise.
Much better than a standard amp that has to be wastefully padded down
I have mentioned it a few times in DIYaudio, where I see some of your posts too.
Lower VC resistance alters some of the trade-offs in resistor noise, power loss in the feedback network etc.


Best wishes
David.

[pos]

4313b posted the M2 technical manual in another thread.

The manual clearly states there is no replacement diaphragm for the D2430K:


Driver, High Freq.
D2430K
(5032754X)
No Diaphragm Kit
Driver Only

This is quite choking for such an (apparently) fragile driver aimed at professional use.
One advantage of this technology over big Be (or Mg) diaphragms is obviously the cost of the diaphragms themselves, so if one cannot buy replacements this is getting a bit silly.

Then I checked the VTX25 tech manual, and it states the opposite:

Compression Driver (3)
D2430K
(446213-001X)
Diaph Repl
D32RD2430


The 32 ohms marking seems to indicate that the replacement kit is the pair of diaphragms, maybe already assembled as opposing rings?...
That would be logical as matching between the two diaphragms is critical (for distortion canceling), and sealing is also probably a big issue here.
Also interesting to note: the part list for the driver itself is different... (?!)

That said, I have had a pair of D2430K in my hands and to be honest I do not even see how one is supposed to open the damn thing to install new diaphragms...
Maybe under the foilcal, like the old ring radiators?

Would anyone have information (price?) on these replacement diaphragms?

[Mr. Widget]

)...I have had a pair of D2430K in my hands and to be honest I do not even see how one is supposed to open the damn thing to install new diaphragms...
Maybe under the foilcal, like the old ring radiators?

Would anyone have information (price?) on these replacement diaphragms?I wouldn't sweat it... I doubt you would ever be able to buy replacement diaphragms. :(

The current direction JBL is going is free driver replacement while under warranty and buying a replacement driver after that until NLA... my real fear is that NLA may be sooner than would have been considered reasonable before everyone started sharpening their pencils scalpel sharp.


Widget

[JeffW]

JBL Pro took down their Transducer Parts List a while back, no more checking by the public to see if a replacement part is even produced anymore.

[pos]

Well, I think I'll stick with the good ol' 1.5"/4" compression drivers: they are easy to service, can perform admirably (especially with Be), and beside JBL there will always good diaphragms for these on the market for a reasonable price (Radian, Truextent, etc.).

[Dave Zan]

M2 technical manual ...clearly states there is no replacement diaphragm for the D2430K:
...
Then I checked the VTX25 tech manual, and it states the opposite:


...
The current direction... is free driver replacement while under warranty and buy... a replacement driver after that until NLA...

It seems JBL expects the M2 owners not to blow them, and if they do then to have the money to buy a complete replacement.
But PA/tour operators are expected to blow out drivers so can buy replacement parts,
That would almost make sense if the M2 driver is perhaps a selected/matched unit, perhaps why the different part number?
Or is it just an assumption that M2 owners can be squeezed harder?
A >$1000 driver that is a throw-away item would make me very reluctant to buy.

Best wishes
Dave

[pos]

That would almost make sense if the M2 driver is perhaps a selected/matched unit, perhaps why the different part number?
That is exactly what I was told today by KW55 (http://www.kw55.fr/) (he also told me the M2 exceeded by far everything he had listen to (http://www.kw55.fr/p/test.html) in his showroom :))

That makes sense indeed, as matching between rings and proper installation is probably paramount with this push/push distortion cancellation strategy.

[4313B]

It seems JBL expects the M2 owners not to blow them, and if they do then to have the money to buy a complete replacement.
But PA/tour operators are expected to blow out drivers so can buy replacement parts,
That would almost make sense if the M2 driver is perhaps a selected/matched unit, perhaps why the different part number?
Or is it just an assumption that M2 owners can be squeezed harder?
A >$1000 driver that is a throw-away item would make me very reluctant to buy.

Best wishes
DaveThe D2 is considered a replacement part rather than a finished good like other JBL compression drivers so it runs around $1.5k a pop instead of $2k a pop.

Harman has gone to a whole driver replacement strategy.

There were D2 replacement diaphragm kits, I would assume they are still available to JBL Pro Service Centers.


That is exactly what I was told today by KW55 (http://www.kw55.fr/) (he also told me the M2 exceeded by far everything he had listen to (http://www.kw55.fr/p/test.html) in his showroom :))
The performance of the M2 isn't trivial. JBL was not blowing smoke when they called it a game changer.

The only problem I have with the entire scenario is people having spent serious money on K2's and E2's... my very first reaction to the M2 was within the context of the K2 and E2. "Uh oh..."

[pos]

What about the "selected D2" scenario for the M2?
Have you heard anything along those lines?
That would explain the difference in part number between the VTX25 and M2 spec sheets.

[4313B]

No, I have not discussed that with anyone.

[Paul W]

Having seen conflicting info, I'd like to check my understanding...

The 2430K uses 3" VCs, the 2415k 1.5" VCs. Correct?

[4313B]

That said, I have had a pair of D2430K in my handsCan you please post an impedance curve of one with the resistor pad from the M2? (13 ohm series, 11 ohm parallel)

[pos]

Sorry, I did not run any impedance measurement on them, and I returned the pair to the seller (after having tried to replace just one, but the replacement I received also had "issues").
My conclusion is that those drivers are too fragile to be bought used, the faston terminals especially: gently pushing a terminal during measurement could change distortion figures by up to 20dB...
62692
(lower traces are 3rd distortion)

Knowing that one cannot buy replacement diaphragms...
No thanks, not for me, not even new and enclosed in a speaker...

[ivica]

Sorry, I did not run any impedance measurement on them, and I returned the pair to the seller (after having tried to replace just one, but the replacement I received also had "issues").
My conclusion is that those drivers are too fragile to be bought used, the faston terminals especially: gently pushing a terminal during measurement could change distortion figures by up to 20dB...
62692
(lower traces are 3rd distortion)

Knowing that one cannot buy replacement diaphragms...
No thanks, not for me, not even new and enclosed in a speaker...


Hi POS,

Thank You for the measurements You have done. I do not know what kind of horn You have used, but the response over 13-14 kHz is not promising too much. May be the driver was faulty...

Regards
Ivica

[pos]

Hi Ivica

Please disregard the amplitude response in this measurement: I use an uncalibrated 1/2" mic for distortion measurement (although I should calibrate it really...)

Measurements and comparisons using a much flatter 1/4" mic can be found here (http://www.audioheritage.org/vbulletin/showthread.php?33345-D2430K-compression-driver-information&p=362742&viewfull=1#post362742).

(http://www.audioheritage.org/vbulletin/showthread.php?33345-D2430K-compression-driver-information&p=362742&viewfull=1#post362742)The three D2430K I measured had all pretty much the exact same amplitude response, faulty or not, with or without fiddling with the terminals...

[more10]

BMS now has a driver with dual diaphragms, the 4599ND (http://www.bmsspeakers.com/index.php?id=bms_4599nd)

http://www.bmsspeakers.com/typo3temp/pics/5d1b3714a8.jpg



The BMS 4599ND dual diaphragm driver incorporates two identical 3.5” concentric annular ring diaphragms, connected to a common 2” throat, providing extremely high acoustical output.


It is available from USSpeaker (http://www.usspeaker.com/bms 4599ndhe-1.htm). They have a version with aluminium demodulation rings, the 4599NDHE (http://www.usspeaker.com/bms%204599ndhe-1.htm). There is no information from BMS on this driver yet.

[ivica]

BMS now has a driver with dual diaphragms, the 4599ND (http://www.bmsspeakers.com/index.php?id=bms_4599nd)

It is available from USSpeaker (http://www.usspeaker.com/bms 4599ndhe-1.htm). They have a version with aluminum demodulation rings, the 4599NDHE (http://www.usspeaker.com/bms 4599ndhe-1.htm). There is no information from BMS on this driver yet.

Hi,
The shown data is promising concerning the SHD and THD, but the frequency response is (on my opinion) fare from being useful ( less then 10kHz)
If in BMS would decide to enhance the F/R , I believe that they have to develop a new type of horn, so may be some horn such as M2 with the "stiffen" part of the throat (in order to introduce a kind of "soft diffraction slot" in order to enhance the horn coverage angles at higher frequency) would become available.

Reagrds
ivica

[more10]

but the frequency response is (on my opinion) fare from being useful

It is a midrange driver. Not comparable to the JBL D2. Maybe they will introduce a dual diaphragm driver with smaller VC?

[ivica]

It is a midrange driver. Not comparable to the JBL D2. Maybe they will introduce a dual diaphragm driver with smaller VC?

Hi more10,

as I have remembered D2430K has 3.5-inch annular ring dual membrane,
and mentioned BMS 4599 has 3.5-inch annular ring dual membrane,
so just from that point of view they are very similar,
but the rest ( phase plug-s, VC coil weight , etc...) thing are not know (to me).

reagrds
ivica

[johnhere]

If you are talking about the new studio monitor thread, it was removed at the request of JBL Pro. Once the scheduled release date has passed there should be no problem.


So you guys removed A thread without given reason and now it still isn't back yet?

[JeffW]

So you guys removed A thread without given reason and now it still isn't back yet?

Reason was given, JBL requested it. It's currently Posted Here (http://www.audioheritage.org/vbulletin/showthread.php?33972-JBL-Master-Reference-Monitor).

Both statements in your post seem to be from left field.

[globulegl]

What is the difference between d2430h and d2430k. Lower frequency response for the d2430k?

[pos]

Hello, no need to spam three different threads with the same question ;)

My guess is that these are the same drivers, but wired differently: D2430K as used in the M2 and VTX F12 have their two 10/16 ohm diaphragms wired in series for 20/32 ohm load (hence the letter K, as it seem they skipped letter I and went directly to J for 16 ohm for some strange reasons), whereas the D2430H as found in the VTX M20 would be a 5/8 ohm version with the two 10/16 ohm diaphragms wired in parallel (hence the letter H) for increased sensitivity.
If that is the case going from one to the other would just be a matter of using a different wiring schema, and I'd bet the D2430H has a D2430K foilcal.

[Dave Zan]

(hence the letter K, as it seem they skipped letter I and went directly to J for 16 ohm for some strange reasons)...

Probably just to avoid confusion with I and 1, a few letter to number codes do this or similar.

Best wishes
David

[Flodstroem]

Anyone here who knows where to buy the D2ś :blink:

[globulegl]

Hello, no need to spam three different threads with the same question ;)

My guess is that these are the same drivers, but wired differently: D2430K as used in the M2 and VTX F12 have their two 10/16 ohm diaphragms wired in series for 20/32 ohm load (hence the letter K, as it seem they skipped letter I and went directly to J for 16 ohm for some strange reasons), whereas the D2430H as found in the VTX M20 would be a 5/8 ohm version with the two 10/16 ohm diaphragms wired in parallel (hence the letter H) for increased sensitivity.
If that is the case going from one to the other would just be a matter of using a different wiring schema, and I'd bet the D2430H has a D2430K foilcal.


....my d2430h make 32ohms. I bought on ebay. They was used. I have made the measure without horn at 2 inch of distance. I don't know if this measure is good. I find the attenuation strong in its the acute

MAESUREMENT REW FILES (http://frog-publicite.com/images/blog/2430h/2430vs.mdat)

[ivica]

....my d2430h make 32ohms. I bought on ebay. They was used. I have made the measure without horn at 2 inch of distance. I don't know if this measure is good. I find the attenuation strong in its the acute

MAESUREMENT REW FILES (http://frog-publicite.com/images/blog/2430h/2430vs.mdat)

Hi globulegl,

I have no idea the application of the CD drivers WITHOUT horn, not to measure the meaning of 2-inch distance measurements.
As I have remembered CD drivers have to be measured from over 1m distance, say 2m better, if the full driver-horn response
is of the interest (in the home listening environment).
For large aerial environment distance about 3m would be better.


regards
ivica

[sguttag]

So has ANYONE found a difference between the VTX version of the D2 (product number D2430K) with a part number 446213-001X and the M2 version of the D2 (also product number D2430K) with a part number 5032754X?

I'm a cinema guy so my experience with the D2 is zero though at a friend's recommendation, I've begun a DYI M2 project (with matching SUB 18ish subs). I am a JBL certified reconer so I have access to parts and I can tell you that the 446213-001X is MUCH easier to lay one's hands on than the 5032754X. But the price is also MUCH higher.

The diaphragm kit, D32D2430K is very much available (in-stock in the USA, as of this writing) and reasonably priced, for what it/they is/are. I haven't changed one so don't ask what is involved (I've yet to have the driver in my hand).

Has anyone measured or worked with both? Are they just two different part numbers for the same piece? Is the M2 version somehow different?

-Steve

[Dave Zan]

...Has anyone measured or worked with both? Are they just two different part numbers for the same piece? Is the M2 version somehow different?
Hi Steve

The difference in the M2 version appears to be that it is measured and selected from the D2430K run.
So it meets closer tolerances, proven to be within specification.
I suspect the odd price structure is because there is no specified replacement dia. kit for the M2 version.
Theoretically you replace the whole unit to maintain performance, because a field repaired unit would not be provably within spec.
So JBL seem to have reduced the mark-up on the M2 version to keep repair costs reasonable.
That makes the M2 version a nice deal if you can find them but the VTX unit should be fine, especially if you can test it yourself.

Best wishes
David

[ivica]

So has ANYONE found a difference between the VTX version of the D2 (product number D2430K) with a part number 446213-001X and the M2 version of the D2 (also product number D2430K) with a part number 5032754X?

I'm a cinema guy so my experience with the D2 is zero though at a friend's recommendation, I've begun a DYI M2 project (with matching SUB 18ish subs). I am a JBL certified reconer so I have access to parts and I can tell you that the 446213-001X is MUCH easier to lay one's hands on than the 5032754X. But the price is also MUCH higher.

The diaphragm kit, D32D2430K is very much available (in-stock in the USA, as of this writing) and reasonably priced, for what it/they is/are. I haven't changed one so don't ask what is involved (I've yet to have the driver in my hand).

Has anyone measured or worked with both? Are they just two different part numbers for the same piece? Is the M2 version somehow different?

-Steve

Hi Steve,

As You have said, You can compare the diaphragm prices for M2 and STX drivers, as I can imagine only the differences would be in the diaphragms.

regards
ivica

[sguttag]

I suppose this could be a reason for the long-lead times on the M2 version. If say only 1 out of 100 or even 1 out of 10 D2s meet the M2 tolerence, it would significantly lower the yield. If it doesn't measure within the M2 needs, slap a silver sticker on it and off to the general uses it goes. If it measures within M2 needs, gold sticker and goes to the smaller pile.

[Dave Zan]

...If say only 1 out of 100 or even 1 out of 10 D2s meet the M2 tolerence...

Or it could be that most of the production run meet M2 tolerances, JBL just need to be sure that a "reference" speaker meets its specifications.
Whereas small variations in an occasional driver would hardly make a difference in a line array with many drivers.
So it's a bit conjectural, no one has had the money to buy a batch of each and do a statistical analysis.

Best wishes
David

[sguttag]

Okay...my next question...

Has anyone determined the D2's sensitivity (on the M2 wave guide)? Preferably 1W/1m. And if so, what was the bandwidth measured? While I had my rig set up to measure the sensitivity of the LF section of the M2 (I came to about 93dB at 1W/1m, which is close to JBL's 92dB and since I'm not in an anechoic chamber, I'm probably going to be a little high due to room gain since my response was not flat when I pulled the mic back 1m (it was pretty flat close-miced). I'm coming up with about 101dB 1W/1m for the D2 on the M2 waveguide. Of course, with a 32-Ohm driver, it takes a bit more voltage to get to 1W than the average driver. Then again, with that 11-Ohm resistor across the driver, you are sort of capped at just shy of 3.5W to the driver.

I'm wondering if the 101dB 1W/1m estimate is good. I see on the VTX-V25, using an entirely different horn/waveguide, JBL lists it as 116dB 1W/1m but with three drivers playing...that implies that each driver is contributing just over 111dB to the SPL and that each driver is rated for 200-Watts. On the VTX-F12, we have a single D2430K, still a 200W power rating but JBL muddies the waters by claiming a 108dB 1W/1m but qualifies it as 2.83V at 3.3-feet. 2.83V into a 32-Ohm driver is 1/4-watt. My personal measurements of the D2430K is that it is indeed 32-Ohms. On the VTX-F12 Tech sheet, they are claiming 20-Ohms, which I think is as much a misprint as the 20-Ohm figure as well as the 2.83V figure because even in 20-Ohms is still only 0.4-watts.

So I'm still coming up with about a 7dB spread between the M2 waveguide with the passive network versus a seemingly straight up D2 with a 90x50 waveguide. I can believe that given that much of the power going to the driver in the M2 is going into a resistor.

Anyone take any more definitive measurements of it?

[hlaari]

Hi more10,

as I have remembered D2430K has 3.5-inch annular ring dual membrane,
and mentioned BMS 4599 has 3.5-inch annular ring dual membrane,
so just from that point of view they are very similar,
but the rest ( phase plug-s, VC coil weight , etc...) thing are not know (to me).

reagrds
ivica

are you sure about that?
I thought they were with dual 3" membrane

https://www.huss-licht-ton.de/images/products_download/Datasheet_14032_2.pdf
http://www.jblproservice.com/pdf/VTX%20Series/VTX-V25.pdf


Ari

[zgtsang]

The impedance and SPL are exactly the same

[Ian Mackenzie]

It depends on either a series or parallel connection of the D2 voice coils.

I extrapolated the following ref 2.83 volts

Series VC 104 db on the M2 horn
Parallel VC 110 db on M2 horn