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pos
08-28-2011, 10:26 AM
Here is a set of measurements I made of the Truextent Be4016 beryllium dipahragn (16ohm version) in a 2450SL core (1.5") on the rectangular 90x50 PT waveguide (PT-F95HF).
For comparison purpose the measurements also include other JBL OEM diaphragms.

All measurements were taken under the exact same conditions:

- dayton mic calibrated by cross spectrum
- mic at ~40cm from the horn mouth (not far enough to get a meaningful response curve, but ok for comparison purpose), exact same position for all measurement
- Studio Projects VTB1 V preamp ("tube blend" turned off)
- creative labs sound card (line level), not calibrated
- holmimpulse software in sweep mode
- Ev dx46 active crossover in digital input mode, no eq or filter except a FIR HP at 600Hz (no influence on phase)
- Ram-audio S4044 power amp set to a very moderate SPL
- 75uf protection capacitor (shall not have much influence on phase above 1.5khz, even for the 8ohms diaphragms)
- PTF-95HF horn (no really usable under 1khz, so only the HF response can really be compared)
- 2450SL core (1.5" coherent wave phasing plug, 4" diaphragm, neodymium motor)

The diaphragms under test are:

- JBL D8R2450SL (2450SL): 8 ohms 4" Titanium diaphragm without ribs but with aquaplas, used in the 2450SL, 2452H-SL, and 475nd
- JBL D8R2450 (2450Ti) : 8 ohms 4" Titanium diaphragm with ribs, used in the 2446H/2450H/2451H
- Truextent Be4016 (2450Be) : 16 ohms 4" Beryllium diaphragm

The 16ohms truextent diaphragm was of course given 3dB more level in the active crossover, so every diaphragm received approximately the same wattage, as is confirmed by the fact that the levels are matched in the low end.

As you will see the measurements do track the ones found in the Truextent white paper quite well:
http://www.audioheritage.org/vbulletin/showthread.php?30412-Truextent-White-paper-for-Large-Format-Diaphragms&p=305351#post305351


In a second set of measurements, post #4, the 2450Be is compared to a 2435HPL

pos
08-28-2011, 10:27 AM
amplitude
52647

phase
52648

noise
52649

THD
52650

2nd harmonic distortion
52651

pos
08-28-2011, 10:27 AM
3rd harmonic distortion

52652


impulse comparisons

52653

52656

52654

pos
08-28-2011, 10:28 AM
Hereafter is a second set of measurement, taken under very similar condition as the first one, this time comparing the 2450SL with Truextent diaphragm (2450Be) to a not aquaplassed 2435HPL (2435).

Note: it is well known that the 2435 short phasing plug has a "problem" with the PT-F95HF that results in a dip at ~13khz (as well as very poor off axis behavior). This problem does not exists (or to a much lesser extend) on the H9800 and some other horns (the off axis behavior remains bad in the UHF tho, because of the 3 slits phase plug)

amplitude
52657

phase
52660

2nd harmonic distortion
52659

3rd harmonic distortion
52658

impulse
52661

Mr. Widget
08-28-2011, 03:02 PM
Cool... any other horns on the horizon?

Widget

pos
08-28-2011, 03:50 PM
I have pairs of 2332 and H9800 that I will also try to measure (but probably only with the Be, and not the other diaphragms anymore).
I chose the PT waveguide as it was the most well behaved in the HF, and the most representative of the natural behavior of the driver.
The H9800 will probably be the horn I will use in my final system.

Jan Daugaard
12-09-2011, 02:11 AM
Concerning SPL, you only state that the amp was "set to a very moderate SPL". Could you be more specific? 2nd and 3rd harmonic distortion vary greatly with SPL.

pos
12-09-2011, 02:37 AM
Sorry I do not have any absolute SPL figure. All I can say is that it was equal for all drivers, so it can be used for comparison purpose.

jf65
12-09-2011, 07:37 AM
Now, what conclusion can you draw from these measurements? Maybe i'm not right, but to me they seem much alike, at least until 12000 Hz. What happens above is very chaotic for each diaphragm. It would be interesting also to see how they behave from 500 to 1000. I say that because i have 2445 between 600 & 8000 and i'm flirting with the idea of putting Be diaphragms - collecting information about them .
Best regards, jean

Robh3606
12-09-2011, 09:21 AM
Hello pos

How much smoothing are you using?? Is that 1/6 octave?? I always liked the 2435 on the PTH1010, always seemed to work better than the other PT's

Rob:)

richluvsound
12-09-2011, 01:14 PM
I look forward to seeing the Be H9800 plot ... Btw , are those ones you showed when you were here .... ?

Have a wonderful Christmas Mr and Mrs Pos

pos
12-09-2011, 01:21 PM
Now, what conclusion can you draw from these measurements? Maybe i'm not right, but to me they seem much alike, at least until 12000 Hz. What happens above is very chaotic for each diaphragm. It would be interesting also to see how they behave from 500 to 1000. I say that because i have 2445 between 600 & 8000 and i'm flirting with the idea of putting Be diaphragms - collecting information about them .
Best regards, jean

The Be has a ~3dB advantage in the midband compared to the Ti and Ti SL. That means it needs half the power to get as loud as the others, wich translates into less power compression and better dynamic.
The Ti diaphragm has nasty breakup peaks around 12khz and 17khz.
You can also look at the impulse responses (and imagine the resulting CSD). The SL is the smoothest, and certainly the most cost effective solution, but the Be sounds much better.

With a 2445 you have an older phasing plug, so maybe you would not benefit that much of the SL or Be diaphragms?...

pos
12-09-2011, 01:23 PM
Hello pos

How much smoothing are you using?? Is that 1/6 octave?? I always liked the 2435 on the PTH1010, always seemed to work better than the other PT's

Rob:)No smoothing per se. It is a gated response, around 600Hz, so the response gets more precise as precision rises.
One PT waveguide I would really like to try (with the 2450Be) is the square 95 one,to get a better vertical directivity control than the rectangular one!

pos
12-09-2011, 01:26 PM
I look forward to seeing the Be H9800 plot ... Btw , are those ones you showed when you were here .... ?

Have a wonderful Christmas Mr and Mrs Pos

Yes I will do these measurements also!
I don't remember which measurement I showed you in London :dont-know:
Merry christmas to you Rich! :bouncy:

JeffW
12-09-2011, 05:29 PM
I swore that 1audiohack did some plots with the Be 'phragm in a 2450 mounted to the Woody Horn (sort of a Yuichi A290 which is sort of a TAD TH4001 IIRC), but I haven't found it.

wrager
12-18-2011, 04:07 PM
Will the 4088 be a replacement for a 2430?

jw5115
12-21-2011, 02:32 PM
Any JBL 2" format driver (except 2480,2482) will sound better, smoother , more detailed;
Than any Alum. or Ti. fitted driver PERIOD Field coil versions of the truextent 4" and 3" 2435 dia
are even better. Unless you are committed to a "vintage" sound .
The driver/horn combo must remain the same in your comparisons.
Frequency graphs will show "smoothness" but give no indication of detail,attack and decay,
which are all a part of proper music reproduction
jw5115

pos
01-16-2013, 02:10 PM
A little update with a more recent measurement comparing a 2452H and a 2450SL with truextent diaphragm on a PT-F95HF waveguide.

It should be more reliable than the measurements on the first page because the noise/distortion coming from the amp has been minimized to have no impact on the measurement (using an autoformer or a Lpad, can't remember...).
It is the 3rd order harmonic distortion only, as my mic is not good at measuring 2nd order harmonic distortion...

57956 (http://img11.hostingpics.net/pics/3195202452Hvs2450Bedisto.png)

Mike Caldwell
01-16-2013, 05:16 PM
Here's a link to Vue Audiotechnik and their info article on using Truextent diaphragms in their latest products.
http://www.vueaudio.com/about/beryllium/

Champster
07-22-2014, 08:22 PM
Here's a link to Vue Audiotechnik and their info article on using Truextent diaphragms in their latest products.
http://www.vueaudio.com/about/beryllium/

I had an opportunity to get a personal tour through VUE with Ken Berger, CEO. What a great guy and cool business. I wish I could work there... What great products too. Their DSP systems are killer. They have an isobaric sub with 4 - 18" drivers that I would love to try out at home. They are the only Pro company using Be as far as I know and, based on their growth, it sure looks like that gives them a great competitive advantage over the other guys.

grumpy
07-22-2014, 10:47 PM
"They are the only Pro company using Be as far as I know"

I can think of at least one other... :D

speakerdave
07-23-2014, 01:24 AM
Two.:)

Champster
07-23-2014, 08:55 PM
"They are the only Pro company using Be as far as I know"

I can think of at least one other... :D


Two.:)


You're both so cleaver. Care to share?

Mr. Widget
07-23-2014, 09:29 PM
You're both so cleaver. Care to share?
Well... they both use three initials for their names. ;)


Widget

Mr. Widget
07-23-2014, 09:32 PM
Oh, what the heck... TAD and JBL.

Since the mid '70s TAD had something of a monopoly on Be in the Pro world, but in the last decade JBL has stepped up. Heck, if they hadn't I'm pretty sure the higher end JBLs and even the Revel tweeters probably wouldn't be made of pure Be foil.


Widget

grumpy
07-24-2014, 06:43 AM
Then there were the Yamaha NS-series monitors...

hint of snark perhaps due to this being a JBL forum where many would have been exposed to the use of Be in TAD and JBL drivers.

...so, I'll take the cleaver.

Champster
07-24-2014, 08:01 AM
Then there were the Yamaha NS-series monitors...

hint of snark perhaps due to this being a JBL forum where many would have been exposed to the use of Be in TAD and JBL drivers.

...so, I'll take the cleaver.


Hey this is a hobby. We're supposed to be enjoying this and I love the snarky responses. It makes the discourse more entertaining...to me.

However, in my defense, I think the, "as far as I know" phrase was my out. And when I use the term "professional" I mean professional venues. Not home audio using Pro gear. Granted, TAD was an oversight. Of course I know that they play in the Pro space. However, re JBL, and again, to the best of my knowledge, JBL has never used a Be phram in a commercially available Pro box. Is that true or false? If so why haven't I found it within all the collective wisdom in these pages and what is the part number?

grumpy
07-24-2014, 08:40 AM
Here you go :) :

2435H

Tech Sheet
http://www.audioheritage.org/vbulletin/showthread.php?14369-2435h

Pro Example
http://www.jblproservice.com/pdf/VerTec%20Series/VT4889ADP-ANCNDA.pdf

Champster
07-24-2014, 10:44 AM
You guys are a great resource. So I learned something (else) new today...

Was/Is the 2435h a commercially successful effort? Is it (with a Be phram) still available? I've read how well regarded the 435Be is, but does the 2435h share the same praise?

I purchased a few TruExtent phrams on my visit to VUE. So now I have a pair of 2446h with the original Ti ribbed phrams, a pair of TAD 4001's with Be and the TruExtent Be phrams for the JBL's to play with in my homebrew DIY system... That is, after I get past all of this woodworking.

Thanks again! You guys are great!!!!

martin2395
07-24-2014, 02:04 PM
Then there were the Yamaha NS-series monitors...

hint of snark perhaps due to this being a JBL forum where many would have been exposed to the use of Be in TAD and JBL drivers.

...so, I'll take the cleaver.

I have a pair of those Be loaded Yamaha NS1000M studio monitors. Sometimes you could think that there is something wrong with either the speakers or your source / amp as they are amazingly revealing, certainly not for everyone's taste.

BTW, I'm not sure if it's Be or aliminium with Be on it.

SEAWOLF97
07-24-2014, 03:06 PM
I have a pair of those Be loaded Yamaha NS1000M studio monitors. Sometimes you could think that there is something wrong with either the speakers or your source / amp as they are amazingly revealing, certainly not for everyone's taste.

BTW, I'm not sure if it's Be or aliminium with Be on it.

I've got some Yammy's with Be HF too , in an L100 type config ...the HF dias are green, I think ....

(found a pic, yes they are)

And yes, they are very revealing ...;)

cooky1257
07-25-2014, 03:06 PM
Love my NS 1000M's too. I thought they were vapour deposited Be mid and tweet? Either way they are incredibly revealing speakers
and a bit of a bargain s/h.

richluvsound
03-13-2018, 11:54 AM
Hi Pos,

Did you ever publish the graphs for the 2450/be h9800
combo ?

Thanks , Rich.

pos
03-13-2018, 01:36 PM
Hi Rich,

Here is the TD4003 vs 2450SL-Be on the H9800 clones.
Both are 16 ohms drivers.
Note that the TD4003 has a 39mm exit and the H9800 is a 38mm horn, which might be responsible for some defects (9kHz?).

80448