Truextent Beryllium replacement diaphragms

[angeloitacare]

Truextent has a wide range of Beryllium replacement diaphragms with proprietary polymer suspension. Someone already tried these diaphragms ?
I would like to know particularly, how their replacement diaphragm for Radian 950pb performs. If some kind of improvement compared to the original diaphragm could be expected.

http://www.truextent.com/sign.phtml

http://www.electrofusionproducts.com...mDiaphragm.pdf

[Pano]

It would be interesting to hear them. Also interesting to see measurements on the same horn and in the same driver compared to the aluminum and titanium 'frams. Not just FR, but also harmonics, decay, impedance.

[EarlK]

There are some comparitive FR plots ( residing over at LHF ) .




<> cheers


ps ; The plots are all highly smoothed .

[kevinkr]

The Truextent diaphragms have been widely discussed on Lansing Heritage. I'd take a look over there. Whilst I have not heard them yet myself, they seem to be well received there and elsewhere. Unfortunately the Truextent diaphragms are really expensive, however if you don't like them there may be a good chance of reselling them eventually.

My understanding is that Radian's diaphragms are amongst the better ones out there, but may not be everyone's cup of tea. I guess the objection arises due to the polymer suspension used on some radian diaphragms - some people like that sound, but others don't.

I've got JBL 2440 drivers with JBL D16R2445 titanium diaphragms installed - widely considered to be the least desirable diaphragm choice in this driver, but they sound quite good. I am considering the purchase of a set of Radian 1245-16 at some point as a potential upgrade. The Truextents are beyond reach for now anyway..

Horn geometry might be a red herring, but nonetheless you might want to be sure that the horns you are using are not responsible for the issue you are having. Lately I have tried 16.5 x 5.5 exponentials, 350Hz Edgar Salad Bowls, and JBL 2397 Smith Horns - all sounded distinctly different, and even with the Ti diaphragms the 2397 sounds smooth, detailed, and well tonally balanced. Images well too. The Edgars on the other hand were more like searing laser beams in my modest room, and didn't image quite the way I expected them to, and the exponentials were a little harsh at times, but are a better compromise tonally and wrt to imaging IMHO in my room when compared to anything except the 2397..

So what horn have you got attached to your Radian 950B CDs?

[Pano]

Thanks Earl! OK Kevin, I'll look on the Heritage site.

[bear]

Assuming they are taking advantage of the mass benefit to the beryllium, I'd expect somewhat better HF results. But, the 288 is not particularly good up high to begin with... I have seen some response curves for the 288 that are at odds with some 288 curves I have seen posted, not sure if perhaps the ones I have seen are actually equalized? But the 288s I have measure all looked like convex curves with the high point around 1.5khz if memory serves...

I have yet to hear a 288 that I wanted to listen to for long... of course that is subject to update, if and when that happens...

Kevin, consider the LeClerch design for a horn... or even the Geddes idea...

i think the JBL drivers are also problematic, as they share the same heritage and not much divergence from the original (Wendt?) Western Electric design that gave birth to All Technical and then JBL...

Of course in theory the beryllium diaphragms ought to have less breakup modes, but at the levels we typicallyl (I think) run at, it may or may not be terribly audible...

But then again, everything seems audible, eh?



_-_-bear

[Robh3606]

i think the JBL drivers are also problematic, as they share the same heritage and not much divergence from the original (Wendt?) Western Electric design that gave birth to All Technical and then JBL...

Not the newer ones. Different phase plugs and no throats.

Of course in theory the beryllium diaphragms ought to have less breakup modes, but at the levels we typicallyl (I think) run at, it may or may not be terribly audible...

You can hear it just fine at the levels we use.

Rob

[bear]

Rob, I have not heard the newer neo JBLs...

My opinion is that what you are hearing in the 288 and similar speakers may not be the diaphragm breakup at all... others have other opinions.

_-_-bear

[more10]

I sent a message to Materion using their web form , asking for information on Truextent for Radian and Altec drivers with 1,75 inch voice coils.

I got an answer within 24 hours. They will release a diaphragm with 1,75 inch voice coil for Radian drivers in january 2013. I really hope this is not confidential :-).

This e-mail and any attachments are provided for the sole use of the intended recipient(s), and may contain information that is confidential, privileged, proprietary or otherwise protected by law.

[LineSource]

The Altec forum measurements(fig 1) match data from several other sources. Aluminum and Titanium diaphragms have break-up modes between 10KHz and 15KHz, but beryllium does not typically break-up until above 18Khz, and usually only above 20Khz. This SPL data shows the more extensive break-up of titanium over aluminum diaphragms.

The general viewpoint on the Altec forum is that a beryllium diaphragm has little value with a 2" exit compression driver because the 4" mechanical diaphragm plus phase plug frequency limit is below 10Khz, especially when distortion is also considered. Aluminum diaphragms typically do not start break-up until above 10Khz.

The general viewpoint on the Altec forum is that the $400+ expense of a Be diaphragm is probably only justified for a 1.4"-1.5" CD to remove Al/Ti 10K-15Khz break-up distortion, or marginally valuable for a 1" CD to avoid break-up distortion until over 20Khz(example: TAD 2001). High frequency boost compensation can now extend a flat response to near 20KHz.

Today there are plastic compression driver domes, as well as robust plastic suspensions with aluminum domes. This allows a 1" compression driver to be used at low home SPLs down to 700Hz, and cover up to 20Khz. For my home DIY experiments, these wide BW 1" CDs are the most interesting.