Any experience with aftermarket diaphragms from orange county speakers?

[pos]

Does anyone have experience with these type of aftermaket 2426 diaphragms (http://www.speakerrepair.com/page/product/JBL-Diaphragms/10-925.html) from orange county speakers?
These are said to be made "to JBL specs"...

Considering current D16R2425 pricing (http://www.speakerrepair.com/page/product/JBL-Diaphragms/10-253.html)these look like an interesting alternative...

Measurements, opinions, rant, anything would help :D

[fpitas]

Hi Thomas,

I haven't heard those, but a friend is using these:

http://www.parts-express.com/radian-1225-16-diaphragm-fits-most-jbl-1-16-ohm--294-722

To my ear, they're very good sounding. Obviously they're aluminum instead of titanium, but to me that's a plus for home use. His response measurements were very similar to those in the 2426 datasheet.

Francis

[pos]

Hi Francis,

Thanks!
I have heard good things about the Radian, probably the best replacement (and alternative) for DIY as you say.

In the present situation the replacement would ideally be used with an unmodified passive network, so the response and impedance curves have to be as close to the original as possible. I am not sure the Radian would fit the bill but I'd be curious so see measurement comparisons.

The price is on par with the unknown aftermaket diaphragm from OCS, and the review in the part-express page (http://www.parts-express.com/radian-1225-16-diaphragm-fits-most-jbl-1-16-ohm--294-722) certainly looks encouraging:


Sounds Better Than OEM JBL Diaphragm, IMHO...


I have successfully replaced around 1/2 dozen OEM JBL diagrams in JBL horn drivers. I sweep them at 500Hz to 1Khz while carefully tightening the mounting screws to insure the voice coil is not rubbing along with the rest of the replacement procedures. We had a pair of JBL 4430 studio monitors in the audio lab at RCA in Indianapolis. They sounded wonderful and I still consider that model my personal listening reference for all my audio work. The 4430's horn driver used a diaphragm that this item replaces. Anyway, I have a pair of the 4430 horn and drivers in current use in a larger room used for live performances. I have tried everything using all JBL OEM drivers, but I just could not get the rich smooth sound I remembered from the studio monitors. We lost another diaphragm recently due to microphone feedback. A vendor recommend I try this diaphragm as they are reportedly a bit more sturdy and smooth sounding than the OEM JBL. I was very reluctant to move to a different brand than JBL, but I just installed one of these. In my opinion, this diaphragm duplicates the rich and smooth studio monitor sound using the clean analog source material with the built in analog crossovers built into the 4430's. I am very pleased with the sound of these diaphragms. Snare drums have sharp and accurate attack and sound very real. Vocals are smooth and pleasing. I have not run pink noise on these yet compared to the OEM JBL diaphragms, but I will certainly log the difference in my notes for future reference. I recommend using this model compared to off brand replacements if one is looking to save money. Again, in my opinion, these sound better than the OEM JBL replacements. -hightechhick


another one from the 8 ohms version page (http://www.parts-express.com/radian-1225-8-diaphragm-fits-most-jbl-1-8-ohm--294-720):


Great Upgrade for Ti 2425/2426 JBL 4430/35s


If you have speakers that use JBL 2425 or 2426 horn drivers, you probably know that the diaphragms are titanium, and that the earlier 2421 Alnico drivers had aluminum diaphragms. The AL diaphragms are sought-after, and widely considered to sound smoother, with less distortion, than the Tis. But unfortunately, their surrounds are also AL and over time they fatigue and can fracture. They also handle less power, which is why JBL switched to Ti, following a very embarrassing public fiasco where a bunch of their PS systems failed at the Academy Awards (R), or so I have read.
This situation would leave one with a choice of smoother, but weaker and more expensive (AL), or harsher, but more robust (Ti). Miraculously, though, Radian has stepped in with an AL diaphragm that has a robust Mylar (R) surround, combinging the best of both worlds. I just installed them in my JBL 4430s, with 2425 drivers, and the installation was a basic drop in. (word of warning: Control all ferrous metal fasteners and wires to prevent damage to the diaphragm from magnetic attraction, and replace the gooey foam in the back cap with felt. Also pay careful attention to the order in which the fasteners and terminals are stacked in terms of rubber and metal parts, and maintain the OEM polarity, with green or red indicating positive on the diaphragm).
The DC resistance of the diaphragms is about 3.1 ohms (stock Tis was 4.1) but based on what I;m hearing and the graphs published by Radian, the output seems to be very equivalent. As compared to the Tis, though sound seems smoother and less compressed at high output levels; it really opens up these speakers and smooths them out. And if you call up Radian, as I did, you may be able to speak directly to the engineer who builds these things; he gave me tons of interesting details regarding their construction, and I gather that their team includes ex-JBL and Altec engingeers who continue to build drivers in Orange County, CA, and Radian claims that it it the only remaining US-based driver manufacturer in the world (!).
In sum, I say, there are a remarkable value.


If it is similar enough to the original to fit a 4430 (after sorting out the 8 vs 16 ohms contradiction between those two reviews...), then it should be more than good enough for a 434x...


Thomas

[fpitas]

Thomas,

His measurements were on a 511B horn, and he didn't measure with the titanium diaphragm, so there was no direct comparison. The overall shape of the response was very similar to that in the datasheet, but if you are locked into a particular EQ network there's no guarantee it won't need tweaking. Of course, that can be said of almost any aftermarket diaphragm.

Francis

[pos]

That is definitely worth the test :D
I will report back here...

[martin2395]

The Radians are much smoother and fuller sounding, also more laidback but you don't lose the detail in music.

[more10]

I am very happy with my Radians in 2420 drivers on 2370 horns.

[fpitas]

FWIW, I found this old thread about Radian diaphragms:

http://www.audioheritage.org/vbulletin/showthread.php?31988-JBL-4425-Questions-JBL-2416H-vs-RAdian-1225-8

[pos]

Thanks Francis, I was looking for that particular thread I remember reading long ago, but could not find it!
I'd be curious to know what tweak Barry did to the diaphragms.
Could be simple alignment work, but I think I also heard about some more involved tweaks with these Radian diaphragms (and drivers) ...

[pos]

martin2395, mor10, did you compare them directly to the original JBL drivers?
Did you by any chance measure their respective responses?
Were you using the original passive network with them?

[fpitas]

Thomas,

Getting them properly installed takes a few minutes. My friend and I used a function generator set to about 1kHz, and swept the frequency up and down while gently moving the diaphragm around until the tone was clear, then tightening the mounting screws. That procedure was recommended by Radian for best results. It's easier and quicker than it sounds. The output from a computer sound card could also be used.

Francis

[more10]

Thomas. I didn't compare with JBL diaphragms. I have not made any comparing measurements.

[martin2395]

No I had not compared them to original aluminium JBL's. Only to beaten up smooth Ti's and I liked the Radians more.

The 2441 drivers have alignment pins so there is nothing to align by hand, they just fit. The latter drivers are a bit more tricky, 2450 for example. I still have to test it on 1KHz but I don't have the motivation to remove the front baffle of my 4343 again and again and again, last time I already dent one dia when my hand slipped with a screwdriver.

[more10]

Martin, the thread is about diaphragms for on inch drivers.

[martin2395]

Of course but I think that the sound difference between the JBL dia's and Radians will be the same for both sizes.

[pos]

Here is the kind of problem I was thinking of: http://www.diyaudio.com/forums/multi-way/100392-beyond-ariel-1217.html#post4129886

[fpitas]

Thomas,

That discussion seems to be about the design of the Radian drivers, not the diaphragms. Unless I'm missing something.

Francis

[pos]

It seems to be (partly?) related to the surrounds:

I know one trick that was often used on the older Radian drivers was to punch holes in the Mylar surround used on those Radian drivers, the Mylar is too stiff and non linear in the way it is used.

[fpitas]

Well FWIW, when we measured the 2426 with Radian diaphragm using a 511B horn, there were no upper frequency notches.