Hello,
is it possible to change the alluminum diaphragm in the 2441 driver with the TRUEXTENT beryllium dia´s without changing the 3155 crossover?
As the 2405 covers all frequencies above 10khz, is their any real benefit in the beryllium diaphragms anyway?
I don`t need extended freq-response, so is it worth it ?
Is beryllium that much superior to the alluminum D16R2441 diaphragms ?
Thanks a lot,
Olaf
The aluminum diaphragm is what you want! Don't change anything!Originally Posted by Dr.db
C
I went down this road with my 4350's. I loaded a second pair of 2440's with TruExtent diaphragms and loaded them in the cabinets with another pair of 2405's. I honestly could not hear the difference swtching side to side. I left them fully loaded for a couple of months and finally took them out.
In a better horn they are an audible improvement to me but in the 2311/2308 they are not discernibly different.
Barry.
If we knew what the hell we were doing, we wouldn't call it research would we.
From local JBL pro re blind-fold A-B: "Yes, they are better, but the difference is extremely subtle. Thing is, there are many things you can do with your system to improve performance more. Once you get everything else perfected, this might be a consideration . . . but it is certainly is NOT worth the money." He recommends the 2441. Mike
What I would do though, is to update your crossover. I'm not a fan of coupled at all but it's up to you!
C
Yep. I purposely built my 3155 in non-cc configuration, fully intending to "upgrade" and then report the results (One test is worth 1000 expert opinions). Thing is, it sounds good enough that I largely lost interest in the test! Higher priorities. Kind of like the Be diaphragm thing (post #4 above).
Hmm. I experimented with beryllium and aquaplas dusted diaphragms for the treble in my 4345's, which uses the horn for basically the same frequency range as the 4350/55. One thing I never got around to trying was new aluminum diaphragms. I heard improvement with both the things I tried. However these were not controlled experiments because there were other changed factors. That is the beryllium was in TAD 2001's and the dusted diaphragm was in the JBL 2450. I was messing around with this because I wasn't liking the tizzy tizzy I was getting from the treble. When I turned the horn down enough to make it tolerable the image, which was never very well defined in the 4345, had disappeared into the speakers. This problem went away with both of the alternate drivers. The larger diaphragm in the 2450 probably inherently has less distortion, and of course both alternate drivers have different phase plugs. Still, I think the relevant factors are something else. First, the mass break point for both titanium, the material in the dusted diaphragm, and aluminum are within the relevant range. That of beryllium is outside it (above). The aquaplas dusting dampens the rattle in the material, but it adds mass. The beryllium is not only not rattling, but it is also lighter than the other materials, so it will follow the waveform of the signal more accurately. This is an advantage over the whole frequency range. HF extension is a secondary benefit. The irritation of the tizziness was gone with both materials, but the beryllium had the added benefit of greater accuracy as well. The audible effect was what some listeners call greater inner detail, which opens up the music considerably, especially with complex sound such as orchestral music. I wouldn't characterize the differences I was hearing as extremely subtle. They were quite evident and identifiable.
Anyway, that's my theory. I settled on the beryllium.
"Audio is filled with dangerous amateurs." --- Tim de Paravicini
I did some experiements on the 4345 also.
I had similar finding with the dusted titanium 2425 over the non non dusted 2425.
I preferred however the overall presentation of the non dusted 2425 with the stock 3145 network. It seemed to voice more coherently.
The Tad 2002 however voiced correctly in the stock 4345 network.
The horn is tightly controlled in the passband so the Tad is just doing a better job.
I agree the dusted driver lacks some spatial dynamics and can sound recessed compared to the agressive sparkle of the non dusted driver. Its kind of mellow.
I put this down to the Tad being a more refined driver than the 2425.
In the 4344mk11 network the dusted driver is setup up to run almost full range and the 2405 voltage drive is different. The transition is blended well. The voicing with the dusted driver is spot on.
So l think the system needs to be voiced accordingly to get the optimal results with dusted drivers.
This all goes back to Floyds subjective listening and subjective measurement theory. Greg and his team were ahead of their time in the way they were able to emperically voice these amazing heritage systems.
The business effectively ended an era with a self inflicted orbital lobotomy when they sacked Greg.
I'm glad you mentioned the stock 4345 network, because it might be important. Some of us involved with these experiments wondered why we were getting away with substituting an 8 ohm TAD for a 16 ohm JBL and thought it might have been the tapped inductor in the treble shelving circuit. Just a guess, I would say. Of course, that is not present in the DIY versions.
"Audio is filled with dangerous amateurs." --- Tim de Paravicini
DIY M2
Seriously...
Send that stuff to Japan, get a bag of gold for it and pick up the M2 components.
There is nothing to be a fan about. As both Ed Meitner and Greg Timbers have maintained, it is a valid topology. I am aware of the fact that there are numerous people against the practice but nobody that matters cares. We are talking about guys that use a notch above state of the art gear that costs tens of thousands of dollars.
It is like the Be diaphragms, simply put, most folks systems and hearing won't be able to take advantage of the increased performance. The truth is that the Be diaphragms are a SIGNIFICANT improvement over any other material, including Mg. If a person can't hear the difference then YEE HAW! They just saved a bunch of money arguably better spent on beer.
At this point in time I would just leave these legacy systems as they were originally designed. If they no longer do what you want them to do then move on.
Another one of G.T.'s neat ideas based on his R&D.
With the D2430K at the ridiculously low price it is, dusting legacy diaphragms is a thing of the past.
Thanks all for your replies, very appreciated!
Would there have to be any changes to the 3155 crossover when using the Truextent dia´s in your opinion ?
One thing that I've never seen addressed is the polarity of the TruExtent. They sell the same diaphragms to fit many different drivers, even different brands. But some of those drivers - even within the brand in JBL's case - have different polarity. Probably only matters with drivers already installed in a system, a raw driver could just be hooked up red to + and confirmed with measurement. But what about swapping a -SL diaphragm from a 2450SL (negative polarity/red to -) into a 2452 (positive polarity/red to +) or replacing the stock diaphragm in a 2450SL/2451/2452 with a TruExtent? The 2440 pdf doesn't mention which way the 2440 is wired.
I didn't see the list of drivers supported on the TruExtent website any more, but OCS is showing them to drop in fit the negative polarity drivers, as well as 2440 and 2441.
Anyway, just something to consider when swapping diaphragms.
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