Lynn Olson's comment on aquaplassed diaphragms

[pos]

I found this interesting comment from Lynn Olson on the diyaudio.com forum about the aquaplassing of compression drivers diaphragms:

One of the things I'll be mentioning to Great Plains Audio is applying Aquaplas (now called Antivibe) to the tangential surround of the aluminum compression driver diaphragm. JBL applies Aquaplas/Antivibe to the whole diaphragm when you buy a 435Be, but I feel this is a mistake. The part of the diaphragm with the most chaotic radiation is obviously the surround, and it's an area where mass-damping and outright suppression of radiation is desirable. That is NOT true of the diaphragm dome, where low-as-possible mass and uniform emission into the phase plug assembly are primary goals. Raising the mass of the diaphragm is extremely undesirable, since it depresses efficiency and decreases HF extension.

Since the dome of the diaphragm and its surround operate in completely different ways, and in fact have completely different functions, it only makes sense to treat them differently, rather than applying damping goo to the whole thing. Adding a bit of mass damping to the surround seems like a good idea, and is likely to improve the mechanical termination between the moving diaphragm and stationary mounting ring.

http://www.diyaudio.com/forums/showt...26#post1552226

Has anyone here tried to aquaplass only the surround of a diaphragm?

[GordonW]

I found this interesting comment from Lynn Olson on the diyaudio.com forum about the aquaplassing of compression drivers diaphragms:


http://www.diyaudio.com/forums/showt...26#post1552226

Has anyone here tried to aquaplass only the surround of a diaphragm?

This sounds similar to the rationale that Renkus used, when creating the Symbiotik diaphragms for Altec. A different material combination for the surround, to damp vibrations...

However, as that project proved, this idea is sometimes harder to do, than to talk about. IME, Radian finally "got it right", with their implementation of that idea... so, it can definitely work...

Regards,
Gordon.

[gtimbers]

Everyone is entitled to his opinion, however, we have hard measurements in addition to much subjective listening that shows that the application of Aquaplas to the metal diaphragm of our compression drivers improves the sound. There is a slight additional HF roll off which is introduced but we can normally equalize it out in the network. Even the Beryllium diaphragm improves. The effect is in the time domain and does not show up in simple response and harmonic distortion measurements. We have seen up to a 10 dB reduction in hash on ETC measurements. The sonic effect is an increase in detail and smoothness coupled with a reduction in harshness.

Applying the treatment to the surround can often help also. Unfortunately, the sensitivity loss can be greater due to the large area of the surround. The hash reduction is not realized when the surround is treated, although sometimes there is a small response improvement.

[Robh3606]

Thanks Greg for responding and setting the record straight. I like what Aquaplas has done for my drivers.

Rob

[spkrman57]

If you go to the trouble of having diaphrams "aquaplas'd" I would think it would not be worthwhile to only treat the surround.

As GT mentioned, JBL did extensive testing and treating the entire diaphram is a definite improvement.

Regards, Ron

PS: Thanks to GT for providing his input. Many of us here hold his wisdom in high regard!

[Hoerninger]

My thank goes to Mr.Timbers as well.
And a delightful demonstration of the EVII showd me "no flaws".
____________
Peter