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pos
07-02-2008, 02:26 AM
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 (http://www.audioheritage.org/vbulletin/archive/index.php/t-6653.html) called Antivibe (http://www.acoustiguard.com/pipesandducts/Dampingmaterial/antivibedl.htm)) 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/showthread.php?postid=1552226#post1552226

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

GordonW
07-02-2008, 04:52 AM
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/showthread.php?postid=1552226#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
07-02-2008, 09:45 AM
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
07-02-2008, 10:10 AM
Thanks Greg for responding and setting the record straight. I like what Aquaplas has done for my drivers.

Rob:)

spkrman57
07-02-2008, 10:15 AM
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
07-02-2008, 10:24 AM
My thank goes to Mr.Timbers as well.
And a delightful demonstration of the EVII showd me "no flaws". ;)
____________
Peter

4313B
07-02-2008, 10:41 AM
Thanks for the post Greg!


PS: Thanks to GT for providing his input. Many of us here hold his wisdom in high regard!Yep, he has certainly provided alot of us with many years of mighty fine transducer, filter and system designs.

cooky1257
07-02-2008, 02:06 PM
Does this Aquaplas'd improvement only apply to the Be and Ti dias or does it work on the aluminium 2441 dias too?
Cooky

4313B
07-02-2008, 02:13 PM
does it work on the aluminium 2441 dias too?Yes.

cooky1257
07-02-2008, 02:16 PM
Yes.

Thank you.
Anyone know a man that can.....?

GordonW
07-02-2008, 02:18 PM
some one should post this explication for mr lynn to read in diyaudio

I would wonder if Lynn Olsen is already familiar with the conclusions Greg Timbers noted from the JBL research, or not.

If not, then yes, it might be useful, in promoting discussion, to present it to him.

If so, then it may be an example of possibly "agreeing to disagree", or something of that sort... I've seen very talented speaker designers (sometimes all capable of fantastic products in their own rights) go seemingly diametrically opposed directions before... it can be bewildering sometimes. :dont-know


Regards,
Gordon.

speakerdave
07-02-2008, 02:34 PM
some one should post this explication for mr lynn to read in diyaudio

or he could listen to a 2450SL or whatever

Robh3606
07-02-2008, 03:10 PM
or he could listen to a 2450SL or whatever

Thank you! If he listened to a pair of coated drivers OK fine. To just apply textbook physics to say it was done wrong?? Come on. Talk about the tail wagging the dog, at least give it a listen.


Rob:)

Ian Mackenzie
07-03-2008, 02:19 AM
I really would not pay too much attention to what Lynn thinks and says.

He has after all by his own admission been outlawed by the audio industry for some of the things he has said and done over the years.

Guido
07-03-2008, 03:34 AM
I install aquaplassed dias in almost every speaker I build or upgrade. Not one of the people that own the speakers now wasn't completely satisfied with the sound.
So, who cares .......

pos
07-03-2008, 04:54 AM
Lynn's response:

Just saw the Greg Timbers (http://audioheritage.org/vbulletin/showpost.php?p=213900&postcount=3) post over at the Lansing Heritage forums.

I stand corrected - a 10 dB reduction in hash in the time domain decay characteristic is damned impressive, and especially noteworthy for metal-diaphragm compression drivers. If Aquaplas/Antivibe can do that, by golly, I'm a convert. 10 dB is a huge reduction and should be immediately audible within the first moments of listening. (By comparison, playing around with felt in strategic areas is typically only good for 3-5 dB of hash/reflection reduction, and is not as immediately audible.)

The reason I bring this up is that the time domain is the one area where compression drivers and horns are traditionally at their weakest, with significant amounts of delayed energy compared to the best direct-radiators. Of course, in terms of headroom and dynamic range, compression drivers and horn/waveguides have it all over direct-radiators.

Until very recently, that was always the hard choice - good time-domain performance with rapid decay characteristics, or outstanding dynamic range. Choose one or the other. Ribbons, electrostats, or ionic speakers in the first group, and compression drivers in the second.

It now looks like low-diffraction horns and waveguides, combined with appropriately damped compression drivers, will start to compete in the time domain with direct radiators - which is really good news for the entire audio industry. Something to look forward to.

P.S. If you think I'm emphasizing the time-domain decay characteristics, you're right. I'm with Newell and Holland on this one - the speakers with the most rapid, and resonance-free, decay characteristics are usually the best.
http://www.diyaudio.com/forums/showthread.php?postid=1553319#post1553319
:)

Here are some mesurement Widget did comparing a 435Be and a 2435 (albeit not a "factory new" one) :
http://www.audioheritage.org/vbulletin/showthread.php?t=6050&page=2#28

The 3rd harmonic are 20dB lower on the 435Be. The reasonshere can be the state of this particular 2435 (most probably, but the 2431 in the third graph shows similar results), the smaller back cap, and the lack of aquaplass.
Anyway it is quite a difference!

Rob also did some mesurement on an aquaplassed 035Ti (ala 053Ti)
http://www.audioheritage.org/vbulletin/showthread.php?t=14236&page=2#30
I don't know if this is the 2nd or 3rd harmonics that are shown here

Robh3606
07-03-2008, 06:06 AM
So, who cares .......

Hello Guido

I see bad information in the various audio forums all the time. I have been a participant in that thread for a couple of months and there has been a lot of negativity specifically about JBL in the thread. As Greg says everyone has a right to their opinion so I have ignored it unless it was factually incorrect.

With the Aquaplas everyone who has tried it, as far I know, liked what they heard. I know I did. When you have someone who is respected by many, what they type carries weight. Even if the information is not entirely correct. Many times it's just a quick, not well thought out response, that's not what we are talking about here.

In this case you have a "New Product" announcement made by a third party about the use of Aguaplas on compression driver diaphragms. This then goes on to say that JBL's method is "wrong". Now the person making the statement has no in depth knowledge about this materials application or use and has never listened to a driver with JBL coated diaphragms. With those last two points in mind I find it hard to hold my tongue.

To be fair from a pure physics stand point he is correct however we all know that good driver design is a balance of trades offs. Without in depth knowledge of the materials used and testing you don't know what the real effects are and they may not be where you would expect them. This happens to be the case in this situation. JBL has been coating diaphragms for what 20 years now? It obviously works and works well as we have all heard. I thinks it's great that it is being considered for use with classic Altec drivers as well.

Rob:)

Robh3606
07-03-2008, 06:07 AM
Lynn's response:

Well good for him.

Rob:applaud:

4313B
07-03-2008, 07:26 AM
there has been a lot of negativity specifically about JBL in the threadConsider the source...

With the Aquaplas everyone who has tried it, as far I know, liked what they heard.There have been a few people who couldn't figure out what to do with them afterwards but all in all I think most are pretty damn happy about it.

Robh3606
07-03-2008, 07:34 AM
At the very least, I could have been reading a nice book from the library instead.

You know your right. I think we are all a bit guilty of that from time to time. It's perfect weather outside, I have ton of stuff to do and here I am typing a response:blink:

Rob:D

Ian Mackenzie
07-03-2008, 12:51 PM
From the outset that thread for what 12 months now has been a blog of recollections. Olsen's immobilty means (as a result of an accident) he literarally cannot do much other than therorise about what may or may not be.

This was sighted quite early on when it was realised no hard data was being published to support some of the dialogue.

It will be interesting to see what his reponse is after auditioning the K2 at Ayre.