Lynn Olson's comment on aquaplassed diaphragms

[pos]

Lynn's response:

Just saw the Greg Timbers 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/showt...19#post1553319


Here are some mesurement Widget did comparing a 435Be and a 2435 (albeit not a "factory new" one) :
http://www.audioheritage.org/vbullet...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/vbullet...4236&page=2#30
I don't know if this is the 2nd or 3rd harmonics that are shown here

[Robh3606]

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]

Lynn's response:

Well good for him.

Rob

[4313B]

there has been a lot of negativity specifically about JBL in the thread

Consider 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]

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

Rob

[Ian Mackenzie]

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.