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Thread: Diaphragm Damping Agents

  1. #46
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    Quote Originally Posted by Robh3606 View Post
    The second file with the Aquaplas is about 1db lower in amplitude.
    G.T. does two thin coats of aquaplas diluted with water using a modeler's paint brush. One should see a drop of about 1 dB at the top end.

    I use the same method as G.T. but then I hit each coat with a water mist to create a nice uniform coat. That just seems to work best for me personally. D.S. was concerned that any kind of manual method could cause pooling and I am extremely conscious of his concern. For concave surfaces one should wick away any pools that might form. As both G.T. and D.S. have stated, done correctly, there should not be a measurable night and day difference. I believe they were referring to a typical response curve. The resonant frequencies should shift downward somewhat but nothing dramatic.
    Quote Originally Posted by Robh3606 View Post
    Giskard could you please post a before and after if you have them. I don't know if the aquaplas sample I have is the same exact material as the real deal you use. I added pigment to mine to make it black. I would love to see if our measurements show the same changes.
    I suppose. It should probably be done on a PWT and I don't care enough to whip one up just for this. Of course we're also talking about a ferrofluid recharge here too so...

  2. #47
    Administrator Robh3606's Avatar
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    G.T. does two thin coats of aquaplas diluted with water using a modeler's paint brush.
    That's the same method I tried to do. Good idea on the water mist between coats.

    As both G.T. and D.S. have stated, done correctly, there should not be a measurable night and day difference.
    What changes???

    I suppose. It should probably be done on a PWT and I don't care enough to whip one up just for this.
    Thanks, I understand about the PWT.

    Rob

  3. #48
    Senior Member Steve Schell's Avatar
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    Hi Rob, those are very interesting spectral decay plots. It would be nice if you could make them have identical vertical scales for a more perfect comparison, but they are still instructive. The main change I see is that the decay gets out of the red zone much quicker at most frequencies with the Aquaplas.

  4. #49
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    Thanks Steve.
    Quote Originally Posted by Robh3606 View Post
    What changes???
    Basically what you guys have shown. D.S. thought that under high enough resolution one might see a bit of roughness removed from any FR curves.
    Quote Originally Posted by Robh3606 View Post
    There were changes but I don't think they were significant enough to worry about.
    That's pretty much the consensus so far.

  5. #50
    Administrator Robh3606's Avatar
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    The main change I see is that the decay gets out of the red zone much quicker at most frequencies with the Aquaplas.
    Hello Steve

    Agreed but looking back they are not scalled the same one is at 0 the other at 1. I have to redo them to see if that is "real" or not. I will repost them once I get it worked out.

    These are rescalled but also show a faster decay it subtle that's for sure look at the 12K peak as an example and the level of the 7th line. No coated first


    Rob
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    Last edited by Robh3606; 06-04-2007 at 08:42 PM. Reason: Posted New plots rescalled normal Waterfall presentation

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    Rob

    Nice Work ! ( with those Spectral Decay plots ) .

    - Though I'm used to looking at the standard "waterfall" type / I do like the color versions . Once you work out the details / I'd enjoy seeing a repost of the "colored types" .

    - Right now, the standard "waterfall" plots don't highlight much visible difference ( that I can easily find ).
    - To find & view any differences , one would need to implement a finer scale ( ie ; within the time axis, something like 0 to 2.5 ms, & in db axis , and 0 to 10 db ) .

    - FWIW: Pictures ( scales ) like these are all quite subjective. They usually end up reflecting the testers own biases. This happens through the choice of scales ( or colors ) that seem to show ( or not ) things that the tester wants to be seen. ( ie ; if I was convinced that I could identify the portion of the decay signature in a titianium diaphragm ( that I found irksome ) / I'd be high-lighting that area in red ). Of course, assigning "red" to a certain range of decay will also "assign" a subjective judjement, ( ie; good or bad ).


  7. #52
    Senior Member Ian Mackenzie's Avatar
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    The only other way would be to do an impulse amplitude test with the mic capsule in close proximity to the mouth of the horn or in a plane wave tube and look at the ringing after the inital pulse. I imagine the damping to effective well under 1 millisecond.

  8. #53
    Senior Member UreiCollector's Avatar
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    Quote Originally Posted by Joe Alesi View Post
    I have known of some audiophiles that have applied vaseline (petroleum jelly)
    I have found that KY applied to drivers, results in quite a 'slick' system.


    sorry, I couldn't resist......
    Frederick "The Urei Collector"

  9. #54
    Administrator Robh3606's Avatar
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    For all you curve junkies here are new plots with better resolution and the same scalling. First is no Aguaplas

    Rob
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  10. #55
    Senior Member Russellc's Avatar
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    This is extremely interesting, I wish I had all the equipment for testing you guys had, and am very interested in aquaplas and other dampening agents and am trying to learn if they will do any good in my particular application. Thanks for the contribution.

    Thanks for the info,
    Russellc

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