AudioCircle
Audio/Video Gear and Systems => The Lab => Topic started by: Mark_Walsh on 8 Apr 2004, 05:38 am
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Evening All,
I have just purchased 2 "nice" subwoofer drivers (Jaycar CW-2145) which have their cone materials made of woven carbon, similar I guess to the Kevlar cones of B&W, but not as dear and probably not as good.
BUT, the weave leaves little gaps between the fibres which, on testing with a soft suction cup, appear to leak air.
Reading my "Bullock on Boxes" it would appear that this is a highly undesirable feature and that I should consider sealing the weave. "Back then", he used rubber solution for that purpose.
I have checked with Jaycar themselves and they are unable to provide any information about this, and they do not see it as a problem because they have been selling the driver for 10 years. Sometimes the dust caps pop off and they are repaired with a PVA glue (similar or the same as what I know as Aquadhere). This is the same glue they use for their new "rubber surround" re-rolling kit.
Any thoughts:
1) Ignore it.
2) Quantitate it as a Q box loss.
3) Seal it with ... what: rubber solution, PVA, ?diluted silicone gap ssealer??
All ideas seriously and gratefully cogitated upon.
Regards,
Mark Walsh.
PS I asked the Jaycar dealer whether he has noticed the driver "badged" differently by other distributors. He has not come across this despite looking.
Here are the details:
http://www1.jaycar.com.au/productView.asp?ID=CW2145&CATID=15&keywords=&SPECIAL=&form=CAT&ProdCodeOnly=&Keyword1=&Keyword2=&pageNumber=&priceMin=&priceMax=&SUBCATID=383
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Mark,I could see light through the weave in the Audax carbon fiber 8in woofers I used in my DIY speakers and I thought they might also be "leaky" cones but I went ahead and put them in the box anyway and they work fine. The rough surface of the weave is going to be hard to get a seal on with a suction cup. I would assume they work. Any sealer you put on them will raise the Mms figure and change the Fs. They will also slow down and loose some efficiency. Nice looking woofers by the way.
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Thanks for the advice Scotty.
I had thought I might put them in a sealed box (smallish volume) and try to test the parameters, and also listen for leaks.
Of course, this paralysis by analysis thing could stop me from ever getting anything built.
(The suction cup was a soft silicon face mask used by anaesthesiologists on babies' faces, courtesy of a friend at work ... I really do think they leak a bit.)
I looked at the predicted responses with a higher Q loss (box) on Win ISD and it looked as though not much was going to change in the overall plots, so maybe I could ignore the effect.
Regards,
Mark.