[Boatanchors] Disc caps vs paper caps

[Richard Knoppow]

----- Original Message ----- 
From: "J. Forster" <jfor at quikus.com>
To: "Glen Zook" <gzook at yahoo.com>
Cc: "Boatanchors at mailman.qth.net" 
<boatanchors at mailman.qth.net>; "Mark Foltarz" 
<foltarz at rocketmail.com>
Sent: Thursday, September 27, 2012 9:29 AM
Subject: Re: [Boatanchors] Disc caps vs paper caps


I bet I could easily construct a fair test where nobody 
could tell the
difference.

-John

    Someone did this (audio coupling caps) and found no 
detectable difference.  I may have bookmark the site and 
will look.  He also measured distortion etc and could find 
none.
    One point often missed is that coupling caps always have 
a large amount of DC on them which would swamp out any 
variation due to voltage coefficient of capacitance.  In any 
case that is measurable.  Storage factor (dielectric 
absorption) is of importance in timing circuits but not in 
general audio circuits.  Paper caps have low storage factor 
but certain modern film dielectrics are just as good or 
better.
    When I could hear and was selling professional audio 
equipment I discovered that a lot of what I was told were 
subtle differences were not subtle and were plain old 
measurable distortion.  I also tested some "magic" speaker 
wire made by Kimber Kable.  On about a twenty foot run it 
_did_ make an audible difference compared to No18 lampwire. 
I measured the series resistance and found it was about a 
fifth of the lampwire, THAT was what made the difference.


--
Richard Knoppow
Los Angeles
WB6KBL
dickburk at ix.netcom.com