[sdiy] Hand-matching capacitors for filter stages

[thx1138]

On 2/9/10 12:18 PM, "David G. Dixon" <dixon at interchange.ubc.ca> wrote:

>>> ... What specific quality of polystyrene is so
>>> desirable for filters, and how exactly does this enhance the filter's
>>> performance?
>> 
>> I assume that you've read Harry's treatise?
>> <http://www.musicsynthesizer.com/txt/caps2.txt>http://www.musicsynthesizer
>> .com/txt/caps2.txt
> 
> Yes, several times.  It is largely silent on why a filter would sound better
> with polystyrene, and says that mica is good, C0G ceramics are good, and
> both polypropylene and polycarbonate are decent replacements for
> polystyrene.  
> 
> None of this answers the original question, which was directed more at Tom
> Wiltshire's breadboard experiments.  Specifically (and without trying to
> sound too snarky), I'd like to know how the filter was better when one cap
> was used instead of another.
> 
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Hi David,

Wellthen, this is directly my question, what does better imply?

Without hearing it or seeing a measurement in parallel how are we to
ascertain sonic quality or difference when caps are inserted in circuit?

Can someone describe the sonic characteristic before or after cap changeout?

Or is there some other parameter or parameters we are measuring here besides
acoustic properties such as frequency or resonance stability when Q is
turned up etc.

Regards,

Terry