[sdiy] Sonic qualities of parts..

[George Hearn]

My tuppence.. Ceramic caps CAN be bad but can also be very good, it depends
entirely on the type and the value required.  Dielectrics tend to be
NP0/COG,X7R/X5R or Y5V/Z5U.  NP0 or COG ceramic capacitors are often the
best choice for VCO timing, filters etc.  as they have the benefits of both
long term stability and temperature coefficients easily as low as 30ppm/C.
The 5% specified tolerance is usually much better in practice and the
voltage ratings are usually good 50V+.  For values less than 1nF I would
almost always use NP0 or COG ceramic for everything (other than where 1%
tolerance required).  However, X5R/X7R ceramics should be avoided for all
such applications other than AC bypass or DC blocking and Z5U/Y5V are only
good for power rail decoupling and large values.
For intermediate values up to 1uF then plastic film capacitors offer the
best option for filtering or timing (could be
polyester,polystyrene,polypropylene).  
It is an in depth area.. golden rule for me is ceramic (stone=solid as a
rock) NP0 or COG for all values less then ~1nF.  Beyond this you are into
film up to 1uF then beyond (1uF+) is likely to be coupling and decoupling
only and as JH says it's almost certainly not going to matter for audio
quality (although some may last longer than others).

-----Original Message-----
From: synth-diy-bounces at dropmix.xs4all.nl
[mailto:synth-diy-bounces at dropmix.xs4all.nl] On Behalf Of JH.
Sent: 16 September 2008 21:36
To: Robert Lorentz; synth DIY
Subject: Re: [sdiy] Sonic qualities of parts..

Don't worry too much about caps.
They may make a difference, in some puristic High End audio reproduction 
gear. I have no doubt about it.  (though I don't consider myself an expert 
in this, either.)

But when you mangle a signal with BBD delays, I doubt you will notice much 
difference from the capacitor type, unless you have an extemely bad and 
microphonic ceramic cap.

JH.



----- Original Message ----- 
From: "Robert Lorentz" <robert.lorentz at gmail.com>
To: "synth DIY" <synth-diy at dropmix.xs4all.nl>
Sent: Tuesday, September 16, 2008 9:50 PM
Subject: [sdiy] Sonic qualities of parts..


> I'm sourcing parts out for the JH String Filter and was intending to
> use the WIMA polyester film caps recommended by his BOM.  Sourcing
> from Mouser, I found these caps in some of the values required, but
> many weren't available.  Browsing around I noticed a similar boxed
> capacitor from AVX (metallized polyester film) that is available in
> every value required.
>
> Instead of mixing caps, I thought it best to stick with the AVX that
> are available through all values that I need.  They're also about 1/3
> the cost.
>
> This brought me to consider how it's often stated that certain caps
> are higher "audio quality" than others.  I understand that different
> materials and construction techniques result in different
> characteristics of a capacitor, but how do these differences translate
> in to real, tangible, and measurable, differences in audio circuitry?
> And to what degree does it actually matter?  Sure it feels good to
> throw the most expensive capacitor with a 400volt rating in to every
> Cxx spot on a board, but is this achieving any meaningful results?
>
>
> I started my audio adventure in the domain of guitar
> amplifications/effects and these "quality" statements regarding caps
> (et al) were thrown about *extremely* loosely.  Whether the statements
> are accurate or not, the people stating them to me certainly didn't
> know any tangible details... I peg the group here as a much more
> scientific bunch that won't see this email as heresy
>
> Robert
> _______________________________________________
> Synth-diy mailing list
> Synth-diy at dropmix.xs4all.nl
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> 

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