[sdiy] (de)coupling capacitors

[Theo]

IMO rubbish.
As a buffer cap for power supply decoupling a elco will do fine.
Only in High-end equipment aimed at gold-eared bimbos MKS are sometimes used as power buffer, marketing claim could be that this gives more depth to the silence.
Obviously nonsense, only manually rolled paper/silver foil caps filled with 5 times filtered hand pressed chestnut oil are acceptable.

Think for signal coupling in a synth a elco would do, that is if there are no polarity issues.
As you mention 10u is rather large. Usually the large caps are needed to prevent low frequency loss when input "resistance" of the next stage is low.
Maybe you can redesign for use of a 1u MKS?
Often the cap and input "resistance" form a RC HP filter. 
The cutoff would be f = 1/(2piRC) 
So if you need 15hz to pass you need a C = 1/(2pi*R*10) capacitor.
In this case if it needs to be 10u then go for the elco.

In general for signal coupling a plastic cap like MKS or MKP type would be the quality choice.
Silvermica would be highend for mic amps and critical stuff.
Paper/oil the pick for pp who need expensive stuff to show other pp they have very good ears.
But commercial HIFI equipment often uses ceramics or even elcos.
So take your pick.

Our Happy Hairy Harry wrote a cap guide that is on line at multiple sites.
Don't have a link at hand, but sure others will mention it. 

HTH
Theo


  ----- Original Message ----- 
  From: M.A. Koot 
  To: synth-diy at dropmix.xs4all.nl 
  Sent: Sunday, July 18, 2004 3:34 PM
  Subject: [sdiy] (de)coupling capacitors


  Hi all,

  This subject has probably allready been discussed, but I'm affraid my synth-DIY database isn't large enough to find that may-have-past discussion.
  The situation is that I'm building a filtercircuit which has a coupling and decoupling capacitor of 10uF. This is rather large, and since I believe these capacitors have to be rather good, I'm questioning myself what kind of capacitor would be best.
  In fact, what capacitor would be overal best for coupling/decoupling functions? Styroflex maby?

  Since this particular one is that large, I can use a electrostatic one (bad, isn't it?), or an expensive MKS one. Could anyone maby tell me if it's worth the price to buy a MKS, or better, does one hear actually a difference using MKS instead of electrostatic, or is that just rubbish?

  Cheers,
  Michiel
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