Paul' capacitor FAQ

[Eric at Svetlana Electron Devices]

You skipped over paper capacitors. Probably the right thing to do.....
they did predate Mylar by about 60 years.

In case any of you want to experiment with "bad" capacitors, there
are new paper-dielectric capacitors being made for the more extreme
audiophiles. Audio Note is the major brand. Also, Sprague/Vishay
sill manufactures the old phenolic-impregnated-paper Vitamin Q
types.

All very expensive, and very leaky. Definitely not recommended for
time constants in VCOs or for temperature-sensitive uses.

Also, there are the oil-filled capacitors still used in high-voltage
AC applications. Some audiophiles build DIY tube amplifiers using
oil caps to filter the high-voltage plate supply. I built such an amp
2 years ago, and have to admit, those big oil-filled jobs have some
major advantages over electrolytics (sound quality being only one).


At 07:15 PM 10/26/97 -0000, you wrote:

>Q: How come mine are so small??
>A: Because people figured out if you replace the plates with plastic film,
you could roll them up like a pastry.

>Q: What about Mylar?
>A: Mylar, also called polyester, is to be AVOIDED!! Mylar is popular for
ONE REASON: PRICE. They are not
>suitable for serious audio work. Mylar was the first film cap available
(about 1953) and most 'old-timers' 
>associate film caps to a Mylar cap.
>
>Q: Why?
>A: They have 2 problems: over time, they 'age'. THey change their
capacitance. The second problem is Mylar isn't
>that good of a film: is is "leaky" and the charge bleeds off. THat's why in
VCOs and S/H a Mylar cap is the WORSE
>choice you can make.
Eric Barbour
Svetlana Electron Devices
Portola Valley CA USA