ASC Oil-Filled Polypropylene: Excellent for high voltage
power supply applications.
are non-inductively wound, metallized non-polar polypropylene,
Spearinol III oil filled aluminum cans. Operating temperature
ASC's design includes a partial impregnation technique
utilizing a non-toxic natural oil based coolant that
avoids the problems of swelling and premature failure
which can occur with polypropylene films immersed in
more commonly used synthetic hydrocarbon and petroleum
According to "The
Tempo Electric Cap Test", these are the best
capacitors for power supplies.
If space allows, this capacitor-in-a-can is superior
to any electrolytic on the market, Period. This includes
Black Gate, Nichicon, or Panasonic.
For curiosity, we tried a 2.0uF ASC X386 in the signal
path, but ended the experiment after 30 seconds. Keep
them in the power supply section, especially of amplifiers,
where they belong. Though there is a point of diminishing
returns, the higher the value, the tighter and deeper
the bass will be. Even ones with 10% rated tolerance
measured within 1%. Also sold under the Angela Instruments
brand. Primarily rated for use with AC, they can be
used in DC applications, as well. Curiously, they did
not perform as well when used as AC line filters (see
below). Downside: Large size, awkward mounting.