[R-390] Vitamin Q Caps

[2002tii]

Carole wrote:

> I've noticed about a half-dozen Vitamin Q caps in the AF deck. What's
> the collective opinion on these caps? Should they be replaced only if
> shown to be leaky or should they routinely be replaced?

> My other question pertains to the yellow caps that I saw in the IF
> deck. They look like metalized polyster. Some of them are lopsided,
> more oval than round. Should they routintely be replaced? How do they
> get lopsided?

Vitamin Qs were some of the best '50s-'60s-era caps. I'm not sure I've
ever needed to replace one. Many audiofools will pay dearly for them,
even used, for their supposed better sound.

The oval metallized mylar caps were probably made that way. Lots of
these caps were used on PC boards, where the oval form factor is often
preferable. If the goal is postponing the need to go back in for as
long as possible, I would always suggest replacing metallized film
capacitors with film-and-foil ones, for reasons I've explained here
several times. Electrocube, in particular, made a popular series of
yellow, oval, metal film capacitors that packed almost three times the
capacitance into the same form factor as an equivalent Gudeman, etc.,
by using verrrry thin mylar, and these failed with regularity if they
had significant DC across them (although they worked fine for, say, an
input coupling cap with little or no DC across it). The tube hi-fi
manufacturer Audio Research had lots of trouble with these.

Best regards,

Don