WEST-CAP, How about sonic reputation

[ja2dhc]

Recently, I bought vintage capacitors of WEST-CAP in China
as shown in the attached photo.

I am not familiar with American vintage components. Is it
an oil-paper capacitor?

Does anyone know its reputations on the sonic?

Below is the printed information on the capacitor.

WEST-CAP
C45805
12.0-MFD, +/- 5%
200-VDC
32159-7028

[Miles Prower]

Given the size and polarity marks, these are electrolytics. PiO capacitors of 12uF would be much larger. Since they are so old, I'd be very careful about returning them to service. After sitting around for so long, it's highly likely that the dielectric will need to be reformed.

As for sonics, that depends on how you're going to use them. As signal capacitors, electrolytics are just plain awful. See: The Sound of Capacitors for more details on how signal capacitors affect sonic performance.

It probably doesn't make much difference if these are being used as ripple filter capacitors (most likely use for 12uF capacitors in a VT amp). It could make a big difference if these are to be used as DC blocking capacitors in a parafeed design.

[wrenchone]

Given that the tolerance is 5%, I doubt that they're electrolytics - more likely metallized polyester or some such. I have caps film caps of similar rating and size. If they're classic film and foil (a remote possibility), the red dot may mark the outer foil connection. Another possibility may be that the caps were cherry-picked for tighter tolerance and marked accordingly with a color dot - wouldn't be the first time that's happened...

[adam2a3]

Hello, I have several WEST CAPS 0.47 600V CQR39A1 JAN that are encased in a metal cylinder sealed by a grey glass like material at both sides. I cut one to check inside and it has a plastic film, no oil, no paper. I guess it is MKP. Sound is good when used for tube coupling. adam2a3

[impsick]

Originally Posted by adam2a3

Hello, I have several WEST CAPS 0.47 600V CQR39A1 JAN that are encased in a metal cylinder sealed by a grey glass like material at both sides. I cut one to check inside and it has a plastic film, no oil, no paper. I guess it is MKP. Sound is good when used for tube coupling. adam2a3

CQR39A1 = Paper and Polyethylene

If you look closely when you cut it open you will see a very thin layer of paper. It's easy to miss and can be confusing because it's very thin but there is paper.

[impsick]

Originally Posted by ja2dhc

Recently, I bought vintage capacitors of WEST-CAP in China
as shown in the attached photo.

I am not familiar with American vintage components. Is it
an oil-paper capacitor?

Does anyone know its reputations on the sonic?

Below is the printed information on the capacitor.

WEST-CAP
C45805
12.0-MFD, +/- 5%
200-VDC
32159-7028

Definitely mil. spec metalized plastic film. Red dot if anything indicates outside foil. Outside foil to ground for lower noise. Sonics... Like any other metalized film.

[bob91343]

Those are probably pretty good capacitors. If they measure okay on a bridge, I'd not hesitate to use them. The company made good parts and often made high quality units for the military. Not electrolytic capacitors. With a wide tolerance of 5% they weren't used for standards but more likely in timing circuits. With a 1 megohm resistor you'd get a 12 second time constant. Or they could be used in oscilloscope sweep circuits (also a timing application).

[elecon]

West Cap of Arizona (with a history starting from 1952) became Arizona Capacitors from ca. 1990. They specialize in wound film capacitors:

>>Arizona Capacitors designs and manufactures all types of wound film capacitors including mylar, Teflon, polyester, polystyrene, and polypropylene film capacitors. They not only build custom film capacitors, but offer a line of standard film capacitors, as well. Arizona Capacitors also manufactures oil filled and hermetically sealed film capacitors. <<

About Arizona Capacitors

I happened to meet their representative Daryl Stahler at the recent CES in Las Vegas Jan 2011, and I heard an excellent amplifier/speaker combination that is employing their capacitors.

Disclaimer: I have no affiliation with this company whatsoever.

[jlsem]

My guess is metalized polycarbonate. I have any number of West Caps in this value range and that's what they are.

John