6PS caps drifting or relabeled?

[dbharris]

Hi All,

I bought these 220P .022 uf caps off of Ebay and they all measure right around .030-.034 uf. These are 10% caps that are 50% above. I am aware caps can drift over time, but this seems like maybe they are just relabeled .033 uf caps? Some of the print on these caps looks faint or like the printing was partially applied.

Ebay-6ps.jpg

I also bought some 220P .001 uf caps from the same seller and they check out fine.

These 2 caps would be placed as a coupling cap right after V1B and also right at the phase inverter entrance from the return jack in a clean amp.

Should I just use these or contact the seller for a refund/replacements?

Thanks,

Dan

[ijedouglas]

Hey Dan,

I have had the same experience. I bought a bunch when I first started out and they were all way out of tolerance. I also found the ones with a double foil stripe were worse than the single stripe version. I never ended up using any of them

[xtian]

I can't see how film caps can drift in value. E-caps, sure.

[pompeiisneaks]

I can't see how film caps can drift in value. E-caps, sure.

Agreed,

What are you using to measure this? The smaller the capacitance the worse things like lead length can alter the readings. You might have some good readings, but if the device you're using is off by 30 to 40% then it gets a lot closer to the 50% error you're showing.

The shorter the leads the closer the measurement should be.

~Phil

[ijedouglas]

You are both very welcome to test mine, I'll send if you like

Fluke 87-V and a YF-150 Capacitance Meter and all other caps measured are within tolerance. The old double-stripe 6PS caps have mostly drifted up in value

[pompeiisneaks]

That one definitely fits the bill.

Just throwing it out as a possibility. Otherwise then I'd wager mislabeled.

I have the 87-V as well. Love it

~Phil

[dbharris]

Thanks for the replies. Looks like I will order a couple caps from AES. Too bad they just shipped me a big order. You all would know better than me about caps drifting, I know electrolytics are more prone to that, but I thought I had read it happens in other old caps too. I was thinking mislabeled since they all measure so close to spec for .033 uf.

Here is a pic of my capacitance meter, not a Fluke by any means...Honeytek A6013L.

IMAG2089.jpg

But I have measured hundreds of caps on this meter from a few pf to 1500uf all except this set of 5 caps have been within spec. My leads are approximately 10 inches long.

-Dan

[xtian]

Dan, how do you know they "drifted" ? Did you measure them when you first received them?

[sluckey]

I don't believe those caps have drifted. I believe they were that value from the day they were made. The only mystery seems to be why they are labeled as .02. Were they really manufactured as .033 and somehow got mixed in with a run of .022s before labeling? Or were they intended to be .022 but something went wrong with the manufacturing process and slipped by QC (I suspect that only a small sample is tested by QC?) Or was it something else. Lot of speculation but we'll probably never know for sure.

[Charlie Wilson]

Those things are earlies ones with paper in them. They are always drifted when I get them but not as much as those caps.
CW

[dbharris]

Hi Xtian, I just received them yesterday and measured them today. I thought they may have drifted since the measured value was so different from the printed value. But as Charlie and Sluckey pointed out it's unlikely they drifted this much and I guess it could be some error at the factory way back when. Mislabelling seems to make the most sense.

When I was ordering old parts I didn't expect everything to fall right on spec and even a little outside the tolerance window would be fine. I am just trying to decide now whether to give these a go in the build or order new production from AES and eat the shipping for 2 caps. I was shooting for as much NOS in the signal path as possible. This will be for a 100W JM Wonderland build.

-Dan

[xtian]

As you mentioned above, these will be used a coupling caps, and so will let a little more bass thru than 0.022 would. It will be a small difference.

[sluckey]

I'd use them. Maybe make a note to change them out the next time you make an order. I would not make a special order just for a couple caps.

[dbharris]

OK thanks so much, I appreciate hearing everyone's opinion. I will give these a try first.

-Dan

[Richard1001]

You are both very welcome to test mine, I'll send if you like

Fluke 87-V and a YF-150 Capacitance Meter and all other caps measured are within tolerance. The old double-stripe 6PS caps have mostly drifted up in value

I would not use those old caps anymore. Old caps 'drifting up' means that they are getting leaky. A capacitance meter measures the time it takes to load and unload a cap. When the cap is leaking, this takes longer. The meter translates this in a higher value.