Capacitor outer foil test box....

[surfsup]

I just did the scope test with a bunch of caps. They all displayed varying noise from one side to the other. I marked each of them on the side with less noise that had the alligator ground clip.

Another thing i noticed is some caps really displayed a far larger signal vs others of the same brand and value. So a batch of four caps, one will usually have quite a bit more noise. Not sure if i should be concerned about amplitude, or the difference between the amplitude of the signal on both sides?

I also tested some non film. For example, mica caps. Micas seem to really scope out with a huge signal compared to films. Not really sure what that means.

[Masco]

I just did the scope test with a bunch of caps. They all displayed varying noise from one side to the other. I marked each of them on the side with less noise that had the alligator ground clip.

Another thing i noticed is some caps really displayed a far larger signal vs others of the same brand and value. So a batch of four caps, one will usually have quite a bit more noise. Not sure if i should be concerned about amplitude, or the difference between the amplitude of the signal on both sides?

I also tested some non film. For example, mica caps. Micas seem to really scope out with a huge signal compared to films. Not really sure what that means.

There isn't an outter foil w/ micas, just layers stacked.

[surfsup]

Yes i know. The point was to compare the amplitude of the signal.

[Raja]

I just did the scope test with a bunch of caps. They all displayed varying noise from one side to the other. I marked each of them on the side with less noise that had the alligator ground clip.

Another thing i noticed is some caps really displayed a far larger signal vs others of the same brand and value. So a batch of four caps, one will usually have quite a bit more noise. Not sure if i should be concerned about amplitude, or the difference between the amplitude of the signal on both sides?

I also tested some non film. For example, mica caps. Micas seem to really scope out with a huge signal compared to films. Not really sure what that means.

Was the orientation of the printing to the outer foil side always the same with the ones you tested?

[CHIP]

I built one, it works great. I only tested 6ps and 715 orange drops. I think AFAIR smaller values aren't as easy to discern, but you still can tell the difference in noise.

[surfsup]

Was the orientation of the printing to the outer foil side always the same with the ones you tested?

For caps of the same brand, no. Unfortunately.

[C Moore]

What about when the cap is in circuit. Can somebody hear which way the cap is installed......10 times out of 10.....if they do not know the orientation.?
That is....can/has somebody hear/identify the outer foil orientation, in a blind test.?
Thank You

[brewdude]

What about when the cap is in circuit. Can somebody hear which way the cap is installed......10 times out of 10.....if they do not know the orientation.?
That is....can/has somebody hear/identify the outer foil orientation, in a blind test.?
Thank You

In the circuit, I would expect each cap installed with the outer foil in the wrong orientation would add just a little bit more noise in an accumulative way. I would like do every thing I can to keep the noise floor as low as possible.

[Structo]

What about when the cap is in circuit. Can somebody hear which way the cap is installed......10 times out of 10.....if they do not know the orientation.?
That is....can/has somebody hear/identify the outer foil orientation, in a blind test.?
Thank You

Most likely not but what we are after by using this technique is to lower the overall noise floor.
So even though a person probably can't hear if one cap is backwards, if all the caps are backwards the noise floor will rise theoretically, so by putting the outside foil to ground, we can be sure that we have done the best thing for the circuit at hand.

[surfsup]

Assumption here but I think the first few coupling caps in the circuit are most important due to the signal being amplified? So really worring about it on the first couple tubes is valid.

If the noise is on the, example, e-3 level, anything after that won't be heard by anything/anyone except dogs?

[Tone Junkie1]

I built mine and it worked really well I love being able to switch the direction back and forth quickly it helps with those caps that just make a small amount of extra noise.
Bill

[brentm]

Not to drudge up an old thread here... but I wanted to share an alternative to the outside foil box method. Someone before me mentioned they used a freeware oscilloscope and that got me going down this path.

Here's a free VST plug in oscilloscope.

http://www.jaggedplanet.com/VST/jscope.html

If you have recording software that can host VST plugins, this seemed like a one of the better ones to use... I basically chopped the end off a cheap instrument cable and attached an alligator clips to the center conductor and to the shield. Plugged this into my audio input and armed track 2 to record and squeezed the cap.

Here's a couple of screen shots... With the outside foil connected to ground, I wasn't able to get the sine wave to get any larger than the first picture. The second picture I flipped the cap around.

HTH!

[paulster]

And that, folks, is exactly what you'd see on a real scope!

[roberto]

Yes, it works, and you can reduce noise level on your amps.
I don't use the switch, just because the simpler the circuit, the simpler to recognize outer and inner foils.