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In Reply to: RE: FINAL TALLEY - Clip lead Orientating Film Caps in SET Amp posted by drlowmu on August 22, 2016 at 12:14:40
Thank you for sharing your experience.
If you're suspicious of the correlation between the capacitor markings and its "polarity" between each batch, I can suggest you to measure each for the outer foil using an oscilloscope. Later, you can listen to this particular capacitor model how it suits you better sonically - with the inner or the outer foil towards the input.
I believe it's a faster method if you have to manage a large batch of capacitors.
Best regards,
Alexander.
Follow Ups:
Don't you THINK I have thought of that?? I have. Just because we can measure for the outer foil, that does NOT mean you have answered the question of " What orientation sounds BEST, in any particular circuit !!"So, since I plan to keep this amp, and my VOTTS for personal use, I took the time to listen to each film cap both-ways IN CIRCUIT, and KNOW for SURE.... what is best sounding.
There was a lot more CLARITY to the presentation, listening last night for the FIRST TIME, with all 10 or 12 in place correctly !! I use Brendel playing solo piano, Beethoven Waldstein Sonata, VERY good to A-B, 20 second (or less) snippets. Its amazing how many notes can get played and heard in a SHORT time by a great pianist !! AND, with solo piano, there are MANY things to listen for !!! Once all is aligned - enjoy the whole piece !!
If I were to build duplicate amps, same design ( why of course, what else but a two stage DC SET ?? ) I could disconnect wires connecting caps on THIS amp, and test for outer foil and denote it. That, I may do, but now, I just want to "perfect" this amp for my own use on my ALTECS. Amps, not speakers, are the turkeys, the real weak link in audio.
Thanks for thinking and sharing up here. I would like for you to please send me your email address, so I can send you a document on amp-designing I authored. Thanks.
Jeff Medwin
Edits: 08/23/16 08/23/16 08/23/16
for a 10uF capacitor, it's damned difficult to determine which lead is connected to the outer foil for capacitors of this value, and above, in theory because impedance to typical test frequencies is low, either way. I tried all the well known methods, and I never felt that I got a definitive result that distinguished one orientation from the other. I don't know where the cut-off point might be for getting a reproducible unequivocal result, but it's below 10uF for sure. That said, I did not try very very low frequencies, where Z might be high enough to make a determination, like 20Hz and down.
Hi Lew,Tell me this please : Did you ever try using a scope?
Dennis suggested tonight I do it that way with film caps' outer winding determinations, and not a DMM as Percy suggested.
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Dennis Fraker uses a simple single trace scope for multiple transformer alignment ( Ef XFRS to B+ transformers on AC fed DHT filaments, and one power transformer to another power transformer on his monoblocks ) all the time.
Let me know please.
I keep thinking, in my mind's eye, of how pretty the cam covers used to look on a vintage Alpha engine. Send us a photo please if easy to do. Old times.
Jeff
Edits: 08/23/16
The experience caused me to do some internet surfing, and I did find that I am not crazy. Others have also found that the usual audiophile methods for determining polarity of a film cap do not work so well for high value capacitance. The one qualification I would make as regards my finding is that I am not immersed in this business every day of my life. So when I encounter a new problem in electronics, I often have to re-educate myself with respect to the relevant science that I may have forgotten due to not using it. I cited one example of where I may have erred in not subjecting the capacitor to very low frequencies, where impedance might have enabled me to see a difference. I think I went down to 50Hz with my audio signal generator. I actually short-circuited the problem by deciding to use some 10uF Auricap XOs, which come from the factory with color-coding, denoting the lead connected to the outer foil. That decision was made based on the idea that the Auricaps would sound better than what I had (Cornell-Dubillier), not just because of the lead markings on the former brand.
Now you've got me thinking that it would be interesting to try lower frequencies on the 10uF CDE capacitors, which went back into my stash after I decided not to use them in this application. Just to see if that works.
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