Change in Sound Due to Cap Foil Orientation?

[ayan]

The topic of cap foil orientation has been discussed a few times, starting in the old days at Ampage when Randall Aiken began experimenting with this. I think most of the previous conversations have historically focused on the potential benefit form a noise supression standpoint, etc. By the way, for those that want to read about it, you can go here and read all about it: http://www.aikenamps.com/OutsideFoil.htm

For this thread, I am more curious about what your experiences may have been in terms of how you perceive the tone to change when flipping the orientation of the caps. I have a bit of a thoery about this which I realize is statistically flawed because I only have one subject in my sample. This is an amp I built a few years ago as a back up to my gigging amp, and which went unattended for years until I got the itch to toy with it recently. I've rebuilt it a few times, but was never quite satisfied with its sound. Recently, I decided to pluck out all the orange drops and test them for the outer foil orientation -- which I hadn't done when I built the amp. As it turns out, a good 60% of them were "backwards." After I was done, I found the amp sounded less boomy than before and probably more focused on the high end too, not brighter, just more focused.

So my theory is that, probably, whatever change takes plays, sonically, when flipping the caps around has to do mostly with the low end. For higher frequencies, I would think a caps look like a dead short and I don't think having the outer foil towards the low impedance makes much of a difference. Also, for higher value caps, even the lower frequencies are probably not that severley affected -- as can be seen by the fact that it is really hard to detect the outer foil using 60Hz in say .47uF and greater caps. But for the smaller value caps, especially around the tone stack and the V1B coupler, there could be some interaction between them and the foil orientation could make a difference. What if those caps picked up some of the signal and the lower frequencies "got stuck" on the outer foil? If the outer foil were connected backwards, they would find their way to the next stage's grid, making the sound bassier, whereas if the foil is connected to ground, they'd just go away.

Does anyone have any stories they may want to share?

Gil

[Structo]

I can't say I noticed a difference when I oriented mine correctly but I sure slept better knowing all those caps had the foil end towards the low impedance side.

[Bob-I]

I did something similar to one of my amps, although I only found maybe 4-5 caps backwards. I did hear a difference, but honestly it could have been ecause of changes in the solder joints or lead dress as well.

[erwin_ve]

Gil that's a interesting theory, especially on the low freq. part. Is there some hint to the feedback topic of Tony?

[pamaz67]

never tried seriously to play with caps orientation.
But just to understand, are the differences you get ( let's say as "magnitude") something similar in changing the brand of the cable of the guitar, or are we talking of something more subtle?

[roberto]

I found the amp sounded less boomy than before and probably more focused on the high end too, not brighter, just more focused.

I've always thought this added focus it's due to the less noise picked: if you have an audio track and add some noise to it, you'll loose smaller signal's clarity, covered with the noise. Remove it and all small signal informations will be noticed.


PS
Hi pamaz, have you receipt my email about the site update?

[Structo]

I think it can be subtle.

But if you are really familiar with your amps tone you may hear a differece.

I should correct what I said previously.

I believe my amp was less noisy, say at idle with no input the hiss or air you hear through the speckers seemed to be less.

If I had dogears I would probably be able to tell that the guitar was cleaner going through the stages.

[Mark]

I have done this on several occasions but I can't say I've heard a difference. Dumbles are a sensitive amp so nearly anything is possible.

[llemtt]

I have done this on several occasions but I can't say I've heard a difference. Dumbles are a sensitive amp so nearly anything is possible.

yes, even if you take a component (capacitor) out and then you resolder it exactly the same way in the same place sometimes there's a little change in sound...

cheers
teo