Capacitor Outside Foil Placement Dumble

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norburybrook
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Re: Capacitor Outside Foil Placement Dumble

Post by norburybrook »

martin manning wrote:The benefit is possibly a bit lower noise floor. The theory is that the lead connected to the outer foil should be shown the lowest possible impedance to ground to minimize any noise voltage developed there due to stray EMF.

so we're saying POSSIBLY here :)


thanks for the explanation Martin, sounds like one of those things that if it's easy to do you should do it but doesn't really matter that much on a guitar amp.

If I were building a studio mastering EQ or compressor then I think it would matter more.


Marcus
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martin manning
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Re: Capacitor Outside Foil Placement Dumble

Post by martin manning »

I've seen arguments suggesting it shouldn't make any noticeable difference, but it can't hurt either. As you can see in the comments above it is sometimes hard to see the effect on an oscilloscope, even when pinching the cap between your fingers.
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ayan
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Re: Capacitor Outside Foil Placement Dumble

Post by ayan »

martin manning wrote:The benefit is possibly a bit lower noise floor. The theory is that the lead connected to the outer foil should be shown the lowest possible impedance to ground to minimize any noise voltage developed there due to stray EMF.
That is what one would expect, and I think Randall Aiken alludes to this as well in his write up on this matter. In reality, however -- and in my opinion, of course -- the difference can be radical depending on how the caps were placed before they were put in using the "correct" orientation. The first thing one will notice is that the amp will be a lot "cleaner" than before, to where you have the preamp volume and OD control turned up but the amp doesn't "grind" and seems to just sustain instead.

You will find that not a lot has been written about this subject matter on this forum, and the reason is that people starting doing this and appreciating the huge difference it made, but it was too easy to give away to the competition. So it was merely de-emphasized and downplayed. As I have said in the past, orientation of coupling caps and the proper setting of the phase inverter trimmer can really make any amp sound much better. By the way, not all the caps will have the same effect when oriented "correctly" vs "incorrectly". The V1b, V2a and V2B coupling caps, for example, will be very noticeable.

Gil
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glasman
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Re: Capacitor Outside Foil Placement Dumble

Post by glasman »

As far as can you hear a difference, I recently got a call from Gil Ayan about this very thing. I had talked to him a long time ago about polarizing the PS caps. He had never tried it until recently.

Gil said it made a marked improvement in the sound of the amp.

NOw that is funny, Gils post got in before mine lol.
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ayan
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Re: Capacitor Outside Foil Placement Dumble

Post by ayan »

Recently being about 6 years ago, Gary. Time flies. :(

G.
glasman wrote:As far as can you hear a difference, I recently got a call from Gil Ayan about this very thing. I had talked to him a long time ago about polarizing the PS caps. He had never tried it until recently.

Gil said it made a marked improvement in the sound of the amp.
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M Fowler
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Re: Capacitor Outside Foil Placement Dumble

Post by M Fowler »

I admit that I don't bother to orient coupling caps. I did on several Express builds.

Mark
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martin manning
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Re: Capacitor Outside Foil Placement Dumble

Post by martin manning »

On the amps I have built I followed the crowd and payed attention to the orientation, so I have never had anything to compare against. Now, if Marcus can be convinced to check his, then, depending on how they are situated, we'll have a bit more data.
JD0x0
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Re: Capacitor Outside Foil Placement Dumble

Post by JD0x0 »

The first thing one will notice is that the amp will be a lot "cleaner" than before, to where you have the preamp volume and OD control turned up but the amp doesn't "grind" and seems to just sustain instead.
This interests me greatly. As I kind of like the effect you describe. I noticed recently in another amp I worked on, which I mostly changed out cheap polyesters for 6PS and a few 715P's here and there, the tone of the amp did seem to get 'cleaner' and less 'grindy' after swapping.
I now wonder if it's more due to the caps orientation (which I didn't pay attention to, when swapping) rather than the capacitor composition and build quality.
A lower noise floor is never a bad thing to me either. I will have to pay more attention to this stuff. I might pull that other amp open, and reorient the caps, and see if it makes a difference. Is this something that's mainly only beneficial/relevant to 6PS/Polyester caps, or will other compositions of caps such as polyprop, silver mica, etc also have similar effects?
It's true i've lost my marbles and i cant remember where i put them
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martin manning
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Re: Capacitor Outside Foil Placement Dumble

Post by martin manning »

It's beneficial if the cap has a rolled construction. No difference for stacked or single-layer ceramic or mica. See Aiken's white paper on this topic: http://www.aikenamps.com/index.php/wher ... capacitors
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Re: Capacitor Outside Foil Placement Dumble

Post by Charlie Wilson »

Hello, I have played around with cap orientation and I can say to my ears it does make a difference. I was listening for tone and feel difference rather than noise level. What I did was switch caps around one at a time and listen before I marked the outside foil lead. This way I was not influenced by the way people say it should be orientated. I found that one way the sound was mid range focused and more compressed. The other way it had more bass and brighter on the top end and not as sustained. After marking the caps I found that the middy compressed orientation was outside foil towards the plates on all the caps other than the two on the PI. Now it gets a little dicey on my circuit because mine is a classic tone stack which means my mid cap has a 100k pot usually set half way to ground. 50k to ground is less than the 100k slope resistor and the 100k plate resistor combined so the according to the rule the outside foil should go towards the pot. However I found that I got the compressed sound with the mid cap towards the plate.
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10thTx
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Re: Capacitor Outside Foil Placement Dumble

Post by 10thTx »

+1 on it making a difference in a quieter and smoother tone.

With respect, 10thtx
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norburybrook
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Re: Capacitor Outside Foil Placement Dumble

Post by norburybrook »

martin manning wrote:On the amps I have built I followed the crowd and payed attention to the orientation, so I have never had anything to compare against. Now, if Marcus can be convinced to check his, then, depending on how they are situated, we'll have a bit more data.


Can I check them in situ with the alligator clip/amp noise method as I don't have a scope?



Marcus
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ayan
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Re: Capacitor Outside Foil Placement Dumble

Post by ayan »

norburybrook wrote:
martin manning wrote:On the amps I have built I followed the crowd and payed attention to the orientation, so I have never had anything to compare against. Now, if Marcus can be convinced to check his, then, depending on how they are situated, we'll have a bit more data.


Can I check them in situ with the alligator clip/amp noise method as I don't have a scope?



Marcus
Marcus, you can't check them using any method at all if they are in circuit, i.e., connected to something.

G.
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martin manning
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Re: Capacitor Outside Foil Placement Dumble

Post by martin manning »

You'll have to remove them, but an alternate way to find the outer foil is to connect them across the input of an amp. One orientation will produce more hum, and in that case the outer foil lead is connected to the tip terminal of the amp's input jack. This is most easily done by wiring up a DPDT switch with short clip leads so you can reverse the "polarity" of the cap quickly.
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norburybrook
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Re: Capacitor Outside Foil Placement Dumble

Post by norburybrook »

Thanks. Much as I love you guys, I'm not taking them out. it's a PIA as there's always the possibility something might fall through when trying to remove those caps and then end up having to remove the whole board.


Next time :D or if I get really bored one day and I don't have a million other jobs that need doing around the house :D



Marcus
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