Build Your Own Clone Message Board

So Im researching all I can for my next amp build to be refreshed. I run into this article and video this morning about non polarized caps and how they should be positioned for less noise in the amp. It deals with were the outer foil inside the cap is and thats the side that goes to the ground path. You cant see it and not all cap makers mark it. Its a real easy test do and you can here the noise difference and he shows you on the scope too. Here is the link to EL34's site. http://www.el34world.com/Forum/index.ph ... 158651#new
????? Would it make a difference in pedal builds as well????

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I wouldn't fret about this too much. I think this sums it well:



So basically, you can improve the signal to noise ratio by paying attention to orienting non polar caps the 'correct' way. But as long as you are following other best practices, it's not going to ruin the amp if you don't do this.

I don't know cap construction very well, but I don't think that a stacked metal film cap (box cap) has an outer foil. The small film caps (panasonic & greenies) might.

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MasterDelayer/Reverbrador/Ampaholic/TopJacker

Hmmm, when I do get my next build going I will look into this and take notes.

I've said it before and likely will have to say it again.

ELECTRONS DON'T CARE.

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Granville Guitars - Guitar & Amplifier Repairs - Custom Effects Pedals - Hand Wound Pickups
http://www.granvilleguitars.com/

Test it and prove to yourself if it makes a difference or not. Personally, that sounds like too much work for me considering the amp circuit is stuffed in a Faraday cage when it's mounted in the head shell.

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-Mike

Im gonna take your word and save myself time

That's a good point. The quote I put up is from the Aiken site. I didn't notice before that he seemed to suggest that fluorescent light radiation is going to penetrate the chassis and add noise to your improperly orientated coupling caps. I've always considered it as an extra step to beef up shielding from internal sources of interference, like how one would use shielded cable from the gain pot to the tube grid on a longer run.

OTOH, if a non polar cap is marked, I'll go ahead and stuff in on the circuit board in the "proper" orientation. If it isn't marked, I've never tried to chase down the outside foil.

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MasterDelayer/Reverbrador/Ampaholic/TopJacker

What he is suggesting is correct, but I'd take a different approach at fixing it which is the unmentioned part of my previous post (assuming it was a problem, I try not to chase rabbits down holes, you tend to find hookah smoking caterpillars that way). I'd choose a little more systematic and complete approach as opposed to one that is fiddly and time consuming.

The wavelength of the EMF, and the size of the openings in the shielding (chassis, head shell foil), will determine exactly what gets in. So if the EMF from the fluorescent light can get through a hole in your chassis, it could show up in the output. But following this idea down a little further, given that a circuit's signal path is composed of more than just a capacitor, any EMF that effects the cap is by default going to effect these other parts too. So instead of worrying about cap orientation, which is really just a partial solution, I'd seal up the Faraday cage better. The long seam between the chassis and the head shell foil will determine the lowest frequency (there is a formula for this, it's simple, but I don't have my noise book here and don't really want to dig for the equation right now). Given the low frequency of audio, I'd start by sealing that up. The other holes are probably going to only let in RF which largely isn't a problem provided the layout and build practices are good

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-Mike

Here is the Board I will build, I like the fact that everything is on one board and modifcations from better tremolo, bias adjustment etc have been done here. I need to find the mod to adding a mid pot to this, I forgot where I seen it, I found it never mind. Im no amp guru so it"ll probably be awhile for me to figure out. I live in a old apt building and the electricity isnt the cleanest

Defaced, that shielding seems alot easier, Ill just foil the shit out of cabinet inside. I have rolls of HVAC foil tape that is like 4" wide

Hi All,

Sorry, I'm late to this discussion and I'm not an amp building expert.

I'm building my Brit 50 after checking the foil end of the non polarized caps. So, here is what I've seen so far. I went through the yellow coupling caps and I noticed that there was very little difference in noise by using my fingers as the source of the noise. Maybe the scope I was using wasn't sensitive enough. I them tried the 500pf and 47pf caps and found they were noisy in either direction. Then I tried Sozo cap (current production ones) that I bought for experimenting. These definitely had a viewable/measurable "polarity" (foil end). Interestingly the end of these caps foil end lined up with the printed line on the cap. It tested 10 for 10. Might be luck, can't be sure. So we'll see how this goes. Based on my understanding of this, if the wiring of the amp doesn't require noise sensitive wiring to cross "noisy" areas of the amp there should be no real big issue. Looking through the amp layout, there aren't too many places where you will have particularly noise sensitive wires crossing noisy areas of the circuit. There are only a couple places where the might even make a difference. I also have some metal film resistors to see if I can keep the noise lower. The whole reason I even went through this stuff is because a friend of mine has an older Marshall 1987 and some older 1959's that sound great. These amps are really noisy. Could be a problem with those amps, I don't have a scientific control group.

All that being said, I built my Brit 45 kit exactly like the instructions and it is a really quiet amp. No testing of caps. No parts substitutions etc. Just stock. My Tweed Deluxe was built the same way. It started out a little noisy. The biggest cause of noise was the 1st preamp tube. I changed it and the amp was a lot quieter.

I next did the Faraday cage with foil tape which ended the remaining noise. Thanks Morgan!

Yes, it does really matter how completely/thoroughly you get the shielding. First time through I didn't have everything completely encased. I found the problem, not enough contact with the the amp chassis.

If I find anything out of importance along these lines with the Brit 50, I'll let you know.

If anyone reading this doesn't know about the capacitor direction debate.
View this from YouTube:
https://www.youtube.com/watch?v=BnR_DLd1PDI

Interesting. Too bad it takes an oscilloscope to test 'em....

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“My favorite programming language is SOLDER” - Bob Pease (RIP)

My Website * My Musical Gear * My DIY Pedals: Pg.1 - Pg.2

You can also use your amp, that’s I how used to do this. cut the end off a old guitar cord and put alligator clips on both positive and ground. Clip one lead to each capacitor leg and hold cap body between finger tips with amp on. The way where it’s quietest mark the side thats hooked up to ground, that’s the outer foil

Thanks for the suggestion! I have an amp build coming up shortly and will definitely give this a try!

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“My favorite programming language is SOLDER” - Bob Pease (RIP)

My Website * My Musical Gear * My DIY Pedals: Pg.1 - Pg.2

Thanks! I'll give it a try. I had to borrow a scope to test, so this would make it a lot easier.