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Capacitor question

Started by soldersqueeze, September 07, 2013, 01:16:32 PM

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soldersqueeze

 I found an old 4MS nocto loco board I want to finally build up, but have no 1uf electrolytics to hand. Can anyone tell me if I'm able to use film caps instead?



Sorry for being such a n00b. I really don't understand circuits very well, I just like building them...  :-[

catfud

I'm still learning about components and component properties, but from what I remember from my own reading, you can replace a polarized electrolytic with a film cap of the same value. I've read that in various places, and I found a few links to support my recollection after a bit of googling:

http://www.diyaudio.com/forums/solid-state/196405-electrolytic-cap-can-i-replace-film.html
http://www.audiokarma.org/forums/archive/index.php/t-210239.html

The following was an excellent article I found really helpful when I was finding out more about caps when a cap noob myself, I hope it helps:

http://www.beavisaudio.com/techpages/Caps/

chromesphere

This question came up a few months back on DIYstompboxes and specifically directed at the electrolytic on the input of the fuzz face.

That 1uf in your schematic, near the volume output pot is on the signal path and arguably SHOULD be a film cap.  Apparently the dielectric material of electrolytic capacitors will degrade faster if they a varying current applied to them (your guitar signal), the positive and negative varying on each side of the cap. A film cap doesn't have this problem. 
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croquet hoop

So, to sum it up, when a cap is in the signal path, the first choice should be film, then MLCC (C0G or X7R), then electro, right? (and where does tantalum go?)

I know there has been experiments that showed there was no audible difference between different sorts of caps, but since the question of dielectric quality has been raised...

chromesphere

I'm not touching 'tone' with caps :) I was referring to durability I guess you could say more so then quality. Not sure about tantalums.  I guess they are polarised so the rules apply..? Chances are in pedals any cap will work fine (and sound fine), but I believe amongst the EE's, its best to avoid electros when there is not a distinct, constant plus and minus.  A guitar signal is AC.  One side might be more plus then the other but its not cut and dry and will degrade the dielectric faster as the dielectric needs to polarised to regenerate.  Just another way of saying what I said in my last post, and my interruption of what people with vastly more knowledge then I explained in that cap thread.
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