Electrolytic capacitors when running 18V pedal

[richard44]

Hi all,
I'm in the process of building my first stompbox (a "crunch" style distortion box), and had a question on the voltage values for the electrolytic capacitors.

This effect normally runs 9V, but I thought I might want to try to run it 18V as well for more headroom. Initially I purchased 25V electrolyic capacitors (with 10% tolerance) which I thought would be enough to run at 18V. While some people think this is okay, I see some other people say the capacitor value should be at least double the voltage or you risk shortening the life span of the cap. As there are only a few polarized caps in this build, in a separate parts order, I also purchased 50V caps, but the best I could find had a 20% tolerance.

So my question is, if I wanted to run this effect at 18V, which of the above is better:
a) 25V caps at 10% tolerance, or
b) 50V caps at 20% tolerance.

Thanks for any insights!
Richard

[Dirk_Hendrik]

If your caps are rated at 25V it should work at 18V. That's still within the 10% limit. (which goed both ways)
However, as it is close to that limit you'll have to pay attention to your power supply and make sure it doesn't accidentaly exceed that 18 volts. "At least double" is bull, but it gives you a decent error margin.