Civil War pedal and wall warts

[Randall]

Got a Civil War dirt pedal in to solder something, and when I plugged it into a 9v wall wart, it emits a loud buzz. I figured I had a bad supply, so I tried another one, with same results. Tried my bench supply, better but still unusable. Totally quiet on a battery, and also on my VooDoo Labs brick supply on my own peddle board. I have never seen a pedal do this. I tried flipping polarity and different voltages, it just doesn't like wall warts. I wonder why?

[nosaj]

Got a Civil War dirt pedal in to solder something, and when I plugged it into a 9v wall wart, it emits a loud buzz. I figured I had a bad supply, so I tried another one, with same results. Tried my bench supply, better but still unusable. Totally quiet on a battery, and also on my VooDoo Labs brick supply on my own peddle board. I have never seen a pedal do this. I tried flipping polarity and different voltages, it just doesn't like wall warts. I wonder why?

The Voodoo Labs brick is a quality unit filtered regulated DC I believe. I bet your wall wart is noisy . A better quality one would probably alleviate the issue.

nosaj

[The Dude]

^^^^^^ Agreed. I've run into the same thing with some Boss pedals. They only like Boss power supplies, which seem to be better filtered. If you or customer doesn't want to have to worry about it, you could tack in an additional filter cap inside the pedal.

[bob p]

Be careful not to use a lesser PSU with a Fulltone pedal -- I've read reports claiming that Mike Fulton voids peoples' warranties for doing that. I can't remember the exact URL, but I've even seen people claim that he's refused warranty service because it was "obvious" that they used his pedals with someone else's supplies, allegedly claiming that other peoples PSU damaged his pedals. For that to be the case I'd think his pedals would have to be poorly designed.

[Randall]

I just put my two warts on my scope with no load, and yes there are saw tooth waves. Customer tells me he uses a one spot, not sure how well filtered they are.

[Enzo]

Did you ever load down your warts to scope them? Load them to at least half their rated current. At no load, most warts will look real clean, but draw current from them and see how poorly they are filtered - or how well. Imagine a B+ supply with a 1uf filter cap instead of 40uf. It will be smooth until you try to pull any current out. That should show the difference between a Boss wart and a generic one.

[Randall]

I just scoped one of my 300mA generic warts. I don't know what the load is of the pedal, but I can confirm the saw tooth increased by a factor of almost 3 when the box was switched on. The onespot supplies are touted as being very clean, so I guess that is where the answer lies.