Wall wart worrywart or legitimate concern?

Frequently asked questions regarding powering your pedal.

Wall wart worrywart or legitimate concern?

Postby varimac » 16 Jun 2009, 01:06

I've acquired an MIJ Boss ACA adapter in a 'bits and pieces' deal (I'm told this is the older type). It's in great condition but I'm not sure what to use it for as it only puts out 100mA. I'm more used to seeing adapters with 300mA or more. What does the average stomp box actually need in terms of mA? And if it works with a pedal and doesn't get hot should I just use it and quit worrying about burning out a pedal? :scratch:
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Re: Wall wart worrywart or legitimate concern?

Postby RnFR » 16 Jun 2009, 01:51

i'm going to move this to the FAQ's section. i think it's a good question!
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Re: Wall wart worrywart or legitimate concern?

Postby Paul Marossy » 16 Jun 2009, 15:20

For the average overdrive/distortion pedal, I would assume 10-15mA.
For a digital delay and chorus pedals, I would assume 50-75mA.
For a digital reverb pedal using a Belton Digi-Log unit, those use between 75ma & 100mA (verified).
For a flanger or phaser, I'm guessing about 35-40mA.
A wah pedal is probably in the area of 10-20mA, depending on make & model

Going with these (assumed) figures, with a 100mA wall wart, you could power:

1. 7 distortion pedals and a wah pedal
2. 1 dist pedal, 1 wah pedal and a digital delay
3. 1 digital reverb and possibly 1 dist pedal and a wah pedal
4. 3 dist pedals, a wah and a flanger

I'm probably a bit conservative on most of those figures, I just throw out some examples. Every pedal is going to be a bit different in terms of current draw. I don't know about things like tuners and stuff like that.
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Re: Wall wart worrywart or legitimate concern?

Postby lolbou » 16 Jun 2009, 15:46

But the ACA is not regulated. It's more a 12V. A resistor in old Boss pedals was used to drop the voltage down to the correct 9V.

It acts like a battery: U=E-ri. The output voltage U is equal to the electromotive force E (i.e. the voltage with an infinite load) minus the ohm's law applied to the inner of the transformer (who has a resistance called r and who delivers a current called i).

The more the ACA drives pedals (= deilvers current), the lower its real voltage is.
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