I have a Boss PSA-240 power supply. Its specs are as follows: Input: 230V~50Hz Output: 9V-200mA Regulated - to + It is a three pin Irish plug.

I want to know is this power supply the right one to use for my boss tu-3 chromatic tuner, boss dd-3 digital delay, boss tr-2 tremolo, boss ab-2 2 way selector and boss bd-2 blues driver. Furthermore, I have other pedals like ehx little Big Muff pi, ehx holy grail, and Dunlop cry baby. Will it also be safe to power them. Please note that I have the older psa-240, and not the newer psa-230 which has replaced it. I don't want to have to upgrade if it is not necessary. I'd rather use what I have. Finally, is there a list of all pedals which this power supply will power safely.


1 Answer 1


The following list is based on actual current draw, not on the 'power supply requirements'. Boss, for example, say that their BD-2 needs a PSA power supply which can provide 200mA at 9V. Of course they will, because they sell a PSA power supply which provides, believe it or not, 200mA at 9V. But - the actual current draw of the pedal, as measured by a mA meter, is much smaller. If it wasn't, those 9V batteries you can use as well wouldn't last very long..

Things to be aware of;

  1. If the pedal needs 9V, give it 9V. Don't give it 18V unless the manufacturer says it can take it (ignore any anonymous people on the internet). Sometimes a higher voltage will work, and sometimes you'll get the acrid smell of all life leaving that pedal. Giving a pedal lower voltage isn't normally an issue (some people do it because it affects the sound, like a dying battery does) - but many times, the pedal just won't work. Give it the right food, and it'll be perfectly OK.

  2. Take a note of the polarity. Some pedals are pin positive, shield negative. Some are the other way around. Don't just guess - look at the input on the side of the pedal. You can get converter plugs if you need them.

  3. To see if your power supply can do the job, add up the mA current draw of the pedals. If it's less than the mA that the power supply can deliver, you're good. Except.. some pedals, usually digital ones, don't like being daisy-chained. If you get a high pitched squealing after putting it all together, then that's where you need to look for the problem.

Current draws

I found these from Google searches; you should do your own research, especially for expensive pedals. I take no responsibility, IANAL, etc...

Crybaby needs 9v at 2mA

Holy Grail needs 9v at 220mA

Little Big Muff Pi needs 9v at 4mA

Boss BD-2 needs 9v at 20mA

Boss TR-2 needs 9v at 20mA

Boss DD-3 needs 9v at 35mA

Boss TU-2 needs 9v at 55mA

The PSA-240 can supply 200mA at 9V. Do the math. I'd recommend looking at a OneSpot (other power supplies are available..), which can deliver up to 1900mA.

  • That DD seems very low in consumption. When I first had mine, it would eat two batteries per gig. PSU bought PDQ!
    – Tim
    Feb 22, 2019 at 17:44
  • @tim I was surprised at the Big Muff Pi consumption as well. But these are internet stats, so we can say that the figures are definitely correct and have been exhaustively tested.. not! :)
    – PeteCon
    Feb 22, 2019 at 21:12

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