In theory there is enough current supply to power the amplifier and 3 pedals (overdrive, distortion, tuner).

But when I connect the power supply to the amplifier, it does not turn on.

I have another, 2 A, power supply (that is not "musical"; I got it for my hobby electronics lab) and that seems to be able to power the amp just fine.

Could it be that they badly screwed up the amp rating on the amplifier? Maybe they wrote 750 mA but it needs more than 1 A. It would be a fairly silly mistake, but I presume it could happen. In my books, if the required max currents are less than the current supply, everything should work.

I ask this because I want to power everything (amp and pedals) from a single wall outlet. How can I make it work (and why what I have is not working?).

I am looking to do this on a budget :-D And I am based in the U.S.

FWIW, I am aware of this answer How much power do I need to power my daisy chain

Update: it was the polarities As pointed out by Tim, polarities sometimes are not compatible; I got myself a Reverse Polarity Converter Cable 5.5 X 2.1 which I used to bridge one of the DC connectors on my pedal DC power supply to my practice amplifier. With that, everything seems to power on.


2 Answers 2


A 2A adaptor should be capable of driving that - there's probably no more than just over 1A with everything plugged in. There are plenty of adaptors that will supply more than the rated 2A you tried with, Maybe the original is old, cheap, and obviously not up to the job.

A 5A will make you futureproof - always a good thing. The gear will only pull what it needs, so no worries about frying. Watch the polarities, though.

So, in summing up - yes, if all components are the same polarity. No, if they're different. Unless - you use a 3/4 socket strip, with separate wall warts for each.

EDIT: it's entirely possible to change the polarity of a dc plug. I do several a month on occasions. So you could split the wire at the plug end, to have two different dc plugs with different polarities. Important to mark them clearly, as they only work in the appropriate appliance. Most are diode protected, but not all. I've done this for many years, but wouldn't recommend it to someone who doesn't know exactly what they're doing. A sparky would do it though.

  • 3
    Good point about polarities. The pedals are likely to be center-negative, but the amp is likely to want center-positive. Feb 11, 2021 at 8:13
  • 2
    @luserdroog - never understood why there can't be an 'industry standard' for polarity. It used to be a pain for me, and I ended up fixing two wall warts inside my amp, (in sockets) with a 4 pin XLR socket/plug to my (mixed) pedalboard. Quick set-up/breakdown.
    – Tim
    Feb 11, 2021 at 8:18
  • 1
    > Watch the polarities That was it Tim! I did check them once with a multimeter but I must have gotten confused that time, because I don't remember seeing a minus sign on the display and everything looked okay. Maybe I was tired :-P. After reading your answer I tried again today and it's exactly as @luser droog said, the 2 A adapter, that happens to work with the amp, is center-positive. The smaller adapter that works with the fx (and was correctly recommended by Amazon) is center-negative. I'll try to find/make some sort of polarity reverser. I'll let you know how it goes. Thank you guys!
    – damix911
    Feb 11, 2021 at 8:46
  • 1
    Years ago, I fixed a double socket into the back of the amp I was using (Peavey Renown), and used two psus. One of each 'sex'. They were hard-wired into a 4-way XLR socket. I then used a matching plug to my pedalboard, on a long (4-way) wire. Plugging in for gigs was easy, and from memory, in the snake were the audio leads too, so everything was either front of stage (pedals) or back (amp/speakers), and it worked well. Quick setup/breakdown. And, no, there was no noise interference, as it happened.
    – Tim
    Feb 11, 2021 at 9:06
  • 1
    The (very expensive) Sony Walkman Professional cassette recorder could be completely fried by the wrong polarity power adapter. I know :-(
    – Laurence
    Feb 18, 2021 at 13:16

Ground loops!

If you get an increased noise (esp. grid hum) it may be because you are using a common power supply.

Other than that, and save for extra attention needed about polarity and voltage specs for all devices, it should work.

  • 1
    How would ground loops come from wall warts that had no earth pin connected? Most are live and negative, the earth pin not being connected.
    – Tim
    Feb 11, 2021 at 14:16
  • 2
    The loop is between the power supply, the first device and the second device.
    – fraxinus
    Feb 11, 2021 at 14:59
  • 1
    In the past, I've got rid of earth loops by (naughtily) removing an earth connection. If that's not there in the first place, as in most power supplies, how can the lack f it produce hum?
    – Tim
    Feb 11, 2021 at 15:09
  • 1
    @Tim As fraxinus explains, mass of various devices is connected via the signal cable shield and via the power supply. This forms a loop that might pickup noise. Feb 11, 2021 at 16:59
  • 1
    @user1079505 - I understand - it used to happen at one particular venue I played frequently - in UK almost a G pitch ( I guess 60 Hz), but would that actually be a ground loop - earth hum, per se?
    – Tim
    Feb 11, 2021 at 17:12

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service and acknowledge you have read our privacy policy.

Not the answer you're looking for? Browse other questions tagged or ask your own question.