Power Supply Question-center negative-center positive

[Mattr4president]

I just purchased a AMT E2 pedal and it looks like it takes the 9v and 12v power adapter and everyone says the 12v is the way to go. I'm looking for adapters online and I'm having a hard time coming up with something to work other than the $30 adapter direct from the company. The manual says its 110-220 input 12V 1,25 A center negative and everything I'm coming up with looks center positive or is different in some way. This first question is almost purely to quench my curiosity, but is this common? Is this way with most guitar pedal power supplies? Next, should I just suck it up and buy the pedal direct from the company or are there alternatives? Long term, should I look at getting a power brick? Will I then run in to the same problem with 'center negative'? I've had the same boss 9v power supply for years and I've never run in to these questions before so pardon my ignorance but I've just never put that much thought in to my power supply. It just seems a bit much to spend $30 on one adapter when, for slightly more, you can get a small brick and do everything.

 

[PFDarkside]

Re: Power Supply Question-center negative-center positive

Center negative had become an industry standard for pedal power supplies. But then again, so has 9V (as opposed to 12v) so maybe that's why you don't see an abundance of 12V center negative? Also, 1.25A is a decent amount of current from a wall wart, so that's a factor as well.

It's always safest to use the manufacturer supplied power supply until you really understand power requirements, etc.

 

[Darg1911]

Re: Power Supply Question-center negative-center positive

Do any DIY? You can always cut the plug off and re-solder, swapping the wires around. Or, cut the plug off and solder in a new plug (2.1 x 5.5 mm) and wire it for center negative (negative tip).

 

[Funkfingers]

Re: Power Supply Question-center negative-center positive

If you can open the case on a generic PSU, you could reverse the output cable connections inside.

Some PSUs have polarity reversal switching. This can be advantageous but also brings the possibility of inadvertently inflicting damage on the ICs in your effect units.

$30 for the official/approved PSU has to be less than the cost of replacing the effect unit itself.

 

[Mattr4president]

Re: Power Supply Question-center negative-center positive

Should there be a huge difference in sound with a 9v compared to a 12v? I'm assuming there will be some, but I'm not too familiar on how the power supply has an effect on the sound. Anyone shed some light on this?

 

[PFDarkside]

Re: Power Supply Question-center negative-center positive

Generally speaking running at a higher voltage should increase the headroom. I'd try it at 9V first, then search for your 12V adapter. I believe both of my power supplies (Voodoo Lab Pedal Power 4x4, T-Rex Chameleon) are able to do 12V. So if you go with an isolated supply in the future you can try it out both ways.

 

[Darg1911]

Re: Power Supply Question-center negative-center positive

Should mention that if you do go with a generic supply, it should be regulated. Most of the cheapest ones aren't. An unregulated supply will output 2 or 3 volts above its rating with no load. With a load, the voltage will match the rating but most pedals present such a small load that the supply may still be outputting more voltage (depending on its current delivery capacity). The cheap supplies are also not usually filtered as well and can be noisy.

Personally, I would run it on your existing 9 volt supply until you can either get the "right" supply or a decent regulated supply.