Dumb idea? Reverse polarity of power supply

nellie48 · #1 11-15-2009, 10:36 AM

I have a Fulltone Bassdrive which I have been running off a 9v 1 spot. This pedal can be run up to 18v which gives more headroom. I would like to try it. I have a 18V ac adapter that will work but the center pin is positive and not negative. Can I just splice and swap the wires so that the polarity is reversed. I would like to know before I fry my pedal or commit to dropping $20 on a Dunlop AC adapter.

Thanks

**Bryan R. Tyler** · #2 11-15-2009, 10:43 AM

Is your AC adapter 18v AC, or an AC adapter that puts out 18v of DC power? You might want to be sure on that one

nellie48 · #3 11-15-2009, 10:47 AM

it says ac/dc power adapter with an output of 18v 2.23A LPS. this is an adapter to an old printer

nellie48 · #4 11-15-2009, 11:31 AM

I suppose a multi meter (if I had one) would answer this question. Although I'm not sure how you would use one on a barrel and pin connector.

**Bryan R. Tyler** · #5 11-15-2009, 11:51 AM

If it says DC output then I imagine it'd be fine. One Spot even makes reverse polarity adapters you can pop on to the end of a barrel connector.

nellie48 · #6 11-15-2009, 12:16 PM

I'm still apprehensive to do this. apparently a regulated power supply is recommended. I guess that means that the voltage will remain constant. Not sure if this adaptor could vary and go over 18v.

Taylor Livingston · #7 11-15-2009, 01:22 PM

Swapping the polarity is no problem, but your 18v supply probably isn't regulated, and it's also probably pretty noisy since it's not meant for audio use, so if the pedal's power filtering isn't great you might get noise and hum.

At the same time, a pedal that can handle 18v can probably handle 20v ok, too. It would be a dumb design if the recommended voltage was so close to the maximum voltage.

nellie48 · #8 11-15-2009, 01:59 PM

Quote:

conical johnson;8244702]Swapping the polarity is no problem, but your 18v supply probably isn't regulated, and it's also probably pretty noisy since it's not meant for audio use, so if the pedal's power filtering isn't great you might get noise and hum.

Yeah, that is one of the possible drawbacks. Is a 1 spot regulated? Or is that only necessary for higher voltages like the 18v.

Quote:

At the same time, a pedal that can handle 18v can probably handle 20v ok, too. It would be a dumb design if the recommended voltage was so close to the maximum voltage.

That makes sense. I might be splitting hairs, but I have 15v adapter that I could switch the polarity on and use. These fulltone pedals take anywhere in between 9v-18v

Thanks

nellie48 · #9 11-15-2009, 03:48 PM

I just tried it out. it sounded amazing at first then it slowly got staticy. Even with the pedal in bypass mode it sounded like bad static and distortion. i guess im gonna have to buy a regulated power supply.

JustDavid · #10 11-15-2009, 04:30 PM

Are you having headroom issues? What's your signal chain?

Kael · #11 11-15-2009, 04:42 PM

Does running a fulltone bassdrive on 18v yeild more clean headroom before the dirt kicks in? I find myself wishing that mine would give me a little more play before gritting up my signal.

ie: less over all dirt with more knobs twisting yeilding more control to fine tune the tone

nellie48 · #12 11-15-2009, 05:08 PM

thats exactly what it does, it seems more dynamic, and it also felt bassier

Kael · #13 11-15-2009, 05:32 PM

Thanks man. Sounds like it is time to rewire the ol' DC Brick into the sucker.