120v effects question

[UncleBubba79]

I have a big box DMM and an old red Ross flanger both of which run at 120 volts. I love the tone from both, but have always wondered if they would run quieter if they were modded to run on 9 or 18vdc. Not sure if the benefit would outweigh the cost. I saw a thread about a diy mod for the flanger, but it was a little intimidating.

So do you think it's worth it or even possible to mod them? Also, any opinions on what it might do to the resale value (not planning to sell anything, but maybe someday)?

 

[tibbon]

Modifying vintage pedals (for better or worse) seems to ding their value, even if the mods are common sense.

I don't know about the Ross, but if memory serves me the DMM runs with a rail at -15.7VDC internally. I assume that there's a small transformer inside that's getting the voltage down a bit, and then a solid state rectifier (just diodes) along with some caps for filtering (much as you'd do in any power supply).

The mod if going to be a little more complicated than just giving it a +18VDC power supply if you want to keep it in spec. The datasheet on the MN3005 asks for -15VDC. Unsure why the DMM uses -15.7VDC but I'm guessing its close enough. -18VDC might work, but +18VDC certainly won't. You can fix this with a voltage regulator internally, but it still won't fix that - vs + DC. 9VDC certainly will not work.

As for noise, the DMM just isn't silent. Its S/N is 75dB at best, and the companders help a bit, but don't fix the problem overall. Add in the fact that you're pushing through additional significant gain stages afterward (guitar amp) with potentially noisy input (guitar pickups) and silence just isn't something to be expected.

Could I mod it? Sure. Would I? Probably not. Just live with the noise, or use another pedal really. If you absolutely need something with long delay time, relatively quiet and using the MN3005 chips, check out either the Moog delays, or the Echoczar Quad.