O.C.D.

I'm using a fulltone o.c.d. with a 1-spot nine volt adapter..Their sight says that the ocd works even better with a 12 or 18 volt adapter..Has anyone tried these higher voltage adapters and if so is the difference obvious, or is it one of those changes that only Lassie would hear..

IMO it's obvious, but not always for the better.

The opamp chip used in many pedals was originally slated for use in other audio equipment, where 9 volts is simply ridiculously low to get a nice clean signal. Most chips will run at 12 volts with no problems. I don't like to go above 15 even though some will do 18 without any problems.

Mike Fuller went with an odd chip choice for the OCD - a TL082, although the pedal that the OCD is derived from (Voodoo Labs Overdrive) uses the good old trusty TL072. I've used the '82 in a bunch of different builds, and don't find it to be sonically much different from a '72, 4558, etc. Both the '72 and '82 will handle 18 volts without a hitch.

Basically, you get more headroom before clipping when you run a pedal at higher voltage. The signal now has to be larger than the max amount of juice possible before distortion occurs. This is probably the best way to run any opamp type of pedal, since you want the distortion to come from the clipping diodes and not the chip hitting the rails and clipping in a not so pleasant way.

thank you my friend...

.011 Gauge...
Dang, you're a smart one! I knew I should have paid more attention in my high school electronics class! Wait, they didn't have opamps back then!

Wait, they didn't have opamps back then!

But op amps have been around a pretty long time. It's just that they're only now getting around to using them in pedals how they were originally designed to be used in stereo equipment...

I guess that the next logical step will be ultra low distortion op amps running at 18 volts, with very odd diode clipping arrays. It seems to be the "last frontier" for pedal builders, as just about every other idea has been exhausted.

Next up: the AD8599 and AD8022. The hi fi crowd loves these chips. They're all bailing on their Burr Browns for one or the other. I only know of one or two folks who are trying them in stompers, with lukewarm results. I suspect that once they get the diodes right, these pedals will be a hit, especially if they're run at 15VDC or higher. Then the 4558 and TL072 will be referred to as "old school."