O.C.D.

[fancychords]

Is there a big difference running the O.C.D. with 18 volts as opposed to 9 volts..Is the switch worth it..

[vjf1968]

Depends if you want more headroom from the pedal.

[fancychords]

Thanks but I'm not sure how headroom applies to a pedal..Can you explain a bit more..

[Charless]

Originally Posted by fancychords

Thanks but I'm not sure how headroom applies to a pedal..Can you explain a bit more..

The OCD works by clipping the signal (providing the overdrive) by how hard the signal (pick attack) it receives.

From the P.A.S. Fulltone page http://www.pedalarea.com/ocd.htm


Using a higher supply voltage will affect the clipping threshold through the floating bias point and thus give more headroom to the signal

Basically the pedal has to work harder to clip the signal so you get a more clear defined sound .. much more amp-like to these ears .. I love it at 18v and this might the greatest overdrive pedal ever made.

Check out v4 - it has I believe a germainum circuit in it. Really dynamic and open sounding.

[benadrian]

Distortion and boost pedals amplify the signal level cleanly. Then, they clip off the tops of the waveforms to add distortion. After that, the volume control pads the level down more.

Usually the input signal is a tens of millivolts, and the output signal is louder, anywhere between .25 to a few volts, I'd guess. For argument's sake, let's say the input is 50 mv and the output is 1000mv (aka 1 volt). That's an amplification factor of 20 times.

Guitars are not static. The voltage changes depending on how hard the guitar is played. In many cases the voltages can get close to a volt on the transients.

Let's say you hit a loud chord and the peak level is .75 v. The op amp would amplify it 20 times, and the output should be 15 v. With an 18v power supply, this should be able to be reproduced fine. However, with a 9 volt power supply, the most amount of voltage that it can put out will be 9 volts. that transient that should be 15 volts will be clipped off at 9 volts.

So, you have the clean boost section of the pedal adding clipping before the distortion section of the pedal adds clipping, and before you pad the output level down with output volume control.

You notice this the most if you use the pedal for more of a clean boost or a mild clipping. If you crank the gain, it will be a much more subtle difference. Also, perhaps you LIKE the tone of the lower voltage? It's all totally subjective. Some pedals makes actually lower the voltage. For instance, the Hotcake has an 8.2 volt Zener diode in the power supply. No matter what voltage you feed it, it lowers the voltage to 8.2v.

Cheers!
Ben

[fancychords]

Thank you all for the reply..I've been using a 1 spot with nice results, but I've ordered a dunlop 18 volt from Z sounds..