|andy fuchs||Re: Old Styl Dumple OD: ears ringin!|
Gil: As we had previously discussed, the issue of caps on the OD stages is an interesting one. I don't think they were put there to stop oscillations (unless they may be momentary signal related transient oscillations), but the circuit without them simply sounds spitty, brittle, and brash. The range of values is more according to taste than anything else. 330 to 470 pf seems to be a value that most people like. It's absolutely imperative that the builder has a circuit thats totally free from any stray oscillations to begin with. These caps will "fix" oscillations, and the resulting sound is drastically different that a circuit that was clean and stable to begin with. If you build a circuit and put them in place without checking for stability first, they could actually mask other problems and the resultant sound will not be good. These caps should be mounted right at the tube socket pins, and hi-voltage ceramics (to my ears)sound best. The best stability test is all controls on ten in overdrive mode. You should hear hisssssssss and only hiss. If it whistles, oscillates, activates your garage door opener, or makes the metal plate in your head warm up, it needs to be fixed first !