Lord Valve

Originally posted by Paul J. Edwards Yes you can. Don't but the snake oil that tube dealers sell to make an extra buck. I'm a tube dealer, and I say balanced PI tubes are bull{censored}. If you *really* want your PI stage to be "balanced," the best way to do it is witha $3.00 pot, not a $30 tube that's been dipped in snake oil. For a typical Fender PI stage, for instance, you use a 100K linear pot. Remove the two plate load resistors (100K and 82K, for a blackface) and connect the pot's wiper to the B+ eyelet (where the two original resistors were connected together; there will be a wire coming off this eyelet that is connected to the HV supply) and then solder a 47K 1/2W resistor to the pot's two outside lugs. Connect the free ends of the resistors to the two eyelets which formerly had the plate load resistors in them. That's it. Now you can tweak your PI stage's "balance" to your heart's content. Set it where it sounds best. Once you have it where you like it, put the amp on a testload and scope the output. I betcha fifty bucks you set your PI stage balance pot so that the PI stage was fairly unbalanced. I have, in fact, put these pots in a number of amps (stuck through the back panel, where the geetah-picker could twiddle 'em) and I can't remember a single time where the amp came back with the PI stage in a balanced condition. Don't waste your money on "balanced" PI tubes. There are situations where a tube with two "matched" triodes is required, but very few of them are in audio circuitry, and fewer still are in musical instrument amplifiers. Lord Valve Expert

Originally posted by LordOVchaoS ??? I have no idea where to start! THere's so many different types! A 5 MHz single-trace will do fine. You don't need any of that TV sync {censored} or triggered sweep, either. There is a scope made in China/Korea/wherever that shows up all over the place with different brand names crunched on it - Elenco, Tenma, etc. - you can often find these for less than $200 brand new. DON'T get a Heathkit (chances are, it was wired in the dark by a drunk baboon) or blow a wad on a Tectronix. Guitar amps ain't rocket science - stay away from the pricy {censored}. Lord Valve Expert