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Original Message
RE: Schematics (1 of 2)
Posted by koon on June 16, 2008 at 00:02:53:
Can OTL amp really good guitar amp? I am too interested. The clipping distortion and recovery is not the same as transformer output, but may be I can do something about it if you email the schematic to my email address. I think there are ways to make the clipping better 1)configure the amp in voltage follower instead of cathode follow mode, in the rca otl I believe it is in already in voltage follow mode which is prefered(?) 2)use positve feedback to ensure sufficient gain even at clipping and also can have better damping factor with lesses negative global feedback. 3) allow driver to clipp first before the output by shunting across the 2 plates of driver (2nd tube 6SN7 with 18K plate resistor) with a variable resistor say 250K-B or suitable choke.
For driver level it's 160V P-P in upper arm and 120V P-P in lower arm. The gives 40V P-P or 25W into 8 ohms or 80V P-P or 50W into 16 Ohms. Like flaw in old Willaimson amp, this old otl amp may have same flaw, the cathode bias resitor my be too low a value which I hope it may be verified.