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The following was anonymously added to LeslieAmplifierModifications. I've moved it here. (Take it with a grain of salt. If components in your amp have drifted way out of spec, of course that's a problem; but I don't think that everyone agrees that Leslie amps need to be extremely precisely balanced.) --JeffDairiki

Here's a couple tips for optimizing your leslie 122 amp.

  1. Use a matched driver tube. The driver tube is the 12AU7 nearest the volume knob. TorresEngineering is a good source for all of the parts I'll mention. [Also see PartsSources -ed].
  2. Carefully match C9 and C10,the .01 600v coupling caps in between the aforementioned driver tube and the output tubes. Here's a link to a site with schematics Orange drops sound good here.
  3. Also match resistors R5 and R7, 1 MEG 1/2 watt. Ohmite carbon comp are a good choice, just buy (and measure) 10 or 20 and you'll get a good match

These changes provide a much more equal signal to both sides of your output tube. You'll hear the difference in volume, maybe a huge difference if your original components are very uneven.

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