Re: Plate resistors on circlotron output stage

OTL Asylum

OTL, Output Transformerless Amplifier User Group.

0

This mod works! Many year ago at Vacuum State Research, in the '70s' we experimented with parallel tubes for many reasons, lower noise, higher transconductance, higher power disapation, etc, in both our differential direct coupled OTL preamp, and in power amp stages. We found it essential to use some kinf of resistor to force current sharing. Usually the best place was found to be in the cathode circuit. It always bothered me that the M-60s, at the state of design when Mike and I got involved, had no current sharing provision. I suggested this Ralph, and later with the Host of this WEBSITE. The big question was plate or cathode side. Engineering rational could be argued for either location. but the truth in in the listening, and Mark did the deed. I followed suit and was immediately rewarded with expected results, as described earlier in this string. Better bass, more detail from lower distortion, and inproved power. These are the same results we found 25 years ago in similar situations. IT WORKS! It is not expensive, and can be done in a few hours time.

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Schiit Audio

Topic - Re: Plate resistors on circlotron output stage - Jennifer WhiteWolf Crock 02:04:50 11/27/98 (0)