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Post by JonesKY on Jul 26, 2022 16:24:24 GMT -7
Dr Z or others, typically if using a half power switch or pulling two outside tubes (for example, on a 100w Marshall or Fender), then the higher impedance output jack would be used with the same speaker...
ie 100w marshall w 4 tubes (100w)> 8 ohm jack > 8 ohm speaker or 100w marshall w 2 tubes (50w)> 16 ohm jack > 8 ohm speaker
Q: does the Dr recommend the change to the higher impedance tap/jack when switching to 1/2 power on the switch? or is the mismatch OK?
thanks for your help and insights, j
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Post by DRZ on Jul 26, 2022 18:17:32 GMT -7
You are correct with your definition of pulling two tubes in a Marshall or say a Twin Reverb and doubling the reflected impedance . But you do not know how I do my half power circuit in my amps. All four tubes receive full plate voltage and full bias voltage and do not operate in an altered mode ( i.e. Triode Mode ) . I will not post what I do, but I do not in any way alter the Plate Impedance , that is why my half power circuit works so well. The output tone remains the same just at half the output signal strength .
DR.Z
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Post by pcns on Jul 26, 2022 18:56:50 GMT -7
Dr Z's half power switch is really a thing of beauty. You don't have to compensate for it, you can just use it and enjoy less power when you need it.
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Post by JonesKY on Jul 26, 2022 19:38:57 GMT -7
You are correct with your definition of pulling two tubes in a Marshall or say a Twin Reverb and doubling the reflected impedance . But you do not know how I do my half power circuit in my amps. All four tubes receive full plate voltage and full bias voltage and do not operate in an altered mode ( i.e. Triode Mode ) . I will not post what I do, but I do not in any way alter the Plate Impedance , that is why my half power circuit works so well. The output tone remains the same just at half the output signal strength . DR.Z ah... ok, thank you, Doc! didn't know you designed a proprietary half power circuit. without getting into the details, your reply answered my Q regarding the concern for having proper impedance matching when in half power. thanks again and all the best! j
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