Tube DIY Asylum: RE: McIntosh C20 Pre-amp Right Channel Buzz by Triode

Tube DIY Asylum: RE: McIntosh C20 Pre-amp Right Channel Buzz by Triode_Kingdom

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RE: McIntosh C20 Pre-amp Right Channel Buzz

24.27.41.140

Triode_Kingdom

In Reply to: RE: McIntosh C20 Pre-amp Right Channel Buzz posted by mr9iron on May 22, 2025 at 00:24:38:

Is the shell of the Volume control well grounded? The preamp's bottom cover is making good electrical contact? The connection at the grid of the output tube is extremely high impedance due to the bootstrapped cathode follower, probably about 10 Meg. The Volume control is the only thing pulling this area of the signal path toward ground, so all of this wiring is susceptible to hum pickup. I would be hesitant to use shielded wiring due to the likelihood of high frequency attenuation.

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Topic - McIntosh C20 Pre-amp Right Channel Buzz - mr9iron 16:44:05 05/21/25 ( 3)

RE: McIntosh C20 Pre-amp Right Channel Buzz - Triode_Kingdom 20:27:20 05/21/25 ( 2)
- RE: McIntosh C20 Pre-amp Right Channel Buzz - mr9iron 00:24:38 05/22/25 ( 1)
  - RE: McIntosh C20 Pre-amp Right Channel Buzz - Triode_Kingdom 05/22/25 07:38:43 05/22/25 ( 0)