Amps using Silicon diodes can sound harsh and
brittle because the diodes are slower in response than a tube rectifier(they're so nice). By replacing the diodes with FREDs or Schottkys your amp
will have a smoother/sweeter top end, more detailed tone definition and be a touch more responsive. FREDs are
much faster than the cheaper diodes that most amp manufactures use. Although they seem kind of simple, rectifiers are not well understood from an RF-emission standpoint. If you think
of them as really crude Class B (not Class AB!) high-power output stages, the mental picture will get clearer.
The rectifiers commutate the AC waveform just like a fast mechanical switch, and like a mechanical switch, the
zero-crossing region is not dealt with cleanly. Conventional silicon diodes actually knock a hole out of the
waveform thanks to charge-storage effects. Fast/soft recovery diodes(or zero recovery SIC Schottkys) do a much smoother/quieter job of it. It would be nice if the power supply filter caps in your amp could rid the DC output of all of the garbage created, but they don't.
brittle because the diodes are slower in response than a tube rectifier(they're so nice). By replacing the diodes with FREDs or Schottkys your amp
will have a smoother/sweeter top end, more detailed tone definition and be a touch more responsive. FREDs are
much faster than the cheaper diodes that most amp manufactures use. Although they seem kind of simple, rectifiers are not well understood from an RF-emission standpoint. If you think
of them as really crude Class B (not Class AB!) high-power output stages, the mental picture will get clearer.
The rectifiers commutate the AC waveform just like a fast mechanical switch, and like a mechanical switch, the
zero-crossing region is not dealt with cleanly. Conventional silicon diodes actually knock a hole out of the
waveform thanks to charge-storage effects. Fast/soft recovery diodes(or zero recovery SIC Schottkys) do a much smoother/quieter job of it. It would be nice if the power supply filter caps in your amp could rid the DC output of all of the garbage created, but they don't.