Print

Please login or register.
1 Hour 1 Day 1 Week 1 Month Forever
Login with username, password and session length

[Stephen Kirby]

Ned, I know a lot of trad bass players (including a friend who plays with Musslewhite) who love Showmans.  More power than a Bassman but similar tube feel.  Maybe try advertising on bass forums.

[Bob Leonard]

I wish you guys all lived near Boston. We could spend our days in my basement building, modding, and jamming our collective asses off.

Thanks for the compliments Ned. I remember the rebuild well. Labor of love that one was, with a huge dose of "This one's for Ned."

PS - Don't tell Steve Hurt I already miss the 1965 Super Reverb I sold him.

By the way, I have a 1961 re-issue LP with sideways Vibrola for sale cheap. It's almost a virgin.

[Steve M Smith]

The AC30 is a strange design.  Only the bright channel has treble and bass controls, but there is a high cut control which brings in a capacitance between the grids of the opposing pairs of EL84s.

The amp I am working on has reverb which is operational on all channels, but there is another version which feeds the vibrato/tremolo channel into the opposite side of the phase splitter (the grid which is usually decoupled to ground with a capacitor) so this channel doesn't send to the reverb circuit.

Then there is the claim of being a class A amp. It's realy a combination of driving the output valves past the manufacturers specifications (50mA per valve instead of 36mA) and not really being class A at full output.


Steve.

[Luke Geis]

You are correct that the AC30 is not a true class A amp. It is at certain operating points, but in typical use will be running in a class A/B standard.

The high cut is a neat idea really. It just feeds a signal between the polarity inverted sends from the phase splitter tube to the output tubes. The CMR of that signal between the plate signals will null and hence a high cut is created. It is sort of the same idea as a presence circuit. In either case cancellation is used as the base for the circuit.

I'm looking to build a Princeton or Champ based circuit next. Fender cleans just slay.

[Ned Ward]

Ned, I know a lot of trad bass players (including a friend who plays with Musslewhite) who love Showmans.  More power than a Bassman but similar tube feel.  Maybe try advertising on bass forums.

Funny you should mention - last two times it saw service was as a bass amp head going into an SVT 2x10. Sound was glorious.

[Bob Leonard]

You are correct that the AC30 is not a true class A amp. It is at certain operating points, but in typical use will be running in a class A/B standard.

The high cut is a neat idea really. It just feeds a signal between the polarity inverted sends from the phase splitter tube to the output tubes. The CMR of that signal between the plate signals will null and hence a high cut is created. It is sort of the same idea as a presence circuit. In either case cancellation is used as the base for the circuit.

I'm looking to build a Princeton or Champ based circuit next. Fender cleans just slay.

That's Steve Hurts Princeton Reverb on the top of the Twin Reverb going through final testing. He also bought the 1965 Super Reverb on the floor to the left. He's spoiled.

[Luke Geis]

Was just looking at kits and BOM's a bit ago for an AA764 build!!!  Hopefully Santa loves me this year

[ProSoundWeb Community]