Tube Amp Archive

The main issues now are: 1. Hum in high volumes. It's a low-end hum that comes in at around 8 on the volume. There's also a bit of high end hum in the reverb section. I have all grounds except for the mains ground attached to the ground buss, as per the Valve Wizard's site. 2. Weak reverb. The rever...

Here's the schematic.

Thanks for your advice! I managed to fix the amp. It was almost completely a bias issue. I looked up some of the schematics for Sunn amps and managed to play with the values of the voltage divider circuit enough to get all of the voltages on all tubes in the right place. The bias voltage is now sitt...

Thanks so much for your response - and sorry for my late reply. I hope to get to those tests on Monday, but it all makes sense. What voltage divider resistors would you suggest in order to get the voltage bias to the right bias point? Currently, I've got a 470 ohm 1watt resistor (typical in twin rev...

Hello all, I'm in the process of building a pedal steel amp for a friend. It's based on a blackface Twin Reverb, but instead of four 6l6's, it has two 6550's. It also has a four knob reverb (Dwell, Mix, Treble, Bass). I designed the amp to have some of the common mods done to Twin Reverbs for Pedal ...