Tube Amp Archive

Super useful informations ! thanks Ok for the switch but how would you lower the voltage the output ? with Zenher Diodes ? no overheating ? I found a transformer for the 20w Head It refers as "Mains" i assume it's an input transformer ? and Mercury have an output transformer for 20W Hiwatt but much ...

My suggestion for the output transformer would be a quality Hi-Fi one like from the Dynacos (ST35?) - just wire it in Pentode-mode rather than Ultra Linear. There should be some Dynaco equivalent in Europe. Using an OT designed for a Marshall 18W might saturate too early and not have the wide frequ...

PI means "inverseur de phase" (Phase Inverter). It is the ultimate pre-amp stage and no, you can't use anything but transformers dedicated to some "20W" amp, for the power tubes are crucial, both in terms of required (current, voltage) for the power transformer and of reflected impedance (& power h...

Hi Mark, Thanks a lot for your answer. What do you mean by PI ? sorry English is not my native language. So good news for the preamp stage ! that said there is 3 version of the 4in Preamp : Early mid and late 70's. Is there a difference in sound ? Concerning the transformer does a DR504 one could fi...

Hello, I have a project to make a Hiwatt DR20 clone and have few questions. But i cant find any diagram ou wiring scheme. Only the Custom 20 here Ideally i would like to have the same than DR20, 4 preamp input and 0.5W switch. Could i use the preamp circuit of the DR504 and the power circuit of 20W ...