I'm thinking on how I can make the most improvement with the easiest method for my Eico ST-70. The schematic shows 440v to the anodes with a 1800ohm dropping resistor to the screens (no choke)that gives 390v. The amp uses a 5AR4 rectifier.
I was wondering how I could make significant improvements without changing design much. I like this amp and am planning to replace a lot of components and tubes.
I have a thought for the power supply that I would like to throw out here. Weber has a power transformer for a Fender Twin rated for 400mA. It has a 320-0-320 and also tapped for 300-0-300. Is it possible to use a SS rectification on the 320-0-320 for the plates and then use the 5AR4 rectification on the 300-0-300 for the screens and preamp section? This would give me voltage very, very close to original specs and do it with a transformer that is made for my home's voltage (which is usually right around 125AC). I could use a CLC after the tube and have the choke be more around 100 ohms (maybe less, haven't checked) instead of 1800 ohm resistor. Much better filtering and much better impedance, correct?
Then again maybe you just can't do this with a power transformer. Thanks for any help.
I was wondering how I could make significant improvements without changing design much. I like this amp and am planning to replace a lot of components and tubes.
I have a thought for the power supply that I would like to throw out here. Weber has a power transformer for a Fender Twin rated for 400mA. It has a 320-0-320 and also tapped for 300-0-300. Is it possible to use a SS rectification on the 320-0-320 for the plates and then use the 5AR4 rectification on the 300-0-300 for the screens and preamp section? This would give me voltage very, very close to original specs and do it with a transformer that is made for my home's voltage (which is usually right around 125AC). I could use a CLC after the tube and have the choke be more around 100 ohms (maybe less, haven't checked) instead of 1800 ohm resistor. Much better filtering and much better impedance, correct?
Then again maybe you just can't do this with a power transformer. Thanks for any help.