I'm looking for some advice. I have a Fatman 252, (dared mp60) which serves me well. The chassis looks good and fits well where I have it and most importantly passes the wife test.
Over the years, I've swapped valves, and most of the capacitors in the amp, also had to add resistance to the heater lines to get them to 6.3v with a 240vac uk supply.
I'm now considering a complete rebuild and transformer swap to lundahl 1663pp, but am unsure of whether I need to swap other component values to suit. I don't have, and so far haven't been able to get a schematic, but guess I'll have to draw one out. I also don't understand how to design a valve amp, although I've put kits together, and built a few dacs and power supplys.
Given that I want to retain the chassis, I've spent money on the valves, and prefer to retain that topology, 12ax7-Mullard m8137, 6sn7-Sylvania vt231, 6l6gc-Philips 7581a in pp ultralinear, will I get myself in trouble swapping the transformers, without changing the values of other components around them?
And comment or help gratefully received.
Over the years, I've swapped valves, and most of the capacitors in the amp, also had to add resistance to the heater lines to get them to 6.3v with a 240vac uk supply.
I'm now considering a complete rebuild and transformer swap to lundahl 1663pp, but am unsure of whether I need to swap other component values to suit. I don't have, and so far haven't been able to get a schematic, but guess I'll have to draw one out. I also don't understand how to design a valve amp, although I've put kits together, and built a few dacs and power supplys.
Given that I want to retain the chassis, I've spent money on the valves, and prefer to retain that topology, 12ax7-Mullard m8137, 6sn7-Sylvania vt231, 6l6gc-Philips 7581a in pp ultralinear, will I get myself in trouble swapping the transformers, without changing the values of other components around them?
And comment or help gratefully received.
Cathode Bias amp are more stable and easier to work with. You might be able to get away without changing anything. Changing the transformer can alter the plate loading and UL feedback. I would monitor the bias current on the Cathode resistor while power up slowly (using a Variac). Measure the Cathode current before the transplant. Change the Cathode resistor if it is too much off, after the transplant. A little bit off doesn't matter that much.
Be-careful there are high voltage there and follow all safety rules.
Be-careful there are high voltage there and follow all safety rules.
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