@orpheus10 Sorry for the delay.
For the PV-12, there are 2 sets of caps which are really key. As I wrote before, the output caps are really most critical If they are 2uF, upgrade them to 4uF, maintaining or exceeding the original voltage. Alternatively use a pair of 2uF caps on each. How crazy you want to go is up to you. The sky is the limit in your spending.
After this there is a large electrolytic which I believe is on the heater or something like that. It basically just maintains a DC voltage to the tubes, but it’s part of the signal instead of the DC supply, so it’s not fed directly by the regulators.
After these two, the PV-12 (if memory serves) has a 2 level voltage regulation stages. A pre-regulator, and then 1 more per channel. You can identify the stages by the chain of zener diodes in each.
Don’t go too crazy, but it may be worth replacing or bypassing the filter caps on the outputs of each of these 3 stages. Save your money for the output caps though!
Lastly, add heat sinks to each of the transistors used as regulators. They go out frequently and sinks are cheap. :)
One more advanced mod which I never did and now don't remember is to lower the total gain. That preamp has too much gain, and you don't need it. Lower the gain and you'll get much less noise.
For the PV-12, there are 2 sets of caps which are really key. As I wrote before, the output caps are really most critical If they are 2uF, upgrade them to 4uF, maintaining or exceeding the original voltage. Alternatively use a pair of 2uF caps on each. How crazy you want to go is up to you. The sky is the limit in your spending.
After this there is a large electrolytic which I believe is on the heater or something like that. It basically just maintains a DC voltage to the tubes, but it’s part of the signal instead of the DC supply, so it’s not fed directly by the regulators.
After these two, the PV-12 (if memory serves) has a 2 level voltage regulation stages. A pre-regulator, and then 1 more per channel. You can identify the stages by the chain of zener diodes in each.
Don’t go too crazy, but it may be worth replacing or bypassing the filter caps on the outputs of each of these 3 stages. Save your money for the output caps though!
Lastly, add heat sinks to each of the transistors used as regulators. They go out frequently and sinks are cheap. :)
One more advanced mod which I never did and now don't remember is to lower the total gain. That preamp has too much gain, and you don't need it. Lower the gain and you'll get much less noise.