I think checking the main a second time is a good idea. Neutral and grounds. Do I think there is a problem in the main? NO. If your confident with you’re electrician.
Electricians and mechanics are NOT in short supply in my family, my brother retired as the local BA in Martinez CA. 12-15 last count. 4 HD local 3 mechanics.. No shortage of skilled labor, or muscle :-)
ALL of them learned what "tight" is from Uncle Scotty..(ME)
ALL were taught how to torque properly..
I use a Variac when I run into things like this.. Most electricians DON’T have them. Most old audiophilers DO.. You have a voltage difference between a "piece" of equipment and usually ALL the rest. or You have an old piece that need to percolate for 10-40 hours to tighten up the old caps.. So they just don’t leak all over..
Tube rectified in a preamp? MATCHED and checked for noise. NO excuse, on that one... You have to make sure it's not noisy at YOUR house... Not the Tec....Your house.
audio2design, mentioned an isolation transformer. A variac is, with the added feature of being able to VARY the voltage.
I suggest (only for a test) to very the voltage from 110 all the way to 122 VAC, SLOWLEY, and see if the noise goes away.
1. I would recheck MY main. I don’t trust anyone more than me.. NO
ONE. Check for 120 (A) 120 (B), 240 between. To ground less than 1% of the total being checked..
2. I would make sure I had a good PC going to my Pre amp. I’d change the PC no matter what. Just to test... I would pull the fuse clean the pocket with Isopropyl, LET IT DRY and inspect the HECK out of the fuse holder look for carbon trails.. LOOK close.. Reinstall a new fuse, a busman will do. NO fancy fuses for now...
3. The valves for the PS you know where the noise is coming from.. those valves would be changed (just for a test) MATCHED and checked for noise. NO EXCUSE on that one for sure. The pins and pockets on ALL the valves need to be cleaned and reseated, and pin pockets need to be checked for tightness and brushed and cleaned.
All this takes about 1-2 hours, from the mains to cleaning everything..
I would test NOW, did you get lucky, no luck go to # 4
4. I’d smoke a little weed about now.. :-)
Mind you, after everything you did THINK.
Clear your ears and
5. Hook up the Variac a DMM and turn it to 100 volts and go from there up to 122 or so.. You have to have a DMM, (no analog). LISTEN.
If it goes away, because of a voltage difference, LOL don’t be surprised.
If it doesn’t go away don’t be depressed.. Closer than you think..
Regards..
Electricians and mechanics are NOT in short supply in my family, my brother retired as the local BA in Martinez CA. 12-15 last count. 4 HD local 3 mechanics.. No shortage of skilled labor, or muscle :-)
ALL of them learned what "tight" is from Uncle Scotty..(ME)
ALL were taught how to torque properly..
I use a Variac when I run into things like this.. Most electricians DON’T have them. Most old audiophilers DO.. You have a voltage difference between a "piece" of equipment and usually ALL the rest. or You have an old piece that need to percolate for 10-40 hours to tighten up the old caps.. So they just don’t leak all over..
Tube rectified in a preamp? MATCHED and checked for noise. NO excuse, on that one... You have to make sure it's not noisy at YOUR house... Not the Tec....Your house.
audio2design, mentioned an isolation transformer. A variac is, with the added feature of being able to VARY the voltage.
I suggest (only for a test) to very the voltage from 110 all the way to 122 VAC, SLOWLEY, and see if the noise goes away.
1. I would recheck MY main. I don’t trust anyone more than me.. NO
ONE. Check for 120 (A) 120 (B), 240 between. To ground less than 1% of the total being checked..
2. I would make sure I had a good PC going to my Pre amp. I’d change the PC no matter what. Just to test... I would pull the fuse clean the pocket with Isopropyl, LET IT DRY and inspect the HECK out of the fuse holder look for carbon trails.. LOOK close.. Reinstall a new fuse, a busman will do. NO fancy fuses for now...
3. The valves for the PS you know where the noise is coming from.. those valves would be changed (just for a test) MATCHED and checked for noise. NO EXCUSE on that one for sure. The pins and pockets on ALL the valves need to be cleaned and reseated, and pin pockets need to be checked for tightness and brushed and cleaned.
All this takes about 1-2 hours, from the mains to cleaning everything..
I would test NOW, did you get lucky, no luck go to # 4
4. I’d smoke a little weed about now.. :-)
Mind you, after everything you did THINK.
Clear your ears and
5. Hook up the Variac a DMM and turn it to 100 volts and go from there up to 122 or so.. You have to have a DMM, (no analog). LISTEN.
If it goes away, because of a voltage difference, LOL don’t be surprised.
If it doesn’t go away don’t be depressed.. Closer than you think..
Regards..