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As I'm getting ready to do capacitor surgery on the Art Jota, I figured I'd hook up the neglected and miserably lonely Audio Electronic Super Amp in the interim. But instead of music, I got a horrendously loud hum on first power up. So easiest things first -- swap tubes. As the hum was of equal (perceived) loudness through both speakers, swapping left-to-right didn't seem too logical so I just swapped all of them. Didn't change anything. Crap. Now I'm pretty good at soldering and pretty good at putting a kit together, but I'm highly underqualified as a trouble shooter. Poked around inside, and didn't see anything obvious like a cooked component. Checked resistors and capacitors as best I could in-circuit, and just as I was about to give up and post here for some suggestions, I bumped the resistor on one of the 6CG7 sockets and the solder tab on that pin popped right out. Not a bad resistor or bad soldering -- the solder tab had broken off of the upper part of the pin socket! New one for me, and I have no clue how that could even happen other than some defect in the metal that was there all along. These were even some fairly expensive ceramic base, gold contact sockets I'd substituted for the kit sockets when I first built the amp. Fortunately I had another socket (and resistor) in the parts bin, so 20 minutes later the amp was up and running....without hum. I'd forgotten how good this inexpensive little amp sounds. While the Jota is in no danger of permanent displacement, I could listen to the Super Amp all day and enjoy it tremendously. I'm just happy the fix was easy...and that I was lucky enough to find the problem.
I am with TK, as those sockets are made with poor tolerances and QC. I had one socket where you could almost fully install an octal tube with the tube being misindexed. Once i had this problem where the tube would light up because contact was made with the filament but there would be no sound because the plate pin was not making contact. That had me scrambling around for a couple of hours before i noticed the issue. Who needs something like that?
"These were even some fairly expensive ceramic base, gold contact sockets I'd substituted"
Glitzy Chinese parts, no doubt. I'd replace them all with NOS Amphenol or Cinch. Glad it was an easy fix.
Buy Chinese. Bury freedom.
I hate those sockets and cringe when I see folks touting the high build quality of amplifiers that use them.
"Confusion of goals and perfection of means seems to characterise our age." Albert Einstein
Or for just a cuppla bucks get the light Brown Beltons from Parts Express or Parts Connexion. Tight and well -made.
You're right....even though these sockets had the right "qualities," they didn't have the right quality. :) If only I'd known about the Amph's or Cinch's back then....
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