120hz hum coming from all-tube system - but only at high volumes
I suggest you get thee a simple tube tester to help diagnosing this problem and have for the rest of your life https://www.ebay.com/sch/i.html?_from=R40&_nkw=tube+tester&_sacat=0&LH_TitleDesc=0&_... make sure you get the manual or can download it. I am going to part with my 157, works just fine, I recently bought it’s bigger brother 257. tested my preamp’s 17 tubes on both to confirm, they agree with each other on their meters. seller says this one has problems, just to show a 157 https://www.ebay.com/itm/274957651485?hash=item4004c0ce1d%3Ag%3APQUAAOSwHeZhS3Ng&LH_BIN=1 this 257 to see it, this one also has comments https://www.ebay.com/itm/393411222024?hash=item5b9922da08%3Ag%3Aki4AAOSwcXhgzNw-&LH_BIN=1 |
If it was there all the time and only became audible at high volume then I would say it is just the way it is, perfectly normal run of the mill noise, and you can track it down if you think it is worth it. But "occasionally" and "fine for a bit" then reappears indicates to me this is heat or power related. Could be a tube, could be something else, but more than likely not right. Since you run mono then if it is both then probably not the amps, but more likely the preamp. |
