05-23-2018, 09:58 AM
(05-23-2018, 07:29 AM)slider313 Wrote: Octals are prone to microphonics. The good news is the New Sensor made Tung Sol 6SL7 and 6SN7 tubes are, for the most part, very quiet.
https://www.ebay.com/itm/Tung-Sol-TWO-Fa...7526!US!-1
Yeah, that's a possibility. The thing is that I bought one of their 6SL7s last year. I was rather unimpressed. It sounded fine, can't deny that. But the triodes were woefully imbalanced. I expected more, given the price.
Anyway, I have a bit of an update on this. As I have mentioned, I am actually chasing several hums, or so it seems. My current hypothesis is that the loudest hum, the one that grows over time is actually a power tube. I've swapped those out, and we'll see (it got late).
But the ground loop issue remains, and my current point of focus is the intensity pot. This pot links the trem section to the grid stoppers of the power tubes. It is currently grounded to itself. This hum increases as the intensity is reduced. I'm planning to experiment grounding this pot to one of the other ground points (either the cap can or the input jack). We'll see if either of those options help.