Hello, I have a tiny problem with my crack in that when I use 6SN7 tubes via an adaptor* I get a noticeable low level hum. When I use 12AU7 or equivalent it is dead silent. The hum is present with all 4 6SN7 tubes that I have.
It is more noticeable since I added speedball and upgraded to film caps. I have choke, cree diodes and the ground breaker installed as well.
*I have 2 adaptors and with both I get this hum. One is the ebay China one and the other is the Garage 1217 (crack version.)
Was wondering if it might be something to do with wiring alignments (heater wires / Noval socket) that are affected more by slightly different load of the 6SN7? Maybe both adaptors are dodgy? It isn't a major problem because it does sound great with 12AU7 but would just like to be able to use the 6SN7s as well.
attached are 2 pics. The before speedball, as the wiring is pretty much the same as it is now and then the "now" pictures:
