I am aware that to reduce hum, it is recommended to add 2 x 100ohm resistors (1 on each lead) of the 6.3 line to ground, usually done at the lamp.
When I tried to do this, it immediately blew the 1 amp fuse. I removed the resistors, and installed a new "1 amp" fuse and made sure everything was working properly again – which it was.
When I checked the heater lines more closely I saw something different on this amp. At the end of the chain, just before the last tube (the tremolo tube), one of the lines connected directly to ground. From ground it went to its filament connection on the tube, then to the centre pin of the tube. There were no resistors or caps in this chain. The other 6.3 line went straight to its tube connection.
I found this odd, as all my other tube amps simply connect the 6.3 lines to the tube filaments. There is never a connection to ground unless done through the 100ohm resistors.
1: Has anyone ever seen this, and can they explain it to me?
2: Would this connection to ground be the reason the fuse whenI tried to install the 100ohm resistors?
3: Is it safe to remove that entire ground connection, and simply connect the second 6.3 line directly to the tube as it normally would be.
4: If 3 is safe to do – can should I then be able to install the 100ohm resistors?
5: Should I just leave well enough alone – LOL!
Thanks,
Sean