Chosen Solution
This is a very old guitar amp probably from the late 1940’s. I believe it is single ended in that it has an 80 rectifier tube, a 6C5, a 6N7 and a 6L6. The socket for the 6L6 says 6N6. The amp works but I can see on my variac amp meter the current draw goes down instead of up when I strum the guitar. This seems odd to me as all other amps I’ve tested this way increase the current draw. It also seems to have a large current draw at idle, (no input signal) at .9 amps. The amp has had some work done, perhaps a lot as much of the circuit has been rewired and new capacitors. What if anything is out of the norm here? In other words shouldn’t the amp meter rise with a strong input signal? If so what might be the reason it’s decreasing?
Hi @bigdrums , Does the amp have a model number on it? If so then this link may be of some help. (The ‘donate’ option is up to you) For what it is worth it seems as though your amp’s circuit has been modified to accommodate the 6L6 valve in lieu of the 6N6. If it has you may have to “trace all the wiring and draw it out” to get a circuit diagram of the amp that you can work from. According to this link: Some known problematic tubes to replace: 6N6 (chinese), 6N6P (russian). This tube has NO known direct replacement: the best replacement is another 6N6 – 6N6P. However if you are experienced, and with the proper tools, it could be replaced (given socket rewiring and maybe some circuit tweaks) with 5687, 12BH7, ECC99 or E182CC. This last tube seems to be the closest equivalent.
