On 3/19/23 12:23, Iain Jamieson via Jukebox-list wrote:
Hi Jay,
I have added pics to my Google Drive, here is the link - Hopefully works ok. https://drive.google.com/drive/folders/1DTal-_lQXpSz-hBsA4dcv0DcAt4E2wqt?usp...
A bit of History, I purchased this Amp and Crossover from the USA to replace the missing audio gear as the Jukebox had been butchered and didn't have any audio gear in it.
Hopefully those pictures show enough detail?
Based on the wiring, it looks like the sockets are indeed for a 6L6 or 6V6 tube. The components seem to line up with the connections. Pin 8 looks to be the cathode baased on the electrolytic and power resistor for self-bias. Pin 5 looks to be the grid based on the 100K resistor and coupling cap. Pin 3 has what looks to be the output transformer primary which would be the plate, and pin 4 looks to be the screen. Heater on 2 and 7 as with most octal tubes. This would be the standard pinout for most octal power tubes in the 6L6, 6V6, etc. family
If you look closely you'll see a pair of mounting holes punched in the chassis at each socket to accommodate the 9-pin sockets for 6973s. The riveted sockets suggest that it was made with the larger sockets at the factory. Possibly it could have been built either way or the larger holes were a factory modification due to unavailability of 6973 tubes.
So, the question is what tubes to use. Assuming that the design was for 6973s with a 450ma heater, the 6V6 would be relatively close but its maximum plate and screen voltages are lower than those of the 6973. 6L6 tubes would work but their heater current is twice that of 6973s and could overload the power transformer.
One option is the JJ Tubes 6V6S. They have a 500ma heater and plate and screen voltage ratings are in line with the 6973. Other 6V6 tubes will probably be fine, you could measure the plate voltage to be sure it isn't exceeded. I assume there were no tubes installed when you got the amplifier.
Some of the solder connections in your photos are kind of sketchy, you might want to clean that up.