It Glows!!!

Glowing pilot lights are a good sign!

Heater Wiring 

Wiring all the tubes together to the proper lead from the transformer allows them to each receive some voltage so that they can do their job. This voltage is referred to as the "heater" voltage, since it allows the tubes to get warm and glow. It is recommended that you wire the heater wire before any of the signal wire on a new project. Heater wiring should be routed as neatly as possible and as far away from any signal wiring channels as possible to prevent hum. If the heater wire does indeed have to come in contact with a signal wire, it is usually recommended that it cross perpendicularly rather than running parallel. This way, if there is magnetic field leakage, at least it's only on that one spot as opposed to the length of the wire run.

I was able to tuck the heater wire neatly against the corners of the chassis and make nice straight runs (it is the green wire in the photos).

After I got all the heaters wired up, I was ready for a test. This would be the first time I plug the contraption in to 110 volts. As Morgan Jones says in his book, the first time you test equipment in progress, even the most experienced builders have the same emotion: sheer controlled panic. I was a nervous wreck, but I plugged it into a power strip with an on/off switch in case I needed to quickly disconnect. I also used a few "throw-away" tubes I had lying around so that if something was wrong, I wouldn't damage my nice expensive vintage tubes. 

I plugged it in, took a deep breath, and switched it on. Nothing. No noises, pops, crackles, puffs of smoke, nothing. I looked closely at the tubes, as properly heating tubes will glow and emit heat. Nothing. The pilot light on the front panel was lighted, so I knew something was wired properly. I scratched my head, unplugged it, and took a closer look. Upon looking at the schematics and double-checking that I had wired the heaters to the proper solder tabs on the tube sockets, it dawned on me: I forgot to ground the tube sockets! AC needs + and - (hot and ground) to work, so if it only sees positive, nothing is going to happen until it is grounded. I grounded the appropriate tabs, popped the tubes back in, and plugged the amp in again. Deep breath, switched it on, and finally! Glowing tubes! Small success!

If you look very closely, you can see that the tubes are glowing.