Connecting Tube Heaters in Series

[Tom Phillips]

Another thread contained the following question:

Not to hijack this thread, but the topic is related. Can I put the filaments of two power tubes in series and use 12V transformer to power the filament? Mainly I am referring to 6L6 and 6V6.

The answer is yes but there are restrictions. When you connect heaters in series, each individual heater must have the same current draw specification. Therefore, two 6L6s connected in series will operate just fine on 12.6 volts drawing 0.9 Amps of current with the voltage split evenly between them. A 6L6 connected in series with a 6C4, for example, would cause a problem because the 6L6 heater is rated at 0.9 A and the 6C4 heater is rated at 0.15 A.

To prevent a hijack just start a new thread

Cheers,
Tom

[Enzo]

Peavey runs the heaters on their Valveking amps in series. The four 6L6 at 0.9A each work fine together. But they also put three 12AX7s in there, wired for 6v, and the three in parallel. A 6v 12AX7 draws 0.3A, and three of them in parallel makes 0.9A, which neatly operates in series with the 6L6s. Actually kinda clever, I think.

[Alan0354]

Thanks guys, I was not going to push it in the other thread either, I'm glad you answer my question. Yes, it's going to be identical tubes, either 6L6 or 6V6.