RE: Tube heat

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In Reply to: Tube heat posted by saki70 on March 3, 2014 at 12:06:38:

I think as far as heat goes, accounting for power, the EL34 is as cool as it gets. I don't have first hand experience with designs other than Push Pull setups, so perhaps I'm overextending myself. But, I think of these things:

- Efficiency of the circuit and speakers; class A versus AB; availability of distortion-free power
- Average current and wattage - what output levels are you looking for?
- Heater current

Triode, Class A power is the least efficient kind of power there is. So, if you're looking to reduce heat, I don't think it's the way. In Class A, you're running the tube at near max current with zero signal.

Output levels the speaker tap are important to consider. What kind of power are you looking for? 10W, 20W, 40W? Given your suggested tubes, you may want to consider the B+ you'll be operating at! Datasheets say, at 5%, your EL34s can produce 40W of PP power each channel at 450V. The 845, running 1250V (!!!), would produce 30W. At a more reasonable but still sweat-breaking 750V, you'll get 15W. The 300B is a safe option at 7W at 350V.

Heater current wouldn't be much a saver. For example, an 845 draws 30W to each heater versus your EL34's at 9.5W a piece. That would make 20W versus 30W each channel... The 300B draws 6W, which is pretty reasonable.

Again, it depends on your output requirements. Maybe there's a higher powered option to the 300B that isn't as crazy as the 211 or 845?

I hope that sort of helped. I may have made mistakes in my logic. I hope I didn't. I hope the community corrects me accordingly haha
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May your tubes be lively, warm, and long-lasting. Holy be thy heater.

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Follow Ups Full Thread

Topic - Tube heat - saki70 12:06:38 03/03/14 (7)

RE: Tube heat - Caucasian Blackplate 21:24:54 03/03/14 (4)

RE: Tube heat - saki70 04:23:09 03/04/14 (3)

RE: Tube heat - Caucasian Blackplate 08:34:11 03/04/14 (1)

RE: Tube heat - saki70 11:37:24 03/04/14 (0)

211 versus 845 - TubeAcolyte 07:52:22 03/04/14 (0)

RE: Tube heat - TubeAcolyte 14:45:45 03/03/14 (1)

RE: Tube heat - saki70 17:31:45 03/03/14 (0)

Follow Ups

RE: Tube heat - TubeAcolyte 14:45:45 03/03/14 (1)

RE: Tube heat - saki70 17:31:45 03/03/14 (0)

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