RE: Filament DC bias

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In Reply to: Filament DC bias posted by Thermionic27609 on May 2, 2015 at 08:02:31:

I've seen it done both ways. Some amps use a voltage divider off the B+ to apply a + voltage to the heaters. Others (that are cathode biased) use a direct connection from the cathode of the power tube(s) which is also a + voltage.

I have also seen some as you describe, that use the - bias supply and apply that to the heaters through a high value resistor, biasing the heaters negative. And these were 40's-50's guitar amps. This seems counterproductive to me, though. I always thought you needed a + voltage to stop the heaters from emitting electrons in tubes with cathodes.

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Follow Ups Full Thread

Topic - Filament DC bias - Thermionic27609 08:02:31 05/02/15 (3)

RE: Filament DC bias - Alpha Al 11:56:59 05/02/15 (2)

RE: Filament DC bias - Thermionic27609 18:16:06 05/02/15 (1)

RE: Filament DC bias ... maybe like this... - drummerwill 17:49:29 05/04/15 (0)

Follow Ups

RE: Filament DC bias - Alpha Al 11:56:59 05/02/15 (2)

RE: Filament DC bias - Thermionic27609 18:16:06 05/02/15 (1)

RE: Filament DC bias ... maybe like this... - drummerwill 17:49:29 05/04/15 (0)

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