Re: 300B running on low primary impedance?

SET Asylum

Single Ended Triodes (SETs), the ultimate tube lovers dream.

In Reply to: 300B running on low primary impedance? posted by jantle2 on March 2, 2007 at 10:46:15:

The trick is to match the operating point to the load impedance. At the low load, the tube must run fairly low voltage and high current to keep the distortion in check. At the maximum rated current of 100mA, I calculate about 300v plate to filament, plus maybe 55v bias.
The WE data sheet shows a point at 250v, -45v bias, 80mA plate current, and 1500 ohms load.
Efficiency is lower at these "low and hot" conditions, so you might only get 6 or 7 watts output. Damping factor is also lower, maybe 1.5-2 instead of around 3 normally. Some claim better sound, though I am not yet convinced the comparisons are free of enough other changes.

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Topic - 300B running on low primary impedance? - jantle2 10:46:15 03/02/07 (5)

Re: 300B running on low primary impedance? - Paul Joppa 17:45:40 03/02/07 (0)

I think Super 300B (300BXL ) will be comfortable with the load (nt) - limono 16:11:29 03/02/07 (0)

You can use it in a mid-hi amplifier. - sser2 11:44:51 03/02/07 (2)

Very bad practice using 1.25K for single 300B... - Thomas Martens 15:33:14 03/02/07 (1)

thanks for your advice... - jantle2 17:47:35 03/02/07 (0)

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Re: 300B running on low primary impedance? - Paul Joppa 17:45:40 03/02/07 (0)

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