RE: active loading with parallel feed?

MagneQuest/Peerless Forum

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Posted by Paul Joppa (P) on February 12, 2011 at 23:33:43

In Reply to: active loading with parallel feed? posted by DanK tubes on February 12, 2011 at 21:59:00:

It sounds great this way, no question. Finding the right parafeed cap is still a difficult problem though - the OPT inductance is all over the map as a function of frequency and voltage. The solution as far as I can see lies in the losses - eddy current and hysteresis in the transformer core. These are never quoted as part of the standard transformer specs, and are not exactly easy to measure, or to interpret.

There is no high frequency problem, believe me!

The idea certainly goes back at least to Doc B's "Soul Sister" preamp (1998). Tucker did a 45 amp at the Vancouver VSAC this way, which is still the best 45 I've heard - yes, I believe it was a TFA-2004Ni output. I'm working on a few variants currently, and the Bottlehead Repro tape preamp uses this approach with an Altec 15095 output transformer.

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Follow Ups Full Thread

Topic - active loading with parallel feed? - DanK tubes 21:59:00 02/12/11 (13)

how about a gyrator as an active load? - dhsettim 21:17:52 02/14/11 (2)

RE: how about a gyrator as an active load? - DanK tubes 22:38:46 02/14/11 (1)

RE: how about a gyrator as an active load? - dhsettim 21:14:12 02/15/11 (0)

Thanks everyone! - DanK tubes 14:37:32 02/13/11 (0)

RE: active loading with parallel feed? - Paul Joppa 23:33:43 02/12/11 (0)

RE: active loading with parallel feed? - gluca 22:31:43 02/12/11 (7)

Gianluca. Could you calculate a rough estimate of the B+ - Bas Horneman 08:16:04 02/13/11 (6)

RE: Gianluca. Could you calculate a rough estimate of the B+ - mqracing 09:36:50 02/13/11 (4)

Thanks Mike! nt - Bas Horneman 15:29:48 02/13/11 (3)

Using the calculations I arrive at a B+ of around 444V - Bas Horneman 12:09:44 02/14/11 (2)

RE: Using the calculations I arrive at a B+ of around 444V - mqracing 06:07:11 02/15/11 (0)

RE: Using the calculations I arrive at a B+ of around 444V - Bas Horneman 12:15:55 02/14/11 (0)

The planned heatsink - Bas Horneman 08:38:01 02/13/11 (0)

Follow Ups

RE: active loading with parallel feed? - Paul Joppa 23:33:43 02/12/11 (0)

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