RE: Heathkit W-6

Posted by Eli Duttman (A) on April 6, 2015 at 17:31:31

In Reply to: RE: Heathkit W-6 posted by Crazy Dave on April 6, 2015 at 14:41:36:

It's Williamson style, with an added "twist". Cathode followers are DC coupled to the "finals". Blocking distortion can't occur and a bit of positive g1 current, for which KT88s/6550s are rated, can occur.

Considering that the differential gain block is a 'X7, cathode followers are a damned good idea. The 'X7 triode "can't fight it's way out of a wet paper bag".

A 2nd look at the schematic suggests that reducing the open loop gain might be reasonable. Notice the attenuating resistor network, right at the I/P jack. FWIW, I prefer a simple 100 Kohm grid to ground resistor, along with a CC grid stopper.

I like high gm in circuits that employ GNFB. Open loop gain could be reduced and gm improved by changing the tube used in the differential gain block to a 12AV7. Heck even a 12AY7 would (IMO) be an improvement over the OEM 12AX7.

Eli D.

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Follow Ups Full Thread

Topic - Heathkit W-6 - mark.korda@myfairpoint.net 14:46:07 04/05/15 (24)

Arrrrgh, the pain returns! - vinnie2 05:12:30 04/08/15 (3)

RE: Arrrrgh, the pain returns! - PakProtector 05:37:01 04/08/15 (2)

RE: Arrrrgh, the pain returns! - vinnie2 14:31:49 04/08/15 (1)

RE: Arrrrgh, the pain returns! - PakProtector 16:23:04 04/08/15 (0)

The best output transformers ever - garymuffley 16:43:12 04/06/15 (2)

RE: The best output transformers ever - Jim McShane 15:16:57 04/07/15 (1)

RE: The best output transformers ever - Crazy Dave 08:03:56 04/15/15 (0)

Glad I got my two...:) - PakProtector 09:07:28 04/06/15 (0)

RE: Heathkit W-6 - unclestu 17:11:57 04/05/15 (9)

RE: Heathkit W-6 - mark.korda@myfairpoint.net 21:29:11 04/05/15 (8)

RE: Heathkit W-6 - Eli Duttman 09:52:43 04/06/15 (5)

RE: Heathkit W-6 - Crazy Dave 14:41:36 04/06/15 (4)

RE: Heathkit W-6 - Eli Duttman 17:31:31 04/06/15 (3)

RE: Heathkit W-6 - Crazy Dave 08:15:49 04/07/15 (2)

RE: Heathkit W-6 - Eli Duttman 09:00:50 04/07/15 (1)

Great information as usual, Eli! - Crazy Dave 09:44:27 04/07/15 (0)

RE: Heathkit W-6 - johnmil 05:40:34 04/06/15 (1)

real numbers? - PakProtector 06:02:28 04/09/15 (0)

RE: Heathkit W-6 - Steve O 15:29:34 04/05/15 (2)

RE: Heathkit W-6 - Eli Duttman 16:40:28 04/05/15 (1)

RE: Heathkit W-6 - bcguitar 09:00:52 04/07/15 (0)

RE: Heathkit W-6 - bcguitar 15:11:01 04/05/15 (0)

Copy and paste pictures? - 1973shovel 15:01:04 04/05/15 (1)

RE: Copy and paste pictures? - Awe-d-o-file 06:27:22 04/06/15 (0)

Follow Ups

RE: Heathkit W-6 - Eli Duttman 17:31:31 04/06/15 (3)

RE: Heathkit W-6 - Crazy Dave 08:15:49 04/07/15 (2)

RE: Heathkit W-6 - Eli Duttman 09:00:50 04/07/15 (1)

Great information as usual, Eli! - Crazy Dave 09:44:27 04/07/15 (0)

RE: Heathkit W-6

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