RE: Replace 12ax7 with 12at7

Posted by Michael Samra (D) on April 1, 2012 at 14:04:10

In Reply to: RE: Replace 12ax7 with 12at7 posted by Jim McShane on April 1, 2012 at 12:23:47:

Jim
Thats actually what they did with mc275,they used the 12at7 in the final stage.

I've never understood why Mac ran the relatively beefy tubes (12BH7, 12AU7, etc. ahead of the drivers and then used such a wimpy low transconductance tube as the driver.

Its kind of strange but the 12uau7 of course is the phase inverter and the 12bh7 is where the voltage gain takes place.Mac does most all their voltage ampification in those primary stages and once its fed to the output stage,the kt88s produce a 2 to 1 gain but its also amplifying current with the unity coupled circuit.You can actually pull the output tubes out of a mac and drive most speakers to listenable level.You won't have any bass due to the impedance mismatch but you can drive them.
"For every complex problem there is an answer that is clear, simple, and wrong" H. L. Mencken

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Follow Ups Full Thread

Topic - Replace 12ax7 with 12at7 - pegwill 05:18:39 03/31/12 (18)

Think E80CC instead - andy evans 11:44:35 04/02/12 (0)

RE: Replace 12ax7 with 12at7 - BCR 05:35:45 04/01/12 (0)

RE: Replace 12ax7 with 12at7 - Neff 07:34:16 03/31/12 (0)

RE: Replace 12ax7 with 12at7 - Blackdog 06:01:39 03/31/12 (14)

RE: Replace 12ax7 with 12at7 - pegwill 06:12:29 03/31/12 (13)

one other thing. - Blackdog 06:41:41 03/31/12 (2)

RE: one other thing. - pegwill 06:54:37 03/31/12 (1)

RE: one other thing. - Alpha Al 20:53:13 03/31/12 (0)

RE: Replace 12ax7 with 12at7 - Blackdog 06:35:38 03/31/12 (0)

RE: Replace 12ax7 with 12at7 - FenderLover 06:35:16 03/31/12 (8)

RE: Replace 12ax7 with 12at7 - Jim McShane 11:49:48 03/31/12 (7)

RE: Replace 12ax7 with 12at7 - Michael Samra 04:39:23 04/01/12 (5)

RE: Replace 12ax7 with 12at7 - Jim McShane 12:23:47 04/01/12 (2)

RE: Replace 12ax7 with 12at7 - Cleantimestream 18:40:02 04/03/12 (0)

RE: Replace 12ax7 with 12at7 - Michael Samra 14:04:10 04/01/12 (0)

RE: Replace 12ax7 with 12at7 - Neff 05:19:01 04/01/12 (1)

RE: Replace 12ax7 with 12at7 - Michael Samra 14:04:34 04/01/12 (0)

RE: Replace 12ax7 with 12at7 - FenderLover 17:53:23 03/31/12 (0)

Follow Ups

RE: Replace 12ax7 with 12at7 - Michael Samra 14:04:10 04/01/12 (0)

RE: Replace 12ax7 with 12at7

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