12A*7 Phase Inverter as Power Amp

General discussion area for tube amps.

Moderators: pompeiisneaks, Colossal

Post Reply
Xander8280
Posts: 100
Joined: Wed Apr 30, 2014 8:18 am

12A*7 Phase Inverter as Power Amp

Post by Xander8280 »

Hey guys,


Has anybody replaced the plate resistors of the typical long tailed pair inverter with a reverb driver transformer?
B+ on the centre tap and maybe a little trimmer to balance (since the 100k/82k were ditched).

Seems like an easy mod and gets a good preamp out with the inverter's distortion. With this not being a SE setup like the reverb driver transformer is wound would the output impedance work best with a 16ohm load? Tube life isn't the concern in this though.



Any input would be cool!
tubeswell
Posts: 2337
Joined: Thu Mar 27, 2008 6:42 am
Location: Wellington. NZ

Re: 12A*7 Phase Inverter as Power Amp

Post by tubeswell »

Yeah check out the AX84 amps Firefly with a self-split PP output stage using a 12AU7 with a 440R tail
He who dies with the most tubes... wins
User avatar
roberto
Posts: 1841
Joined: Tue Nov 27, 2007 4:45 pm
Location: Italy

Re: 12A*7 Phase Inverter as Power Amp

Post by roberto »

Stevem
Posts: 4551
Joined: Fri Jan 24, 2014 3:01 pm
Location: 1/3rd the way out one of the arms of the Milkyway.

Re: 12A*7 Phase Inverter as Power Amp

Post by Stevem »

Tweaking things to work with a 12BH7 would make for a longer lived output tube even if run at only 3 watts a side!
When I die, I want to go like my Grandfather did, peacefully in his sleep.
Not screaming like the passengers in his car!😊

Cutting out a man's tongue does not mean he’s a liar, but it does show that you fear the truth he might speak about you!
Rockwell666
Posts: 136
Joined: Mon Nov 21, 2016 4:56 pm

Re: 12A*7 Phase Inverter as Power Amp

Post by Rockwell666 »

Stevem wrote: Wed Dec 13, 2017 12:00 pm Tweaking things to work with a 12BH7 would make for a longer lived output tube even if run at only 3 watts a side!
so a standard LTP P.I feeding a 12bh7? the output transformer is the tricky part. a SE reverb trans is cheap
Post Reply