EF86 AC4 kind of amp.

[Thomas_H]

Hi,
finished my last build inspired in the schematic of Doug over http://www.dougcircuits.com/neon.html
It also has a tremolo, but opamp based. The neon lamp wasn't working properly.

I'm using a greenback 10" speaker in this small cab, which used to have a transistor amp with two 6" speakers.
The schematic started with the AC4 with an extra 12ax7 for extra gain and ended with 4 different preamp configurations:
The series configurations EF86->12ax7->12ax7->EL84 really has a nice gain.


some pictures of the finished build:

[tubeswell]

Those 10" Greenbacks are ideal for SE amps. I built an EF86 inspired SE amp a few years ago which sounded far better with the 10" GB than with 12"

[Chris Crunch]

Hi,
I found this old thread and I am very interested in building an AC4 with an EF86 and topboost circuit combined.
Are you still satisfied with the amp, did you do some changes?
The schematic looks good, but isn’t the bias cap for the EL84 missing?
Thank you for sharing!

[ChopSauce]

Nice pick! How could I have missed that...

That seems really well done. I wish I knew some more about that chassis, too...