5E8a builds

[crashtm1]

Has anyone built a high powered version?
Specifically the 5E8a , not 5f8.
How about with a PPIMV?

[centervolume]

Yes, I built a 3-12 version 4x5881 twin circuit 5F8-A

[crashtm1]

Digging through my stash, I found these two beauties. A Mono tweed bassman PT (340v) and a MM JT4550-G4 (380v).. I've emailed MM for the specs and diagram.
What difference will I see between these two? More power? Tone?

[drew]

What "high powered" configuration are you contemplating? Both of those PTs are for amps that use a pair, not a quad, of power tubes.


Re: the PPIMV question, http://el34world.com/Forum/index.php?topic=15984.0 may be useful.

[crashtm1]

I'm currently building low power tweed twin 5E8a. I had considered dumping the 2 rectifier tubes and converting it to a 4x6L6 amp with SS rectifier. But for now I'm going to stay with the original layout.

[crashtm1]

Can someone explain the B+ voltage change notes at the bottom?
Does this mean the B+ changes depending on the rectifier?

[sluckey]

Can someone explain the B+ voltage change notes at the bottom?
Does this mean the B+ changes depending on the rectifier?

Bottom of what? If you are referencing some schematic post a link so we can see it too.

[crashtm1]

Been a long day..

[Joel]

Tube rectifiers are not as efficient as solid state rectifiers.  So yes, the B+ changes depending on what sort of rectifier device/s you are using.

[crashtm1]

Solid state.

[ac427v]

If that is a MOJO 752 it would have a solid state rectified B+ of around 500 volts! The 5E8-A schematic shows 400 volts to two 6L6G power tubes. A 5R4GYB tube rectifier would get you a lot closer to the original voltage. I also see that this Twin needs an uncommon (for guitar amp) choke because it must handle the entire high voltage load, not just the preamp tubes and power tube screens. I bet someone on this forum has found a suitable Hammond choke. I think it would be a very sweet amp if you can get close to original voltages.
Craig