• WARNING: Tube/Valve amplifiers use potentially LETHAL HIGH VOLTAGES.
    Building, troubleshooting and testing of these amplifiers should only be
    performed by someone who is thoroughly familiar with
    the safety precautions around high voltages.

EL34 SE triode mode A class sch wanted

This old topic is closed. If you want to reopen this topic, contact a moderator using the "Report Post" button.
trancy said:
thanks....but this is tetrode way....please, send me if you can...also PSU...I¨d like to see PSU too....tube type if its possible

Look again. EL34 is triode strapped. Power supply is tube (5U4). No 6SN7. if You are able to do that can try to design your own driver stage or whole amply otherwise You've to accept what community has.

The whole schematic are somewhere over internet, search Michel Leluaux EL3. I have the full article if You are really going to built it.
Re: Re: EL34 SE triode mode A class sch wanted

Tubes4e4 said:
Hi Trens,

Here´s an example.

Loosely based on a JELabs design, it really sings and was not expensive to build.


Hey, Thinking about building this. Has anyone here tried (or heard it). I'm thinking maybe some custom wound OPT's. I don't quite understand the high B+ and high OPT input resistance. Could someone explain it in simple terms, as I am just learning to read plate curves. Also any overall opinions on the design would be welcome. Thanks Jay
Hmmm, That one electron design is interesting. I allready have a PT, (salvaged) but it doesn't look like it has enough heater current. In its original application it was running 4.56 amps worth of heaters. The one electron design would call for 8 amps. Tom's circuit calls for 4.2. I might add this is my first DIY amp, so I'm trying to use stuff I have laying around here in the man cave. Also Tom's circuit looks a little simpler for a first timer, I just don't understand the high 10K load he has the tube working into, or the seemingly high B+. I've had some help doing load lines, but am having trouble deciphering exactly what they are telling me. I guess I could just build it, but I would kind of like to understand the effects of the 10K Z. Thinking of doing the power supply like this.


  • my psu (medium).jpg
    my psu (medium).jpg
    24 KB · Views: 965
different input stages ?

Hi all,

I thought better to revive this old thread instead of opening a new one, as I already found numerous SE EL34 designs....

However, I keep finding two different input stages,
as illustrated in enclosed attachement.

Wich one is "better", soundwise ?
I'm aiming at the best possible fidelity.

Driver tube will be a 12AT7 (ecc81)

oh and as a learning experience,
can you also explain why ?




  • difference.jpg
    48.8 KB · Views: 835
This old topic is closed. If you want to reopen this topic, contact a moderator using the "Report Post" button.