High screen voltage on EL84

[Tonewood]

Will the screen/anode voltage combination (on the attached image ) cause trouble with modern tubes? I usually read that the screen voltage should be lower than the anode voltage. I also see that the JJ el84 sheet says 300v max screen & anode. I would like to change the input ckt to look more like a (very small) guitar amp if it won't cause trouble with the modern El84s.

Anyone have single triode /el84 guitar amp out there?

Thanks

[Enzo]

Should, ought to, preferably, etc...

Lots of folks can chime in and tell you how they would have designed it "better," but this thing likely worked just fine for years and years for whoever bought one. So even if it is "wrong," it is no big deal.

I don;t recall the last time I saw an ultralinear tap on a single ended amp.

The amp won;t care that you feed it a guitar signal instead of a cheap phono cartridge output.

[Steve Conner]

What Enzo said, plug in, crank, tinker randomly, be happy. I got my first taste of tube amplification that way, plugging my guitar into a record player pulled out of a dumpster.

If the screen grid is unhappy you can often see the wires lighting up through the holes in the plate. A bit of red seems to be OK, but if they glow brightly when overdriven, adding a screen resistor might be a good move. Amps in record players were not designed to be overdriven, but that's the first thing any guitarist will do to a 3 watt tube amp.

[mooreamps]

All comments written so far here are true enough.... But, you would still want the screen to be a little lower voltage than the plate... You want the plate at a higher voltage than the screen, because you want mostly plate current, not screen current... Also, record players and tube based HF transmitters don't get subject to being hauled around on a regular basis back and forth between gig's..

-g

[Tonewood]

Thanks you guys!

Turns out I got it up and running and all the voltages are within 1% (one %) of the voltages listed on the schem except the plate voltage is 336 instead of 310 which puts it above the screen. I don't know how that could be if the schematic of the transformer is correct. If that makes sense to anyone, please let me know why.

Thanks again.