What's the most plate voltage you have ever seen on an el84?

[HeeBGB]

The absolute max without destroying the tube?

[zaphod_phil]

There used be an amp made by Seymour Duncan, that got 50W out of a quad of EL84s - yes, 50W! It ran a B+ of 560V on those tubes. The reason they survived is that the screens ran at 280V. Apparently the amp still sounded like c**p You can run most tubes at quite ridiculous voltages, as long as the screen grids are within spec, and the overall screen and anode dissipation is carefully controlled.

[richon]

i have a Crate Vintage Club head with 4 EL84 and it's rated at 50watts...

but i still don't know how to look at Voltage and disipation.... maybe it's my bad english ...

[Mr_dB]

What are the B+ and Screen voltages for the Peavey Classic 50?

Music Reference makes a hifi amp that is rated at 30W from a single pair of EL84s. Apparently only selected Czech 84s will take it.

[Ethan]

My '61 Tremolux runs its pair of EL-84s in excess of 440V. I use '70s GE 6BQ5As and they seem to take the voltage OK. I've been meaning to add screen resistors for several years and still haven't gotten around to it. I want to drop those screens about 100V just to play it safe.

Peace-
Ethan

[rjgtr]

I actually owned one of those Seymour Duncan amps. It was rated for 40 watts and it sounded pretty good. Certainly on a par with the Peavey Classic 30 and Crate Vintage 30. Unfortunately, it was built about as good as the others too! The cabinet was the weakest part, being mostly partical board.

Plus wattage can sometimes be labelled deceptively. I worked in a music store in the early 80s and we sold Peavey. The CS800 power amp is rated for 800 watts bridged. Carver and Crown had 500 watt power amps that were louder. Why? Because the THD rating on the Carver and Crown were the industry standard value of .5%, but the supposedly more powerful Peavey's THD was 5%. Not exactly the same.

[OldTroll]

I was interested in seeing these posts especially after seeing how high the votage was on my Peavey Delta Blues and compare that with the Max rating listed for an EL84 in my RC-28 RCA tube manual. The Manual rates the EL84 at 300V MAX. My Peavey amp's schematic shows a plate supply of 332V. That amp is rated at 30 watts from a quartet of EL84s. Mine has Sovteks in it. My amp tech states that Peavey's Classic 50 actually does an honest 50 watts. Bear in mind that amp has a cooling fan in it !!! I would suspect much wow will befall an amp with a failed fan, because those poor EL84s must be being run at some ridiculous voltage to get 12.5 watts per tube. The comment by another poster about running the screens at half the plate voltage, or even lower, is quite correct for allowing elevated plate potentials. One of my favorite output tubes, the 6146B, is rated for 750 volts on the plate but only 250 on the screen. (for those who've never come across this squat little wonder it was meant for the amateur radio market and can give a 6550 a run for it's money in raw output as an AF amp)

the Old Troll

[jersey_aaron]

At 360v, my EI's redplated.

[richon]

can you please explain me how to messure those voltages???

i guess (cause i'm new to this ) taht you put (-) at groud and the (+) at a place in the circuit and it should give a voltage value.... is this right??? is it what you use to say if a tube has to much bias or not?

[Luigi]

My Traynor Studiomate had ~450V on the plates.

[bitsandvolts]

When I had the voltage problems here at the house last summer, I was getting main line voltage at 140v!!!!

This caused the b+ of my Ghia clone to jump up to around 420 for the time I was experiencing the boost in voltage...

After that day, the 84s in this amp redplate on any hard play...they're still alive....but the 84s took some damage..

I've been meaning to get around to replacing them but I'm too friggin lazy....maybe I'll bring the amp with me to the 'fest....so you guys can laugh at my glowing z-clone!

-F