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Po-Telam plate voltage in SE configuration (& longevity)

Posted: Fri 03/31/06 12:19 pm
by billv
I'm wondering if anyone knows the approximate maximum plate/anode voltage on a Polam/Telam EL84, SE config.

Posted: Fri 03/31/06 2:17 pm
by zaphod_phil
The sweetspot for most EL84s is with around 300V to 310V. At that point they're running on the border of Class A and Class AB, and get a great gritty edge to their tone.

Posted: Fri 03/31/06 2:51 pm
by allynmey
Polems/Telams are fantastic! But, if you run them at high voltage prepare yourself for the snaps, crackles, and pops! I use them in my three best sounding amps and they are some of the best sounding el84's I've ever heard! If you run them above 330V make sure your screen voltage is kept in check. They seem to take higher voltages better when the screens are around 25V lower. YMMV.

Allynmey

Posted: Fri 03/31/06 4:13 pm
by billv
Excellent advice. I'm wondering if I shouldn't save these Polams for an 18w/CG type of amp, and use a Siemens E84L for that single-ended thing.

You guys ever try one of those S&H E84Ls in a Champ/AC-4 design? I'm wondering especially what it sounds like, when the plate voltage is near the design point of (iirc) 450V 8O

Posted: Fri 03/31/06 5:34 pm
by zaphod_phil
Most EL84s sound pretty much like crap when run single-ended at much above 300V, as then they're operating in Class AB. Very brittle tone and lots of distortion - not of the nice kind. Like I said, their sweetspot for tone is in the 300V to 310V area, regardless of what they may be rated at.