There was a recent thread where it was suggested that Lord Valve advised that current production EL34 should be treated as if their plate dissipation rating was only 20W. Having read the Lord Valve piece I was going reply to that thread, but unfortunately I can't find it now
Never mind, the gist of Lord Valve article is that in regard of EL34, 20W is his suggested upper limit of static (plate or plate + screen grid) dissipation. He is not suggesting that its actual plate dissipation limit is only 20W, ie rather than the 25W design centre limit listed in manufacturer's info.
TABLE A
Suggested MAX static dissipation wattages for common guitar amplifier tubes...EL34 20 watts MAX
Well if you need the power and only want to pay the price of a new non NOS tube then the Groovtubes EL34S with there added plate structure is a 30 watt tube so running them at even at 25 watts has them at 17% below there rating.
This is well more then the normally accepted difference between being biased in at a normal 60% or 70% for the hot end of the range!
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Stevem wrote: ↑Thu Jul 16, 2020 10:07 amWell if you need the power and only want to pay the price of a new non NOS tube then the Groovtubes EL34S with there added plate structure is a 30 watt tube...
Hmmm...
The blurb for their E34L notes that the plates have added heat wings and can dissipate 15-20% more power, see p9 of https://www.fmicassets.com/Damroot/Orig ... 202012.pdf
But the only actual info I can find that puts numbers to that notes its absolute max as only 25W, design max 22W. Which using a typical 'design max' to design centre' derating factor of 0.86, would put its design centre max (by which the EL34 gets its 25W plate limit) as 19W!
But then the page seems somewhat dodgy, try the Rk arithmetic on their 'typical operation characteristics' https://guitaramplifierblueprinting.com ... _1999a.pdf
