What is the most powerful audio output tube, as far as RMS wattage
output?
I have gotten some powerful sound from four 6L6 tubes in push-pull
parallel. but I want more. I know it's possible to use eight 6L6 tubes,
which I believe is called " push-pull parallel - parallel", but I'm
looking into other possible tubes.
At one time, I thought the 807 tube was more powerful than the 6L6, but
after careful research, it's almost identical, but with a different
envelope (plate on the top cap).
I'm looking to get a full 500W RMS (or more) output (per channel), from
all tubes, .... With four 6L6 tubes in PPP, I can only get around 120W
RMS (per channel).
Your initial question asks what is the most powerful vacuum tube, and if you were to consider those used for Russian AM radio stations transmitting say 500kW to jam Radio America then you'd need huge power supply, and tubes are as big as one of the rooms at the Kremlin.
But seriously, a pair of 6L6GC can put out a safe reliable 40W class AB1 with Ea = 450Vdc, Ia of each 6L6 at idle = 30mAdc, and PP OPT anode primary load of about 4k0.
For 500W, you just need 13 pairs of 6L6, Ea = 450Vdc, Iadc for 26 6L6 = 0.78Amps dc, and OPT anode primary load = 308r, but with core and wire all rated for 500W, not 40W.
You will find that you could use 8 pairs of 6550, or 6 pairs of KT120 for similar high power.
In 2001 I made two "300W" amps which could actually produce 400W each with 6 pairs of 6550. Each amp had a PS weighing 25Kg, and with audio chassis weighing 25Kg, including a an E&I OPT with 50mm tongue x 110mm stack height.
See my website at
www.turneraudio.com.au
What you will find is that as the power goes higher, the cost per Watt of power goes lower, and that if the PSU and audio chassis is doubled in weight, you can get 2,000W.
Patrick Turner.