Me too, the most I have ever gotten out of a pair was 32W.. (40W is possible, but at some expense in linearity.) I suppose if you use tubelab's power drive circuitry to drive the 300B into AB2 territory you could do this, but IMHO given that they aren't designed for any grid current at all and taking what they cost into consideration I wouldn't want to try for a few extra dB of headroom.
He was asking for PPP (parallel pushpull). So in your case it would be 64W or 80. 😀
IMHO, the 300B works well if driven into positive grid. You only need a strong low impedance driver. No trade-off for linearity because up to a quite good amount of Pout it works just like many other amps....or even better!
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There is a design in the Sept. 2008 issue of audioXpress magazine. The article is entitled, "A $450 Triode/Ultralinear Integrated Stereo Amp".
It is PP, self-bias, class AB1, using 6550, 5687, and 12AT7 tubes, and 28W triode/50W ultraliner.
AudioXpress back issues can be found here:
AUDIO AMATEUR BACK ISSUES
It is PP, self-bias, class AB1, using 6550, 5687, and 12AT7 tubes, and 28W triode/50W ultraliner.
AudioXpress back issues can be found here:
AUDIO AMATEUR BACK ISSUES
Kevin, the 300B PPP was another question from another forumer who was looking for 50W.
I am not sure I would go for a 2A3-40 PP. Using true 2A3's will be cheaper from every point of view: cheaper tubes (already including you need 8 instead of 4), lower voltage, cheaper capacitors, cheaper transformers, easier to drive (in the worst case you will need 120V peak-to-peak). Golden Dragon or Billington Gold 2A3's are very good and have gold plated grid, too. The only disadvantage I can see is the size. But it is fine if you go for mono amps.
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