A 1 Watt battery powered elctron tube audio power amplifier in class A

At your risk. Use suitable fuse in series with batteries etc. Using a PCC84 double triode electronic valve. Both triode sections can be paralleled as on EMI BTR2 replay amplifier output stage using a B65. PCC84 or ECC84 can operate at 100V Vb. This can be made from 2 4AA battery holders holding 12 6V 4LR44 batteries. Grid input voltage needed seems small, of the order of 3V so an input transformer can be used and no other tube. The output transformer which should have an air gap or (be made from a ferrite ring core?) can double the power efficiency from 25 per cent to 50 per cent since the induction at the primary doubles 100V to 200V, see load lines - Applied Electronics - Gray - MIT. 14mA are possible from each triode. A 4000ohms to 4ohms output transformer ie a 30:1 ratio would make this current x30. Other class A Pleiades lab considerations are a downscaled Musical Fidelity A1 using a BD139 driven by a BC549 emiter follower, load the speaker itself (at your risk), feedback from collector to driver transistor base, a resistor from driver base to ground as on K. Jones amplifier, see previous posts. Or for push pull class A adding a BD140, BC559 pair below. Or istead of feedback adding a output transformer at the output and an input transformer (Langenvin style) and using just 2 BD139 or if needed another 2 BC549, . Single ended has the advantage of not cancelling even order harmonic generation which is octaves really. See previous posts on BD138 single transistor power amplifier with output transformer. No feedback makes a gentle curving curve with no abrupt overlod distortion. Distortion tends to 0 as the signal gets smaller which is very important for music signals. Just one amplifying device creates small order distortion products which are not further multiplied by other cascaded active devices. How would the PCC84 sound like?