Push Pull 12BK5 Amp, Mosfet PI, 70V Transformer, High Voltage Module.

[printer2]

I am doing a cheap and dirty amp, well it might not be too dirty with a single 12AX7, being powered by a 12V laptop power supply. The 6BK5/12BK5's were designed as a cheap TV audio tube putting out 3.5W single ended. It has a hefty current demand of 6.3V@1.2A but this gives it a high sensitivity with a bias value of -5V in single ended service. So hopefully a single 12AX7 will fulfill the gain duty with a Bassman styled bass and treble tone stack. Using a MOSFET phase inverter with it being unity gain, I have used the IRF830 for it but want to try the LND150 this time. Using the 70V transformer because it is cheap and I do not really have a suitable transformer for this tube. Hope to get about 6W out of it. Could do 6W just with a SE amp and less complications but that has been done before.

[printer2]

Nothing fancy, may give it a shot of paint later. To sit in a Tweed type of cabinet, maybe with an 8-10" speaker.

[PRR]

> powered by a 12V laptop power supply. ... 6BK5/12BK5

'BK5 is suggested for 250V. Are you really going to run it on 12V?? Power output per tube will be under 8 milli-Watts.

(I was just looking at a type '48 farm radio. On 95V-120V the '48 was good for 1W-2W. On 32V farm (windmill) power a pair made 1/4 Watts. Better than nothing and OK on a quiet farm, but....)

[printer2]

Got a high voltage inverter module supplied by the 12V, I think I may run it at 250V but it might vary depending on how the tubes get along with the 70V transformer.