Kingston
Well-known member
ppa said:Nice, since the circuit is small which uses one tube only so the heater current is reduced so it is possible to place side by side 4-6 channels in a single 2U chassis, with the PSU inside.
What do you think a version with an output stage with a solid state buffer with the advantage to have a trasformerless out too? It could reduce price and space.
12AV7 heater current is somewhat on the high side, 0.45A/6.3V or 0.225/12.6V.
A solid state buffer would be strange. You would have to drop from the high voltage 12AV7 plate to a sensible output voltage via attenuator, and also provide a separate PSU for it. If you were to do this, you could pick a better tube since you would no longer need the semi-low output impedance of 12AV7 (needed to drive a transformer). You could even use a 12AX7 with some optimisations and then you would have very low heater requirements also.
Or maybe you were thinking of some unique (high voltage?) solid state buffer instead?
Since 12AV7 is happy to drive a 4:1 transformer, take full advantage of it and pick some cheap but good performance Edcor for example (read: WSM10K/600, which is also quite small). If you invest in decent input transformer it's a winner combo.
I can certainly picture 4-6 channels and a PSU in a 2U chassis, like a small scale vintage broadcast mixer. But I hope you can shield the PSU extremely well!