Solid State Rectification

[rschleicher]

A few random comments on the above discussion:

Old vintage amp designs were "all tube" by necessity, and basically it is possible to do all of the functions of an amp using just tubes, plus passive components such as resistors, capacitors and inductors/transformers:

- AC power rectification
- pre-amp gain stage(s)
- phase inverter (for amps with push-pull power-amps)
- tone controls
- post-amp gain stage (sometimes)
- power amp.

But for modern amps, the definition of "all tube" is all over the map. The purist view would say that all tube means no use of semiconductor devices, whether diodes, or transistors, or integrated op-amp circuits, not to mention any use of digital signal processing/modeling.

BUT, there are lots of "all tube" or "mostly all tube" amps in which the pre-amp (and sometimes post-amp), and power-amp gain stages are using tubes, but there is still a lot of solid-state devices used for the other functions listed above.

FWIW, Fender and Marshall have been using solid-state (diode) rectifiers since the 60's. These are just being used to create the high voltages that are applied to the plates (anodes) of the tubes. Other than tube rectifiers having some propensity to "sag" at high output levels, which might contribute to some compression, there's no real sonic advantage to tube rectifiers. And solid-state rectification helps maintain headroom, which is why Fender and Marshall both went to diode rectifiers so early....

Probably the most controversial thing in the "all-tube or not" debate is whether the phase inverter is implemented with a tube circuit.

One other random comment is that ECC83 tubes (12AX7) are dual-triode tubes, so you can get two gain stages out of each tube. It is not totally clear to me whether our amps are using the ECC83 tubes as two gain stages per channel, or if they use one tube for the pre-amp, and the other for some other function, like the phase inverter. But in any case, I think it is clear that all of the gain/amplification stages of our amps are implemented with tubes.

I've heard some comments to the affect that BS amps use diode-clipping for creating distortion, but I don't think this is the case. Certainly the tone controls, ISF, and other tone-shaping circuits are making use of solid-state electronics (and the digitial reverb as well), but that's different than using diode-clipping to create distortion. Maybe someone from Blackstar can comment, but my sense is that the distortion on our amps is from the pre-amp tubes, or if really cranked, from the power tubes.

In any case, the proof is in the tone!