Solid-State Versus Tube Rectification in Pre-amp Power Supplies

[Ron Resnick]

Regarding solid-state rectification versus tube rectification in preamplifier power supplies, have you noticed any correlation between a tube rectified power supply and a greater sense of weight or body or tonal density versus solid-state rectified power supply preamps?

What has been your experience?

 

[Mikerdaniels]

New owner of Cary SLP-5 no Ultimate upgrade.. It’s about 15 y.o. With a solid state power supply. Confused about tube power supplies .

 

[adrianywu]

Regarding solid-state rectification versus tube rectification in preamplifier power supplies, have you noticed any correlation between a tube rectified power supply and a greater sense of weight or body or tonal density versus solid-state rectified power supply preamps?

What has been your experience?

I think this really depends on whether there is regulation, and which type of regulation. My preamp has SS rectified B+ using Hexfred diodes, followed by a CLC filter, followed by a shunt regulator. I run the idle current of the shunt quite high, about 2x the load current. This gives very fast transient attacks and no dynamic limitations. One of the problems with tube rectifiers is the high source impedance. This tends to soften transient attacks and limit dynamics. This can be mitigated with a well designed regulator, but this makes using tube rectification pointless, other than its slow start characteristic. Fasting switching diodes nowadays like Hexfreds have no switching noise. In my opinion, tube rectifiers are best left for the vintage amps.

 

[Musica Bella]

I think this really depends on whether there is regulation, and which type of regulation. My preamp has SS rectified B+ using Hexfred diodes, followed by a CLC filter, followed by a shunt regulator. I run the idle current of the shunt quite high, about 2x the load current. This gives very fast transient attacks and no dynamic limitations. One of the problems with tube rectifiers is the high source impedance. This tends to soften transient attacks and limit dynamics. This can be mitigated with a well designed regulator, but this makes using tube rectification pointless, other than its slow start characteristic. Fasting switching diodes nowadays like Hexfreds have no switching noise. In my opinion, tube rectifiers are best left for the vintage amps.

I agree. It really depends on what you want to hear and how you hear it. I prefer the fast transient attack and dynamics of solid state power supplies. On the other hand, I have really enjoyed many tube rectified preamplifiers and have built both for customers. Always use at least a CLC configuration.

 

[Tubes1988]

My Mystere CA 21 preramp responded well to a solid state rectifier, had to move the speakers out from the wall, great bottom end extension for a $10 part, I'm impressed, give it a try. cheers.

 

[Atmasphere]

Regarding solid-state rectification versus tube rectification in preamplifier power supplies, have you noticed any correlation between a tube rectified power supply and a greater sense of weight or body or tonal density versus solid-state rectified power supply preamps?

No.

I've yet to see a case where the preamp didn't sound better with solid state!

If the preamp is at all serious it will have a regulated power supply which will render any effect of the rectifier(s) moot.

Tube rectifiers are nice because they are low noise but that's about it. You can get the same low noise with solid state (for example, using HEXFREDs which have been available for well over 30 years) plus tube rectifiers have a significant Voltage drop across them that will vary with line Voltage even if the load on its power supply is constant (due to the heating of the rectifier's filament changing with line Voltage).

That will exacerbate the tendency of the preamp to change in sound quality with the AC line, which often changes with the time of day.

Put simply, the only argument for a tube rectifier in a preamp is if the preamp is vintage and you want it restored to its stock condition.

In re-reading all this I note that my post above may not be addressing your question directly about "weight or body or tonal density". Such things can be caused by distortion and a tube rectifier can add to distortion since its output can be variable- lower B+ Voltages often lead to greater distortion. But I would not expect that Voltage change to have such a profound effect on a tube preamp (which usually has medium to high mu tubes installed) so my surmise is any such effects would be minimal and likely the result of marketing and confirmation bias.

Put another way you could get more important audible (and measurable) improvements by simply installing better tubes in the signal path.