[Big Bad Bob]

On 09/10/15 11:58, Peter Wieck so wittily quipped:
On Thursday, September 10, 2015 at 1:11:15 PM UTC-4, Big Bad Bob wrote:

I tried one type of regulator (cheap design), which helps but not
enough. An RC filter isn't enough. You need a stable voltage reference
and a diff amp to control the regulator. 3 transistors, and a handful
of other parts. Now I just need to order the parts, to prove the concept.

If you are confining your efforts to instrument amps, and have what I might only describe as the "typical" attitude towards fidelity that goes with instrument amps, a switching supply might be perfectly acceptable - just another 'effect' device. Given the fascination with leaky "black cat" or "bumblebee" capacitors in this aspect of the hobby, nothing surprises me.

But, if you are looking at audio amps (tube), then a switching supply will take more heroics to make acceptable than a conventional supply. To that end, if you really want portability, get Solid State. Solves several issues (weight, portability and cost) quite nicely with results almost guaranteed to be better than a tube amp with a switching supply.

Peter Wieck
Melrose Park, PA


interesting opinion, though. maybe nobody else will try it now. As for
me, I refuse to be discouraged. there's a lot of info on this project
that I haven't disclosed, after all.

A switching PS won't (by itself) add noise to the system, not when you
have a stable linear regulator [as long as there's no 'ground loop' issue].

I did a simple test using a transistor's 'Vceo' breakdown in lieu of a
zener [since I'd have to order zeners to do this], simply because I'd
just thought of it. Proved it would work, too. power supply noise was
virtually eliminated.

In any case, you'd think that the advantages of having a DC supply for
the heaters, plus being able to do a 'ramp-up' so you don't wear them
out from power on surges, might outweigh any possible disadvantages a
switcher might have [mostly the problems with ground loop noise].