My first design. PSE 211 to review.

[EC8010]

Hmmm. My experience is that you probably do need two stages of LC smoothing on the HT with a single-ended amplifier.

[SY]

Or active regulation. A nice MJ423 (darlingtoned with a small-signal HV npn) standing off an LM317 could do wonders for hum and noise.

(ducking and running)

[EC8010]

Or a nice MOSFET. Or even a valve regulator. Perhaps even shunt. Given a chance, your amplifier could be completely redesigned - with the bonus that none of the "designers" would take any responsibility for the outcome.

[Radames]

Re-designers is exactly what I am looking for! As I come here because my knowledge ran out. Hopefully, many of my mistakes (I'm sure there is many) can be easily spotted by the more seasoned builders and designers.

With respect to regulation, I contemplated the possibility but I stayed clear of it in the interest of simplicity. I also looked at many designs for SET amplis and many of them came out without regulation.

I do not discard the idea, but I will dive into it only if necessary.

Rada

[EC8010]

Fair enough. When you don't have much experience, it's better to keep things simple. Regulators can have all sorts of nasty problems that require considerable investigation with a decent oscilloscope. Consider a dual chassis design with power supply on one chassis and amplifiers on the other. Perhaps leave room for a regulator and choose power transformers that could accomodate a regulator at a later stage.

[SY]

Or a nice MOSFET. Or even a valve regulator. Perhaps even shunt.

Aaaaaggggh! Talk about chrome-plating a pig's ear. A nice, simple, stable bipolar Maida (LM317) reg is easy to implement and (even allowing for popping a transistor or two during initial checkout) much cheaper than proper LC sections. Morgan Jones has a nice version in his book; a simpler and (to my mind) as-good-or-better implementation is Joe Curcio's from the ST-70 mod article in Glass Audio.

Why anyone uses valve regulators in this day and age can only be attributed to sheer cussedness. Or (in my case) laziness.

[EC8010]

I made a valve regulator recently and was pleasantly surprised by its stability and noise. Naturally, it needed dedicated heater supplies and attention to their noise. And it took up a bit of chassis space. And it dropped twice as many volts as silicon.

[SY]

it needed dedicated heater supplies and attention to their noise. And it took up a bit of chassis space. And it dropped twice as many volts as silicon.

"Other than that, how did you like the play, Mrs. Lincoln?"

[Radames]

I downloaded the LM317 datasheet and I am going to study it.

As for Morgan Jones, I got most of the basics from his book and I found it superb. I remember, however, that in the case of his only single ended example (The Scrapbox Challenge), he went for a solid state regulator because he did not have at hand the adequate components for an efficient LC filter.

I will try to implement a solid state regulator based on his designs. Back to studying again!

Cheers,

Rada

[SY]

Better yet, find Michael Maida's applications brief for using the 317 at high voltage. Note that MJ used the 317 as the regulator for the Crystal Palace amp.