New SE With Triode Mode KT120/150

[izzy wizzy]

What does it look like with the 320mH jobbie in PSUD?

[Cressy Snr]

What does it look like with the 320mH jobbie in PSUD?

[izzy wizzy]

Well personally I wouldn't want 300R in series in a power supply. I imagine the 320H might not do much for ripple but it should do something at higher frequencies. Not sure a bit of overshoot is a terrible thing either as it settles well.

As it's the ear that decides, have you listened to it with the resistor?

Went back to look at your schemo and you have a .22u on the input but not the sim?

[Cressy Snr]

Well personally I wouldn't want 300R in series in a power supply. I imagine the 320H might not do much for ripple but it should do something at higher frequencies. Not sure a bit of overshoot is a terrible thing either as it settles well.

As it's the ear that decides, have you listened to it with the resistor?

Went back to look at your schemo and you have a .22u on the input but not the sim?

The 0.22u is a spike suppressor. I wouldn’t have thought it would alter things by any significant amount.
The amp is virtually silent at idle, with the RC filter in place. There’s too much hum in a quiet room, with the 320mH choke, which rather negates all the gains it might have otherwise given at HF.

The whole thing sounds great; good dynamics, fast and sweet.

The thing might be better with a CLC supply for the output stage, but the HT would be far too high, even on the 375V transformer tap.

As we can see, I’m not a big expert in power supplies, so the question I have to ask is, why are RC filters undesirable in terms of what they do to the music?

Morgan Jones talks about cascaded RC filters and even gives an old table by Scroggie, showing how many sections can be used, to best effect given the amount of resistance one might have available. I don’t get why RC filters in valve amp power supplies are so frowned upon, and I’m being genuine here. I’d like to know what it is I’m missing.

[izzy wizzy]

Looks like you have your answers. Doesn't hum, sounds good, job done. Must have missed the hum bit hence your fiddling.

We all have our preferences. Mine is not for resistance in the power supply unless I need to decouple. But then I have iron everywhere and it all weighs a ton. Pros and cons. And I know nothin about SETs so I'll go back to lurking

Edit: Not sure PSUD gives definitive answers for a great power supply but it can help you avoid bad ones; ringing, instability etc.

[Cressy Snr]

Looks like you have your answers. Doesn't hum, sounds good, job done. Must have missed the hum bit hence your fiddling.

We all have our preferences. Mine is not for resistance in the power supply unless I need to decouple. But then I have iron everywhere and it all weighs a ton. Pros and cons. And I know nothin about SETs so I'll go back to lurking

Edit: Not sure PSUD gives definitive answers for a great power supply but it can help you avoid bad ones; ringing, instability etc.

I know nothing about SETs either
The reason these PSUs are choke input in the first place, is because the mains transformers I had, were too high HT and I needed to reduce it as the TXs were all I had. I haven’t a clue why they would be better than cap inputs, apart from bits and pieces I’ve picked up piecemeal, and the fact that somebody in a book says they are.

They should produce an “Electronics For English Graduates” book.

[izzy wizzy]

I like choke input coz it keeps things nice and smooth in that the current isn't delivered in big pulses like cap input. You can see that in PSUD by looking at the current through the diodes. But some folk prefer cap input but don't ask me why.

[Cressy Snr]

I like choke input coz it keeps things nice and smooth in that the current isn't delivered in big pulses like cap input. You can see that in PSUD by looking at the current through the diodes...

I think far too much in voltages, that’s been the barrier to my learning by the look of it.
Thanks Stephen, my eyes have been opened (a little bit anyway.)

[Paul Barker]

My finding is choke input is leagues ahead SE. cant prove it to you and don’t care to, do as u please and ill do as i please.

[Cressy Snr]

My finding is choke input is leagues ahead SE. cant prove it to you and don’t care to, do as u please and ill do as i please.

Eh?

[Nick]

The big advantage about choke input is better regulation. Adding that 300R defeats that, with the choke in its got what looks like a source impedance of 300R, with the resistor in 600R. YMMV, really it wants a larger second choke, that ones not doing that much.

IMHO, lower impedance power supplies sound better all other things being equal, but its not always easy to make them equal.

[Paul Barker]

My finding is choke input is leagues ahead SE. cant prove it to you and don’t care to, do as u please and ill do as i please.

Eh?

I only build choke input power supplies, is that clearer?

[Cressy Snr]

The big advantage about choke input is better regulation. Adding that 300R defeats that....really it wants a larger second choke, that ones not doing that much.

IMHO, lower impedance power supplies sound better all other things being equal, but its not always easy to make them equal.

Cheers Nick. I cant fit another choke of the required current capacity. Tomorrow, I’ll have a look at the effects in PSUD, of a brute force, single LC, but with a larger value cap in the filter. That might get the ripple down, without compromising the regulation. But ‘slugging’ the music comes into my head again with large caps.

Anyway it can be now tried out on the computer without the risk of blowing up rectifiers.

[Cressy Snr]

I only build choke input power supplies, is that clearer?

Yes.

[simon]

It's easy to play almost endlessly with PSUD chasing a notionally "good response". But whether it correlates to what you would hear is another matter. Sometimes extra R can smooth out ringing, but does that actually sound better than having less resistance?

It looks like your stepped current jumps from 25% to 100% Steve - I've always seen 75% suggested as the initial load and that's what I've used. Instinctively it feels like the voltage should settle much quicker with a smaller current step so that might be distorting things a little compared to some sims? There again if you can get a good response with a larger step that bodes well.

PSUD will get you in the right ballpark, and it sounds good so job done . Or not as the case may be .