audio-talk

Here is the LC supply sim:
to get it to behave like the real branched one, I put the two 20H chokes in parallel, so halving the inductance and internal resistance, then doubled the last capacitor value to reflect the two 50uF caps, one per branch.
The true behaviour probably lies somewhere in between the previous sim and this one.
I bumped the transformer voltage up to give the voltage I get out of the real supply, due to the 0-280V toroid being way over specced for the low current the amp uses. Looks fine to me. And the final schematic: That's that, I’m winding down the hobby for a while.

I get that.

I think that ps config is the same as the one I gave Ant on the sv572. It worked for me.

Paul Barker wrote: ↑Thu Mar 31, 2022 7:50 amI get that.

Yes, I’ve reached a point where in order to make any noticeable improvements I’m going to have to start forking out for exotic output transformers, and in my view, unless you are prepared to get serious (much more serious than I’m prepared to get) about single-ended direct-heated triodes, then IMO it’s not worth the expense.

The thing about these single ended pentode amps and their various local feedback schemes: either Alex Kitic’s designs or my own E-Linear derived thing, is that they sound great, they are simple and they can be nice and powerful if that’s what you want, for not much money.
I have the system as I want it, so I’m not going any further. I’ve done ‘one last tweak,’ and lost the sound far too often over the years, so unless I hear something that for the same outlay, blows it out the water, then I’m done.

Edit: irrelevant bit removed.

ed wrote: ↑Thu Mar 31, 2022 8:11 am I think that ps config is the same as the one I gave Ant on the sv572. It worked for me.

That’s good to hear.

Yes, I’ve reached a point where in order to make any noticeable improvements I’m going to have to start forking out for exotic output transformers, and in my view, unless you are prepared to get serious (much more serious than I’m prepared to get) about single-ended direct-heated triodes, then IMO it’s not worth the expense.

Or you do as I did and try and work out just what it is you like about what SET's do and if there are any cheaper way of doing the same thing (and possibly doing it better). That's what I did and why I don't make them anymore. The only reason i would consider it now is nostalgia. I do have a 2a3 amp part built, that may get finished one day, maybe not. Not that that in any way reflects on your set of choices.

Nick wrote: ↑Thu Mar 31, 2022 11:10 am
Or you do as I did and try and work out just what it is you like about what SET's do and if there are any cheaper way of doing the same thing (and possibly doing it better). That's what I did and why I don't make them anymore. The only reason i would consider it now is nostalgia. I do have a 2a3 amp part built, that may get finished one day, maybe not. Not that that in any way reflects on your set of choices.

+1.

I know the better bit is contoversial but I have thought that for a long time. Fwiw as a hobby I've always found that fets and bjts are far more interesting and challenging to mess about with but that maybe because I don't come at it from an expert standpoint. cheaper? deffo!

ed wrote: ↑Thu Mar 31, 2022 12:38 pm

Nick wrote: ↑Thu Mar 31, 2022 11:10 am
Or you do as I did and try and work out just what it is you like about what SET's do and if there are any cheaper way of doing the same thing (and possibly doing it better). That's what I did and why I don't make them anymore. The only reason i would consider it now is nostalgia. I do have a 2a3 amp part built, that may get finished one day, maybe not. Not that that in any way reflects on your set of choices.

+1.

I know the better bit is contoversial but I have thought that for a long time. Fwiw as a hobby I've always found that fets and bjts are far more interesting and challenging to mess about with but that maybe because I don't come at it from an expert standpoint. cheaper? deffo!

Yep, I agree with you Ed (yes I know you were pushing this way ago, but took me some time). I think that both the interesting part and the challenging part are important. TBH, I have lost the interest in doing it with valves as it seems simple and just a natter of following the recipe. The problem is following the recipe gets expensive very quickly and all that is left is looking for magic solutions that allow valves + quality + cheap. IMHO just removing the valves part from that equation solves the cheap part and leaves the search for quality.

In my view its a variant of "its better to learn to drive a slow car fast than to drive a fast car slow".

Though I hate to admit it, the fact is, apart from the 45, I don't really like the sound of SETs; not when compared to SEP SEUL or E-Lin.
I simply prefer those kinds of output stages. They give me what I want from an amplifier.
There are no niggles, especially with the the E-Linear config, which is the simplest of the pentode setups. Things just sound 'right.' You can use inexpensive valves and they get the best out of common or garden output transformers. I don't really know how else to describe things.

Easy to live with is the best I can come up with and that's what I want. I can turn on the system, put some music on and enjoy it, without wincing feeling that there's something missing.

Though I hate to admit it, the fact is, apart from the 45, I don't really like the sound of SETs

Then I would suggest then that you have only heard bad other SET's. In my (maybe less humble than it should be) opinion, that if the SET's you heard didn't at least sound like the 45 then they were broken. They get harder to make and more expensive as they get bigger, so while it may be possible to cut corners so much its possible to make a bad 45 amp, its hard. Its very easy to make a bad 300b, there are loads about, and onward up to the point that while you can make SET produce 20W, even the best one will be broken, maybe to the point where its not usable. That's why I stopped making them.

Now, your SEP's I don't know well enough to have an opinion on, but I still think that MoFo amp I heard at Steve's generally removed, for me, the point of any amp with a valve output stage, and relegated the reason one would make one to the same camp as restoring old bikes and steam engines, nostalgia but with the realization that old isn't in these cases the same as better.

Hi Nick,
I'm not trying to claim that a valve output stage of any description is better than a MoFo or for that matter anything Nelson Pass has made available to home constructors. I'd be equally happy with the F5 our Ant has. The F5, the MoFo and the SEP, have a certain neutrality and ease of presentation that I get on with. I've simply fallen out with triodes and triode strapped pentodes in general. If everyone else likes them, fine. It's me who is the odd one out.

Personally, I'm coming to agree with the viewpoint of you and Ed, it's just that I'm now happy with what I have. 45 years I've been messing with hi-fi and I've not felt as positive as this about any system I've had before.

I'm not trying to claim that a valve output stage of any description is better...

I know you weren't. TBH, I could hear things I didn't like about the F5 that I didn't hear in the MoFo, so I would go further than you. (with the condition that he MoFo is less forgiving to speaker choice in practice)

If everyone else likes them, fine.

Of course, but I do still have my own set of opinions as to if I agree with them.

…nostalgia but with the realization that old isn't in these cases the same as better.

Aye, I’d generally agree with that in the case of valve amps per se, but I would tend to make a sub category in there regarding triode strapping pentodes and claiming that they sound better than using the things as they were designed to be used ie in ultralinear or full pentode mode with feedback.

I’ve absolutely no problem with 1930s American and British power triodes. From hearing them at Steve’s and at various fests, using proper output transformers, they are on a different performance level entirely to the post war power pentodes/tetrodes strapped as triodes. In that case, new is in no way better and the case is easily demonstrable to anyone who doesn’t have cloth ears.

In the case of modern valves, and if SE operation is being used, I much prefer them in SEP, SEUL with plate-to-grid feedback or e-Linear configuration. In this case ‘new’ is definitely better.

Anyway I’ve already said more than enough to get me lynched, so I’d best be on my way.

Interesting to read the thoughts of you guys on valves and SS. Perhaps an effective compromise would be a DHT preamp providing the voltage gain into a MoFo or F4?

iansr wrote: ↑Wed Apr 06, 2022 3:16 pm Interesting to read the thoughts of you guys on valves and SS. Perhaps an effective compromise would be a DHT preamp providing the voltage gain into a MoFo or F4?

I'm going to (one day) do a modular 12A gain stage as part of the input stage on a revised 833a amp.

Being modular, I also hope to use it with my MoFo.