Power Supply Wars

[Cressy Snr]

I've just come across a very strange flame war on another forum concerning power supplies, in particular, those for direct coupled-amplifiers.

What the heck is this LSES "Low Storage of Energy Supply"?
Having read about the supposed advantages of this thing, all it seems to me to be, is a means of making the maximum possible hum and the minimum possible control over the bass.

There is a variation of this thing by called the "flywheel" where a choke of around 0.5mH gets used with a 20uF first cap.
How this is supposed to work is beyond my meagre comprehension.
How can a choke that small in a SET amp possibly achieve critical L unless amps of current are being drawn?
Indeed the fact that it does not achieve critical L is touted as the reason why this PSU sounds so much better than a "normal" choke input supply.
If it does not then all we have is a cap input supply so why put the choke in?

OK so the LSES supply also has to have your mains transformer leads replaced by multiple runs of Kimber cable, then you have a half ohm choke, which does not achieve critical L. You use the smallest caps possible, measure your internal wiring down to the last quarter inch so as to avoid delays in the signal because the signal takes longer to go down a three inch wire than it does to get down a two and three quarter inch wire. So the idea is that even a quarter inch difference between two lengths of wire will be audible.

I have always used stiff power supplies and latterly regulated power supplies. Indeed my PSU for the Mazda amp uses 800uF of capacitance in its LCRCLCRC arrangement.
There is NO hum and bass is nice and controlled from my amp, but according to the philosophies of the two proponents of low resistance low capacitance supplies, the sound of my amp and everyone else's must be crap, because it has two 82R chokes and two 22R resistors in it, plus the 28R DCR of my Danbury 0-450V HT winding, not to mention the series R of the UU10 valve rectifier.
That's 336R given the 100R effective resistance of the rectifier at the 50 and a bit mA the amplifier draws.

Clearly then designing power supplies for SET amps using established engineering procedures is not the whole story.

I have never built a LSES supply so am in no position to make any comments as to the superiority or otherwise of this type of PSU.
But is does seem awfully counter-intuitive.

As I said earlier in my limited brain, all this low resistance/low capacitance stuff would do is make the amp hum and ensure that there was no reserve in hand for peaks, so the thing would sag terribly most of the time the amp was passing a signal.

Apparently this argument has been going on for four years. The most vociferous proponent of this type of supply promotes an amp that has 24 cathode bypass caps in it, ie 6 in parallel on each of the two input and two output valves, all "chosen by ear"
He exhibits regularly at RMAF, his build quality is fantastic and by all accounts the sound of his amplifiers is quite special.

Now I am well aware of Paul's advice not to go for a particular valve or topology just because the established theory suggests it is better than anything else, but isn't this LSES business I don't get. I can see the need for low resistance but low capacitance? How do you get the ripple down unless there is some sort of noise cancellation happening.

I mean it seems to be a power supply designed deliberately to piss of electrical engineers.

So I suppose the beginner's question is, which is the best way of getting high end sound?

Stiff versus flaccid power supplies then.
Can anyone throw any light on this "trying to get going" trend across the pond for these very low DCR PSUs.
I don't get it, but then I'm pretty thick.

[Nick]

That debate killed most of that section of AA, for gods sake dont start it here

[Cressy Snr]

Yes, what I read seemed to be pretty heated, with a lot of insults flying around.

[Paul Barker]

I haven't read it, don't intend to, but i wander if enough parties actually tried what they argued against?

Talk is cheap.

[Nick]

I haven't read it, don't intend to, but i wander if enough parties actually tried what they argued against?

Talk is cheap.

It was hard to do that, the target kept moving. if someone tried it and liked it then they had got it right. If they tried it and didnt then they had broken some (up to that point) undisclosed requirement.

Henry tried a lot of the ideas, but did come up with the flywheel concept out of it which did have some interesting advantages, but was not part of the LSES mantra.

[Mike H]

Remind me what "AA" is

There is a variation of this thing by called the "flywheel" where a choke of around 0.5mH gets used with a 20uF first cap.
How this is supposed to work is beyond my meagre comprehension.

Could it be a tuned circuit operating in the audio band to take out mains noise at that frequency? Have heard of such things.

[simon]

Audio Asylum. I rarely go there but whenever I do there seems to be a perennial argument about low DCR supplies raging. Perhaps why I don't bother looking in much. He contacted me out of the blue once a few years back, trying to sell me ultra-low DCR chokes he was having wound.

[Mike H]

Ah yes, thanks.

[izzy wizzy]

Another request not to debate this here. It taints virtually every post on AA and has driven many good contributers away. Now I know Jeff Medwin isn't here which is the main problem but this "one way to Nirvana" stuff, as most sensible people know, is crap.

cheers,

Stephen