Raymond Bates 1949 Direct Coupled 6V6

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simon
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#16 Re: Raymond Bates 1949 Direct Coupled 6V6

Post by simon »

steve s wrote: Sat Jan 22, 2022 11:56 am When the signal gets more complicated and also with increased volume, the ac signals are spread through the power supply and the sound folds.
I've read this a few times Steve and I'm not sure I really understand what you mean really by "ac signals spread through the power supply". Can you explain a bit more?
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#17 Re: Raymond Bates 1949 Direct Coupled 6V6

Post by Paul Barker »

I remember Darren when he scoped his valve dual plate rectify and rang me to say “my rectifier is playing the music! Does that help? Capacitors too play the music and in my case. when I’m making a fully committed build my shunt valve is push pull with my SE amp. My experience is that the shunt valve sounds better than any capacitor. But motor run or Black Gates are good enough. Just not as good.
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#18 Re: Raymond Bates 1949 Direct Coupled 6V6

Post by Cressy Snr »

You see this is what I don’t get about this power supply playing the music business. Amps are modulated power supplies. If the power supply is stopped from playing the music then nothing will come out of the speakers.

Or… are we talking about different sections of the audio circuit itself talking to each other via the power supply and causing random cancellation effects due to reverse phase interaction. If that is so then the louder the signal, the more the effect feeds itself until the sound collapses into the middle and all the focus disappears.

I’m fine with that argument and preventing these feedback effects is a worthy goal to aim for to stop this kind of thing from happening as far as it is possible to do so. How to go about doing it apart from the employing the usual RC decoupling arrangements that have been used since the beginning if time: that is the question that never seems to get answered. I thought I had achieved it by series regulating with 6080s but some wag then came along and told to think again because signals can go backwards through regulators, so that wasn’t it either. I gave up after that, my brain couldn’t take any more. :)

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#19 Re: Raymond Bates 1949 Direct Coupled 6V6

Post by steve s »

simon wrote: Sun Jan 23, 2022 9:31 am
steve s wrote: Sat Jan 22, 2022 11:56 am When the signal gets more complicated and also with increased volume, the ac signals are spread through the power supply and the sound folds.
I've read this a few times Steve and I'm not sure I really understand what you mean really by "ac signals spread through the power supply". Can you explain a bit more?
I'll do my best simon..
In a say 'normal' valve amplifier with a 'normal' power supply...

The signal that each valve is amplifying, all of that signal is on the that valves ht supply too.

From there it 'contaminates' via the powersupply the other valves in the amplifier
And the other valves are putting out the signal they are amplifying on to the ht too, so the contamination is both ways

So you have on the ht, signals from both channels, and out of phase signals through each stage.

But then you have to take in the effect of the inter stage and inter channel smoothing
The caps, chokes interstage and output transformers.
Simple amps have very little smoothing here to stop the 'inter' effect.

So a part that combined signal is on the ht of of your input valves and is mixed with the original signal in the valve

The effect of which vary both with volume and the music
Simple music at low volumes suffers less than complicated music at volume.

It one of the many reasons amplifiers can sound well at modest home volumes and not sound quite so good at our owston meets
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#20 Re: Raymond Bates 1949 Direct Coupled 6V6

Post by Paul Barker »

some things you dont have to understand but you rightly picked out intermodulation from various sources.
, which power supply and signal section are all involved in.

I think its better to keep the power supply influence in simple terms, though still waters run deep. In simple terms, the power supply is part of the chain, the weakest link is the strength limit of the chain. This can be heard, oh yes it can. When you have made power supply improvements, youre amp sounds better.
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#21 Re: Raymond Bates 1949 Direct Coupled 6V6

Post by Paul Barker »

Of course Steve s the low volume stuff is also wrecked by power supply inadequacy.

Until we get it better enough well never get back those hair standing up on the back of our neck emotion while listening to Late Junction at night! Its probably even more important to the quality of our amps at low level.

perhaps 1st watt amps are so good at these things because the power supply is easier to make so it isnt the limit.
Last edited by Paul Barker on Sun Jan 23, 2022 11:18 am, edited 1 time in total.
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#22 Re: Raymond Bates 1949 Direct Coupled 6V6

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Cressy Snr wrote: Sun Jan 23, 2022 10:50 am

Or… are we talking about different sections of the audio circuit itself talking to each other via the power supply and causing random cancellation effects due to reverse phase interaction. If that is so then the louder the signal, the more the effect feeds itself until the sound collapses into the middle and all the focus disappears.
You put that a lot better than me steve..

We had a few occasions at mine with some fine examples of that happening and it's effect on the music

I think the worst example was a multi valved otl you brought.. bad at everything except an open sound
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#23 Re: Raymond Bates 1949 Direct Coupled 6V6

Post by Nick »

Or to put it much simpler. Amplifier stages have low psrr and power supplies have non zero output impedance. Sorry but I think both Andrew L and myself gave up talking about this over a decade ago as no one wanted to listen.
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#24 Re: Raymond Bates 1949 Direct Coupled 6V6

Post by Cressy Snr »

Nick wrote: Sun Jan 23, 2022 11:27 am Or to put it much simpler. Amplifier stages have low psrr and power supplies have non zero output impedance. Sorry but I think both Andrew L and myself gave up talking about this over a decade ago as no one wanted to listen.
:sign7: Oh bugger.
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#25 Re: Raymond Bates 1949 Direct Coupled 6V6

Post by ed »

steve s wrote: Sun Jan 23, 2022 11:16 am
Cressy Snr wrote: Sun Jan 23, 2022 10:50 am

Or… are we talking about different sections of the audio circuit itself talking to each other via the power supply and causing random cancellation effects due to reverse phase interaction. If that is so then the louder the signal, the more the effect feeds itself until the sound collapses into the middle and all the focus disappears.
You put that a lot better than me steve..

We had a few occasions at mine with some fine examples of that happening and it's effect on the music

I think the worst example was a multi valved otl you brought.. bad at everything except an open sound
2 stage amp, what about 1 ps for each stage....it worked for me but I can't prove it was better.

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#26 Re: Raymond Bates 1949 Direct Coupled 6V6

Post by Paul Barker »

yes ed, and thats sometimes required but no always. sometimes the interaction is positive. Not to mention global feedback problems and motorboating oscilating away usually at a frequency you dont hear. At least you know when motorboating is there. But what can you not hear.?
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#27 Re: Raymond Bates 1949 Direct Coupled 6V6

Post by Paul Barker »

Often the consensus was in those days Nick mentioned, put all youre effort into one good power supply than split youre effort between two with savings to match budget. The interactions in a single supply with the two or three levels of signal and gender interact at the power supply symbiotically and the dual supply sounds thin. Not always.
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#28 Re: Raymond Bates 1949 Direct Coupled 6V6

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This is all right on topic for this thread ya know. Fill yer boots.
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#29 Re: Raymond Bates 1949 Direct Coupled 6V6

Post by Nick »

Paul Barker wrote: Sun Jan 23, 2022 1:22 pm Often the consensus was in those days Nick mentioned, put all youre effort into one good power supply than split youre effort between two with savings to match budget. The interactions in a single supply with the two or three levels of signal and gender interact at the power supply symbiotically and the dual supply sounds thin. Not always.
Or in other words dogma and poor implementation.
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#30 Re: Raymond Bates 1949 Direct Coupled 6V6

Post by simon »

Good stuff, and good description of the multiple current loops. I suppose I was partly thinking about ways to address this - my GM70 amp uses completely separate PSes for 12GN7 and GM70, it's brute force and a little inelegant but I did notice a difference when I added the driver PS. How much of that was a separate PS and how much was removing burden on the GM70 PS I don't know.

What was going through my mind reading this thread was what makes a better PS? I appreciate this is perhaps in the realms of dogma/prejudice/guruism/religion :-D.

So, a full wave CT trafo. Overspecced trafo current capacity - x2, x3, x5, x10? Choke input. Shunt reg, at least the driver. Or don't regulate. No caps. Or WKZs or motor runs. Single section or multiple section filters?

That's a bit to go at :-).
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