Decoupling...

[Nick]

Yep, that would work well, Or a current source into a shunt, that makes the previous supply’s life simple, and isolates the early supply from the load. The problem with a shunt if you want it to operate down to DC is the shunt needs to be able to cope with the full current in case the load is disconnected (or cold heaters).

[slowmotion]

I'll go read up on shunt regs, then.

[little eddy]

I was considering some form of CCS and/or SS shunt regulator between my B+ and gain stage supply, replacing the current RCRC buffer. Saw this 'Push-Pull/Series-Shunt High-Voltage Regulator' on the following page - I am quite tight on current and looks like this would sink about 10mA so within my TX limits:

http://www.tubecad.com/2007/07/blog0115.htm

Probably a bit simpler to construct than a MAIDA regulator as well.

Do the panel of experts have any views?

[Cressy Snr]

Just found and read through this thread by way of would you believe, a link by Ray from the Transcendent Sound forum.

Interesting indeed. I have three stereo power supplies running on my OTL and the improvement in the presentation of the music is quite something to hear. Wish I’d taken notice 5 years ago, seeing as the last post before this was in Jan 2014.

[ed]

I'm not entirely sure this is relevent or even valid, but..
when I was messing with the latfets at the beginning I tried all sorts of methods for decoupling 2 stages, which culminated in the end at the end of this thread:

http://www.audio-talk.co.uk/phpBB3/view ... 2&start=19

I finally gave up on decoupling the power to 2 stages and tried 2 power supplies in the 5 watt pp latfet I brought to Owston in 2018. I thought the change to complete isolation was remarkable. fwiw.

[Cressy Snr]

....I finally gave up on decoupling the power to 2 stages and tried 2 power supplies in the 5 watt pp latfet I brought to Owston in 2018. I thought the change to complete isolation was remarkable. fwiw.

....‘remarkable’ is the word I was searching for.

[izzy wizzy]

Oh dear. That seems I ought to give it a go for the GM70 amp. I'll have to use mercury of course.

Cheers,
Stephen

[pre65]

I use an anode CCS on the driver stage of my GK-71 amp. I was under the impression that was a fairly good way to decouple from the main supply.

Is it likely that a separate PSU for the driver stage would make a "remarkable" improvement ?

[simon]

Only one way to find out Phil

I'm another in the separate PS for driver camp. In my case it wasn't 'remarkable' but it was clearly audibly better on the LC common cathode stage.

[izzy wizzy]

Purely hypothetical wondering out loud ....

I wonder if the seperate supply for front end would have a larger impact on a SE amp compared to a PP amp as the supply is bouncing around to the music SE but much less so, if at all in a PP amp.

As the saying goes ... only one way to find out.

[Nick]

but much less so, if at all in a PP amp

Why do you say that? The energy that is moving the loudspeaker cone has to be coming from somewhere...

[IslandPink]

Yeh but the current modulation is much less. It's only the imbalance from the valves - significant as one of them approaches cut-off. Changes in the PS and choice of caps / bypasses was much less significant eg. in the 'Aurora ' than any SE amp I've built.

[Nick]

But again I will ask "Why do you say that? The energy that is moving the loudspeaker cone has to be coming from somewhere..."

Also, remember, the load is a Z not a R

[steve s]

Once you get to recognise the effect that a simple single power supply is having on the sound ( ie signal cancellation) my ears highlight to me that push pull class a is probably the worst offender regarding cancellation,
And regardless of what you do with the power supply, the topology is the major influence. Ie the power supply has little effect.

When I pointed it the effect the power supply was having on Steve's amp the other week, you can now see it has taken 6 years of me explaining it before it finally registered (in his ears) with steve.

So what are the audioable signs of there being a too simple to do the job power supply in an amplifier..? Once you recognise them you may realise why I will never build a traditional valve push pull or a simple power supplied amp se ever again.
My thanks go to to Dave the bass who inadvertantly set me on the track of measuring what's going on whilst an amplifier is playing music, and it not what you may think or folklaw says.

[IslandPink]

I'm still thinking, Nick !