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Interesting New Amplifier from Thomas and Stereo. Large capacitor banks good or bad?

O

OzBrit Audio

pfm Member
The YouTuber Thomas and Stereo has released an amplifier which caught my eye under his company Galion.

He is selling a 75WPC class AB amplifier which I believe he has specified and voiced and gets made in China. It sells for 1500 USD.

The reason for this post is not to say this is good or bad as I have no experience of it. But having read a no of very favourable reviews from those who have bought the amplifier and after viewing a couple of other YouTubers who reviewed it, this amp caught my eye. People say its presentation is one of transparency and air, detailed with top end sparkle, a black background but with mid range warmth and thunderous bass drive. It is the last point that caught my eye especially when looking inside the box which claims massive banks of capacitance. Here is Thomas's own introduction to his amp, lots of user comments associated with it.


What got me curious was the power supply design and the claimed effect this has on performance. Looking at the pictures inside the box you can see separate toroidals (definately a good thing), interestingly stacked one on top of each other separated by a metal plate (not sure about this, interaction of magnetic fields?) . The PSU board has one set of PSU caps with additional caps on the amplifier boards a claimed 200,000uf in total.

This configuration obviously works according to peoples reception to this amplifier. It goes against what I have thought gives the best performance for dynamics and bass slam in terms PSU banks. Avondale PSU boards have a maximum of 3 caps 30,000uf per side, Naim typically use a single 10,000uf per side in most of their amplifiers albeit with massively spec'd toroidal and whatever your opinion of Naim one thing they are not short of is bass slam or rhythmic drive.

So curious what others think of this configuration and their experiences with PSU design in their amps?
 
There are certainly some in the DIY community who maximise psu capacitance to the nth degree, and the true believer probably regards Thomas's 100,000uF per channel as a starting point. The concept of a massive reservoir of power is particularly attractive if you play heavy rock or organ music at ear splitting volume. But since it costs money and takes up space the diy enthusiast can indulge him/herself to an extent which would make no commercial sense. (The current spike at switch-on as the cap bank charges up also has to be dealt with.) Any new product in the most competitive market sector needs something to differentiate it from the rest, especially given the improvements in Class D alternatives. Positive reviews plus confidence in the brand/channel have resulted in the first batch selling out already: so far, so good.
 
martin clark said:
Or, one could just design for good 'power supply rejection ratio'; rather than 'pretty pics/spiel for magazine purposes' / marketing' ... and elide this whole kind of nonsense!

It abs is.not a given that just throwing 'more' at ' already enough' helps in any way.
It's also obvious (if you have had a few goes yourself) that so much of such attitude .../ overkill stuff == sign of 'no real understanding of what matters, -oh meanwhile let's sandbag it & make it BIGGER!'


The gestalt, is everything.
But then - so is actually understanding what you are trying to achieve; over merely firing-up the 'Parts Cannon.'
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Martin I posted this thread to generate discussion on sonic performance v size of the capacitor bank supply not to comment on the said marketing video. I did say I wasn't endorsing this amplifier one way or other I just noted the design uses large capacitor banks and many people seem to like it, particularly in the bass region. Yes the video is full of marketing blurb, not interested in that, I posted it so you can see inside the amplifier.

Yes PSR is part of good power supply design but other factors come into play when it comes to an amplifiers sonic capabilities

Some well respected amplifiers use large capacitor banks, others don't. Personally I am moving towards a couple of 10000uf high current low ESR caps for the grunt end of my amplifiers (typically 100W with regulated front ends), this seems to provide the best sonic balance, but I wanted to hear peoples experiences in this area, simples!

No need for a rant now :)
 
Not watched video. What design is it.?

I was talking to Colin Wonfor last week about the Claymore and power supply capacitance.

I've got one of his old designs here that uses quarter of a farad and it definitely doesn't sound bloated and slow :)

Saying that, I remember paying around with NVA amps many moons ago, and while they responded well to huge toroids, anything more then 10k uf on rails made them sound flat and boring. Go figure.
 
quickie said:
Not watched video. What design is it.?

I was talking to Colin Wonfor last week about the Claymore and power supply capacitance.

I've got one of his old designs here that uses quarter of a farad and it definitely doesn't sound bloated and slow :)

Saying that, I remember paying around with NVA amps many moons ago, and while they responded well to huge toroids, anything more then 10k uf on rails made them sound flat and boring. Go figure.
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Class AB apparantly

Interesting to hear your experiences. Smaller rail capacitances with massive toroids is the Naim approach.

What I'm listening to now are Avondale SE400's which I'm 'running in' on a test rig. That has single 22000uf with standard 35A bridges. I'm going to try multiple 10000uf x 2 then x 3 see how that changes the sound. The rectifiers will also go to Schottky so am expecting an improvement.
 
Hideki Kato, chief developer of Soulnote amps, says that too much capacitance leads to a boring sound. The class AB Soulnote A-3 integrated (about 20.000 Euro in Germany) comes with 64880 µF capacitance. And Kato prefers the sound of smallish capacitators (lots of them) over few bigger ones. Hence, a total of 120 capacitors is used in the A-3.
 
There possibly (?probably) is some optimal ratio between transformer VA size, amount of filter caps and average load.
Such as 500VA transformer:22,000uF:1.5A

Thing is, nobody seems to know what it is!

The NAP110 with its smaller amount of PS capacitance was a faster, leaner sounding amp than the 140.
The 42 when fed with the small 3300uF rudimentary 24V supply in the 110 likewise seemed faster and pacier then with gifted with a SNAPS.

But the NAP500 has 120,000uF and sounds anything but slow and bloated.

And there is a well-known YouTuber who adds crazy amount of capacitance (like 3 FARADS) in an external pack connected to the main unit with a Powercon connecter. He has modded Naim power amps, Hicaps, preamps and vintage monster recievers and all of them seem to respond very well to this massive capacitance boost.

So, is there a 'Goldilocks' amount, or is too much never enough?
 
rontoolsie said:
There possibly (?probably) is some optimal ratio between transformer VA size, amount of filter caps and average load.
Such as 500VA transformer:22,000uF:1.5A

Thing is, nobody seems to know what it is!

The NAP110 with its smaller amount of PS capacitance was a faster, leaner sounding amp than the 140.
The 42 when fed with the small 3300uF rudimentary 24V supply in the 110 likewise seemed faster and pacier then with gifted with a SNAPS.

But the NAP500 has 120,000uF and sounds anything but slow and bloated.

And there is a well-known YouTuber who adds crazy amount of capacitance (like 3 FARADS) in an external pack connected to the main unit with a Powercon connecter. He has modded Naim power amps, Hicaps, preamps and vintage monster recievers and all of them seem to respond very well to this massive capacitance boost.

So, is there a 'Goldilocks' amount, or is too much never enough?
Click to expand...
Well with 3 farads your well catered for in the event of a power cut :D

I think with the NAP500 that 120000uf is split over 4 seperate amps so thats 15000uf per rail. Still fairly low compared with most
 
sortof said:
Hideki Kato, chief developer of Soulnote amps, says that too much capacitance leads to a boring sound. The class AB Soulnote A-3 integrated (about 20.000 Euro in Germany) comes with 64880 µF capacitance. And Kato prefers the sound of smallish capacitators (lots of them) over few bigger ones. Hence, a total of 120 capacitors is used in the A-3.
Click to expand...
One thing there does seem a consensus with is several smaller caps rather than one big one
 
I think the ESR (Equivalent Series Resistance) is probably a measurable that matters here. Lower ESR allows more current to flow faster to your output stage. Multiple small capacitors in parallel on a well designed PCB should be good for this. A massive capacitance on the end of a cable with connectors, much less so.

Maybe the ‘recovery time’ for the power supply (thinking the transformer here) to bring the capacitor bank back up to full rail voltage after a big power delivery is an issue, too bigger capacitor bank vs transformer will be slow to recover, compared to a smaller bank?

Could explain the Goldilocks value.
 
Excessive capacitance, especially ultra low ESR, is stressing the rectifiers and polluting the mains supply with potentially a very high and narrow current pulse. The effect of this will depend on the mains source impedance to your house. Strangely this is a variable that never gets mentioned in amplifier reviews. This is an interesting paper that looks at some of these unexpected consequences
 
rontoolsie said:
So, is there a 'Goldilocks' amount, or is too much never enough?
Click to expand...
All else being equal and if the amp has medium to poor PSRR, more capacitance will be better. Like everything else there will be a point where more is unnecessary baggage. It's a cold day, are 2 coats a good idea? Yes. 2 hats? Yes. So I'll wear 5 coats and 10 hats, because that's got to be better again. Hmm.
Also, all else is never equal. Not all circuits will respond equally. Get an amp with good PSRR and the benefits of loads of caps will soom be outweighed by the downsides, like having to lug round 5 coats above.
Puggie said:
I think the ESR (Equivalent Series Resistance) is probably a measurable that matters here. Lower ESR allows more current to flow faster to your output stage. Multiple small capacitors in parallel on a well designed PCB should be good for this. A massive capacitance on the end of a cable with connectors, much less so.

Maybe the ‘recovery time’ for the power supply (thinking the transformer here) to bring the capacitor bank back up to full rail voltage after a big power delivery is an issue, too bigger capacitor bank vs transformer will be slow to recover, compared to a smaller bank?

Could explain the Goldilocks value.
Click to expand...
Except that for any given big power delivery the energy needed to recover will be the same and the big caps will have retained a greater % of their full charge, so they should be no worse off. Beethoven's 5th intro demands so many joules from the capacitors, so the size of the caps shouldn't matter. The big caps are recovering from (say) 39.9V supply rail voltage to 40, the smaller ones are going from 39.8 to 40. The energy required is the same.
 
OzBrit Audio said:
One thing there does seem a consensus with is several smaller caps rather than one big one
Click to expand...
Years ago a friend of mine sent his 555PS to be modded. The first thing that was done was to replace the massive 22,000uF caps with a bank of smaller caps that had the same total total capacitance. This required building a custom PCB. But it sure cleaned up the lumpy bass response of the 555PS. There were also a few other major revisions that were done, but this was considered to be one of the more fundamental ones.

In spite of the NAP500 having large amounts of filter capacitance, by comparing it with other amps, it was obvious my 500 was running out of steam and compressing even at moderate listening levels. We traced this down to the PS of the regulator boards, each of which had its own 10,000 uF capacitor, and yet was still being modulated by the amps output.

The solution was to but a large choke (30H) before the filter caps on each regulator board. These were too large to mount internally, so they had to be tied in via some fly leads.

Once done, this was almost as big as improvement as replacing the 135s with the 500.
 
Except that for any given big power delivery the energy needed to recover will be the same and the big caps will have retained a greater % of their full charge, so they should be no worse off. Beethoven's 5th intro demands so many joules from the capacitors, so the size of the caps shouldn't matter.
Click to expand...
The amount of Joules to recharge the smaller caps may be the same, but the time constant for smaller caps is smaller, so the recharge can happen quicker. This of course may be offset by the fact that there is now a bigger voltage deficit to restore.
 
OzBrit Audio said:
Well with 3 farads your well catered for in the event of a power cut :D
Click to expand...
Well in a 35V supply, that is still under 2000J. Or just enough juice to run a 60W light bulb for barely half a minute.

The same guy who builds these is currently bulding a 400F power supply that is about the size of a table top. NOW we're talking.
 
stevec67 said:
All else being equal and if the amp has medium to poor PSRR, more capacitance will be better. Like everything else there will be a point where more is unnecessary baggage. It's a cold day, are 2 coats a good idea? Yes. 2 hats? Yes. So I'll wear 5 coats and 10 hats, because that's got to be better again. Hmm.
Also, all else is never equal. Not all circuits will respond equally. Get an amp with good PSRR and the benefits of loads of caps will soom be outweighed by the downsides, like having to lug round 5 coats above.

Except that for any given big power delivery the energy needed to recover will be the same and the big caps will have retained a greater % of their full charge, so they should be no worse off. Beethoven's 5th intro demands so many joules from the capacitors, so the size of the caps shouldn't matter. The big caps are recovering from (say) 39.9V supply rail voltage to 40, the smaller ones are going from 39.8 to 40. The energy required is the same.
Click to expand...
I appreciate the bulk power requirement is the same, but is the interaction during that phase of recharging the caps, especially considering the ESR of the caps and current delivering capacity of the transformers, switching speed of the rectifiers etc, going to make any difference?
 
Puggie said:
I appreciate the bulk power requirement is the same, but is the interaction during that phase of recharging the caps, especially considering the ESR of the caps and current delivering capacity of the transformers, switching speed of the rectifiers etc, going to make any difference?
Click to expand...
God only knows. Well, God and electronic engineers with oscillosopes. I suspect that it's minimal in the light of everything else that's going on. As regards switching speed of rectifiers, it's only running at 50Hz. A diode can operate at 50 Hz in its sleep.
 
rontoolsie said:
The amount of Joules to recharge the smaller caps may be the same, but the time constant for smaller caps is smaller, so the recharge can happen quicker. This of course may be offset by the fact that there is now a bigger voltage deficit to restore.
Click to expand...
Yes, indeed. I have seen designs where there are banks of big caps stabilising a PSU power rail, and smaller caps in parallel with them. The argument given is that the smaller caps in parallel with the bigger caps give the best of all worlds. It sounds plausible, like all these things, but most hifi BS sounds plausible, which is why it gains traction and people (I'm no different BTW) who don't have any detailed electronic knowledge pick up on one thing and decide that this is the solution.
 
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