Filter capacitance-how does it relate to amplifier performance?

My understanding of capacitors is that they store energy. Does this mean that my Due amplifier is just as powerful  as the on paper more powerful Atoll in300?

No. It just means that the energy storage for the output section will have less noise so less intermodulation at full power.

But one thing left out is the voltage of the power supply with all these different amps. Its important because in the formula for electron storage in a capacitor, the voltage dominates the equation


W (work) =1/2 (C xVsquared)

where C is capacitance  and V is voltage. So by raising the voltage a little, you raise the storage a lot!

BTW, its the storage in the supply that is usually what is being quoted when the manufacturer states the 'amps' it has- for example 80 amps. If we use that figure we see that its obviously not output power, since using the power formula

P=Isquared x R  (where P is power in watts, I is current in amps and R is resistance in ohms)


If we give the amp the benefit of the doubt and state a 1 ohm load, then the power is simply the current squared. No-one makes a 8400 watt amp. Into 2 ohms this would be 16,800 watts....

So a value like that is actually the current that flows for 10mS when the power supply is shorted out. Its an easier way of understanding the energy there instead of the 1st formula I showed above.

Our MA-2 amplifier has 72,000uf at 150 Volts... it can easily do that 80 amps and its a 220 watt tube amp. Capacitive values like this are there solely because the amp sounds better when they are.

OP, you ask logical enough questions. Except it doesn’t exactly work quite the way you think.

There’s two main ideas behind power supplies. The first one is the one people tend to get fixated on, power. To a certain extent this does work. Amps with big power supplies probably do tend to have better bass and slam and things you would expect to hear from a more powerful amp. I say "probably do tend" because there’s a lot more to it and no shortage of 30 watt tube amps that have more authority and control than 200 watt amps with monster power supplies. Hardly ever helps to focus too much on any one thing.

The other main reason is ripple. Not just with amps but with all components its vitally important to have a nice smooth steady supply of DC power. DC comes from running AC through rectifier diodes. These diodes don’t ever output nice smooth DC. They always have some spikes or ripple in their output. The idea is we use this ripply DC to fill the filter caps which then let out nice smooth DC. The water in a dam metaphor.

Which kinda sorta works. Problem being there are no caps that do this perfectly. This is why you see all these guys asking which caps to use to get what kind of sound in their crossovers, etc. No cap is perfect. They all have some kind of sonic signature.

Put it all together and you can see the way you’re looking at it is pretty much meaningless. First off since no caps are perfect the diodes have as much influence on the sound as the caps. Since ripple matters and ripple is minuscule compared to power then total capacitance hardly matters either. This is why you sometimes will find a tiny little high quality cap in there. The idea is the big caps provide the oomph, the tiny one smooths out the ripple.

Main thing to learn from all this: Its the sum total quality of the whole package that matters. Which you can only evaluate by listening.

The difference by the way with better caps and diodes is a deeper and much more focused image, with less grain and glare, greater resolution of subtle dynamic shadings, and a lowering of the noise floor that leads to a sense of greater power. Even though power as measured by standard measurements is the same.

No one will give you a great answer until you understand what it is doing.

Here's a helpful article:

https://makingcircuits.com/blog/calculate-filter-capacitor-smoothing-ripple/

But basically, bragging rights are the main benefit, followed by enabling low impedance drive are your answer.

Best,

E

Hoping Ralph will comment on the situation with my custom built 100 watt 4 x KT77 monoblocks (built by Charlie Cocci): when I took off the bottom plate to admire Charlie's work, I was shocked to see only 2 x 47mF 630 volt capacitors in the power supply section.  By comparison, my Jon Soderberg updated (200 w/ch.) Threshold Stasis 2 has 4 x 63,000mF capacitors in the power supply section! 

When I asked Charlie about this, he told me (paraphrasing) 'When you've got enough voltage, you don't need as much capacitance.'  I'm thinking that this may be a statement of the Work equation that Ralph posted.  

By the way, the tube amps absolutely kill the Threshold in bass response...much better control of the big 12" woofers in the NorthCreek crossovered Matrix 801 S2s and what sounds like an extra half octave of response.  The tube amps kill the Threshold in every other way as well, but the bass response was a real surprise.  

Thanks for any insight from anyone into how this can be!

By the way, the tube amps absolutely kill the Threshold in bass response...much better control of the big 12" woofers in the NorthCreek crossovered Matrix 801 S2s

Understandable when you look at the very "benign impedance load" of the 801’s
https://www.stereophile.com/images/archivesart/bwll801fig01.jpg

But put something like a Focal No3 Sopra with a magnitude of 2.75 ohms at 96Hz and a combination of 4 ohms and a –56° negative phase angle, then you find the Threshold will be the better.
https://www.stereophile.com/images/417FSop3fig1.jpg

It's all horses for courses.

Cheers George