Filter capacitance-how does it relate to amplifier performance?

First, I STRONGLY recommend you read this:

https://sound-au.com/power-supplies.htm

Here is the summary:

Filter capacitance has roughly 2 functions:

- It smooths the waveform from a jagged form to a smoother one.  This is called the ripple voltage.  The higher the capacitance, the lower the ripple which IS what you want, up to a certain point.  Above a certain value, you do not get much improvement.

- It supplies instantaneous burst current (energy) when needed.

Bottom line is:

- Get the highest capacitance you can afford which fits into your physical space.

- Its voltage rating should be at least about 20 % higher than your amplifier rail voltage measured when the amplifier is powered on but NOT producing any output.

- Get the longest lasting one which are typically around 20,000 hrs at 85 degrees C.

I'm no engineer but, transformer size, filter capacitance, output devices, rail voltage, etc. all play a huge roll in amplifier power. 

You can have an amp with a larger transformer, medium capacitance, and more output devices that will "perform" the "same" as an amp with a smaller transformer, large capacitance, and medium output devices.

Bill

I apologize if I’m veering this thread off course, but wanted to add that the power supply in the Cocci tube amps is unregulated in order to provide speedy power delivery to the audio circuit, while the input section of the audio circuit includes a 3 Henry choke and the output section of the audio circuit includes a 8 Henry choke. Massive power and (200 watt rated) output transformers and Dueland VSFs in the audio circuit. I believe the high speed and great frequency extension of these amps are products of this strategy of quick power delivery to the audio circuit and ’smoothing’ through inductance rather than capacitance.

More than one way to skin a cat...

The bottom line is the higher the filter capacitance the better the amplifier maintains voltage (and power). But there is a limit and any capacitance above that limit is a waste of money.

Power is determined by the voltage in the rails and the filter cap keeps that voltage from sagging during low impedance loading that increases current draw.

The principle is the same as a water pressure tank. If you have well water with a pump but no pressure tank, the water pressure will fluctuate during the time the tap is turned on full and the pump kicks in and then turns off at the pressure set point and then on again as the pressure falls. That fluctuation is the same as power supply ripple.

With a pressure tank, the water piping volume increases and the water velocity slows down, creating pressure. Now, as the water is turned on, the pump feeds the tank and the "ripple" is absorbed by the tank and the water comes out of the tap at a constant pressure, regardless of how much the tap is open.

A pressure tank is just a big pipe, so as the tank size increases the pipe size increases, the pressure becomes more constant. However, there is a limit to the tank size for a given volume of water system to suppress the surges and any size bigger tank does nothing. Just like a filter cap does to the power supply.