Filter capacitance-how does it relate to amplifier performance?


I have a Unison Research Due amplifier that drives my Totem Forest Signature with ease. It has 100wpc in 8ohm and 180wpc in 4ohm. It has a filter capacitance of 80,000uF

I previously had a Atoll in100 amplifier 100wpc in 8 ohm, 140wpc in 4 ohm Capacitance of 31,474 uFMoving up the Atoll line the in200 has 120wpc in 8 ohm and 200wpc in 4 ohm and filter capacitance of 62,000uF
The Atoll in300 has 150wpc in 8 ohm and 260 Epcot in 4 ohm with a filter capacitance of 81,600uF. These also had no trouble driving my speakers.

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?

For comparison sake with my Due amplifier I demoed a Plinius Hautonga integrated amp with 200wpc in 8 ohm and 280wpc in 4 ohm. I did not hear any appreciable difference in bass or other frequencies.

So 3 questions.

1) Is my Due amplifier much more powerful than the wpc  indicates?
2) How does filter capacitance relate to power in an amplifier?

3) Why do manufacturers rarely publish this spec? I could only find a few examples.

Thanks
traceyc

Showing 1 response by gs5556

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.