Amplifier Capacitance


Okay, naive question of the day: except for cost and perhaps size limitations inside the casing, why don't manufacturers go bonzo large on capacitance? For instance, I'm thinking of replacing the caps in this damaged Hafler DH220 I've got and, while I probably won't find any that fit, I started to wonder why limited myself to two 18-19k cans? Why not 50k, 80k, even 100k if I could fit it? (I doubt any of those would, but you get the drift.).

Now, in an exisiny design there is the voltage rating to concern yourself with, I believe. So this limits your choices. But in a newly developed amp the designer has more leeway, correct? So again, why not go bonzo? Capacitance seems like once of those things that should really make a big diffence in amp performance, no? In fact, shouldn't it particularly help offset a somewhat weaker power supply as well?

Okay, my naïveté is showing, better zip up....
aewhistory
Kijanki, thanks for that explanation, it was excellent. Do you teach electrical engineering by any chance? You, bombaywalla, and Atmasphere have done a magnificent job explaining very esoteric (to me) subjects. This is difficult to do, especially when speaking to a layman. I've taught college history now for 12 years and it can be daunting getting people to relate to human history, so I've always wondered how people in the sciences make their subjects more approachable and relatable. Discussing matters here certainly gives me an idea how this can be done as I've never encountered a group with the combination of technical savvy and possessing the ability/willingness to explain as here at Audiogon.
Teaching? No, Almarg would be much better at this. He explains things with much more clarity. History was always difficult for me.
but once we draw less than max current, power supply voltage modulation at low frequencies becomes compensated by amplifier (since it is regulated).
Kijanki, I don't understand this statement. Power amp power supplies are not regulated (I don't see a feedback loop around the power supply). The power amp itself has minimal feedback around itself for sonic purposes (as you already know) & this feedback is for the music signal & not for any vairations of the power supply. The amp is counting on the power supply to be essentially DC. So, any power supply modulation will modulate the output voltage signal (AM-AM modulation/distortion).
I'm afraid that I'm not seeing how the power supply modulation at lower/bass freq is compensated by the power amp. Thanks.
Bombaywalla - Amplifiers are line regulated. It means that amplifier supplied from 40V and set to produce 5V output voltage will still produce 5V output with supply lowered to 35V or increased to 45V. There will be small error because regulation is not perfect but it is in order of one percent or less. There is an easy way to test it - just set your amp at moderate listening level and then reduce line voltage from 110V to 90V. Your amp will play at the same level. You could measure it with test tone and voltmeter.
Amplifiers are line regulated. It means that amplifier supplied from 40V and set to produce 5V output voltage will still produce 5V output with supply lowered to 35V or increased to 45V.
Kijanki, I can believe this BUT I do not think that this is due to "line regulation".
If the power supply rail is 50V (or 45V) & the power amp is outputting a 5V signal, there is plenty of headroom for the output transistors (& the rest of the power amp stages) such that if the power supply rail goes up/down by 5V, the output voltage will not change. I believe that this is the reason that the power amp will continue to output the voltage its being asked to.
If one keeps on lowering the power supply rail, one will come to a voltage where the BJTs will saturate/the MOSFETs will triode & the output voltage will drop as the devices go into the linear region.
I still believe that all power amp stages are very sensitive to the cleanliness of the power amp power supply rail.
thanks.