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Capacitors - Does size matter?

A tired cap may still have the right capacitance but may not be able to charge and discharge as fast as it should translating in lack of energy on music with many instruments played altogether or with a lot of bass.
And today’s caps won’t last longer than older ones unless you use higher quality with longer rated life.
Some are rated 1000 hours at 85 degrees and other can be up to 5000 hours at 105 degrees, the latter will last longer under the same usage and conditions.
 
My experience is that failing elecrolytics actually go up in capacitance and only drop when they have got to the burst case stage. The ESR goes up first.
 
A tired cap may still have the right capacitance but may not be able to charge and discharge as fast as it should translating in lack of energy on music with many instruments played altogether or with a lot of bass.

The dis/charge speed of the cap should be related to the ESR (and ESL). Which is measurable... and as davidrsb says above, tends to increase along with the capacitance as parts "wear out".

FWIW I have just fixed a Creek 4140S2 that is almost 30 years old. The caps all measured fine, so I didn't replace any of them. The owner likes the sound, so no need to "upgrade" caps.
 
Some notes that may help:-
ESR on caps change on different temperature working and on ripple frequency .i.e. pulse current demand and not including the internal ESL.
A tip I learnt when as a young engineer from a wise Walter Halliday 1V ripple at a 100Hz on a 10,000uF cap is 1A, this tiny snippet saved me lots of time and getting calc's wrong .
Also 0.5CVxV = A/S this can help when you have the info on the load and the fastest peak current you will see but do not forget the ESR and ESL will limit the speed and the max current you can suck out. So Ohm's Law and impedance resonant calcs are needed.

Work it out and bung it all on a Microcrap X Hell program.

Caps have a problem, they needs to remove ripple and noise survive inrush or charge current and getting hot and large high speed pulse current demands relative to it ripple frequency , do note I said pulse as music is not a pure swinging sin wave it is pulses and few are in sync with the ripple. ( oh lovely harmonics)

Calculating the values needed can be fairly complex when you add all the things up, the poor cap needs to do, oh and if you think big huge batteries are the solution , sorry they are great for massive current demands, but there ESR goes up at higher frequency and Pb Acid type produce, as to the best description a belching noises when charging and discharging due bubbles. This is great for MC stage, NO.

OK so there are some among us that hate caps and decide to use large inductors that are costly and have inter layer winding capacitance problems and to store large energy needs to be massive or running at high pulse rate, but the energy escapes far to quickly, and open circuit massive high voltages can appear on there terminals. So we stuff yet another cap in so the L & C react to filter the ripple, but the caps become smaller, so what about the pulse current we need to hear the drum beat and the violin ???
 


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