And that's why I spend less and less time at this forum.
I said I was going to do something.
Badman said this is what will happen.
I measured using Arta.
Badmans words where validated
Listening tests further proved it.
Along comes TMM.
Question? are we here to help each other? Are we hear to build better speakers than what you can buy elsewhere.
TMM. Do you work for a speaker manufacturer?. Are you trying to prevent us from building great speakers?
Sorry for the negativity.
No, i'm an electrical engineer my job is objectifying design decisions like this to work out what is the cheapest/smallest/highest performing configuration of electrical components.
So lets take an objective look at the topic. Consider this Panasonic FC datasheet (yes, I know it's a polarized capacitor but the technology is fundamentally the same as electrolytic bipolars):
https://industrial.panasonic.com/cdbs/www-data/pdf/RDF0000/ABA0000C606.pdf
Above I took the data from the 50V capacitors in that datasheet, capacitance and ESR, plotted them and did a line of best fit. As you can see, it fits a power curve, the fitted is y=5.7x^-0.707, y being ESR, x being capacitance. If it were ^-1 it would be inversely proportional (double capacitance, half ESR), being ^-0.707 you do - on average - get slightly lower ESR by using multiple caps but it's not by much. The deviations from the curve are because there are standardised can sizes (4.7uf, 10uf and 22uF are all the same physical size) - either the ESR is directly proportional to the physical size, or Panasonic got lazy and only characterised ESR for each physical size for that particular voltage rating. If this is actually the case or if the 4.7uF's ESR should be a little higher and the 22uF a little lower I have not tested. If they are in fact all the same then it means you need to consider the physical size vs ESR instead of capacitance vs ESR. According to Panasonic's data, if you put two 47uF in parallel (=~100uF) you get 0.3ohms, whereas if you just used the 100uF you get 0.162ohm, significantly lower. The opposite is true for other values so you may need to assess it on a case by case basis.
With regards to distortion, I'm not sure how you manage to measure a difference because in my own testing capacitor distortion is pretty much negligible (<0.01%) compared to speaker driver distortion (>0.1%) for a practical home hifi drivers and listening levels - say a 5-8" woofer and 1" dome tweeter, 1-20Watts. Capacitor distortion only occurs where there is significant voltage dropped across the cap and the speaker is playing at a reasonable volume, which generally only happens in a narrow band of frequencies at the corner frequency of a low/high pass filter. Speaker driver distortion occurs everywhere, so I know which one I worry about more.