Capacitor

There's no easy answer. According to the laws of physics, the best cap is the one with a value closest to 100uF, (a twenty nine cent 101uF cap should in theory perform better than a one hundred dollar 110uF cap, both 100u nominal). However, considering the tolerances of capacitors, the designers had to settle on a nominal value of cap that sounds best to them, and reject values that fall out that tolerance. So if your expensive substitute falls out of that design tolerance, it may not improve things at all.

(I am assuming this is a commercial made speaker and not a DIY. If it's a DIY then the answer is: experiment with different makes)

What value  is important the uf or the vdc

No they are complete build units from Ascendo germany their flagship model the M5 SE with external crossover

Hi there,

This really depends.  With a value this high I have to assume it's a low pass filter.  If so it is likely to go to ground. If so these rarely matter as much as caps in series.  They DO matter, but it's hard to really judge their sonic worth as much.  To hear the difference here you might want to try a non-polarized electrolytic before you spend too much money.  Here's one that costs $2.

https://www.parts-express.com/100uF-100V-Non-Polarized-Capacitor-027-360

Try it and see if you feel it's an important capacitor in your circuit.

What value is important the uf or the vdc

The uF determines the frequency of the crossover filter (gross oversimplification) the VDC determines the maximum voltage.  If you apply too much it will short the capacitor and it will no longer work as expected.  That's a very high value for a speaker where I can't imagine ever needing more than 200 VDC rating in extreme high power speakers but with film caps it's hard to make a lower voltage cap sometimes, do don't go looking to optimize this. 

Best,

Erik

What value is important the uf or the vdc

The critical value is uF, micro-Farads, the unit of capacitance. VDC is voltage, which matters only in that you do not want to use a low voltage cap with high voltage as it can destroy the cap. Crossovers are in the single digits to tens of volts, not hundreds, so this number 630VDC is irrelevant. You just don't want one that is too low. 

Capacitors in crossovers are sometimes called filter caps because that is what they do, filter lower frequencies. The greater the capacitance the more energy the cap stores. Because of this, if you change the value from say 100uF to 150uF this will shift the frequency and this will cause the speaker to sound different.

All caps and resistors have a tolerance, typically of a few percent, often printed on the part along with the value. So if your cap is 100uF +/- 5% it can be 95 to 105uF. If the manufacturer specs this cap that alone should be enough to tell you one or two uF one way or the other is not critical. If you really want to know you can buy a LCR meter and measure actual capacitance and inductance yourself.

The idea someone had that the only thing that matters is the measured value and gives as his "reason" because, physics, is patently false. The better caps do indeed sound better even though they measure the same. And you want to know why? PHYSICS!

What is actually happening inside a cap is electron charges are constantly shifting one way and another, in and out, according to the music signal. When we measure all we get is a static, fixed state number. There is nothing in it having anything to do with how fast and smooth these charges shift back and forth. Which with music is EVERYTHING! That is why some of these expensive caps use such an elaborate manufacturing process, to ensure extreme consistency and sensitivity down to the electron level.

It ain’t cheap. It ain’t easy. And it can’t be measured by no meter. Thus the link to the cap comparison page above.