No! Do not change from Electrolytic to a non-polarized capacitor. This will not improofe the design, but cost more. It might even add instability. The ESR of the E-Cap will also dampen oscillations! You can even recreate this in LTspice. Just try to build a SMPS in simulation. To the ideal output capacitor just add a resistor and an inductor in series to the capactitor. The inductance will create resonance with the capacity. That is, why many differenc capacitors often are combined for high speed decoupling on modern electronics.
Just follow the rules:
- Y/X capacitor for safety, when coupling an isolated PSU to the earth or the input (absolutely required to use a ultra high grade capacitor - otherwhise you could put live voltage on an USB charger, if the cap fails - which definitely happens sometimes - even with Y capacitors this can happen - but much less likelyhood.
- Electrolytics for high capacities and lower frequencies
- Non-polar caps in parallel to the E-Cap, to imrpoofe resonance stability and decouple high frequencies
- For audio it usually does not matter - only remember: E-Cap for audio only, when decoupling a DC signal to AC or the other way around. Negative voltages instantly harm the capacitor. This is a matter of ms, till this effect starts. It will slowly degrade your isolation surface on the Al-foil and lower the voltage rating - and possibly worse. The longer, the voltage is inverted, the more severe the damage
- For high speed decoupling combine caps like 1uF and 120nF. The high capacity will stabilize the "lower" frequencies, however this cap will not react to multy hundrets of MHz. The 120nF likely does. For even higher frequencies, use even smaller caps (yes, also build size affects the frequencie response.
So what to learn for your case: Just replace the capacitors with resonable quality capacitors of the same rating. Higher voltage or lower ESR rating are welcome, but not required. They likely will not help you at all.
If you want absolute quality for your AL-Foil capacitors: Look at the WIMA sortiment. It is more expensive, but has very, very high grade capacitors.
Should you use mouser? Well, not at all! Mouser makes sense for high volume orders with higher reliability. Often however, even Mouser or Digikey screws up and accidentally sells either fake or wrong parts (for high end ICs this can be a huge problem).
Go to Ebay or Aliexpress. The shipping takes some time, but you will not loose like 100 bucks for just some parts. I did this mistake once. Just remember: When buying E-Caps, look out for name brands like Nippon Chemicon. Also try to weight them, if they weight the same as the data sheet says. There where huge E-Caps filled with air and a tiny E-Cap on all markets. Of course this will fail in your product. So make sure, it weights the proper ammount. Like 18650 cells: If they weight half as much as a Samsung INR 25 for example. the cell is just the lowest grade, money can buy. (And also a huge fire hazard)
Long story short: Buy cheaper stuff for 1-2 capacitors. Mouser is kinda expensive and more than often not required at all. Just use the same capacitor as it was before. Nothing lasts forever, even if you spend 100 times the money on a component.
P.S.: You can DIY a bipolar cap by just putting 2 E-Caps in series with one same pole together
like so: + C1 -- C2 +
or so: - C1 ++ C2 -
Remember: Twice the ESR, half the Capacity. But it absolutely works a treat.