Capacitor Replacement in Crossovers

Galu

Member
2018-04-17 6:50 pm
It is safe to replace a polarised electrolytic capacitor with a non-polarised electrolytic.

Think of a non-polarised electrolytic as two polarised electrolytics connected back to back in series. When a dc voltage is applied, the correct polarity capacitor gets the full voltage. When two such capacitors are connected back to back, they will block the voltage in both polarities.
 

Tweet

Member
2015-01-29 6:33 am
If you are going to use Non Polar Electrolytic capacitors make sure you use 100 volt working and avoid using the very small circuit board types as they tend to over heat and deteriorate more quickly. Physically large capacitors of this type are a better choice if used in the low frequency circuit of a bass driver.


C.M
 

eriksquires

Member
2013-05-10 4:11 pm
It is safe, but you have to wonder why.



That is, caps in series divide, so you could replace 2 back to back polars with a single bipolar/nonpolar cap half their uF.




It's worth measuring the ESR if replacing very old (1980's or before) caps as new ones may change this.
 
I would not use regular non polar electrolytic capacitor or 2 regular polarized electrolytic capacitors for speakers crossovers .

TBH, i think advice depends on circumstances.

What we know about wet Electrolytic Capacitors is that they age badly, overheat and have a significant resistance. Alan Shaw of Harbeth admits this.

After 25 years or so, the wet electrolyte dries out and they cease to behave as origonally intended! Evaporation of liquids, an' all that. :D

Nevertheless, they had a place in early Harbeth designs, along with MKT capacitors, this being a Harbeth HL5 IIRC:

643820d1509785064-crossover-upgrade-advice-harbeth-mki-jpg


The blue thing on the left. Way cheaper than a (MKP) polypropylene capacitor of the same value.

What I find interesting about Harbeth, is they use ferrite inductors in the tweeter circuit. Ferite is demonstratably non-linear. Capacitors are far easier.