General purpose capacitors in audio crossover?

[z-adamson]

I recently recapped a crossover using poly caps and it's a bit brighter than what I want for this particular speaker.

As such I intend to try electrolytics. However, not sure which to use.

Nichicon Muse?

Nichicon general purpose?

Does it make much difference?

 

[gadget73]

usually you want bipolar capacitors in a crossover. Personally I'm not convinced the "audio" caps are anything more than standard low leakage ones with a fancy label. They don't have a real datasheet though, so thats hard to prove. The very fact that they do not have a proper datasheet makes me not real inclined to use them.

Reason its probably brighter has to do with reduced ESR. Poly caps are much lower ESR than electrolytic, so you get less voltage loss in the cap. You can add a small amount of resistance after the cap in order to restore that if you'd like. Probably wouldn't take more than an ohm.

 

[z-adamson]

Yes, bipolar. But, which bipolar electrolytic cap? Just any general purpose cap with higher esr than what I have now?

So just match uf and voltage, then look for higher esr?

 

[roger2]

Electrolytics will have higher ESR than poly. You don't need to look for specs. But I 2nd gadget's suggestion to insert a resistor in series with the driver. 1 ohm, 1/2 ohm maybe, and continue to use the poly caps

 

[z-adamson]

Ok, so if I go with electrolytic, is there a particular manufacturer and series I should go with?

I will look into the resistor alternative.

 

[BinaryMike]

I often use the ones from Parts Express. You're likely to have similar trouble even with non-polar electrolytics as replacements, because any decent modern electrolytic has lower ESR than what was common historically. Added series resistance may be the only practical solution.

 

[z-adamson]

Added series resistance may be the only practical solution.

Been thinking more about going this route.

Where exactly does the series resistance go? In line with the lead that goes to speaker positive?

And what kind of resistor? Wire wound? Cement? What wattage rating?

 

[BinaryMike]

Where exactly does the series resistance go? In line with the lead that goes to speaker positive?
And what kind of resistor? Wire wound? Cement? What wattage rating?

Use one resistor in series with each replacement cap. Unless we're dealing with a lot of amplifier power here, I would get a handful of 1-ohm 3W metal film or metal oxide film types and start with a parallel pair to make 0.5 ohm in each position, then work up to 1 ohm or 1.5 ohms or even a bit more if necessary to restore correct system voicing. Low-cost WW resistors should be avoided in crossovers.

 

[gadget73]

WW = wirewound, just in case it comes up. They're inductive, probably not enough to really matter but metal types will be cheap enough to not make this a concern.

 

[JDub]

Why not just buy a pair of L-pads from Parts Express? Then you have adjustable attenuation with constant impedance in one fell swoop, rather than messing with a bunch of resistors, trying to find what you want by trial and error. This should work: https://www.parts-express.com/speaker-l-pad-attenuator-15w-mono-3-8-shaft-8-ohm--260-248

 

[toxcrusadr]

I like the L-pad idea.

I've used the PE NPE's for higher value caps usually in woofer circuits but haven't used the small values in tweeter circuits. There were some other NP electrolytics discussed here recently in a speaker cap thread...wish I could remember what they were.