Speaker Crossover Capacitors- Polar vs Non-Polar

Hi, I am finding conflicting information on this. I’m trying to pick the best capacitor to use as a high pass filter on car audio speakers. Aluminum electrolytic seems to be the recommended material at >100uF. What I can’t seem to get a straight answer on is whether polarity matters or not in this application. All of the pre-fabricated bass-blockers from audio companies are non-polar, but most of nichicon’s audio capacitors are polar, except the Muse ES, which is limited in capacitance values offered.

I tried to find this same answer and did not see much on this topic. Though I have talked to many musicians and people repairing audio products. The series from Nichicon that I have heard the best reviews on is the Fine gold series. It is polarized. The link to some products that are 100uf on our website is: https://www.digikey.com/short/95d0508b . I am sure this is one of many that have great performance. It is just a series that I have heard multiple times. I am not seeing any issues using a polarized product. Though it is something you have to be more careful installing.

When installing a polar capacitor, am I correct that I would connect the + wire to the + side of the capacitor and the - end of the capacitor to the positive lead of the speaker?

For AC signals, like speaker crossover networks, always use non-polarized because AC is continuously reversing polarity.

If you use a polarized electrolytic in a crossover network you probably won’t be able to hear the difference, however measurements will show the difference (human hearing is a terrible measuring instrument).

After an uncertain amount of time (the manufacturers don’t test this since it’s not an approved use for their product) the values will start drifting making the circuit operate even further away way from the intended operation. Again, you may or may not hear the problem but it will be measurable.

The Nichicon “Fine Gold” series capacitors are for use in the DC portions, especially power supplies, of audio equipment not in the signal chain.

It doesn’t matter because the + side marking on a speaker connection is not actually positive, it’s analogous to the hot lead in house wiring. It is marked that way so the phase of the AC signals is consistent between the left/right speaker channels. You can wire the speakers either way around and as long they are both the same way around it will perform correctly.

Fun note: back when I was young and stereo audio systems were still rare and expensive, we used to hook up two speakers with opposite polarity to a monophonic sound source to get a simulated stereo effect from the two out of phase speakers. A decade later similar techniques were used for pseudo-quadrophonic sound from a stereo system.

Thanks for the advice Paul! So would the non-polar Muse ES be a good option in this case? The only difference I can see is that it’s radial rather than axial.

Is 100 WV working voltage?

Yes, the MUSE line is specifically designed for audio signal chain usage.

From the data sheet:

Yes, WV = Working Voltage

When choosing the working voltage for speaker crossovers use Ohms law to determine the WV needed for the systems power and impedance then multiply by two for decades of usable life.

Example: 300W @ 8ohms
WV = sq_root of Watts times the resistance
300 watts x 8 ohms = 2400
sq_root of 2400 = 48.9 volts
48.9 volts x 2 = 98.7 volts
So the caps in the photo are good for 300 Watts into 8 ohms

Great! That’s super helpful! I wanted to make sure it wasn’t different from a plain voltage rating, bc none of the nichicon used “WV”.

The Muse line is actually what actually muddied the water for me, so hopefully you can clear this one up for me too! It appears that the Muse KZ is the premium Muse model, but they are polar. With nichicon saying that the Muse line is for acoustic applications, it really got me confused about the importance of polarity. Would the KZ be just for amps and such?

Yes the KZ Muse line is for DC only. The data sheet does not say “Suited for audio signal circuits”.

Instead they say: https://www.nichiconcapacitors.com/pdf/e-ukz.pdf

Ideally suited for first class audio equipment where qualitative and quantitative comfortableness is required.

They are intentionally being vague and pseudo-scientific because the reality is that when it comes to filtering DC the extra price paid for the KZ is extremely unlikely to produce measurably better results that are within the range of affecting human audio perception. However there is huge money being made on audiophile grade components and they don’t want to be left out of the gold rush.

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I just had another thought…

The speaker in question is my center dash speaker. In order to replicate the channel lost when replacing the factory amp, I tapped into the RF + and LF -, so that the speaker was balanced. I know bridging amp channels basically doubles the RMS capability, but not as clear on whether what I did would have the same result. Each front channel has 60 W RMS. So when calculating capacitor voltage, I’m guessing I’d need to calculate at at least 140W?
It’s also a two-way speaker. Adding this capacitor to protect the mid-range channel shouldn’t impact the high pass filter already on it for the high-range coil right? It would just take out (for example) <100Hz for both, then <1,000 at the high channel?

I’m know nothing about automotive surround sound. In fact until you mentioned a center dash speaker I didn’t know they even existed.

I am familiar with home surround sound and there the center channel is not at all derived form the front left and right channels. The center channel is an entirely different sound source channel used primarily for speech from characters appearing near the center of the screen.

Connecting a single speaker to one connection from each of two amplifiers could eventually burn out both amplifiers and/or the speaker. I would not use the center dash speaker at all without a proper center channel decoder/amplifier.

Same amp, different channels, if that changes your stance at all.