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Cross over capacitor question

endervox

endervox

Active Member
I have a pair of Dynaco A40XL's. These things were BUTCHERED and I have been restoring them. I want to do a proper job so I ordered new caps for the cross over. And thus my question:

The stock capacitor in the cross over is a bipolar 8uf/50v. I ordered a bipolar 10uf/50v (Nichicon Muse ES). My thought was it shouldn't make a huge difference… Now I just want to be sure before I put it in circuit, which I plan on doing in the next hour.

Thoughts? Advice?
 
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By switching capacitance values (8uf to 10uf), you are making a 25% change and significantly affecting crossover point. You'd be better off staying with 8uf but increasing voltage if needed.
 
Ok, I'll leave it as is and order a proper replacement next time I put in an order with DigiKey. I was so preoccupied about getting the best that I didn't really give it a good thought about the actual value… I was rushing my order so I could get it delivered by friday… SUCH A BONEHEAD!!

Thanks ALL!!
 
endervox said:
Ok, I'll leave it as is and order a proper replacement next time I put in an order with DigiKey. I was so preoccupied about getting the best that I didn't really give it a good thought about the actual value… I was rushing my order so I could get it delivered by friday… SUCH A BONEHEAD!!

Thanks ALL!!
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Just be sure to stick with bipolar caps. I believe the MUSE ES series is.

There's a good chance that many of the bipolar electrolytic caps you're going to find will have a value of 8.2uF instead of 8.0uF. This value will be fine and is still considered to be in spec.

Another reputable electrolytic cap is Mundorf. I've used them in a few projects. You can buy these from Parts ConneXion in Canada and avoid any import fees. Another good brand is Erse. The problem with ordering through them is there must be a $20 minimum order.

ecap.jpg
 
If you have a quality 2.2uf cap, you could series that to the 10uf cap, and go that route. A nice PP or MP, in that configuration would be fine. That would be approx. 7.8uf. Well within +/- 5% of 8uf mark.

By using a 10uf cap (approx. 1.8k point) instead of an 8uf (approx. 3k point), you'll be putting more stress on the tweeter, asking it to reproduce frequencies it may not be able to. This could lead to a tweeter failure. Not something you want.
 
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cablephil212 said:
If you have a quality 2.2uf cap, you could series that to the 10uf cap, and go that route. A nice PP or MP, in that configuration would be fine. That would be approx. 7.8uf. Well within +/- 5% of 8uf mark.

By using a 10uf cap (approx. 1.8k point) instead of an 8uf (approx. 3k point), you'll be putting more stress on the tweeter, asking it to reproduce frequencies it may not be able to. This could lead to a tweeter failure. Not something you want.
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Better check that math for a series combination of capacitors. I get 1.8uF for a 10uF and 2.2uF in series.
 
Get them back to original. My friend has a pair of those and I am always impressed when I hear them.

Doug
 
A 4.7uf with a 3.3 across it would also come out to 8uf. Parallel capacitors tend to be more favorable than series due to the lower resulting ESR. We're probably splitting hairs here anyway but thats just how I prefer to do it if I have a choice in the matter.
 
Butting in here but I have a similar situation - trying to restore some Knight speakers. The crossover caps are listed as "8 MFD 50VNP" and ".50MFD and 50 VDC".

I couldn't find caps on Parts Express that would fit exactly and had read that you just want to make sure caps exceed both uF and volts. The replacements Ive ordered are Audyn 8.2uf 400V and Audyn .56uf 400v. Will those work?

Thanks -
 
you want to match value, and meet or exceed voltage. Don't need 400v caps in a speaker, though it probably won't hurt. The 8.2uf is within 3% of the original value. The original cap was probably not that accurate. The other one is a 12% difference. That might be audible, maybe not. I may have gone with a 0.47 since its closer. maybe if I were feeling fancy, it could be strapped with a 0.033 cap to come out to 0.503uf.
 
endervox said:
Ok, I'll leave it as is and order a proper replacement next time I put in an order with DigiKey. I was so preoccupied about getting the best that I didn't really give it a good thought about the actual value… I was rushing my order so I could get it delivered by friday… SUCH A BONEHEAD!!

Thanks ALL!!
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I ordered some "PLAIN" Mundorf E-Caps from Parts Connexion to replace the old NPE's in a set of BA 70's and could not be more pleased with the sound in keeping with the original 'tone' of the speaker. They are well-made 5% NPE's with great leads as well.

I first had tried various metal poly caps and did not like the off balanced result.
 
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moosteve said:
The values of caps in parallel are added together. i.e. 12uF + 12uF = 24 uF

Caps in series are different, resulting in a value less than the smallest cap.

http://www.electronics-tutorials.ws/capacitor/cap_7.html

I am new here, and I hope providing links to explain things is ok. It will explain better than my basic knowledge.
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I really appreciate that. I knew the values in parallel are additive. I thought the values in series were subtractive. Luckily, I haven't used two caps in series yet. :o

Thanks for the link.
 
gadget73 said:
you want to match value, and meet or exceed voltage. Don't need 400v caps in a speaker, though it probably won't hurt. The 8.2uf is within 3% of the original value. The original cap was probably not that accurate. The other one is a 12% difference. That might be audible, maybe not. I may have gone with a 0.47 since its closer. maybe if I were feeling fancy, it could be strapped with a 0.033 cap to come out to 0.503uf.
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Also having similar capacitor search results as folks above. I was also looking for a 8uf 50v cap to replace in my one KLH 24 (this is a RCA insert one, not the 24's with the speaker wire posts, which have 4uf 50v caps in them.) I was wondering if replacing a cap with the same farad value but with higher voltage would alter sound results if at all? It seems the farad value is more important for sound than the voltage. It seems there's 8uf, or 8.2uf caps for bigger voltage 150 and up but didn't know how the voltage value can/would change anything. Sorry for a noob question, just not trying to ruin anything by misunderstanding and want to understand how caps affect speaker sound. I swapped out the caps in the speaker wire versions of the KLH 24's I have and the sound did clear up a good bit, bass is tighter now but maybe not as punchy.
 
also curious about how capacitor quality between a name brand cap and a cheap no brand cap of the same value can differ? I bought the cheapest cross capacitor from Parts Express for the KLH 24's, Realistic Nova 15's, and Layfette 1003's that all had the same value cap. Seems to some people that shelling out for a better cap is only worth it for nicer speakers than the one's i've just listed. but also some name brand caps are only a few dollars more which i would be willing to dish out for better speaker sound but didn't know how much of a difference in sound we're even talking.
 
bluepine27 said:
also curious about how capacitor quality between a name brand cap and a cheap no brand cap of the same value can differ? I bought the cheapest cross capacitor from Parts Express for the KLH 24's, Realistic Nova 15's, and Layfette 1003's that all had the same value cap. Seems to some people that shelling out for a better cap is only worth it for nicer speakers than the one's i've just listed. but also some name brand caps are only a few dollars more which i would be willing to dish out for better speaker sound but didn't know how much of a difference in sound we're even talking.
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The sound quality improvement that you can get from using high quality crossover components can be very significant. You will get all kinds of different opinions on this and in the end the only way to really know for yourself is to try it yourself.

Going up in voltage with the caps is not a problem, do not go down in voltage rating. You can also use 2x 4µF caps in parallel to get 8µF.

Cheers,
James
 
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