Nippon Chemi-con 100uf 100v BP electrolytic cap

[ten-d]

Hi all!

I just bought a pair of ADS L810 speakers, which I've heard are some of the best speakers from that time (late 70's) into the early 80's. I was super excited to test them out and hooked them up and I was very underwhelmed by the treble. The treble was awfully muffled. I've been doing some restoration work on 70's stereos and a couple of speakers here and there so I am really just a beginner. I do know that capacitors in speaker crossovers filter out the lows to allow only the highs up to the tweeters and mids. Inductors filter out the highs to allow the lower frequencies to the mids and woofers.

So I pulled out the crossover and found that it has quite the robust crossover. 4 inductors, 4 film capacitors and 1 bipolar electrolytic capacitor. I have attached some photos in case they would be of any help.

I haven't tested the film caps as I did some research online and read that the film caps that ADS used were very high quality and shouldn't be going bad. The electrolytic on the other hand could be suspect. I pulled it out and tested it with my LCR meter. This is a 100uf 100v bipolar cap and when I tested it on the LCR meter (which I zeroed out prior to testing the cap), it showed these numbers:

@ 1 kHz = 99.33 uf / 0.03 esr
@ 10 kHz = 96.1 uf / 0.00 esr
@ 100 kHz = open line
@ 100 Hz = 103.68 uf / 0.5 esr

I tried finding the original specs of this Nippon Chemi-con CE04P capacitor but couldn't find anything on it.

As I said before, I am still learning and am only just starting to scrape the surface of understanding the theory behind these things, so please take that into consideration when reading this post.

So I have a few questions:

1. Why would it show zero esr at 10 kHz and and open line at 100 kHz but showed pretty high esr readings at 1 kHz and at 100 Hz?
2. I'm guessing that the esr is bad since it's reading 0.5 at the high end - am I correct in thinking this?
3. What would be a good replacement cap if this is indeed a bad cap?

Thank you very much! I look forward to learning and to also helping others once I get better!

Cheers

[sam_sam_sam]

I found some of them from an EBay seller I can not tell you if they are genuine or are fake but they are bipolar type of capacitors do not use the normal type capacitors they will not work in this situation

https://www.ebay.com/itm/153740556084

[ten-d]

Interesting that they are making replacements. I just went over to mouser and checked for a new equivalent but having trouble finding one. I'll keep looking for a bp cap.

Do you think that the cap I have and tested is bad?

[redwire]

That capacitor is for the woofer, it can only affect low mids if it goes low value. I would say it is good.
What make/model ESR meter do you have, it seems to be crapping out at 100kHz - not that a crossover network is a SMPS, totally different things- no need for low ESR at 100kHz here.

Most important is polarity of the drivers and loudspeakers - you can use a 1.5V battery to bump and watch the cone go out or in and confirm (+) and (-) when jumpered to a driver. Some speakers reverse the mid polarity. Make sure all drivers are alive and the right polarity. There are no L-pads? They can go dirty or open.

You can check Parts Express or Madisound or Solen for parts.
If you change over to big film capacitor, they usually end up rattling around inside the box because mounting them is a bear. Not really needed unless you are running big power.

[ten-d]

Thanks for the reply redwire. I appreciate it.

That capacitor is for the woofer

Ahhh. Okay. I was wondering why it was such a high capacitance. So the 4.7 uf film caps are for the tweeters then? I was trying to find a crossover schematic but there doesn't seem to be one online for my version of the L810's and I'm so not experienced enough to figure this stuff out quite yet.

What make/model ESR meter do you have,

I've got a DER EE DE-5000 LCR meter. I have the tools but still am learning how to interpret what these things mean.

Most important is polarity of the drivers and loudspeakers - you can use a 1.5V battery to bump and watch the cone go out or in and confirm (+) and (-) when jumpered to a driver. Some speakers reverse the mid polarity. Make sure all drivers are alive and the right polarity. There are no L-pads? They can go dirty or open.

No L-pads on this set. The person I bought them from was the original owner and was not tech savvy so my assumption is that no one has ever been inside those speakers until I did. This is totally a guess though. But I will check the polarity nonetheless!

Also - prior to reading your reply, I did purchase these. Since the replacement is an axial I was planning on mounting it to the circuit board sideways. But if you think that the cap is okay, I may not end up replacing it. I'll run the replacement through the same tests on my LCR meter just to check as well to compare the two.

[stj]

the esr is too low, it may indicate leakage.
use film caps instead of BIpolars.

old bipolar caps used in tv's and crossovers can handle more current than the modern ones.

[ten-d]

Thanks stj - I would love to learn this but how would you be able to determine at which frequency is the correct frequency to test the cap's ESR at without being able to look at the data sheet for this particular cap? The esr is all over the place for this cap at different frequencies so how do you know which one is the correct esr? Thank you!

[spiros.p]

The capacitance is not normal for 40+ years cap even new capacitor don t measure like this.It is for low frequency there and the best is to replace with indentical value new cap same or better quality.For the film caps is all ok but if you like to upgrade with new better audio capacitors go on.

[stj]

the common frequencies to read esr are 10KHz for old stuff - really old i mean, and 100KHz for stuff from the 80's onward.
the figure to look at in datasheets is ripple current - the current the cap can charge and discharge.
thats what is needed for audio or driving deflection coils in a crt.
not that there is any difference - the speaker is still a high frequency coil.

[redwire]

Wondering if OP's DER EE DE-5000 LCR meter is working properly? I would see how it reads with some vanilla parts like a polarized 100uF cap.

[ten-d]

Quick update. I received the new Jantzen BP caps and they had the exact same readings as the ones I took out of the crossovers. So it looks like the original electrolytic caps are still good. I may still replace the old caps since I have new ones of the same specs just to help extend the life of the crossovers.

I'll test my LCR meter with some normal caps too just to make sure it's reading them accurately.