JM Labs Electra 915 crossover advice

hello all this is my firtst post ,i have a pair of jm labs 915's that were abused and i want to recap them . to the revised 915.1 i think it was for better bass. i have the schematic .maybe i can post it but i think it for the 915. focal uk was helpful to supply me with this. so what i am looking for it suggestion on new caps and such. i see the mundorf is very favored so i am willing to use them. i have attached the crossover schematic file for all to look at.

thanks any help will be grateful.


  • jm labs 915.pdf
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Hey there! Those always kind of captured my imagination as mini-Utopias. The 100uF cap is your best bet for the bass, but your chances of making it better are 50/50. I suggest a Mundorf electrolytic, or a combination of Axons. The biggest issue I have with Focals is they rely on inexpensive SCR/Solens for the films. I suggest if you can, try replacing the 3.9 and 6.8 with Mundorf MKP caps. You'll definitely hear a change, and you'll learn something inexpensively. Unlike the Profiles, this looks like a more reasonable, straightforward crossover. Not much more I can suggest to you without being able to measure the drivers too. Oh, try replacing the resistors with Mills. :)

Best, Erik
Hi cegtv,

can you spare a photo of the abused speaker/crossover? I advise to not let yourself be misled by believing in brands. Take your time to evaluate the current state of the parts and once proven necessary, perform the changes. I believe in fair prices, so if I needed a 6.8 uF cap, I'd just go get 10x mkt 250V Roederstein equivalent for 16 times less money than a single white mundorf mkp cap. A bit extreme DIY. :)

edit: Thanks for the filter schematics. Will add to the collection.
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i guess i should have been more clear it was late.
1) cabinets are not great cosmetics
2 )one speaker always sounded lower than the other so i decided i would do a recap as they were made 1998 or so plus i read there was a revision to the speaker. and lets face it ,we are all always trying to improve our audio systems.
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The mids are in parallel and working in the same frequency range, filtered by the same passive components, so i don't think that a recap would help in your case.

It's slightly off-topic, but both your speakers act as you described?

If you just "felt" till now, please ensure on it, might be a bad contact or cracked solder joint or so. Even a bad driver might possible.
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good day i found these on the audio vintage forum it is private . they do not let anyone in .weird any way i found these pics of a 915 crossover upgrade cant read all info on the caps.maybe someone can. thanks a enjoy your day paul i have included a stock pic 915/915.1


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