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ADS L1090/2 Crossover

David_NC

David_NC

Super Member
I just acquired a pair of these knowing they need some love. I fired them up, and they sounded decent. As I listened to them, I noticed quite a few differences in the sound from one speaker to the other. Mid domes were dented in a bit and have lots of lint on them, so I swapped them out with a spare pair from some L780/2's. They are not exactly the same, but the temp mids are in great shape and fit; this is as much a diagnostic as anything. Next, I noticed one woofer wasn't moving as much as the other three while playing bass-heavy tracks. It's not dead but sounds more like a midrange than a woofer. This prompted me to pull the crossover.
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Yep, it's obvious we've got some issues here, but they should be easy enough to resolve. I have two standard round caps (not sure what to call them), three rectangular caps (not sure what these are either), and a very small disc cap. Values on them are:
100V 130uF(K) - the bulging cap
100V 33uF(K) - the other cylindrical cap
100V 6.8uF(K) x 2 - rectangular
100C 4.7uF(K) - rectangular
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I know the first two should be replaced, but how about the rectangular ones? I'm not familiar with those types. Any suggestions on replacements would be appreciated. I haven't checked the other crossover, but whatever I replace on one will be replaced on the other.

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That blue thing might be a polyswitch Need the writing on the unit to verify. Acts like a fuse but resets.
replace the 130µF and 33µF
6.8 and 4.7 are film caps and don't need to be but you can if you want.
 
Well hopefully you will get plenty of replies to this thread. With all the ads folks roaming the halls one would think this one would get some attention in that sub forum but no worries.
 
Blue Shadow said:
That blue thing might be a polyswitch Need the writing on the unit to verify. Acts like a fuse but resets.
replace the 130µF and 33µF
6.8 and 4.7 are film caps and don't need to be but you can if you want.
Click to expand...
Thanks. I’ll check on that poly switch. Any brand suggestions for the standard caps?
 
Sounds like I've got enough to get started... well, once I measure the caps to make sure the new ones will fit! I'm not certain if the polyswitches are bad or not. Can they be tested in place? I could replace the caps and then try each crossovers in one speaker see if they sound different, but it's a pain to work on these models. I have to remove the lower woofer, reach down into the speaker cavity (after removing the stuffing), and unplug all the drivers. I may be able to remove the nut from the coil (which appears to be what's holding the crossover in place) and simply pull the crossover from the mounts. There are 1/4" spade connectors on the input panel that plug in to the crossover board. I sure hope this is how they are designed to be worked on; it'll be way easier than connecting 8 wires blindly!
I came across another thread regarding these speakers, and the radial cap has a split cover and a slightly domed top, just like mine. I've not seen this on a crossover before. Is this simply due to age, poor quality caps, or overdriving them? The OP of the linked thread obtained polyswitches from Richard So, so that might be the way to go, if I can't find them directly. Thanks!
 
Blue Shadow said:
Nichicon UDB if they have em that large. 130 ain't a common value. Gonna need to parallel something to add up.
Or parts express or whoever has non-polar speaker caps.
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Karl vd Berg said:
4 x 33uF/100V in parallel and you have a 132uF BP cap...

Nichicon VP and UEP are available in 100V.
Mundorf 33uF E-Cap Raw caps are available in 100V.
Click to expand...

You are right; that doesn't seem to be a common size at all. If it was the axial cap, this would be easy. with the radial cap... not so much. There's really nowhere to mount four caps, unless I mount them remotely off the board. Parts Express has a 125uF / 100V axial, which I can make work. I'm curious if that's close enough and if PE caps are decent. Madisound has a Bennic 140uF / 100V, but that's even farther from the 130 of the original.
Thanks for the help!
 
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A solution could be using a perfboard with the 4 caps wired (soldered) as tight as possible. But the 125uF from Parts Express is the best option. It's only 4% lower then the 130uF, well within its tolerance.
 
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