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KEF 103.2 find! Yea! Bad Crossover! Noooo!

A

atrac

Active Member
The title says it all. I found a pair of KEF 103.2's in very good condition at a local thrift today. The good news is all of the drivers work. The bad news is, one of the crossovers has an issue and only the tweeter works when they are hooked up.

The crossover is identical to this one:

http://www.hifiloudspeakers.info/Anatomy/SpeakerSystems/103.2/ColinRoyle/KEF103.2XOver.jpg

Not really sure what to do. I pulled that link from a thread where someone was trying to find a replacement crossover.

Wouldn't I be better off finding the bad caps and replacing them?

(I make that sound so easy -- I'm not sure which ones are bad. If I replace all of them, is it going to be expensive??).

Also, there is a red light at the bottom left of each speaker. Not sure what it is for, but it's hooked up to the crossover (of course) and neither of them light up. Are they a clue to anything good or bad that they are not lit?

One thing I CAN be sure of -- the one speaker that works sounds amazing and it's worth the effort to get the other one going!!

Thanks!
 
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A crossover is a fairly simple circuit. It pretty much has to be an open resistor, open inductor, or a bad solder connection. All of these can be checked with a basic ohm meter. You could rule out the pair of 300uF caps by temporarily bypassing them with a wire.
 
Thanks for the advice! I need to get me one of those meters. ;)

I have to say that I am thoroughly impressed with the innards of these cabs -- one can certainly tell the high craftsmanship that went into making these.

I definitely know now that if I see "KEF" at a Thrift store, it's pretty much a must buy.
 
i bet you a bad cap, my 104/2 suffered from one of the legs separating from the body. Maybe KEF got a bad batch back in the day? Anywho, i agree just build a new one with better parts minus the protection.. Better still, build the crossover in a separate box and have it OUTSIDE the speaker and just run short wires to the drivers. This way th crossover is not inside the cabinet and being subjected to the vibrations of the drivers.
 
I'd play with a jumper lead with two crocodile clips first to see what's bust, as most KEFs will run on the inductors and produce a reasonable sound.

On specific causes of quiet working B200Gs look for corrosion or a dissolved track near to the S-STOP rectifier capacitor (little mauve upstanding components) and repair with a paper clip!

:music:
 
On specific causes of quiet working B200Gs look for corrosion or a dissolved track near to the S-STOP rectifier capacitor (little mauve upstanding components) and repair with a paper clip!
Click to expand...

Yep .. fixed mine this way but used cu not steel .. easy solder job just look at the other Xover and follow the same path.
well worth the trouble .. one of my favorite speakers.:thmbsp:

Steve
 
There's a protection circuit built into them that trips to protect them from, I'm assuming, amp clipping and such. It must come on when it's activated as I've never seen it come on on mine in the few months I've had them. They are simply awesome speakers, one of the best stand mount speakers I've ever heard. They go surprisingly low if you put them on some pretty solid, spiked stands.
 
So at 1am last night I decided to open the non-working one up again. Since the woofer wires are soldiered (!) to the crossover at both ends, I hooked up separate speaker wire to it and started touching the positive wire to various parts (capacitors) on the crossover. I got very interesting results (which will be no surprise to those who understand this).

I was able to get various high and mid/low range sound based on what I touched the wire too. Obviously I had stumbled onto the "tweeter" crossover portion with the "highs," so I focused on the "mid/low" range areas. Ultimately, I ended up wiring the woofer to the protection circuit. This was the easiest to do because of everything being soldered and the crossover would be very hard to get out courtesy of strong glue -- and my solder skills stink! So when I hooked everything back up, I got amazing (!) sound out of both of the speakers -- this speakers are amazing!!! (where's that "best small speaker thread again?? ;) ).

SO, one thing I did notice now is that whenever the bass gets *really* low and loud, the red light on the one I hooked up to the protection circuit lights up (let there be light). What I am wondering is -- will this damage anything if I leave it like this? Nothing was clipping or distorting to my bionic ears when the light came on. What I don't know if the juice coming from that to power the speaker is straight from the amp or if it is going through all of the capacitors and then coming out (like I said, both speakers sound balanced). Or should I pick one of the other capacitors that also produced the same/similar sound and go with that by jerry rigging? I am not sure if hooking up to one of the other areas will also give the red light (hopefully, not).

Every capacitor I tried produced sound, so I am not sure what the defective area is. It was late when I finished and I was just happy to hear what these babies are capable of. And as it's been noted, they are capable of a LOT. My second best Thrift store speaker find!!! :)
 
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