KEF Reference 101/2

R

Roycej

New Member
Hi, newbie here and hoping someone might help me out. I came into a pair of KEF 101/2 speakers. There's virtually no information on these online except they were made in about 1990, they use a single Uni-Q driver, and they were pretty expensive new.

They look pretty good with nice wood veneer, a little TLC and they ought to look extremely nice. The drivers look literally like new, no visible problems. Unfortunately, there are some audible problems.

I set them up with my receiver and fed them a white noise (or pink noise) test signal. They both played, but one at a much lower level than the other. Since it has bi-amp terminals, I tested the woofer and tweeter separately. I took off the jumpers and hooked the wires up the the LF terminals. One speaker has a very low woofer output. I switched wires to make sure it wasn't the connection or the receiver. It's definitely the speaker. Then I hooked up to the HF terminals. Much better, approximately equal in volume.

Then I did a listening test with some music. It seems that the speaker with the good woofer has an issue with the tweeter. :tears: There's a definite loss of higher frequencies.

I haven't opened them up yet, which seems to be the next step. I've read about the crossover caps going bad, and these are nearly 20 year old speakers. Can bad caps cause my symptoms? I would expect a bad woofer or tweeter to be totally dead, instead of partially functional. Thanks in advance.

Royce
 
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Roycej said:
Hi, newbie here and hoping someone might help me out. I came into a pair of KEF 101/2 speakers. There's virtually no information on these online except they were made in about 1990, they use a single Uni-Q driver, and they were pretty expensive new.

They look pretty good with nice wood veneer, a little TLC and they ought to look extremely nice. The drivers look literally like new, no visible problems. Unfortunately, there are some audible problems.

I set them up with my receiver and fed them a white noise (or pink noise) test signal. They both played, but one at a much lower level than the other. Since it has bi-amp terminals, I tested the woofer and tweeter separately. I took off the jumpers and hooked the wires up the the LF terminals. One speaker has a very low woofer output. I switched wires to make sure it wasn't the connection or the receiver. It's definitely the speaker. Then I hooked up to the HF terminals. Much better, approximately equal in volume.

Then I did a listening test with some music. It seems that the speaker with the good woofer has an issue with the tweeter. :tears: There's a definite loss of higher frequencies.

I haven't opened them up yet, which seems to be the next step. I've read about the crossover caps going bad, and these are nearly 20 year old speakers. Can bad caps cause my symptoms? I would expect a bad woofer or tweeter to be totally dead, instead of partially functional. Thanks in advance.

Royce
Click to expand...

Actually, have a look at the crossover, and look for any cooked spots under a resistor. If you find any, carefully cut/scrape out the burned area. Also, I don't know if the 101/2 is sealed or not, but I know the original 101 is. If the body is not sealed and it is supposed to be, you will lose energy. It may be worth re-tightening the bolts anyway.

Is the one tweeter totally dead?
 
BrassTeacher said:
Actually, have a look at the crossover, and look for any cooked spots under a resistor. If you find any, carefully cut/scrape out the burned area. Also, I don't know if the 101/2 is sealed or not, but I know the original 101 is. If the body is not sealed and it is supposed to be, you will lose energy. It may be worth re-tightening the bolts anyway.

Is the one tweeter totally dead?
Click to expand...

Thanks for your reply, BrassTeacher. On further testing, I was mistaken, both tweeters seem fine. That is to say, they sound identical.

There is a problem with the woofer on speaker A. Pink noise fed to woofer B sounds sounds fine and more or less matches my other speakers. Pink noise to woofer A is much lower in volume, and seems to be lacking in the low frequencies. I have nothing to measure response, but my ears say the upper frequencies are there, the lower aren't.

By sealed, I take it you mean the cabinet should be fairly air tight. There is no port, so I guess it is sealed. I don't see any place where it looks like it would leak air. The screws that hold the back on were all tight. I think my next step will be to swap the crossovers. The problem should either follow the woofer, or the crossover, shouldn't it? I did take crossover A out yesterday to have a gander. It looked pretty immaculate, and more complex than I was expecting. :eek: But I didn't see any obvious signs that anything had exploded or burned. I'll take a closer look when I get a chance.

Royce
 
As a followup, I switched the crossovers. The problem is the woofer. I haven't taken it out yet, I guess I need a new one.
 
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