KEF 105/3 Problem

[iolaus]

Hello all,

I recently purchased a pair of KEF 105/3s and I'm having a strange issue with them. I noticed quickly that there was a discrepency between the audio produced by the two speakers. I've done a little experimenting to try to narrow down the problem and I was hoping someone might be able to offer an explanation, some advice on how to proceed, and maybe a suggestion of someone in my area (Minneapolis, MN, USA) that could work on them.

I started testing by running a 500Hz to 10Khz sweep at very low volume (just audible) and couldn't really make out any difference between the two speakers. However, I then started testing with lower frequency sweeps (around 200Hz to 700Hz) and got a little braver with the volume. From those test I found that the speaker which sounded brighter to me takes on a strong nasal buzzing sound (kind of like a kazoo) at around 300Hz and that the buzz seems to get better and worse on up through the 700Hz mark. I didn't want to push the sweep much higher because I had to use a medium volume for the buzz to happen and didn't want to damage the tweeters. Do these results suggest anything?

Thanks,
Ryan

[tungsten]

One of the midrange drivers may have become loose in the suspension, causing the coil to scrape in the gap. It can be fixed - ask one of the shops offering new surrounds to old drivers.

If you´re lucky, it may just be some small part resonating. Check ALL screws, bolts and nuts. If you´re in doubt, switch the two midrange drivers and see if the problem moves to the other speaker...

[kexik]

Originally posted by tungsten
One of the midrange drivers may have become loose in the suspension, causing the coil to scrape in the gap. It can be fixed - ask one of the shops offering new surrounds to old drivers.

another possible reason should be partial coil damage - heat produced by overdriven coil can cause volume expansion of fixing resin and insulation polymers - these can cause buzz and cracklings in the magnet then... speaker repairing specialist can fix this, but do not expect low cost of this

[Ron E]

You might just need to tighten the mounting screws, or wedge something between the baffle and driver if that fails. You'll know its the mounting if it goes away when you press on the speaker basket during sweeps.

BTW, here in town I know of 2 reconing shops, not sure if they do KEF, though.

EMI on Central Ave and 20-something northeast.
Midwest speaker on Snelling a block south of Marshall - south of I94.

I'm not sure, but it is possible that the Needle Doctor might know of others in the area.

[iolaus]

Hey guys,

Thanks for all the tips. After some experimenting I think I've pinned things down a bit more. Here's the deal. The buzzing sound during the sweep I had heard was due to me not mounting the tweeters perfectly within the middle woofer. The replacement tweeters are slightly different than the originals and are a bit more difficult to mount without the the woofer scraping against them. Once I had that problem cleared up, I continued testing and found that there was still a very noticeable difference between the two speakers. Upon further investigation I narrowed the problem down to the mid-hi woofer surrounding the tweeter on the left channel. When playing a clean 800Hz tone and going back and forth between left and right channels (with only the mid-hi woofer connected) the left channel has a dissonance and sounds weak, off-key, and tinny or hollow. So... now I guess the question becomes is it possible for the driver to be repaired or should I go straight to KEF and see if they can provide a replacement.

Thanks again for all the suggestions and help,
Ryan

[tlmadsen]

The KEF REF 105/3 are "highly engineered" speakers and if I was you, I would go straight to KEF.

Don't think any "home-made" shop will be able to fix it.

Remember that the x-over it "aligned" with the units within 0,5 dB if I remember correct. Not something you just do.

If you dont' have a kube for them get one.

Thomas