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Kef 104.2 Speakers. Suggestions Discussion Forum

KEF 104/2 SPEAKER OWNERS.

Lets have a tips and suggestions forum on how to improve these wonderful speakers.

Topics could include speaker placement, speaker tweeks, best speaker cables (interconnects, power cords etc), best amps (receivers, cd players etc), best compatible center and rear surround speakers, care and maintence, repair shops and more.

Here is a review (see below) that I found on the web concerning KEF 104/2 Speakers.

In over 10 years of doing high end audio reviews, enjoythemusic.com has given out a total of 59 awards for product excellence. The KEF 104/2's were among them. Out of those 59 awards, only 5 were to speakers and that includes speakers in the $10,000+ catagory. The editor has a section he calls "my personal list of products that deserve to be heralded as something truly special" and the KEF 104/2 speakers are included.

The Review summary: Back in the 1980's KEF was a wonderfully British company making their own drivers with a top-notch team. While their top range model was the 107 that produced deeper bass (down to 20Hz), after careful auditioning the KEF 104/2 was the obvious winner. KEF's 104 model saw various versions and the 104/2 was the final result of the product's evolution. This relatively high sensitivity loudspeaker, at 92dB/W/m at 4 ohms, produced frequencies from 55Hz to 20kHz (+-2dB) with five drivers. The tweeter is KEF's T33 25mm (1") silk dome with slight horn loading. It was flanked above and below by the B110 100mm (5") doped Bextrene midrange cone in a D'Appolito technique. Bass was produced by a pair of coupled cavity B200 200mm (8") paper cone drivers with their center magnets connected by a metal pole.

The midrange/tweeter/tweeter panel (weighting about 25 lbs) is completely removable from the woofer cabinet (at nearly 45 lbs) and both loudspeaker cabinets are very rigid. Each midrange is enclosed in its own sealed section to reduce any interaction while the tweeter is press fit to the cabinet via a rear screw. The internal woofers' output exits via a flanged port the same size as the midrange units. And thus the brilliance! The tricks up the 104/2; proverbial sleeve is that the sound wave of the midrange and the bass drivers is the same size, plus add in the point source-like output from the midrange/tweeter/midrange D'Appolito configuration.

As for sound, the highs are smooth and midrange is very well presented. Bass down to about 50Hz is excellent and tuneful. Do not use the KEF Kube, an external box said to enhance bass down to lower frequencies, as this clouds the sound. If you need lots of bass below 50Hz get a separate subwoofer. The soundscape thrown by the pair of 104/2 is remarkable! When present, not only is the sound totally enveloping, but you get height information too.
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I welcome and look forward to your input.
buyfast1

Showing 2 responses by rdeckard

rdeckard
9 posts
 
I have a circa 1990’s pair of non-bi-wire KEF 104.2’s that I purchased recently. I have wanted a pair since they came out and was able to obtain them for a steal.
Of course, I wasn’t aware of all the caveats involved with owning a pair of these until after I had them for a while.

I have already replaced the rotted inner surrounds on the woofers (the outer surrounds are rubber). I also had to scrape the dried-up ferrofluid from the tweeters, which increased the high-end sensitivity, but of course has most likely changed the response from the original spec. I ordered a pair of replacement tweeters from KEF but have yet to install them.

I have read that replacing the caps in the crossovers is the next step in restoring these speakers and will be a better match with the new tweeters.

Does anyone offer a kit to replace the caps? If not, can anyone recommend what and how many to get?

Any other tips or advice would be greatly appreciated.

Thanks!
rdeckard
9 posts
 
OK so since my last post, I have now replaced the tweeters with the substitutes currently offered by KEF. They brought back a lot of the sizzle that was missing and so far I don't find them harsh.

However, after repeated listening, I started to notice that one speaker had a slightly different timbre than the other, i.e., brighter. At first I chalked it up to one speaker being near a wall and the other next to an open space, but this ultimately was not the cause. Needless to say, this was messing with the imaging, enough that it started to really bother me...

I sent white noise through them in mono and there was definitely a difference between the 2 upper midranges. The left speaker was slightly brighter than the right. At this point, everything I read led me to believe that the crossovers were most likely at fault, since the originals can drift out of spec over time causing the speakers to sound a little dim.

Some time later, a pair of crossovers from a similar-vintage 104/2 came up on eBay for cheap. The owner was parting out an older pair as he found a different pair in better cosmetic condition. I scored them figuring I could at least use the spare parts.

After a good deal of procrastination, knowing just how fun it is to work on these monsters after having servicing the woofers myself, I finally decided to swap out my existing crossovers with the "new" ones. This is no easy feat, as this particular iteration has the crossovers mounted on the inside rear of the cabinet, but it can be done. I was able to remove the crossovers and have a good look.

At this point, I think it's worth mentioning that all the Capacitors on my original crossovers are KEF-branded. I read that these caps are actually manufactured by ALCAP, but the ones that meet the required specs/tolerances are then branded with the KEF wrapper. However, all the caps on the "new" crossovers were branded ALCAP and look to be original, i.e., no evidence of desoldering/resoldering different parts. There was also no evidence of leaking caps or corrosion on either set of boards.

So, after a full afternoon of groaning and scraped knuckles, the new crossovers finally in place and both speakers all buttoned up, I gave a listen...

They sound EXACTLY like they did before. The upper midranges still have a slightly different tone from each other and the left speaker is still slightly brighter than the right. What a bummer.

My next step is to actually swap the entire Mid-Tweet array from one speaker to another to see if this "brightness" follows the driver or stays with the cabinet. I should note that I had done this before and could have sworn the brightness stayed with the cabinet, which is why I was convinced the crossovers were the culprit. You could argue that the new crossover has the same issue as the old one did, but how likely is that?

I was really hoping the problem was not to do with one of the midranges themselves, because they are pretty much non-serviceable.

I have never read anything about ferro-fluid drying up in anything other than the original tweeters, but as there is no buzz or other evidence of a damaged midrange, it almost sounds like the issue I had with the original tweeters, where the fluid dried up and caused them to sound very dim.

Does anyone know if the midranges also used ferro-fluid?

Any other ideas or suggestions about what to do next would be greatly appreciated!

Thank you for reading.
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