Kef 104.2 Speakers. Suggestions Discussion Forum

This should cover a number of questions in this blog.
I recently established a listening room for my old KEF 204.2 (Now about 20 years old) and they sound fantastic. I'm powering them with the Emotiva mono-blocks 500W/side (emotiva.com) and the added power cleaned up the sound stage. My room is not ideal as it's about 13 ft square. The ideal speaker placement for me was on the 8-5 line; 60" from the back wall to the face. Tape a diagonal line on the floor out from each corner intersecting a point 5' from the side wall and 8' from the back wall. Then plce the front center on the line, 60" from the back wall to the tweeter face. For me, that's about 8.5' between the speakers. The sweet spot is also 8.5 feet back making a equilateral triangle. Now, a laser line shot across the top of the speaker (center) should intersect just 2-3 feet behind the listening chair.
Once speakers were set, I had to trim the KUBE. Some advise not to use it but I found sound was MUCH better with; without everything went flat. However, I run with Bass Extend OFF and trim the bass to -2 (db?). This opened up the sound stage.
Tweek1: Sound dampling panels on the side walls at the first and second reflected sound points (a mirror leaned on the wall ans positioned between chair and speakers shows 1st point on R wall when you can see the R speaker; second when you can see the L speaker will be closer to chair. Same for L side. My cheap panel was a 2'x4' T-bar ceiling panel made of fiberglas insulation; plastic face.
Tweak2. I had 12 ga wire and I doubled up with a new 10 gage speaker wire-Python2 brand; really opened sound stage.
Tweak3. I added sound traps in the front corner. My cheap panel used (2) 2'x4' T-bar ceiling panel (made of fiberglas insulation; plastic face); glued together, framed and suspended at a 45 degree angle; 4" out of the corner and 4" down from ceiling; suspended by 30# fish line; long side up and down.
Tweak3. I took my Paradigm Sevo-15 sub into the room but timmed it to only enhance below 50 Hz. Phase needs to be set first with a sound meter and test tones.
The process took several months but I have been richly rewarded.
Recently I auditioned speakers in the 10-15,000 range and did not notice a compelling improvement!

Throw away the Kube and get a sub.

Really a very nice sound, particularly in the midrange.

One way to improve mine would be to repair them! With one of the mids (!) the code is delaminating from the rubber surround. Sounds at moderate levels does not *seem* effected (greatly), but I have not tested at higher levels. Obviously should be fixed, and looks likely to be easy by simpling using a needle-type glue applicator to get between the two, and then, with the rear removed, gently squeeze them together. Probably best to do one spot at a time. Question is: what kind of glue is appropriate for the bextreme / rubber interface?
Thanks.

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.

I finally ordered a pr of the modified Morel tweeters from the guy on Ebay (KEF tweeter). $249 incl shipping may be too rich for some but hey, the 104/2 were $2400 - $2900(rosewood) in the 80's! The new tweeters are incredible & are exactly per KEF spec - 92db 4 ohm - & dropped right in. They are 80w drivers so no worries on power handling. I tried all the "fixing", ferro fluid etc. I have to tell you this guy nailed it & in the trash the SP1191's went!