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.
