KEF owners thread

[mech986]

The more I listen I hate to say it but I like the sound of my 105/2's over my 107's. Am I a mad man? The 107's are capable of far more output but I like the tweeters and sound of the 105/2's for a smaller space (since they are less efficient) much more. Anyone else have this same opinion or is this just my ears?

Hey, good to see you back. whatever happened to the IMF quest?

 

[steve59]

My 107/2's have the metal grills removed, I bought them from the original owner that way so I can't compare. I can recommend biamping though since you can keep the kube out of the top end if you want that way.

 

[mccarty350]

Hey, good to see you back. whatever happened to the IMF quest?

So basically I got an offer to relocate to near Nashville Tennesee and in my time of disappearance sold my house, bought another house, and have been doing a lot of domestic and international travelling. My mother in law also passed away and we have some medical issues with the wife currently so time for the hobby has been tight. I'm just now starting to stabilize and settle in. I missed everyone and the hobby that is for sure!

My IMF quest ended with my restoration of my Professional Monitor VII's a while back, I love them! I have a restoration thread on them somewhere around here.

They are my #1 favorite speaker I own or have owned in all honesty.

 

[mccarty350]

Do you have the KUBE with the 107? You need it for them to sound right, without it they do not have the frequency response the designers intended, but it may well remove the last bit of detail from the highs. The plastic cased cheap op-amp based 102 and 103.3 KUBEs were much worse offenders but just having the extra connections with the better 107 KUBE has some cost.

My workaround for serious listening was to remove the metal grilles that covered the tweeters and mids. Our Kef rep discouraged it saying they were tuned with the in place but I found it substantially improved detail without making them appreciably brighter. The same trick works on the 105.2, as I showed my friend, but as you say they may not need it as much. I use mine for background and they get used as cat trees so I leave the screens in place now.

Indeed I do have the Kube. At some point I need to recap and swap out the opamps in that but have been much to busy.

 

[beatcomber]

 

[ftpols]

UPGRADING ELECTROLYTICS TO MKPS

I read on another site that the Kef crossover calculations took account of the electrolytic capacitors series resistance and good electrolytics were recommended by Kef as the replacements. If the electrolytics were changed to plastic capacitors then the OP was advised to add a resistor in series with each changed capacitor. The value being 1 ohm per 10uf of capacitor.

Could somebody better than me kindly check the attached schematic and confirm or correct my understanding.

1. Add 0.39 hm resistor between C1 and L1 inductor coil.
2. Increase values of R1 (1 OHM to 2 OHM) and R4 (6 OHM to 8 OHM).

Many thanks!

 

[MER71]

Picked up a pair of C7's at a good price.

 

[viennadad]

104/2 KUBE ISSUES
A while back the left channel began to drop in and out intermittently on any source I was using. After swapping receivers and cables out, I believe I have determined the root cause is the kube. What should I be looking at to correct the problem so I can get it back in operation?

 

[leray1]

Use them without the kube to be sure. But I hear they sound better without it, anyway.

 

[viennadad]

I am certain it is the Kube. I have 3 receivers I switched in and out and have plenty of cables so I was able to isolate it to the Kube itself. I agree that with certain receivers it sounds better using tone controls, but I still would like an operating Kube. Anyone have any ideas on where to start with it?

 

[mech986]

I am certain it is the Kube. I have 3 receivers I switched in and out and have plenty of cables so I was able to isolate it to the Kube itself. I agree that with certain receivers it sounds better using tone controls, but I still would like an operating Kube. Anyone have any ideas on where to start with it?

If you have some electronics experience, I would first suggest opening it up and examine all the solder joints from jacks in and out to the circuit board. Then reflow them with new solder. Same for all joints if you need to. If you have a schematic, then Check for all electrolytic caps and replace with like values. Also, DeOxit all switches and controls, and touch up those solder joints. If that doesn't solve the problem, then more trouble shooting is required.

Or do the troubleshooting first and fix just what is the issue, but these electronics are now 35+ years old so preventative maintenance will still be required.

 

[cr4zyg047]

Just a heads up for all you fine folks with Uni-Q drivers - I've finished refurbing the last of my tweeters and have found the following:

• Late 80's NT19 tweeters (from my C-55)
  • Ferrofluid in dire condition - much overdue for replacement.
  • I have four of these tweeters on hand - they are a bitch and a half to refurb due to their age. The glue is very brittle, and the voice coil leads are the most delicate of any Uni-Q tweeter I've worked on.
  • I am rebuilding two that I bought online because they're literally toast - torn diaphragms, voice coils wedged in the air gap with old ferrofluid sludge. Found a chinese seller making new diaphragms and 4ohm VCs that match the dimensions.
• 90's era NT19 tweeter (from my Model 90)
  • Ferrofluid was in fair condition - easy to disassemble
  • Quick and painless repair - the best of the bunch.
• 90's era NT25 tweeters (from my KEF 103/4 and Model 100)
  • The NT25 tweeters from my 103/4 were in rough, rough, rough shape
    • The glue used (at least at the time mine were made) caused one voice coil to detach from the diaphragm before I got it - the other popped off as I opened it up.
    • Had to reglue the VC and diaphragm - but all is well now.
    • Ferrofluid was in the worst shape of the bunch - don't know why. Might just be result of age, usage, and storage.
  • The NT25 from a NOS Model 100 - fresh out of the box
    • Ferrofluid was still viscous - it was likely stored in a temperature controlled environment
    • Some fluid had condensed/gone missing - I cleaned out the old stuff and replaced it with my own
    • The tweeter is the same age, in theory, as the 103/4 - just less used. But did not exhibit the frail VC glue problem. Touched it up with some fresh glue just in case.

Moral of the story - from what I've seen - anything older than mid-nineties KEF tweeters desperately need new ferrofluid (and the 90s ones definitely benefit - but it'll vary based on how they've been treated and stored). I'm pretty sure the gnarly 1989 NT19s I got on ebay were in as bad of shape as they were because of overdriving them as the tweeters lost their volume due to the solidifying fluid. (Either that, or in one case - it looks like the VC ripped off the diaphragm and wiggled its way down into the ferrofluid and got cemented in place).

I've been writing up my how-to on these and I'll post it when it's ready. But be especially careful to not crank the high frequency in EQ thinking that "well this was designed for a Kube!" -- when in reality the tweeters could either be suffering from dried fluid - or actually be damaged.

 

[BoPtiljudrop]

I have restored these Kef Carlton II, a lot of things where wrong. Coating on one of the B200G's were almost gone and the some of the caps actually had turned into resistors. They where absolutely dead!

A resistor in the crossover where meant to be 2R2, they where 22R. The surrounds where quite stiff but sone rubber conditioner sorted the system resonance out and now they play nicely. Sorry about the messy workshop, it's the best picture I have.

There were no ferrofluid in these tweeters, although I got the impression from reading around forums, that they were made with ferrofluid?

Also found out that there are different ferrofluids, something about viscosity, size of the iron particles and a lot more. Can't buy the stuff here in Denmark, but a friend brought home some from the States, good to have I reckon. And good to learn more about this less documented speaker issue.

 

[Raynald]

Those T33 (MK I) tweeters did not have ferro-fluid. That came along with the later T33 MK II

 

[BoPtiljudrop]

Those T33 (MK I) tweeters did not have ferro-fluid. That came along with the later T33 MK II

I see , thanks.

 

[Sansui77]

Hi guys,

I have an early pair of the bailey's transmission line speakers that use the B139, B110 & T27. I have finally listened to them but the T27 seem to roll off too early which you miss all the fine detail at the top end. They have the original untouched DN12 crossover. I want these to sound their best in changing or upgrading the crossovers.

Do I just do a recap of the DN12 crossover?
Do I upgrade to the falcon accousics crossover, maybe adding a coles tweeter
or
Make the Radford crossover?

Your opinions please......

 

[mech986]

Chev, check the tweeters by playing them directly from an amp with low power and the bass and mid turned down or off. If they seem a lot brighter that way, then the crossover needs work. I would definitely refurbish the crossover with new caps and resistors because they are all very old now.

Do you have spare T27's to check against?

 

[Sansui77]

Thanks. I've ordered new caps for both crossovers. 8 electrolytics per xover. Just thought if anyone has tried different - better crossover designs for a better result.

There's nothing wrong with both T27's.
I've posted in another forum selection...british audio - kef

 

[mech986]

Hmm, probably worth a check in with Falcon Acoustics to see if they have an updated version of the DN12. IIRC, that was used in a few KEF kit systems.

 

[arts]

Well,after a couple of decades with my 104/2's,last month I found a deal I just couldn't pass up:

KEF Reference Model 3's in black ash. I purchased them from the original owner (non-smoker),complete with boxes (huge) and manuals.They are absolutely mint,to the point where you'd think they'd never been out of the boxes! From day one,they were used with an all-tube Audio Research system for classical listening only.
What a score,and what a sound!