The Quest for The KEF… Reference 107!

[SaSi]

Uhmm, now you have me thinking... I don't output my SB (Sub-Bass or LF) to anything at this point. I wonder how I can add that into my mains?

Your surround decoder will do that if you declare your L-R speakers as full range. My DVD player has that same option and redirects the .1 channel to the mains if I select them as full range.

I'm currently finishing an experimental 200lt subwoofer using 2xB300 in isobaric chamber along with dual B139 passive membranes. I'll see how this adds to the total result.

 

[SimplySound]

Your surround decoder will do that if you declare your L-R speakers as full range...

OK... so I am feeding the sub-channel to the mains! Thanks SaSi!

 

[SimplySound]

Well the speakers and bass cross-over are boxed and ready to ship to OC. I'm going to have them re-capped. I really want these things to be at their best when I get them finished. OC is saying they will use ERSE's PEx Metallized Polyester Film Capacitors... I'm not an electronics hound so what do folks think? I was thinking Sonicap, but this is what they recommended.


I have the Kube in to a local electronics shop and they are going to "carefully" replace some of the caps in that. You could tell a bunch of them were "over-heated". I also read that the Kube is actually part of the cross-over (active cross-over?). Figure I might as well make sure that is operating to the best of it's ability. I'm not going to mess with the Op-Amps in it unless the shop tells me there's something not quite right.

I'll be on vacation for a week so when I get back hopefully things will be getting finished up. Then it's time to put everything back together. I am doing one speaker at a time, so when this one is finished, I can compare it to the other before I tear it apart.

I'm thinking too that I may redo the internal wiring. Not sure what to use yet, but I may go Cat5. Use a single line for each wire. This will give me 8 individual strands of solid core to make up the connection. Thoughts?

Oh and SaSi... I will put together a photo-montage of the cabinet and get you some measurements. Just give me some time. :thmbsp:

 

[SaSi]

Oh and SaSi... I will put together a photo-montage of the cabinet and get you some measurements. Just give me some time. :thmbsp:

Thanks for your time and effort. I'll be watching this space...

 

[pw5599]

Simply, I really enjoyed your story and you wrote it out so well. You've got me wondering when the movie is coming out!

I dont have any KEF, have never heard any and most likely will never own any. But, as with most all AK'ers I've had my quests and still do. I tend to get attached to things far too often, especially stray, damaged things that need repair or parts. In the past few years I've come to realize the importance of keeping things original, or restoring them back to that state if at all possible.

Recently I've been eying set of speakers I've had for over 30 years that as a silly young lad, frankenspeakered them something awful. Rare things so I found out after much fruitless searching the net. Until one day out of the blue someone is selling a pair. One is damaged but really all I needed was one cabinet and a few drivers. All the parts I needed were there.

The deal is almost complete and hoping the transportation from a far away place comes together and sometime this summer I will get to see them sitting on my floor. Now these arent in the KEF league or even speakers that are talked about alot. I'm not even sure how they sound since mine have never had original tweeters. But, they are unique, rare, and special speakers that are fairly well regarded in the audio community. Once this one is over with, I'll go to my quest list and continue on with the next one.

Beautiful KEF speakers you have there Simply, you're a lucky guy!

 

[SimplySound]

First set is ready!

Well, got a package from Orange County today! They did a beautiful job of repairing the speakers. I know many would say DIY! But I'm glad I left these to the experts.

Here's the "before and after"....

 

[SimplySound]

OK... now it's time to work on the cabinets and the wiring. First off though, OC went through my X-Over and said each and every Cap was to spec and they again recommended NOT to recap them. They were pretty ademate that if it ain't broke don't fix it.

So they sent it back as it was before and charged me $40 for the diagnostics which saved me $100 worth of caps!

I'm going to be using Cat5 for the internal wiring. It will go something like this...

The spade connectors are 3/16 x 22-16 crimp-ons from Shadiorack. Seem to be the right size for the job, but just remember to loosen them up before assmbly. They are a tight connection!

 

[JimPA]

Simply Sound glad you are restoring your speakers. You would hate to lose an old friend.
Do any Kef speaker users have the Kef topic brochures? They were sent to me in a 3 piece binder when I purchased the Dalesford Speaker book by the seller.

I never had any Kef drivers but heard most of the 70's era drivers.

If they ever manufactured the drivers again they would be in high demand for replacements.

 

[SaSi]

I have a couple of KEF Topics in original paper copy but you can download all of them from the KEF site.

Regarding the use of cat-5 cable for internal wiring. Why? What is the advantage? (I can only think of disadvantages due to the use of single core, fragile wires).

 

[SimplySound]

Regarding the use of cat-5 cable for internal wiring. Why? What is the advantage? (I can only think of disadvantages due to the use of single core, fragile wires).

Hi SaSi... The speaker wire they used in the original isn't all that robust. Not bad, but not great...

Not sure I'll hear better sonics with the CAT5, but I figured since I'm in there, I might as well replace the wiring. CAT5 is pretty robust wiring. It's not as fragile as you might think and when twisted together comes in around 16-14ga.

As you can see from the photo (sorry, had to share my album to fix that), it is significantly larger than the original. And from what I've heard on the Man-speaker Thread... larger is better!

 

[mech986]

Hi SaSi... The speaker wire they used in the original isn't all that robust. Not bad, but not great...

Not sure I'll hear better sonics with the CAT5, but I figured since I'm in there, I might as well replace the wiring. CAT5 is pretty robust wiring. It's not as fragile as you might think and when twisted together comes in around 16-14ga.

As you can see from the photo (sorry, had to share my album to fix that), it is significantly larger than the original. And from what I've heard on the Man-speaker Thread... larger is better!

No problem with the Cat5 wire, but the physical comparison is misleading - the Cat5 is larger because each individual conductor is insulated with its own sheathing, thus taking up much more space and then the whole thing is contained within an outer jacket. Regular wire contains all the strands but twisted together without individual insulation, then jacketed.

 

[SimplySound]

No problem with the Cat5 wire, but the physical comparison is misleading...

Agree, but the Cat5 twisted is a bit larger than the original. I'd say 14-16ga compared to maybe 18ga?

So why am I doing this? Cause I can!

PS> I don't think I'm going to mess with the connector to the heads. Why mess-up something that works fine at this point!

 

[SimplySound]

Went from 1/4 Bass to 3/4 Bass

Well this is what I did today... Finally fired them up around 10PM for a checkout. Man they sound sweet! It's late so I'll save the details for tomorrow. All I can say is the bass from these things is tight and uber-smooth! I guess what you would call "Polite British Bass"!

Lower drive unit....

Upper unit...

Full song baby!

 

[SimplySound]

Beware the Butcher!

Well I knew my other cabinet wasn't near as strong as the rebuilt one, so I said to myself, might as well find out what is going on!

I tore into it this morning and found that one of the drivers had been "refoamed" (?) and fortunately the other was original but rotted. No wonder I only felt I was listening to 3/4's of the potential bass from these pair!

Whomever did the refoam job obviously didn't have access to the foam inner donut (or maybe they didn't exist yet). They used some sort of harder plastic inner surround that if I were a betting man maybe lasted a couple weeks until a peak bass passage fatigued and broke out the surround.

They hacked up the leads going to the speaker as if they didn't have a feel for how to get them unplugged and removed from the cabinet. And they didn't even have the speakers seated properly on the rubber seal so the speaker wasn't sealed in the cabinet. That's no good!

Well off to OC it is with these and hopefully they can get that plastic surround off of the cone!

 

[SimplySound]

SaSi... I've started a thread to get you some details on the cabinets. I'll update that from time to time and hopefully by the time I have the other speaker put together we'll have full cabinet info.

Hope that helps!

 

[SimplySound]

Finishing touches...

Well, got the second set of B250's back from OC... they did another exempulary job on these. The one speaker had been "hacked" prior (see images above) so it looks like they had to do some "doping" of the cone to get it "conditioned" for the new surround.

Not sure what this was all about, but I assume it doesn't really impact the sound too dramatically. Yeah the cone weight is probably a little different from the more "original" ones, but it probably is a minor detail.

Anyway, I have them both back together and playing like they were designed to sound! Pretty sweet, no doubt! I will write up some final thoughts on the restoration and the sound in a bit, but right now? I have music to listen to! :thmbsp:

 

[JimPA]

Simply Sound do you know what chemical was used to dope the cone ? Environmental laws have affected the chemicals that can be used in many countries for doping cones
Plastiflex not available in the U.K.. It was widely used on bextrene and paper cones.

 

[rx7rotary]

SimplySound just my 5cents on the wiring. I would suggest the following:
1. Pure Silver for tweeter
2. Silver coated on Mid
3. Good Solid copper (oxygen free) on bass
I have just recently built a pair of speakers with a friend, based on Troel Gravesens design and the wire has proved to be very important. Perhaps I would save cat 6 and cat 5 wire to play around with interconnects and etc...
Dont spare your money when it comes to wire or capacitors / indusctors is a lesson I have learned.
Anyway , that was just my opinion.
Mark

 

[Mystery]

Man!
You drove all the way here, paid a good sum and still have to go through all the repairs.
Hope their sound undermines all that.

 

[SimplySound]

Simply Sound do you know what chemical was used to dope the cone?

SM... I asked this question to Orange County and I'll see if they tell me what they used.

SimplySound just my 5cents on the wiring. I would suggest the following:
1. Pure Silver for tweeter
2. Silver coated on Mid
3. Good Solid copper (oxygen free) on bass

Mark

Thanks Mark (AKA Rotary)... I decided to just use the original wiring, since I was anxious to get these working. Now that I have the Bass Drivers repaired, I have a baseline on what they should sound like. From here I can "mod" them to improve the sound.

I like your comments on wiring and will give this some thought. Since I now have a handle on how to access the cabinets, it should be easier to consider these changes.

Man!
You drove all the way here, paid a good sum and still have to go through all the repairs.
Hope their sound undermines all that.

Oh Mystery, you have no idea... Believe me when I say it was soooo worth the 14Hr round trip AND the $1600 I have in them right now! Plus I got to drink a "Man-Beer" at the Bull & Bush! :thmbsp:

I'm still listening and developing my thoughts. More to come!