Kef reference 104/2 circuit diagram - Page 2 - diyAudio
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Multi-Way Conventional loudspeakers with crossovers

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Old 22nd March 2006, 03:22 AM   #11
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Join Date: Feb 2004
Location: Queensland Australia
Another point that is relevant is this. The review has an helpful "exploded" cut away view of the units and the LF/MF cross over is located behind the mid/hi drivers and the LF components are inside the main box high up on the back panel on a separate board. Neither are in the base so I suspect that you (Clem) are looking at the S-Stop circuit. Also before you go looking for the hi/mid cross-over think twice before you take out the mid drivers. They are not conventional in the sense that they have no support basket. The cone and magnet are located by the precision plastic moulding so if they are taken out you might have the devil of a job putting them back with the necessary accuracy. BTW I hope we are discussing the same speaker. The review I'm looking at is dated Dec' 1984. They were new models in Australia at that time. Good luck.
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Old 22nd March 2006, 04:01 AM   #12
clem_o is offline clem_o  Philippines
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Hi Jonathan,

Many thanks for the additional information. Frankly I never heard of the S-stop circuit, it could be a latter addition. My Kef 104/2's midrange / tweeter assembly is something that's practically impossible to take apart, it is built totally with MDF, and appears to have some kind of sealant (i.e. hardened silicon rubber) poured in. I will take a picture of the thing as well as the crossover when I get home tonight; hopefully I can manage to post it here tomorrow, and might clarify some things.

I really suspect that there are several models of the 104/2 around. My unit is identical to the TWO pairs my brother has. But, I have seen an older version with a different front cover (mine has a plastic frame, this older one was wood), and, from the way this discussion is going, there may be newer models with more complex crossovers...


Cheers,

Clem
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Old 22nd March 2006, 05:18 AM   #13
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Hi Clem, look forward to the photos. The site mentioned by dublin78 is v.good for KEF units but from memory it isn't very helpful on this particular model. There's a forum there that might be worth posting on. I think a guy called Alan runs it and he's helpful. BTW a man called Colin Royal (I think) posts on that forum and seems to know the UK speaker scene very well. You'll get his email address on thsat forum.
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Old 22nd March 2006, 05:40 AM   #14
clem_o is offline clem_o  Philippines
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Hi Jonathan,

Actually I pointed that site out to dublin78; I've been actively posting on hifispeakers.info for some time (and yes, you're right, Colin is very helpful, and certainly knows the history!). The site indeed is more tuned towards the older KEFs, and activity is a bit sparse...

Cheers,

Clem

ps: how's Queensland doing? saw the news re 'northeastern' parts being whipped pretty badly. I lived in Toowoomba for a year...
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Old 22nd March 2006, 06:40 AM   #15
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Join Date: Feb 2004
Location: Queensland Australia
Thanks for the interest. Innisvail (between Cairns and T'ville)copped a hammering with a large % of the homes badly damaged. 95 % of the banana crop wrecked. Worst cyclone in this neck of the woods since 1918. No loss of live miraculously although police say we wont know for sure until communications are restored. The SE area is in a serious drought......we actually need a cyclone down here to fill the dams. Prospect of level three water restrictions in a month or so. We move up from Vic. 8 years ago. Like it here....like the heat. If you give me a postal address I'll send you the review. I haven't got a scanner.
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Old 22nd March 2006, 06:53 AM   #16
clem_o is offline clem_o  Philippines
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Hi Jonathan,

I certainly hope things are on the way to better over there...
I've sent you an e-mail with details of my postal address, many thanks!

Cheers!

Clem
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Old 22nd March 2006, 01:20 PM   #17
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Join Date: Mar 2006
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Hello
I have since managed to get hold of the correct scematics for my 104/2s. They are dated 1990, and seem correct.
There were seemingly different derivatives, even a bi-wire version.
I wanted a scematic, so that I could investigate the possibilities of enhancing the performance with modern components.
I have now decided that the crossovers are extremely complex and carefully balanced, and that any fiddling would do more harm than good.
FYI, my crossovers are one-piece and are located against the back panel of the chassis about half way up. It is not easy to see how they might be removed for service without dismantling a lot of the chassis.
These loudspeakers were built with a "belts and braces" attitude and are increadibly well put together (at the cost of easy access to parts perhaps). All panels are sealed with what looks like a silicon sealer, and the midrange units are completely encapulated in a rubber-esque resin.
Hey, what price perfection?
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Old 22nd March 2006, 06:38 PM   #18
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Join Date: Feb 2004
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Hi dublin 78, that sounds about right. I got interested in the 104/2 yesterday and put it into Google. No extras spec' showed up but there was a pair on ebay and the seller specified that they WEREN"T bi-wireable so I got to thinking that if he'd gone to the trouble of saying that, then this facility must at least have been a possibility on some models. Yours are six years younger than the review samples I'm reading about so a lot could happen in that time.
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Old 22nd March 2006, 08:37 PM   #19
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Quote from Loudspeaker and Headphone Handbook Borwick Focal Press
Excellent book BTW (must have if you are into speaker design)
"as well as the detailed construction of the cabinet affecting the cabinet behaviour the coupling of the drive units to the baffles can have a dramatic effect upon the complete system. Recent techniques for decoupling the drive units from the baffle or the magnet from the chassis have resulted in much lower panel vibrations. For example the Kef 104/2 uses a system of carefully controlled synthetic isolation bushes between magnet and chassis effectively reducing the vibrations transmited to the enclosure. The technique does however require a isolation system that has a good long term stability"
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Old 22nd March 2006, 11:06 PM   #20
clem_o is offline clem_o  Philippines
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Ok everyone, my units are dated Dec 199_, and its definitely a biwirable given the 4 binding posts at the back.

re the post of consort_ee_um, does that refer to the midrange units? The LF drivers are mounted using rubber grommets from chassis to wood, but the magnet to chassis is pretty standardly direct-coupled. Then there's of course the force-cancellation rods between the two LF drivers.

Hey I promised some pics. Here they are...
Attached Images
File Type: jpg r104-2_s.jpg (75.3 KB, 291 views)
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