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The history, and perhaps future, of my 104 and 104ab

 
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fiffel
Introductory Contributor


Joined: 18 Dec 2017
Posts: 2

PostPosted: Tue Dec 19, 2017 8:00 am    Post subject: The history, and perhaps future, of my 104 and 104ab Reply with quote

Hello!

Thanks for the great content on this forum!
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A short (?) version of my KEF history, if not interested in an anecdote proceed to next line.

In my teens a friend of mine who lived nearby had some old weird looking speakers that his uncle gave to him. He showed them to me briefly and explained that we was in the process of selling them. A few days later when he had putten up the ad he sort of complained about the amount of phone calls he had gotten and that he regretted that he hadn't put a larger price tag on them.
Some more days went by and then my best friend at the time approached me and said something like: "Don't you have a friend called Klas who lives here nearby?" "Yes" I replied. My friend went on: "My father (who I already knew was a big retro hifi geek and very knowledgeable about speakers and electronics) bought a pair of speakers from your friend and then called me and said he had made the deal of his life" For many years, and still to this day, we have a lot of laughs about this little episode.
My best friend and me has since enjoyed his pair of 104ab many times, they are in excellent condition and sound fantastic.

Some years later almost the exact same thing happened to me. I had been looking for my own pair sporadicly and one evening I found them. Even though it was late at night I immediately called the man selling them and told him I wanted them and that I could pick them up the next day. We agreed to speak again in the morning and when I called him the next day he complained about the amount of people calling. He was however aware of the speakers quality since he was (i believe) the original owner, but was still surprised about the amount of interest in them. My best friend and I put new wires in them and remade the white painting that the original owner had already done at some point. Apart from having to replace one of the T27s once after an outdoor party (I know, not the right speakers for such a thing, but we are all young and stupid at some point) the speakers have been working fantastically and I am still super happy with them. The only thing bothering me is my best friend bullying me that he has the ab version and I don't.

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Which leads me to my next pair that I recently got, my very own 104ab, with two spare tweeters included in the purchase (older and different versions, uncertain about condition). To my disappointment they did not sound very great when I plugged them in and compared them to my 104s and I am now in considering how to proceed with this.

Basically I am looking for some general advice on how to make them great again. What would be a nice way to restore the 104ab? Could just a rewiring help or do I need to maybe replace the crossovers? I understand it is hard for you to answer this without having seen or heard the speakers.

Another idea, if you guys don't regard that as complete blasphemy, to rebuild them into a smaller speaker for my office where they are currently a bit too big to fit. Basically I have my old 104s in the living room and need a speaker for my office but I (my girl friend rather) would prefer a smaller pair in there.

It would naturally be a Chorale design since the drivers should work very well together also in a smaller closed box without the BD139, or would they? My idea was to simply copy the cabinet of the Chorale and build them really properly out of something like 25mm MDF. But what crossover would I use? One idea is to take the ab crossovers and try in my old pair of 104, but would the 104 crossover sound good with the Chorale layout without BD139? I guess not?

I also saw the new improved chorale crossover at Falcon Acoustic. I imagine a really solidly build cabinet and a new crossover would sound really good with the old drivers? I realize that would not be a very "cost effective" speaker in the end but ever since that first anecdote I have become very fond of these things.

Thankful for any sort of thoughts or help in this matter.
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SaSi
Senior Contributor 200+


Joined: 24 Aug 2008
Posts: 236

PostPosted: Fri Dec 29, 2017 7:29 pm    Post subject: Reply with quote

Hello, welcome and season's greetings.

I liked your post, up to the point where you started the discussion about breaking down the 104ab pair to make a smaller speaker pair.

I would first need to point out that you should not do that - unless the cabinets are in a mess.

And if you do, be aware that the B200 in the 104 enclosures is much different to the other B200 variants in other speakers from the same era. The 104 use the SP1039 variant while the Chorale use the SP1014 (more common) version. The magnet in the SP1039 is massive (much like the SP1022 of the Cadenza) and quite rare.

As you said, it's quite difficult to know what's wrong with the speakers without listening to them or without more information, so I will give a couple of directions for you to investigate.

First, please describe what exactly doesn't sound right with the 104ab compared to the 104 you have. Is it the low frequencies? Do they sound dull and muffled?

First thing to check using a multimeter is the drivers - after removing them from the crossover. They should read a DC resistance of about 6-8 Ohms. If they read zero or infinite resistance then the voice coil is gone and the driver doesn't play a sound.

Another point to check is the crossover itself. The 3 settings switch may have corroded and not do good contact. That would affect the tweeter and muffle the high frequencies.

Or you may have a rubbing woofer / dead woofer in which case you would have no bass coming out of the speaker.

Having checked these basic things first, the next thing would be to examine the crossovers. A friend once cave me a pair of KEF Corelli that sounded muffled and I discovered two blown tweeters but also a few exploded capacitors on the crossover. Capacitors are easy to replace and - thankfully - it is now easy to get T27 replacements from Falcon.

If nothing from the above is true then it could be that the capacitors or some of them have drifted in value and affect the output badly. I've had that on a KEF Calinda pair that sounded muffled and kinda funky. Turned out that one of the high pass section capacitors was quite off on one speaker, a lot on the other. One speaker produced no treble at all and once that was fixed, the pair sounded like they were wired out of phase in the high frequencies.

The age of the 104ab is old enough to warrant caution on the capacitors. They may well have drifted out of spec. If all the other faults described above are not present on your speakers, it's pretty possible the crossover capacitors are causing the problems.
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fiffel
Introductory Contributor


Joined: 18 Dec 2017
Posts: 2

PostPosted: Sat Dec 30, 2017 9:12 am    Post subject: Reply with quote

Thank you. You are completely correct, after reading around I realize breaking the speakers down is not a good option. When I get back home from my vacation I will open them up and investigate everything in detail. I will write a report on my findings! Thanks again!
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T.O. Chef
Senior Contributor 100+


Joined: 31 Aug 2007
Posts: 160
Location: Toronto Canada

PostPosted: Thu Feb 08, 2018 12:03 am    Post subject: Kef 104aB's Reply with quote

I must concur with all the above advice you have received on your 104's.
I have been finding, purchasing, then restoring 104aB's for several years. Yes I love them dearly. I have found so many that sounded flat dull and lifeless and magically with a relatively simple total recap of the crossovers have amazed me with the sound quality achieved.
The drivers are a matter of some concern though. Ideally they should be scanned for variances (from specification). Often they are far from ideal. A good match side to side is important if at all possible. Lacking the necessary equipment to scan at least check coil resistance with a simple meter and hopefully they are close side A to B. If they are, you're likely going to be very happy with a new set of cap's.
NOTE: personally I have found the Solen 0.6uF supplied by Falcon Acoustics in their 104aB recap kit to impart an excessive brittleness to that tweeter. After extensive comparisons I slightly but definitely prefer a 100V polyester capacitor in that aB section.
Please let us know how you make out with yours Smile
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