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KEF 101 recap

 
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mr quackers
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Joined: 20 Jun 2013
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PostPosted: Tue Jul 23, 2013 1:38 pm    Post subject: KEF 101 recap Reply with quote

Hello again - You will not believe what I'm about to explain and I wondered if any experts out there can help - I'm totally bemused.
I have decided to get the crossovers on the 101's recapped.
Falcon will do this for me - I simply have to send the crossovers to them.
I took crossover out on 1 speaker and noted connections.
I then took bottom plate off second speaker and noted connections again - I thought I was going crazy.
On first speaker, + input from amp via red spring connector is connected to +i/p with white cable with spade connector to circuit board and -input from amp via black spring connector is connected to -i/p with black cable with spade connector to circuit board.
However not with second speaker - the spring terminals are reversed - in other words black is on right and red left!!!which means +input from amp is going to -i/p on circuit board and -input from amp is going to +i/p on circuit board - am I going crazy? I've had these speakers for over 30 years and never noticed - have they been connected incorrectly all these years from factory?
How can there be 1 set of spring terminals on 1 speaker with red on right and the other set on the other speaker with red on left? - yet circuit boards have + and - in the same position - I contacted KEF who had never come across this - can anyone help - I'm panicking because I may have been listening to music out of phase for 30 years - what do I do - do I reconnect but with pos to pos or do I reconnect as original - but + to - can't be right Confused
I have pictures but cannot work out how to put them on here - KEF are mystified
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audiolabtower
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Joined: 06 Jan 2009
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PostPosted: Tue Jul 23, 2013 2:55 pm    Post subject: Reply with quote

It's not clear from your description, has each red terminal got the white wire to + on each circuit board? In that case it would not matter if the red/black terminals are in the same position on the back?

If they are truly reversed and there is no possibility anyone else has opened them up at some time - then they must have been wrongly assembled at the factory - which seems very unlikely for the Reference series testing but I suppose anything is possible. I seem to remember the 101 had 4mm sockets on the back? maybe the plate was put in upside down on the cabinet, and the crossover wired without checking the outside?

As for the listening I once listened to my tri-amped system for several days with one power amp away for servicing using a Quad 405 for the bass below 400Hz with a vaguely uncomfortable feeling before remembering the 405 was inverting when the other system amps were non-inverting. I would have thought that 101s would be too bass light or bright if one was out of phase, but so much depends on room and positioning.
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mr quackers
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PostPosted: Tue Jul 23, 2013 4:15 pm    Post subject: Reply with quote

Thank you for your reply.
I just wish I could post the photos - they clearly show the white cable going to the pos in one speaker and the white cable going to negative on the other.
These 101's are the earlier version with the spring clip terminals - it's impossible to assemble these the wrong way round - it's the spring clip terminal assemblies which are different 1 has red on the right as you look at the back and the other has red on the left.
The input terminals on crossover board are directly in line with the spring clip terminals - hence on 1 speaker the pos input on crossover is in line with the red spring clip and has been connected but on the other the pos input on crossover is in line with the black spring clip and this has been connected in the same way as the other speaker - without realising the spring clip terminals are reversed!
If someone had noticed and followed pos to red and neg to black, the connecting wires would have crossed over - they are not - they are straight connections the same as the other speaker - KEF are mystified.
I myself have never noticed this in 30 years - I don't know what to do - how can the spring clip terminals be red on right on one and red on left on the other - how can KEF allow a speaker to leave factory like this - Obviously I'm not imagining this because I physically have the spring clip terminals as proof!!
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speakerguru
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Joined: 18 Nov 2005
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Location: Green Hut, Tovil

PostPosted: Sun Jul 28, 2013 9:56 pm    Post subject: Reply with quote

Sounds like someone boobed. Either the clip assembly was wrong from the start or it was put in upside down and wired wrong. If you have owned them from new then I guess no previous owner has been messing. I have no idea how it would get through the production phase test.

How to move forward; check the phasing of the units before the XO with a 1.5V battery cell, check the two XO boards are the same and wire up accordingly. Start listening with the systems in phase and enjoy the bass. The past is gone...
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mr quackers
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Joined: 20 Jun 2013
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PostPosted: Mon Jul 29, 2013 2:16 pm    Post subject: Reply with quote

Thank you for message Speakerguru.
It is physically impossible to fit the spring loaded terminals block upside down - it is the terminal assemblies which are different - one has the red on the right as you look at the back of speaker (which I believe is correct) and the other has the red on the left!
It is this red on the left which was connected to negative on crossover board so when positive from amp was connected to red terminal it was actually connected to negative on crossover board - I thought the bass was a bit light when I first bought them in 1981 and the stereo image was to one side and the sound sort of 'scewed' when I moved my head - I have re-connected pos to pos and I'm blown away with the bass response - and the image is so well defined you can almost touch the singer - it's like having a new pair of speakers.
Would it be a good idea, however to check with battery as you suggest - if so how? because feed from drivers is terminated by a multi pin plug which plugs into crossover board (this can only be plugged in one way, incidentally).
Thank you for your help. (I still don't understand how they could go past quality control - I have original documentation with signature of quality controller)
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audiolabtower
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PostPosted: Mon Jul 29, 2013 4:17 pm    Post subject: Reply with quote

mr quackers wrote:
blown away with the bass response - and the image is so well defined you can almost touch the singer


A great description of the way they should sound Wink
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speakerguru
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Location: Green Hut, Tovil

PostPosted: Mon Jul 29, 2013 4:46 pm    Post subject: Reply with quote

mr quackers wrote:

Would it be a good idea, however to check with battery as you suggest - if so how?

Only by removing the woofer from the front and unsoldering. Then check the wiring to the XO is the same both sides while you're at it.
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