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KEF 105.4 Crossover schematic?

 
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henryk
Introductory Contributor


Joined: 07 Apr 2004
Posts: 4

PostPosted: Wed Apr 07, 2004 10:20 pm    Post subject: KEF 105.4 Crossover schematic? Reply with quote

Kudos...What a wonderful site!

I have been on the hunt for the schematic diagram for the crossover in the KEF 105.4. Can anyone help me out?

I would also be interested if anyone has modified/upgraded these units with repect to the cross over design, component upgrades, internal wiring and the disabling of the protection circuit "s stop"

Henry
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Parts
Senior Contributor 100+


Joined: 13 Jan 2006
Posts: 174
Location: Edinburgh

PostPosted: Sun Jan 15, 2006 3:43 pm    Post subject: Kef R105.4 Reply with quote

Hello,

Did this guy ever get the info he was after ?
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ColinR
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Joined: 31 Jul 2004
Posts: 1175
Location: Staffordshire

PostPosted: Sun Jan 15, 2006 4:25 pm    Post subject: Reply with quote

Mr Klein probably never did, as the distribution of original crossover schematics, speakers, crossovers and LCR meters across members is not particularly good.

I've only ever received three contributions in terms of schematics from members.

As most of my recent pictures and schematics have been for the inactive "non-KEF speakers systems" part of the site, I've stopped contributing.
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henryk
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Joined: 07 Apr 2004
Posts: 4

PostPosted: Mon Jan 16, 2006 4:01 pm    Post subject: Reply with quote

Colin is correct, however I am still monitoring this site just in case...
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Parts
Senior Contributor 100+


Joined: 13 Jan 2006
Posts: 174
Location: Edinburgh

PostPosted: Mon Jan 16, 2006 8:24 pm    Post subject: Kef 105.4 Reply with quote

Hi ,

I have some stuff in my loft with regards to the 105.4 , If I cannot find the schematics I can still get info with regards to the crossover, as there's a pair on a shelf.
I have not bothered replacing parts on these crossovers, but have removed the S-stop, and rewired Kef R105.4 also done simple bass cab mods to these.

The easiest thing to do is replace the terminals, depending on your connector preference.
If using bannana plugs then DNM amp bannana sockets are superb, simply have an alloy plate cut to size with a couple of holes in the same location as the original, bolt the DNM sockets to the alloy panel, widen the original terminal holes and this panel can be screwed over them.
You can do the same thing to the heads, with DNM on a shaped alloy panel or an XLR connector, if removing the S-stop this terminal can cover the hole left by the dial. The slot for the pin connector is easily sealed.

Rewiring is the other option, I have used Audioquest and Chord, I prefer chord though. An easier option would be Multi core Van Damme.
I have used a four core bi-wire cable to the heads with a common negative connection with three pin XLR, and four core to four bannana sockets on a panel. My favorite was DNM sockets on bass cabs and heads, with chord Rumour bi-wire used as single runs from terminal to crossover to bass drivers, and one run of Bi-wire to the heads for mid and treble, with rumour single for inside the heads.
You have to remember when rewiring the bass drivers to connect a negative and positive of each driver together, with one drivers negative and the others positive connected to the crossover.

Removing the S-stop, I simply traced the mid and treble wires back to the main crossover and disconnected the rest.
I had heard that the 105.4 was meant to split some of the mid to upper bass at high levels, but I didnt confirm this and found no problems with the way I did the wiring.

The bass cabs, I paint all the inside edges with wood glue, two coats. And make sure the brace gets a good coating. I also added a two thin sheets of bitumen per section, not enough to affect volume too much but adding mass and some dampening.
The wheels have to be removed, and on one set I poured cement into the base and fitted a 1" birch ply panel over the bottom and fitted spikes.

One pair had a damaged mid dust cap, these b110's I removed the dust caps and dampening from, I fitted slightly larger dust caps and recoated these.
I then replaced the T33 faceplates with the modern ones.

These mods brought huge improvements in my set up.

Regards
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henryk
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Joined: 07 Apr 2004
Posts: 4

PostPosted: Fri Jan 20, 2006 7:32 pm    Post subject: Reply with quote

Thankyou for your response Parts. Some very interesting work in particular the concrete in the base mod.

I have done some rewiring which amounted to simply replacing the orginal factory wire with some flat ribon Rotel speaker wire some years ago. This simple upgrade certainly had a positive affect. However I was begining to worry that the capacitors in the crossover have now aged significantly and could stand replacing. Unfortunately the orginal values are almost impossible to read the last time I had the crossover board out of the cabinet. A schematic would help however I was also told at one point that KEF revised some the of the values of various components in the crossovers during the production run of the 105.4. Unfortunately I don't know why the change was made, if it was made. The componet value change may have been based on possible physical changes to the units in general or electrical characteristic of the speaker elements themselves, or just an overall engineering tweak. I would hate to to put all the effort in and potentially ruin what I consider to be a fine speaker given its age.
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Parts
Senior Contributor 100+


Joined: 13 Jan 2006
Posts: 174
Location: Edinburgh

PostPosted: Fri Jan 20, 2006 8:09 pm    Post subject: Reply with quote

If the serial numbers are close then so may the crossovers ?

I cant remember the last time I looked at mine , I was planning to rebuild them in spring .
My main cabs and heads are a little worse for ware.
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henryk
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Joined: 07 Apr 2004
Posts: 4

PostPosted: Fri Jan 20, 2006 8:28 pm    Post subject: Reply with quote

No hurry, but when your in the mood this spring I would be interested in following/discussing your upgrade or even getting a copy of the schematic if your lucky enough to locate it.
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