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How to get the most out of 105.2?
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andrelly
Intermediate Contributor 25+


Joined: 28 May 2007
Posts: 26

PostPosted: Fri Aug 24, 2007 12:19 pm    Post subject: Reply with quote

After the long delay..........the newly and massively rebuilt crossover is ready. I would want to post a pix here, but has got no idea how to do it..

BTW, what prior tests should I make on the x-over to make sure it doesn't blow the speaker drivers should there be something wrong with it? Confused Shocked
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proffski
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Joined: 22 Aug 2003
Posts: 1297
Location: Tewkesbury UK

PostPosted: Fri Aug 24, 2007 12:42 pm    Post subject: Reply with quote

andrelly wrote:
After the long delay..........the newly and massively rebuilt crossover is ready. I would want to post a pix here, but has got no idea how to do it..

BTW, what prior tests should I make on the x-over to make sure it doesn't blow the speaker drivers should there be something wrong with it? Confused Shocked


Depends what equipment you have.
If you do not then some white noise (FM radio with no station tuned will do) and then use a cheap speaker connected in turn to each output will clearly show any faults or deficiencies.

If however you have access to a signal generator, audio voltmeter, oscilloscope etc then you could do a proper analysis.
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andrelly
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Joined: 28 May 2007
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PostPosted: Mon Aug 27, 2007 8:59 am    Post subject: Reply with quote

Ok, I couldn't wait over the weekend. I hooked up the rebuilt x-over, now using Solen and Auricaps capacitors, Mills 680ohm resistor and air-cored inductors. Due to the size, x-over board now have to face to the front of the speakers, instead of the usual facing back of speakers (any differentiable effects?). Hook-up wires also changed to DH Labs. However, the connector clips on the board broke, hence to solder the wire directly to the board.
Fired up the system, sound came out from both speakers....however left and right are not balanced. Shocked the right has more extended highs and more transparent mids..... Question All drivers are emitting sound....
What to do?
So the left speaker was dismantled again to recheck the x-over. Everything seems fine. During re-connecting the coloured wires to the head unit (Green, Blue, Black, Yellow, White, Red), I noticed that when I pulled a red wire half way, the hf extension and mid transparency returned...??? Then I crimped the clips to ensure for tight fit..no change...then applied wd-40 to the metal connectors...no change.

Frustration settled in....such a long down time, expensive parts, bruised hands from assembly/dismantling..yet sound is not balanced...
The S-Stop circuit in trouble? Apparently not.....

Later found out that pulling any/some coloured wires half-way returns the extension and transparency. Letting it go returns to the initial condition???

Any ideas??? Confused
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Parts
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Joined: 13 Jan 2006
Posts: 174
Location: Edinburgh

PostPosted: Mon Aug 27, 2007 3:44 pm    Post subject: Reply with quote

Sound like either loose wires, loose connection, or maybe broken/dry solder joints or the cable may be broken inside its insulation?

RE-wire and new connectors?

You can get rid of the silly six pin plastic strip, Maplin stock plenty of locking multi pin plug and chassis combo's.

Or you can remove the S-stop and use 4pole speakon at either the hole the S-stop dial leaves, or fit a cable gland to this hole, have a flying lead from the head, and fit a 4pole speakon chassis mount to the bass cab.

Van Damme used to do plenty of multi core speaker cable suitable for the above application, I use Chord. Though Cat5 and such may be usable too.
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andrelly
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Joined: 28 May 2007
Posts: 26

PostPosted: Tue Aug 28, 2007 11:36 am    Post subject: Reply with quote

Could PCB flex be part of the reason? Seems that it is now overloaded with large components, and the foam would squeeze it somewhere... Question
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speakerguru
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Joined: 18 Nov 2005
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Location: Green Hut, Tovil

PostPosted: Tue Aug 28, 2007 12:30 pm    Post subject: Reply with quote

Unless you enjoy working in the dark Rolling Eyes why not borrow or invest in a signal generator and a meter. Then you can measure what each drive unit is getting fed to it Cool .
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andrelly
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Joined: 28 May 2007
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PostPosted: Thu Aug 30, 2007 5:37 am    Post subject: Reply with quote

Ok, maybe a cd with test tones would suffice? I can't get hold of a signal generator. What kind of readings on the meter should I be expecting?
In any case sound is coming out from the drivers, only the lack of hi-freq extension and slightly honky mid from the left channel.

BTW, the sponge (as opposed to foam in my previous post), is also acting as additional cabinet bracing coz they are so tightly fitted? Rolling Eyes I was thinking of replacing them with fibre stuffings but had a second thought due to this...
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speakerguru
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Location: Green Hut, Tovil

PostPosted: Thu Aug 30, 2007 8:10 am    Post subject: Reply with quote

You're looking for interchannel differences in voltage to each woofer, mid and tweeter in turn. If both channels are the same but they sound different then a driver is faulty. Channel swap drivers to check.
If the voltages are different, a XO is at fault. Assuming the amp is OK, the input voltage to both XOs will be the same; track through from XO input to each driver and you will find at which point the signal changes. Wiggle components and flex the board to see if that causes voltage changes. Consider getting software to use your PC as a signal generator and/or an oscilloscope.
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andrelly
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Joined: 28 May 2007
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PostPosted: Mon Sep 03, 2007 6:32 am    Post subject: Reply with quote

I manage to put a paper roll core to support the x-over that gives the proper sound. Now both sounds balanced. Hence will settle at it currently and let the x-over break in.... Got to sit-back and enjoy something after all the work and delays.... Very Happy
Initial impression: speakers 'disappear' more and has blacker and more defined sound...
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andrelly
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Joined: 28 May 2007
Posts: 26

PostPosted: Wed Oct 10, 2007 6:40 am    Post subject: Reply with quote

Update after the break in: soundstage is more solid now. Very easy to follow the instruments/vocals. mid and top-end is more refined, not splashy as before. Overall sound is smoother, more in line with the current offerings. Just heard top notch systems at an audio show last month, kharma Ceramique 3.2Fe, Thiel and Krell's new speakers, Rockport's, Isophon, Quad 989, Burmester. I loathe for the Kharma, but still found my KEF105.2 OK to live with.....

I saw the new offerings have outboard x-over. HHmmm, would that make a significant difference with the KEF?? I am tempted Rolling Eyes Only thing is the red/blue/green/yellow/white/black cables from the head unit that may complicate things...any inputs and/or ideas??? Cool
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Parts
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Joined: 13 Jan 2006
Posts: 174
Location: Edinburgh

PostPosted: Wed Oct 10, 2007 7:14 pm    Post subject: Reply with quote

Regarding te cable to the head unit, you could use one of the multi core Van Damme studio grade, or two runs of Chord or similar Bi-wire.

There are plenty of XLR and other plugs and sockets available from Maplins and the like, you could use one 4pin XLR for the drive units and one for the S-Stop, or use Neutrik Speakon etc etc.

My own 105.4 will be getting re-built withour the S-Stop, and I will be using a Speakon connector with Chord Rumour 4core to the head.
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andrelly
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Joined: 28 May 2007
Posts: 26

PostPosted: Wed Oct 29, 2008 12:25 pm    Post subject: Reply with quote

New update: saw the current KEF offerings with the head modules having a felt/mat on top of the cabinet....surely to absorb reflections...gotta try...
Also considering tobypass the S-TOP circuit...how to do it? Any pros and cons? Rolling Eyes
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andrelly
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Joined: 28 May 2007
Posts: 26

PostPosted: Wed Dec 10, 2008 7:11 am    Post subject: Reply with quote

Just installed Soundcare's (threaded) Superspike on the KEF with GREAT improvement over my non threaded spikes!! Bass tightens and sound become more vivid with better impact!
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