SpeakerTalk

[andrelly]

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?

[proffski]

[andrelly]

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. the right has more extended highs and more transparent mids..... 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???

[Parts]

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.

[andrelly]

Could PCB flex be part of the reason? Seems that it is now overloaded with large components, and the foam would squeeze it somewhere...

[speakerguru]

Unless you enjoy working in the dark 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 .

[andrelly]

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? I was thinking of replacing them with fibre stuffings but had a second thought due to this...

[speakerguru]

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.

[andrelly]

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....
Initial impression: speakers 'disappear' more and has blacker and more defined sound...

[andrelly]

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 Only thing is the red/blue/green/yellow/white/black cables from the head unit that may complicate things...any inputs and/or ideas???

[Parts]

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.

[andrelly]

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?

[andrelly]

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!