Some time ago I purchased rather cheaply a KEF centre speaker with a Uni-Q driver which had a dead tweeter. As a bonus I got two iQ3 boxes, minus the drivers, just the boxes and the xovers inside.
My search for Uni-Q drivers did not produce a positive outcome, the Oz distributor had no parts available, eBay offered overpriced and in uncertain state options. So more or less a dead end.
Enter the SB Acoustics coax range.
It turned out SB Acoustics are producing a number of coax drivers and one of them looked a good match, its cutout and overall diameter are a very good match for the existing speaker holes, have very suitable T/S parameters, good sensitivity and so on.
The model is SB16PFCR25-04.
Ordered through the local distributor, WES Components, and six weeks later the drivers arrived.
In the meantime I stripped the boxes from their vinyl wrap, sanded and spray painted white.
Covered the internal walls with soft felt.
Fitted the drivers, needed to drill two extra holes in the drivers' frame to accommodate KEF's front arrangement and oh, magic, everything fits.
As a first step decided to use the original xovers and see how that performs. Next steps will be to try SB's suggested xover, and them my favorite - a 1st order Series.
But that will be later.
As a customary habit I always measure drivers T/S parameters and also always run an impedance plot before proceeding to further tests.
What struck me is how smooth the drivers impedance is, I only tested the woof part, and how smooth the overall speaker impedance is with the original xover.
My search for Uni-Q drivers did not produce a positive outcome, the Oz distributor had no parts available, eBay offered overpriced and in uncertain state options. So more or less a dead end.
Enter the SB Acoustics coax range.
It turned out SB Acoustics are producing a number of coax drivers and one of them looked a good match, its cutout and overall diameter are a very good match for the existing speaker holes, have very suitable T/S parameters, good sensitivity and so on.
The model is SB16PFCR25-04.
Ordered through the local distributor, WES Components, and six weeks later the drivers arrived.
In the meantime I stripped the boxes from their vinyl wrap, sanded and spray painted white.
Covered the internal walls with soft felt.
Fitted the drivers, needed to drill two extra holes in the drivers' frame to accommodate KEF's front arrangement and oh, magic, everything fits.
As a first step decided to use the original xovers and see how that performs. Next steps will be to try SB's suggested xover, and them my favorite - a 1st order Series.
But that will be later.
As a customary habit I always measure drivers T/S parameters and also always run an impedance plot before proceeding to further tests.
What struck me is how smooth the drivers impedance is, I only tested the woof part, and how smooth the overall speaker impedance is with the original xover.
Attachments
A quick update:
Assembled the second speaker (I work rather slowly as my garden and vineyard are a priority at daytime).
Again run an impedance test, including one with aperiodic loading. The green is the normal vented arrangement, the black is the aperiodic. I think these drivers are very impressive.
A brief listening session using all sorts of material that I'm very familiar with - a bit of Dead Can Dance, Patricia Barber, Besh-O-Drom, Roels Dieltiens' Vivaldi Cello Sonatas, Dhafer Youssef Electric Sufi, David Bowie Lazarus and some other stuff.
It's obvious that the XO is not ideal, at least not to my taste, but I can live with it for some time.
What is even more obvious is that the drivers are very capable. The sense of space, depth, timing is all there.
The bass, ah the bass, you won't believe it's coming from 6" drivers. And so firm, punchy, well controlled. Feels like these drivers will be the ultimate cheap replacement for dead Uni-Q drivers.
The system in my listening room is Pass B1 pre, feeding ACA 1.8 and occasionally ACA Mini which I am refurbishing at the moment. I usually run the big OB Speakers at the back (93dB) and the volume control stays roughly in the middle.
With the SB16/KEF boxes the volume control is at the end of the run and with some material I can hear some struggle here and there.
Will need to move the boxes to the lounge room with the big Yamaha receiver and looks like they might be great for TV and movies. Time will tell.
Assembled the second speaker (I work rather slowly as my garden and vineyard are a priority at daytime).
Again run an impedance test, including one with aperiodic loading. The green is the normal vented arrangement, the black is the aperiodic. I think these drivers are very impressive.
A brief listening session using all sorts of material that I'm very familiar with - a bit of Dead Can Dance, Patricia Barber, Besh-O-Drom, Roels Dieltiens' Vivaldi Cello Sonatas, Dhafer Youssef Electric Sufi, David Bowie Lazarus and some other stuff.
It's obvious that the XO is not ideal, at least not to my taste, but I can live with it for some time.
What is even more obvious is that the drivers are very capable. The sense of space, depth, timing is all there.
The bass, ah the bass, you won't believe it's coming from 6" drivers. And so firm, punchy, well controlled. Feels like these drivers will be the ultimate cheap replacement for dead Uni-Q drivers.
The system in my listening room is Pass B1 pre, feeding ACA 1.8 and occasionally ACA Mini which I am refurbishing at the moment. I usually run the big OB Speakers at the back (93dB) and the volume control stays roughly in the middle.
With the SB16/KEF boxes the volume control is at the end of the run and with some material I can hear some struggle here and there.
Will need to move the boxes to the lounge room with the big Yamaha receiver and looks like they might be great for TV and movies. Time will tell.
Attachments
That is great Jim.
Unfortunately I haven't got the skills and the tools to do what you've done, but this is brilliant.
I've used the small SB14 to convert an old Vifa P11 to a coax with some degree of success but not to the elegance of your solution. Well done.
BTW, SB14 is the tweeter in most of SBA's coax offerings, so definitely worth trying it as a replacement for KEFs.
Unfortunately I haven't got the skills and the tools to do what you've done, but this is brilliant.
I've used the small SB14 to convert an old Vifa P11 to a coax with some degree of success but not to the elegance of your solution. Well done.
BTW, SB14 is the tweeter in most of SBA's coax offerings, so definitely worth trying it as a replacement for KEFs.