There are many, many Kef B200s in the UK and elsewhere. Mostly SP1014. Both used driver units and 2-way speakers from Kef, Tangent, Monitor Audio etc. All going pretty cheap. Crossovers on these models were always between 3K and 3.5K, which was the style at the time. But several posts have suggested crossing the B200 over lower, like 1.5K to 2K with a more modern tweeter, maybe in a waveguide. Here's the data below, so what do you think?
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A waveguide is going to suit a higher crossover frequency than a dome, and of course not many domes go low. A waveguide becomes a better choice especially as woofers get larger, provided you choose a good one and the right frequency to cross it.
Why not? You have to equalize the mountain between 500Hz en 2 kHz anyway, which may lead to a somewhat more complex LCR contraption than the original DN 13 (?) lowpass.
X/o frequency depends on the tweeter, but any half decent Peerless, SB or Dayton 25-28 mm dome with an Fo of say 700-800 Hz could be used at 1800-2000 Hz with an acoustic Linkwitz-Riley 4e order.
Do you happen to have an impedance file ( .zma) of the B200?
Do you happen to have an impedance file ( .zma) of the B200?
I have only the basic information on the B200 I'm afraid. If we can work out a 1.8 - 2K crossover we'll make many Kef fans happy! And they can start modifying all their old Kef speakers with lower crossover points and tweeters that go low. Most of the originals had 19mm tweeters like the T27.
I have a pair of SP1014 but they are unmounted and I don't have any measuring equipment. Some more data attached
Further data on this French site including impedance curves -
http://www.mes-enceintes-acoustiques.com/2017/12/kef-b200-sp1014.html
Further data on this French site including impedance curves -
http://www.mes-enceintes-acoustiques.com/2017/12/kef-b200-sp1014.html
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Took a look at the measurements on the French site. Issue is that measuring conditions are not entirely clear: I could not find baffle size en measuring mic distance. With 10 dB/div and 1/6 octave smoothing the measurements are somewhat flattering because of the low resolution. Some pictures hint at near field (only?).
Surely DIYA members must have in-box B200 measurements somewhere?
Surely DIYA members must have in-box B200 measurements somewhere?
Given the constraints.. The driver diameter is around 1/2 of a 15" driver, so for a waveguide, cross around twice the frequency that people typically mention for 15s (being a common example). Below this the driver is going to behave pistonically, you can just EQ it after the fact if that's in line with the intended method.
Elsewhere for sure. I have 16 in totes upstairs. Cost $200 CAD.
The most memorable implementation was the IMF TLS50 (you could use a good 3” FR as a midTweeter to emulate that XO point). Next the Tangent TM-1. KEF never seemed to get it quite right.
The B200 starts to get cloudier and cloudier, ie less detail as they go up in frequency.
Lower XO would be beneficial as you would be suppressing the worst of that. They will still have a “character” that you want to match with the companion.
i’ll be interested in what you guys come up with.
dave
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Many of these 70ties x/o are more based on trial and error than systematic design: it is not wise to scale these for a lower x/o point.
What is needed:
1) In-box measurements of B200: near field until 200Hz and than farfield from 200 Hz upward, combined/merged in 1 full range file plus B200 in-box impedance measurement.
2) idem tweeter, but then without the nearfield measurement
3) a measurement file with both drivers in-box parallel and unfiltered, in order to establish their respective acoustic centres.
What is needed:
1) In-box measurements of B200: near field until 200Hz and than farfield from 200 Hz upward, combined/merged in 1 full range file plus B200 in-box impedance measurement.
2) idem tweeter, but then without the nearfield measurement
3) a measurement file with both drivers in-box parallel and unfiltered, in order to establish their respective acoustic centres.
Boden - can you do anything with the information on the French site?
http://www.mes-enceintes-acoustiques.com/2017/12/kef-b200-sp1014.html
http://www.mes-enceintes-acoustiques.com/2017/12/kef-b200-sp1014.html
This morning I already e-mailed the French gentleman....
But the problem of measuring conditions and guestimating the relative acoustic centres remains.
But the problem of measuring conditions and guestimating the relative acoustic centres remains.
TM-2? We were likely the largest Tangent dealer in Canada, likely North America. Never saw or heard of the TM-2.
Thanx.
The TM-3 XO drawing is my work.
dave
Isn't that picture the 3-way Tangent TM-2? Not a 2-way but it has the B200 crossed over to the T27
