KEF B200 in 2-way with lower x-over - 1.5K to 2K

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#21
< DId these vary a lot in T/S specs over the years? Vas, Fs, Qes and Qts are wildly different between all the linked references.

There were a number of different versions
SP1014, 1022 Utilised in the following systems: Cantor(1971), Chorale(1970), KEFKIT1(1974)
SP1039 Utilised in the following systems: 103(1976), 104(1973), 104aB(1976)
SP1047 (1974) Used in: KEFKIT 1(1974)
SP1054 1976 Used in: Calinda(1976)
SP1063 1976 Used in: Caprice(1977), Corelli(1976), C40(1979),
C65(1979)

SP1014 – constructors, small magnet, Chorale
SP1022 – Qts .41, large magnet, OK in 2cu.ft, 50ltr BR
SP1022 delights in stretching 1.8 cu ft (50 L) to 2.0 cu ft!
SP1039 – med. Q, large magnet 104, 104aB, Monitor Audio MA4, 103 Ref. Best
SP1054 – Qts .23
SP1063 – med. Q, small magnet

The SP1014 is the most common and should be the design goal. Don't know how much each version differed between samples....
 
#24
I also have a pair of B200 SP1014. Had them for years. A few months back I measured them to see if I could do anything interesting with them. I used my Clio with the known volume method.

Reults:
MANUFACTURER: KEF MODEL: B200 SP1014 driver 2
Fs 37.35 Hz Re 6.80 Ω Sd 232.0000 cm²
Qms 5.76 Qes 0.83 Qts 0.72
Cms 0.8357 mm/N Mms 21.7238 g Rms 0.88 Ωm
Bl 6.48 N/A dBspl 88.00 VAS 62.8081 L
Zmin 7.12 Ω L1kHz 0.63 mH L10kHz 0.33 mH

MANUFACTURER: KEF MODEL: B200 SP1014 driver 2
Fs 32.96 Hz Re 6.90 Ω Sd 232.0000 cm²
Qms 6.45 Qes 0.76 Qts 0.68
Cms 0.9787 mm/N Mms 23.8244 g Rms 0.76 Ωm
Bl 6.69 N/A dBspl 87.41 VAS 73.5605 L
Zmin 7.07 Ω L1kHz 0.67 mH L10kHz 0.32 mH

Before measuring I run the drivers @15hz full excurasion for about 48 hours. This actually dropped Fs about 6-7Hz and Ts from 0.8 to 0.7. So it seems that this is a necessary step for old drivers like these.

The values I got line up nicely with those that I downloaded from Sixmoons (long time ago, the page doen not exist anymore)

http://www.sixmoons.com/audioreview.../roadtour5.html* Manufacturer: KEF
  • Model: B200 SP1014
  • Piston Diameter = 172.0 mm
  • f(s)= 37.68 Hz
  • R(e)= 7.52 Ohms
  • Z(max)= 59.42 Ohms
  • Q(ms)= 5.965
  • Q(es)= 0.864
  • Q(ts)= 0.755
  • V(as)= 56.650 liters (2.001 cubic feet)
  • L(e)= 1.20 mH
  • n(0)= 0.33 %
  • SPL= 87.34 1W/1m
  • M(ms)= 23.89 grams
  • C(ms)= 0.75 mm/N
  • BL= 7.02

Hope this is useful.
Erik
 
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#26
Too little information. It would be nice to have polars for the tweeter in the designated waveguide as well as for the woofer, along with impedance information.

If that's not an option it may be simpler for you to adjust the existing crossover using quick measurements as you go.
 
#27
andyjevans said:
Still nobody has attempted a crossover!!
Click to expand...
Happy new year!!
The frd used for the simulation of the b200 is the one measured in Arta posted on the French website.
The baffle size I used for the simulation is the one you posted in the other thread. The cabinet volume is 25L (heavy fill).
Tweeter is the SB26adc (no waveguide of course).

1704068221427.png

1704068602614.png
 
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#29
Some lateral thinking while waiting for the opportunity to finish my enclosure (other pressing projects). What if the upper range was not covered by a conventional tweeter but by a full-range unit? I've been reading about these, for instance (there may be others too)....
Scanspeak 10F ---- 85db typical
Fostex FF85WK ---- 86.5db
Peerless TG9FD ---- 84db

Sensitivity would take a hit, but the B200 has a quoted sensitivity of 85db - seems low to me for an 8" but would match.

What would be the pros and cons of this versus a conventional tweeter? I also believe Planet10 might have some input here.
 
#30
andyjevans said:
What if the upper range was not covered by a conventional tweeter but by a full-range unit?
Click to expand...

Exactly what i was thinking when i saw the title in my notices.

Ideally you want the woofer a bit more sensitive than th ewoofer and XO at or near baffle step.

Of the 3 mentioned i prefer the FF85wk but there are a few simple mods that that emeliroate the rough edges.

There are 2 Scans, a FR and a MR. The former is good, the later lacks any real top. The TG9 is a massive step up from the well known TC9, but not in the same league as the other 2.

Another consideration would be the Alpair 5.2/3 (or the bargin CHN-50 is not far behind for really cheap).

This is how i will end up using my B200s, if a separate cabinet i can play on the top.

dave
 
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#37
@audiouli
Hi Uli, yes it is the sp2014 version. I traced the curve measured in Arta and published on the french site (link @ post #10). Unfortunately, I do not have the project anymore as i fotgot to backup some files in the last win 11 installation and I also lost my drivers database... :headbash:
Tchuess
 
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