SpeakerTalk

[cantata]

Dear KEF fans,

I am going to reactivate my beloved KEF loudspeakers which have been suffering in a 35l closed box, sounding strangled (the bad side of beeing married). They are
B139B SP1044
B110 SP1003 and
Audax HD12x9D25 (the T52s have been killed during a party 20 years ago).
They should go into a transmissionline housing similar to A.O.S. Studio 100 TL with reduced midrange volume (5 l closed instead of about 20 l vented).
As crossover I want to use (if no better idea available) a rebuilt version of the KEF DN19/20 (of course, with devices of better quality).
And here is my problem:
I did not find an original circuit diagram for the DN19/20 within the net. Even on this excellent page only a picture of the CANTATA crossover can be found, which seems to be similar (identical?). In this picture two resistors are mentioned (R5 and R10). Does that mean 5 Ohm and 10 Ohm (should have been labelled as 5R0 and 10R0 or so)?
From my stoneage DIYs I have a homemade crossover which is similar in architecture, but has some different device values (e.g. 22uF instead of 7uF in the tweeter circuit and 2.8 mH instead of 4 mH in the midrange part, see attachment).
I dont have any documentation from this time (I was a young student... ).
Simulating the circuits (using eSketch) does not help, both magnitude spectra look not so nice, crossover frequencies are quite similar (300+3000Hz).
Most of the KEF crossovers have a scary architecture (looks like trial and error, but might be better than classical Butterworth without regarding the special response of the speakers.
Any idea what to do?
Any diagram available?

Thanks in advance
Thomas from Ulm/Germany
[img]c:/Temp/KEF_Cantata_DN19-20.jpg[/img]

[ColinR]

As you're new I'll be gentle with you .

Nobody else, apart from those who want to make money out of such information has been inclined to measure and draw out the crossover schematics for KEF designs in their collections, so you just have mine http://www.hifiloudspeakers.info/Anatomy/Crossovers/Cantata/CantataCrossoverIndex.html .

If you don't like R5 or R10 and prefer 5R and 10R, tough, I'm not redrawing the Cantata schematic and inserting the missing bass resistor with my copy of CorelDRAW 8 any time soon.

For a rebuild make a copy of the Radford S90 http://www.t-linespeakers.org/classics/radford.html and put the midrange and treble in a mirrored configuration .

Finally as you're going to use an Audax unit you need the CS7 schematic http://www.hifiloudspeakers.info/Anatomy/KEFDocuments/KEFConstructorSeries/KEFCS7Leaflet/Gallery/pages/KEFCS7-3.htm and use an attenuated 4.7uF, 0.6mH, 4.7uF Bessel filter .
_________________
This post or any other information supplied to this website or any other by myself is not available for any form of commercial purpose i.e. to hi-fi magazines or as sales and marketing material for sleezeBay or Audiodogging pimps and the like.

[cantata]

Dear Colin,

thanks for the info. Be sure, my intention is not to earn money but just waste a huge amount of Euros for an interesting project.
By carefully searching this site I was able to lift the secret about my homemade crossover. Its a CS7 design (can be found on this site, thanks to Steve).
Architecture is similar to DN19/20, but crossover frequency and devices vary. I will test my new speakers with both versions, my ears should decide. Hopefully the new DN19/20 with high-end devices (expensive MKP-caps and air/I-core coils) will win.
The woodwork is close to be finished. If anybody shows interest, I am willing to spread schematic, building description and pics.

Stay tuned
Thomas