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Old 26th January 2012, 01:14 PM   #21
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Question SP1054

Hi everybody!
My name is Michele and I come form nord Italy.
This is my first post in this forum (i think) but i want to say that this forum is great! I've been signed since some years ago and in this place I've always found lots of intersting topics.

I need your help.
I own a pair of KEF SP1054. What do you think about its sound? And there is the crossover network of KEF Calinda speakers which mounted SP1054: Crossover for Calinda. What is this configuration? Why the 5uF cap doens't stay after the 3.29mH coil, in parallel with the woofer to make a 2nd order low pass filter?

Thankyouuuuu!

Miki
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Old 26th January 2012, 01:30 PM   #22
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The low-pass filter for the B200 in the schematic is a modified version of a 3rd-order 'T' type network, so there will be an inductor between the 5uf cap and the drive unit. The modification to the 'T' network is the added damped parallel-resonant trap in the input arm of the 'T'.
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Old 1st February 2012, 10:42 AM   #23
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Ok, that's great! Thankyou! Simulated with MultiSim and I've found a very low crossover frequency (I don't remember, maybe about 250Hz). Any other info about those speakers?
My Sp1054 are mounted in a 18l bass reflex box tuned at 45Hz. I found them good except for the weak bass, but I'm not an expert...
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Old 2nd February 2012, 07:30 AM   #24
system7 is offline system7  United Kingdom
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The original KEF Calinda was a reflex (Well, ABR) design in a 45L box.

Here are the main T-S parameters for a KEF B200 SP1054 (large magnet, low Q) 8" bextrene bass/mid:

Vas 130L
Qm 3.27
Qe 0.25
Qts 0.23
Le 0.45mH
Re 7.0R
Fs 25Hz

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Back of a beermat, I got 18L as a good size for a closed box with F3 at 75Hz. KEF recommend 20-25L. Reflex, well, this is not so good for you at 18L. You need a bigger box for any real bass. 40-50L.

The shunt first bass crossover is unusual these days, especially since series first needs a smaller inductor. The tweeter is on a standard third order butterworth by the look of it. Probably around 2.5 to 3KHz depending on the impedance of the (7 ohm?) tweeter. The LCR trap on the bass is to tame cone breakup on the B200 around 2KHz. The smaller tweaks on the tweeter probably just equalise it a bit.
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Old 2nd February 2012, 08:00 AM   #25
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Typically KEF XOed the T27 at 3.5 kHz.

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Old 2nd February 2012, 08:26 AM   #26
system7 is offline system7  United Kingdom
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Quote:
Originally Posted by planet10 View Post
Typically KEF XOed the T27 at 3.5 kHz.

dave
Quite right. KEF speakers with all their equalisation for smoothness also often had strangely huge peaks in impedance. I think the Calinda peaked at 60 ohms around 1-2 KHz. Michelino, your modded 18L unit probably has huge cone movement at low frequencies, which is not ideal.

A review I read had a huge dip in frequency response at 3Khz too. You'd think the tweeter was better wired the other way for phase alignment, but since the woofer and tweeter centres are nearly a wavelength apart at this frequency, effects would be unpredictable.

My own experience of bextrene bass/mid units is when they got hot at parties, they turned to jelly. Dull sounding too.

8" bass and 1" tweeter is just about as bad as it gets to have good midrange phase alignment and dispersion, but of course, easy to implement. Cries out for a midrange unit really!
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Old 5th February 2012, 05:26 PM   #27
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Thankyou everybody
So... I've just re-simulated the calinda xover but I've found 250Hz @ -3db ... What's wrong? See the picture http://s17.postimage.org/xyvdf8qr3/sim_calinda.jpg .

About my speakers:
The sp1054 are in an 18 liters vented box tuned @45Hz in serie with a 0.5mH coil (cutoff should be at 2.3kHz) and a Zobel network (C=6.7uF, R=15Ohm, not really optimal value).
The tweeter is a Ciare ct 200 with a 2nd order high pass at 1.8kHz ....
Ok, there is something wrong with the frenquency of low pass filter, I actually don't have a bigger inductance

My amp is a modded NAD 304 ( swapped a lot of capacitor, even signal capacitor with polypropylene caps) and at high volume I found no big excursion but it puts out "only" 35+35w.

I've got a panasonic wm-61a mic and an Emu 0204 usb soundcard. Is there any free sotfware for some spectrum measurement?
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Old 5th February 2012, 06:25 PM   #28
system7 is offline system7  United Kingdom
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Looks to me like that crossover schematic is plain wrong. Try L2 = 0.6mH in your simulation and see where -3dB goes. We're looking for about 3KHz crossover here.

I made the B200 Zobel: Capacitor C = 5.88 uF Resistor Rc = 8.75 Ohms

You knew that already.

Last edited by system7; 5th February 2012 at 06:29 PM.
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Old 6th February 2012, 02:18 AM   #29
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Quote:
system7:
Quote:
..Looks to me like that crossover schematic is plain wrong...
Agree.. FYI:

b
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File Type: jpg KEFCalinda-dubious-XO.jpg (218.2 KB, 307 views)
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Old 6th February 2012, 02:20 AM   #30
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High qts. drivers have their limitations compared to low qts. drivers. Search this forum for transmission lines and much insight can be found. IPL Acoustics has used drivers with qts. of higher then generally accepted. I have also tried higher qts. drivers. Drivers meant for base reflex have a higher F ratio [fs/Qts.] compared to closed box drivers.
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