Can anyone identify this crossover design?

mrbubbs · 12th May 2007, 04:28 PM

Hello,

A friend has a pair of McIntosh ML-1C speakers. He is trying to convert them from 4-way to 3-way, perhaps Linkwitz-Riley, I think. We're not sure what order/design is being used in the crossover in the image attached. Can anyone help identify what design is being used? Thanks!

sreten · 12th May 2007, 05:05 PM

Hi,

The electrical design of a crossover is not the required acoustic design.

ML-1C Loudspeaker system, 4-way bookshelf system has :
12" woofer, 8"lower mid, 1-1/2" soft dome upper mid and 2-1/4" tweeter.
Crossover frequencies: 250 Hz, 1.5kHz and 7kHz
Impedance: 8 ohms
Output: 89dB @1w/1m
Power rating: 100w
Size: 26"H, 15"W and 13-1/2"D
Weight: 64lbs.
Sold from: 1970 to 1975
Last retail price: $399.00 each

W is 1st order electrical low pass with zobel
LM is 1st order electrical low and high pass
UM is 1st order lelectrical low pass and 2nd order electrical high pass
T is 2nd order electrical high pass

note the acoustic slopes are not known,
the c/o points above should be acoustic, not electrical.

/sreten.

mrbubbs · 12th May 2007, 06:51 PM

Thanks, sreten! I admittedly don't know a lot about crossovers. I have been doing more with single-driver designs. Your point about electrical versus acoustical turned what little I thought I knew about crossover design into confusion, but I have a few books on order and will read more about it.

Thanks again!

Dave Bullet · 12th May 2007, 09:12 PM

At its most basic - all drivers exhibit their own rolloff at the top / bottom of their operating ranges. This natural rolloff - combined with any electrical crossover slope gives the acoustic rolloff.

For example. Take a theoretical midrange driver that is already rolling off at 200Hz down to 100Hz at a rate of 6dB (first order being one octave between 200Hz and 100Hz). Put a 1st order highpass crossover on the midrange (so it can crossover to the woofer) - you will end up with a 2nd order acoustic slope (more or less). The 6dB of electrical slope combines with the drivers natural 6dB fall from 200Hz to 100Hz to give a 2nd order (12dB) slope.

Cheers,
David.

mrbubbs · 13th May 2007, 04:39 AM

Hey, Dave...

That makes sense now. Thanks for the explanation!

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12th May 2007, 05:05 PM	#2
sreten diyAudio Member Join Date: Nov 2003 Location: Brighton UK	Hi, The electrical design of a crossover is not the required acoustic design. ML-1C Loudspeaker system, 4-way bookshelf system has : 12" woofer, 8"lower mid, 1-1/2" soft dome upper mid and 2-1/4" tweeter. Crossover frequencies: 250 Hz, 1.5kHz and 7kHz Impedance: 8 ohms Output: 89dB @1w/1m Power rating: 100w Size: 26"H, 15"W and 13-1/2"D Weight: 64lbs. Sold from: 1970 to 1975 Last retail price: $399.00 each W is 1st order electrical low pass with zobel LM is 1st order electrical low and high pass UM is 1st order lelectrical low pass and 2nd order electrical high pass T is 2nd order electrical high pass note the acoustic slopes are not known, the c/o points above should be acoustic, not electrical. /sreten.

12th May 2007, 06:51 PM	#3
mrbubbs diyAudio Member Join Date: Nov 2006	Thanks, sreten! I admittedly don't know a lot about crossovers. I have been doing more with single-driver designs. Your point about electrical versus acoustical turned what little I thought I knew about crossover design into confusion, but I have a few books on order and will read more about it. Thanks again!

12th May 2007, 09:12 PM	#4
Dave Bullet diyAudio Member Join Date: Jan 2002 Location: Wellington, New Zealand	At its most basic - all drivers exhibit their own rolloff at the top / bottom of their operating ranges. This natural rolloff - combined with any electrical crossover slope gives the acoustic rolloff. For example. Take a theoretical midrange driver that is already rolling off at 200Hz down to 100Hz at a rate of 6dB (first order being one octave between 200Hz and 100Hz). Put a 1st order highpass crossover on the midrange (so it can crossover to the woofer) - you will end up with a 2nd order acoustic slope (more or less). The 6dB of electrical slope combines with the drivers natural 6dB fall from 200Hz to 100Hz to give a 2nd order (12dB) slope. Cheers, David.

13th May 2007, 04:39 AM	#5
mrbubbs diyAudio Member Join Date: Nov 2006	Hey, Dave... That makes sense now. Thanks for the explanation!

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