Passive X-Over design help..

[Workhorse]

Hi Masters,

I want to construct a 2-Way Passive 24dB/octave Linkwitz-Riley Crossover with crossover frequency point at 2KHZ...

Could anyone provide Links, equations for calculating the Values of Inductors and Capacitors...along with design Tips....

regards,
K a n w a r

[rabbitz]

Have a look at these sites.

http://www.bcae1.com/
See sect 91. for a calculator.

http://www.passivecrossovers.com/
Have a read here as it supplies plenty of detail.

The main thing is not to use the nominal impedance but the actual impedance of the driver at the xo frequency.

[Cal Weldon]

Kanwar,

Try this site also. It's a calculator.

http://www.mhsoft.nl/spk_calc.asp

[Etacovda]

Originally posted by rabbitz
Have a look at these sites.

http://www.bcae1.com/
See sect 91. for a calculator.

http://www.passivecrossovers.com/
Have a read here as it supplies plenty of detail.

The main thing is not to use the nominal impedance but the actual impedance of the driver at the xo frequency.

ahhh, this could explain my rather erractic c/o sound...

OT (but on topic, at the same time) - if im using a vifa driver, i should look at the impedance graph supplied by them at the crossover frequency for my crossover impedance point? Its around 14ohms on the spec's, from the passive XO calc i used it said to measure the driver using a multimeter, i stupidly thought that it just meant the standard impedance w/o load (ie, not connected to anything), which was 5.8ohms... so it should be closer to 14? oh dear, that'll explain a fair bit about how my speakers sound, lol.

[Workhorse]

ThanX very Much to everyone for providing me the valuable informative links...

ThanX once again...
K a n w a r

[rabbitz]

Originally posted by Etacovda


ahhh, this could explain my rather erractic c/o sound...

OT (but on topic, at the same time) - if im using a vifa driver, i should look at the impedance graph supplied by them at the crossover frequency for my crossover impedance point? Its around 14ohms on the spec's, from the passive XO calc i used it said to measure the driver using a multimeter, i stupidly thought that it just meant the standard impedance w/o load (ie, not connected to anything), which was 5.8ohms... so it should be closer to 14? oh dear, that'll explain a fair bit about how my speakers sound, lol.

Forget about nominal impedance or voice coil Re as you need the actual impedance at the crossover frequency.

Ideally it needs to be measured but that requires some equipment and the next best choice is to use the manufacturer's data sheets. That will get you reasonably close and heaps better than the nominal or Re.

For a 2nd order LR low pass,
A nominal calculation will be about 40% out
A Re calculation will be about 60% out
So what you have is too low on the inductor and too high on the cap.

[Workhorse]

Hi rabbitz

Then what you suggest....better....

K a n w a r

[rabbitz]

What I'm saying is use the actual impedance at the crossover frequency and throw the nominal and Re in the bin (OK keep the Re for any Zobels calcs).

If you use the nominal, the crossover is going to be out of whack and will not be an effective filter.

Measured impedance is best, but data sheet's impedance plot is good and will be miles closer than the nominal as you can see from my previous post.

Cheers

[Etacovda]

Hi Rabbitz - ive sent you an email asking a few very quick questions to avoid hijacking Workhorses' thread too much. I will continue to watch this thread, though
Cheers

[Workhorse]

Thanks... rabbitz


K a n w a r