2nd order LR series xover formulae

[PeteMcK]

I notice that Rod Elliot gives different formulae for series & parallel 2nd order xover values, but doesn't explain why, and he only gives the formula for Butterworth:

http://sound.westhost.com/parallel-series.htm
(section 2.0)

Does anyone have the correct formula for 2nd Order Linkwitz Riley series xover values?

cheers,
Pete McK

[PeteMcK]

found them on Art Ludwig's page:

http://www.silcom.com/~aludwig/Sysde...ove_Design.htm

now, to attempt to combine 1st order LP with 2nd order HP, series topology.......

Pete McK

[jcake5]

Pete,

the following should also help.


http://members.aol.com/_ht_a/klehma/radioseries.html

Regards,
Eric

[PeteMcK]

thanks Eric
Pete McK

[PeteMcK]

Can anyone point me to the formula for calculating Zeta for a 2nd order series crossover????

Found the 1st order formula st John Kreskovsky's site.
From the searching I've done, most seem to have put 2nd order series xovers into the too hard basket?
Most calculators will do 1st order but not 2nd.

Cheers,
Pete McK

[rmcferon]

Have you tried the source? Linkwitz Lab

[SamL]

If you are looking for series crossover, you must visit these 2 site.

Andy_G site.
http://users.tpg.com.au/users/gradds...oss-overs1.htm

as well as Tony Gee site.
http://www.humblehomemadehifi.com/Crossover.html


Have fun,
Sam

[PeteMcK]

Thanks for the responses guys.
I've checked those sites, but they don't have exactly what I'm looking for; Guess I'll have to visit a library and check out some engineering tomes....

Pete McK

[Andy G]

Originally posted by PeteMcK

From the searching I've done, most seem to have put 2nd order series xovers into the too hard basket?

Cheers,
Pete McK

Not so much too hard, just not much point.

A series x-o is for "combining" drivers, not for controlling and separating them.

If you need to use a 2nd order series x-o, then use the one discussed on this page..... it gives the necessary control while still combining the drivers quite well.
http://users.tpg.com.au/users/gradds...ss-overs9b.htm

If your drivers need more control than a 1st order series of a 2nd order AR series offers, then you should be using a parallel x-o, not a series x-o.

[AndrewT]

Hi,
I am jumping in without my wings, since I haven't read Art's article.

L-R requires even pole filters and a Q=0.5 for the phase response to match across the crossover region.

I don't think that L-R can be achieved by mixing single and two pole filters.

If going active, this is easily achieved by cascading a pair of Butterworth Q=1/root2 filters giving the required Q=0.5 and cascading ensures that even order poles are met. Passive is a whole other ballgame. Pay special attention to errors resulting from non resistive loads on the crossover and non zero source impedance (less of a problem).