What passive filter type?

[substrate]

hey guys ...

i'm just wondering what type of passive crossover you guys usually build for your system. Bessel, butterworth, chebyshev, elliptic?

I'm pretty versed with filters being a 4th year EE. I was going to go with Butterworth.

I found a neat little program you guys might like:
http://www.filter-solutions.com/


FYI, here is the system:

MTMW config,
AurumCantus G2 Ribons (2500Hz +)
2 x PHL 1240 Midrange (250Hz to 2500Hz)
Lambda Acoustics TD12X (20Hz to 250Hz)


Oh ... and what are everyone's thoughts on series vs. parallel crossover networks? Parallel seems easier to design .. do series offer any benefits?

[Svante]

Originally posted by substrate
hey guys ...

I'm pretty versed with filters being a 4th year EE. I was going to go with Butterworth.

Filter design is simple in the theory, but a bit harder in practice. The reason for this is that the filter is a good place to compensate for the non-perfect driver response, baffle step etc. Also, for passive filters, the impedance of drivers (being not purely resistive) mess things up. So you will need a good simulator to get everything right.

Anyway, your question was about butterworth, bessel etc. If you design odd-order filters as butterworth and even-order filters as Linkwitz-Riley (square butterworth, 6dB down at crossover) the sum of the two branches will have the magnitude 1. Almost all other configurations will not. Then, given the above, you might not want the sum magnitude to be 1.

Originally posted by substrate

Oh ... and what are everyone's thoughts on series vs. parallel crossover networks? Parallel seems easier to design .. do series offer any benefits?

There was a thread about this here just a few days ago, try to look that up!

[sreten]

Just note the full engineering way of doing it is aiming
for realisation of acoustic, not electrical filter targets.

For example a tweeter with a 2nd order electrical
filter will have a fourth order high pass function.

sreten.

[Svante]

Originally posted by sreten
Just note the full engineering way of doing it is aiming
for realisation of acoustic, not electrical filter targets.

For example a tweeter with a 2nd order electrical
filter will have a fourth order high pass function.

sreten.

Right, and using the upper cutoff of a bandpass box as part of the crossover. The responses of the speakers have far more effect than can be expected at a first look, partly due to the phase shifts of the response.