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DSP speaker crossover

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mwillems:

--- Quote from: CraigNZ on June 20, 2013, 12:52:43 am ---Using REW I have now confirmed that cascading two LPF or HPF does indeed drop the amplitude of the signal by -6db at the crossover point, simulating a L-R 24dB filter.  Now how do I check the phase between the two channels?  In theory the L-R filter will generate a 360 degree phase difference between the two filters (LPF and HPF), but is there a way to check that using REW?  Or has someone already confirmed this on here?

My test environment is to take the output of the channel in test (on AF12) and patch it to Input 1, which REW then monitors.  This insures that REW is measuring the output of the soundcard channels rather than upstream somewhere.  For example, for LEFT channel I have HPF output going to Channel 1 and the LPF output going to Channel 9.  To look at either the LPF output or HPF output I then use a TRS patch cable and connect Input 1 to either Output 1 or Output 9.

--- End quote ---

I'll second Nate's point that there's no meaningful way to measure the phase of your system without actually taking microphone measurements.  I can confirm that the JRiver crossovers produce the anticipated phase response (360 degrees off) mathematically (or electrically), but your speaker elements will severely alter that phase response in practice.

If you have a mic, Holm impulse in combination with JRiver's loopback function gives fairly quick and easy method of gated phase measurement for bi-amped speakers, if you feel like branching out from REW. 

CraigNZ:
What I wanted to check was the electrical phasing to insure that cascading two filters did indeed result in a L-R filter, that there was no math or process error in doing so.  Measuring phase response of speakers is a whole different animal and a part of the entire room correction task.  Good to see someone has already checked this.

amdismal:
The PEQ has a L-R filter built in, you don't need to import filters and cascade them.  The 24dB/octave L-R is in there already.

natehansen66:

--- Quote from: amdismal on June 23, 2013, 01:56:14 am ---The PEQ has a L-R filter built in, you don't need to import filters and cascade them.  The 24dB/octave L-R is in there already.

--- End quote ---

Actually those are Butterworth type filters. Two 2nd order BW filters used together will create a 4th order LR type.

guido310:
Hi, i am trying to configure PEQ for a 5.1 system with fronts biamped using a Lynx AES 16 card and external DAC
I would like to have 2.1 when playng stereo, but when i configure speakers with LPF and HPF for fronts i loose all the bass frequencies that have to be routed to subwoofer
Here my config

16 channel configuration
Jrss mixing with 2.1 option check
Silent
PEQ:
Copy channel 1 (front left) to channel 9 (low end of front L)
Copy channel 2 (front right) to channel 10 (low end of front R)
LPF on channel 9 FROM 80 TO 500
LPF on channel 10 FROM 80 TO 500
HPF on channel 1 FROM 500 TO ABOVE
HPF on channel 2 FROM 500 TO ABOVE

ROOM CORRECTION TO ROUTE BASS TO SUBWOOFER FROM ALL SPEAKERS AT 80 HZ

I had to use channels 9 and 10 because if i try to copy on 7 and 8 (RL and RR i don't have) i got no sound on these channels, and if i order channel i have sound from channels 5 and 6, my surround speakers...is there a problem with AES 16 card routing??

Anyway, since now channels 1 and 2 are cut at 500 hz, i have no sound from subwoofer when plaiyng 2.1 (cut at 80 in room correction)

I had to copy again channels 1 and 2 to channels 11 and 12 before appling HPF and LPF and than tell to the Lynx mixer to play that from 1 and 2, so i have bass frequencies to route to sub when playing 2.1...but i think this is not the proper way to do that...

Any advice?

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