EASY FIR crossover PC based+DRC

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thierry38

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Joined 2006
an esay way to build a simple FIR crossover PC based.

using the free software rePhase to generate differents impulses.

rePhase | Free Audio & Video software downloads at SourceForge.net

very steep slopes (till 1000 dB/oct) can be created.
FIR equalization.
FIR crossover.
system phase correction
65535 taps IR lenght

VSThost+VSTconvolver(+SIR v1.011 for DRC and phase correction )
asio4all,a virtual audio cable is needed if internal source is used.


HPF filter,sound card output (example )
noise floor is high,laptop internal sound card :(

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phase linearization

measure 1M before (3 ways,120 hZ,3500 Hz )
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after linearization

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IR's before/after

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final equalization with rePhase and JBL target curve import in HOLM

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synoptic

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to use VSTconvolver:
ConvolverVST

to make a simple config file
Config file

examples of config file

Config examples

i'll show more accurately how to configure the chain
 
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thierry38

Member
Joined 2006
In the second illustration down, the phase goes through several 'wraps' of 360 degrees. This might be explained by a constant delay caused by, say, the distance between driver and mic, with the true phase shift of the speaker riding up and down on top of the linearly descending line, presumably(?). If we somehow infer what the constant delay is and remove it, and yet the phase still goes through several 'wraps', can we still linearise it? Am I really talking about 'minimum phase' vs. 'excess phase'? (two terms whose meanings I don't think I fully understand yet). Programs like REW allow you to export what they call a minimum phase version of the impulse response. How do they separate the minimum from excess phase, and does your program implicitly do the same thing, Thierry?
Click to expand...

Hi,
yes,we can linearize all phase shift,with fine work,phase can be limited to +-20° on the 20 Hz-20 Khz band.
this is not my software,my knowledge do not allow this powerfull tool
i hope the author comes to give some clear explanation.:)

the second screenshot shows the phase shift of the loudspeaker at 1M
this is the minimum phase.(combination of electrical phase shift+acoustic phase shift ).

micro is calibrated spl+phase
the measurement shows,in this case (3 ways )

An externally hosted image should be here but it was not working when we last tested it.


for helping,to correct phase shift,detect the 0° of the phase shift (in reality this is multiple of 360°)

-35 Hz bass reflex tunning
-120 Hz analog active crossover
-3500 Hz passive crossover

with rePhse,the idea is to create a inverse phase shift,generate an IR,apply it to the signal before amp...and it's working...at 1 M.

at the listening point,reflexions of room cause more severals phases shift.

-at 1 M phase shift is about 550°
-listening point,phase shift if above 5000°

i'll show how to use,easily,rePhase to get a loudspeaker linear phase.
 
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