diyAudio

diyAudio (http://www.diyaudio.com/forums/)
-   PC Based (http://www.diyaudio.com/forums/pc-based/)
-   -   EASY FIR crossover PC based+DRC (http://www.diyaudio.com/forums/pc-based/223805-easy-fir-crossover-pc-based-drc.html)

thierry38efd 18th November 2012 12:05 AM

FIR crossover for J River or VSThost
 
an esay way to build a simple FIR crossover PC based.
for j river or other VSThost

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 :(

http://imageshack.us/a/img607/4669/hpf100048.png


phase linearization

measure 1M before (3 ways,120 hZ,3500 Hz )
http://imageshack.us/a/img337/4747/mesuresupport1m.jpg

after linearization

http://imageshack.us/a/img69/3745/mesureapres.jpg

IR's before/after

http://imageshack.us/a/img585/6495/i...sansetavec.jpg

final equalization with rePhase and JBL target curve import in HOLM

http://img208.imageshack.us/img208/6349/jblvsmesure.jpg


synoptic

http://imageshack.us/a/img267/346/chainagevst.jpg



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

boris81 18th November 2012 12:27 AM

It looks great!
Can you (or somebody else) please write a step-by-step tutorial?
I tried setting it up before but I wasn't able to get it working.

boris81 18th November 2012 12:31 AM

By the way is non-linear phase audible to you?
What does it sound like?

thierry38efd 18th November 2012 12:35 AM

yes,i'm gonna give more details

for my little ears,i do not found difference between linear phase and minimum phase,but it's free to do,so let's do it !

i've spend some time to make it working but now it's very simple to build

today,it's late in France.:sleep:
tomorrow

boris81 18th November 2012 01:15 AM

Enjoy your rest!
You deserved it :D

CopperTop 18th November 2012 01:38 AM

I've downloaded it, and look forward to playing with it. Thanks.

The phase thing in general is very interesting, and something I don't yet feel I entirely understand.

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?

Thanks!

thierry38efd 18th November 2012 08:52 AM

Quote:

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?
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 )

http://imageshack.us/a/img543/3723/phaseecole.jpg

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.

1- use the filters linearization tab
insert the theoritical phase shift
-bass reflex or closed box
-electrical cutoff

2- use the PPEQ to refine the curve

http://img842.imageshack.us/img842/5550/rephase.jpg

thierry38efd 18th November 2012 11:07 AM

to create FIR crossover

VSThost+Vst convolver+asio4all
see the links before this post

http://img641.imageshack.us/img641/9236/vst01.jpg

setting asio4all

http://img195.imageshack.us/img195/7618/vst03.jpg

click on the tool tab for advanced config
click on blue tab to active input and output as shown below

http://img211.imageshack.us/img211/6048/vst05.jpg

configure asio input and output selection

http://img839.imageshack.us/img839/9748/vst06.jpg

http://img842.imageshack.us/img842/8851/vst07.jpg

configure output engine and input engine

http://img819.imageshack.us/img819/1691/vst04.jpg

http://img194.imageshack.us/img194/7828/vst08.jpg

http://img22.imageshack.us/img22/3207/vst09.jpg

it's up to eachother to choose wich channel gonna be used
i'm using 1+2 for LPF (front left+front right )
5+6 for HPF (rear left+rear right)

a sound card can be added to reach 2x8 channel,for tri or more multiway systems.

this setting takes less than 2 minutes once driver installed.

now,VST host is ready to work
next step generate IR from rephase
and insert IR in the convolver

later,i'll explain how to easily add a second convolution for DRC+phase correction.

thierry38efd 18th November 2012 01:21 PM

open rePhase

tab linear filter

create an Impulse response you need (kind of filter,frequency,slopes)

adjust the graphic Y axis at -150 dB.(to see eventual ripple)
choose the same number of taps for each IR.

low pass IR (+bass boost if you need with GEQ section )

http://img840.imageshack.us/img840/1841/lpfg.jpg

and another one HPF IR

http://img441.imageshack.us/img441/8615/hpfn.jpg

open wordpad and write:

http://img842.imageshack.us/img842/7...ssover2way.jpg]

save with a name you're choosing
FIRcrossover.txt

explanation (same on VST convolver site)
Config examples
Config file

http://img607.imageshack.us/img607/2415/textconfig.jpg

open VSTconvolver
and select the file .txt you've writed

http://img59.imageshack.us/img59/304...gconvolver.jpg

result

http://img534.imageshack.us/img534/9236/resultfig.jpg


configure all your media player output--->virtual cable

same with HOLM,REW or ARTA
you can check the result with a cable looping back to line in

use multiple instance of VST convolver is difficult.
for DRC and phase correction,
use SIR V1.011 freeware to insert a second (or more ) convolution
i'll will explain the way to do it

it's important to use the same number of taps for each IR in the cross over,delay will be different otherwise
to reduce delay of processing,increase the partition (paralelling process ) less delay,more load processor

http://img593.imageshack.us/img593/3629/lastgh.jpg

thierry38efd 18th November 2012 02:01 PM

it seems to be heavy,but it takes less than 10 minutes to configure

after,let's play with rePhase and differents setting of crossover
( a DX46 FIR commercial crossover cost 2000$,with a max of 512 taps ).

with a basic PC,you get a powerfull Xover+DRC,a full phase linear system,without external hardware.

only power amps connected to sound card.

i've try on a basic laptop,10 stereo convolutions (8000 taps )
load processor is about 23 %

with the desktop,the final config:
1 stereo convolution for DRC and phase correction (8000 taps )
2 stereo convolution for crossover 2 ways (8000 taps )

processor load 5%

example for 3 ways stereo config

crossover6w.txt

http://img341.imageshack.us/img341/9995/configtxt6v.jpg

10 ms delay on HPF filter
-6 dB on the bandpas filter (coeff .5 )

http://img443.imageshack.us/img443/4162/6voiesvst.jpg


All times are GMT. The time now is 12:16 PM.


vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2014 DragonByte Technologies Ltd.
Copyright 1999-2014 diyAudio


Content Relevant URLs by vBSEO 3.3.2