Go Back   Home > Forums > Source & Line > PC Based

PC Based Computer music servers, crossovers, and equalization

Please consider donating to help us continue to serve you.

Ads on/off / Custom Title / More PMs / More album space / Advanced printing & mass image saving
Reply
 
Thread Tools Search this Thread
Old 17th November 2012, 11:05 PM   #1
diyAudio Member
 
Join Date: Jan 2006
Location: grenoble
Default 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

Click the image to open in full size.


phase linearization

measure 1M before (3 ways,120 hZ,3500 Hz )
Click the image to open in full size.

after linearization

Click the image to open in full size.

IR's before/after

Click the image to open in full size.

final equalization with rePhase and JBL target curve import in HOLM

Click the image to open in full size.


synoptic

Click the image to open in full size.



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

Last edited by thierry38efd; 9th December 2012 at 08:34 PM.
  Reply With Quote
Old 17th November 2012, 11:27 PM   #2
boris81 is offline boris81  United States
diyAudio Member
 
Join Date: Oct 2009
Location: white plains, ny
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.
  Reply With Quote
Old 17th November 2012, 11:31 PM   #3
boris81 is offline boris81  United States
diyAudio Member
 
Join Date: Oct 2009
Location: white plains, ny
By the way is non-linear phase audible to you?
What does it sound like?
  Reply With Quote
Old 17th November 2012, 11:35 PM   #4
diyAudio Member
 
Join Date: Jan 2006
Location: grenoble
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.
tomorrow

Last edited by thierry38efd; 17th November 2012 at 11:38 PM.
  Reply With Quote
Old 18th November 2012, 12:15 AM   #5
boris81 is offline boris81  United States
diyAudio Member
 
Join Date: Oct 2009
Location: white plains, ny
Enjoy your rest!
You deserved it
  Reply With Quote
Old 18th November 2012, 12:38 AM   #6
diyAudio Member
 
Join Date: Feb 2009
Location: UK
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!

Last edited by CopperTop; 18th November 2012 at 12:46 AM.
  Reply With Quote
Old 18th November 2012, 07:52 AM   #7
diyAudio Member
 
Join Date: Jan 2006
Location: grenoble
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 )

Click the image to open in full size.

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

Click the image to open in full size.

Last edited by thierry38efd; 18th November 2012 at 08:06 AM.
  Reply With Quote
Old 18th November 2012, 10:07 AM   #8
diyAudio Member
 
Join Date: Jan 2006
Location: grenoble
to create FIR crossover

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

Click the image to open in full size.

setting asio4all

Click the image to open in full size.

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

Click the image to open in full size.

configure asio input and output selection

Click the image to open in full size.

Click the image to open in full size.

configure output engine and input engine

Click the image to open in full size.

Click the image to open in full size.

Click the image to open in full size.

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.

Last edited by thierry38efd; 18th November 2012 at 10:14 AM.
  Reply With Quote
Old 18th November 2012, 12:21 PM   #9
diyAudio Member
 
Join Date: Jan 2006
Location: grenoble
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 )

Click the image to open in full size.

and another one HPF IR

Click the image to open in full size.

open wordpad and write:

Click the image to open in full size.]

save with a name you're choosing
FIRcrossover.txt

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

Click the image to open in full size.

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

Click the image to open in full size.

result

Click the image to open in full size.


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

Click the image to open in full size.

Last edited by thierry38efd; 18th November 2012 at 12:39 PM.
  Reply With Quote
Old 18th November 2012, 01:01 PM   #10
diyAudio Member
 
Join Date: Jan 2006
Location: grenoble
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

Click the image to open in full size.

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

Click the image to open in full size.

Last edited by thierry38efd; 18th November 2012 at 01:30 PM.
  Reply With Quote

Reply


Hide this!Advertise here!
Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Similar Threads
Thread Thread Starter Forum Replies Last Post
iDFT-based XOs (FIR) steph_tsf Digital Line Level 15 5th November 2013 10:59 PM
AVX based FIR VST, crossover / EQ / DRC and delay KOON3876 PC Based 97 26th November 2012 07:18 AM
Is there any PC based software to crossover the L & R channels to the sub? spot PC Based 11 29th November 2011 11:46 AM
Looking for a New PC based Loudspeaker Crossover - What is available? mikaljones21 PC Based 9 28th June 2010 02:53 PM
Linux XO/DRC Fanless PC w. Lynxtwo jon_denmark Digital Source 6 20th July 2007 06:54 AM


New To Site? Need Help?

All times are GMT. The time now is 08:32 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