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[CraigNZ]

Is it possible to select an audio channel (for example left channel) and define a 2 way or 3 way crossover for output to 2 or 3 amplifiers.  I would want to set the crossover frequency, Low Pass Filter or High Pass Filter or both, and the type of rolloff, eg LR24.  Would also like to set the phase and delay time.

I have a 5.1 system but the LEFT and RIGHT front speakers are bi-amped.  Currently what I do is take the audio channels and pass them through an external crossover box (Behringer Super-X Pro CX2310) but it has a lot of limitations that a DSP crossover would do much better at.

So instead of assigning a single output audio channel to a audio stream channel, we would now assign a DSP crossover to the audio stream channel and then assign the two or three outputs from the crossover to multiple output channels.

[Matt]

MC is quite good for this type of task.  It can runs any number of channels and any number of filters.  Everything is done with 64-bit precision.

To start, you might explore 'Parametric Equalizer' in DSP Studio.

[natehansen66]

I use MC for a 3-way active crossover and it's flawless once you figure it out. Like Matt said, dig into the PEQ. "Mix Channels" will be your friend. Let us know if you need help with that. I have a post somewhere that I think JimH added to the Wiki with a how to for mixing channels for an active crossover but I can't find it.

[CraigNZ]

Thanks guys, good to know it can be done, now to figure it out.  The mixing is what I could not see so will look at that closer.  Maybe what we need is a tutorial on setting up a 5.1 system with bi amp'd mains.  If this does not exist I'll make notes and add one.  Using DSP crossovers is amazing what it does for the sound.

[CraigNZ]

Where do assign a source channel to a windows output channel?  For example, I have an Echo Audiofire 12 DAC which appears as 6 soundcards in windows.  If the LEFT source channel is bi-amp'd, how do I assign the high pass filter output (tweeter) to the second channel on the 3rd soundcard and the low pass filter output (woofer) to the first channel?  This assumes the third soundcard outputs will be cabled to the two amplifiers.

[Jamesey]

On this topic, can we also get a proper display of what the Parametric EQ does to the frequency response? I know we can play pink noise and observe the output, but that line bobs up and down. A line like what computer parametric eq's show would be much more useful.

[JustinM]

Where do assign a source channel to a windows output channel?  For example, I have an Echo Audiofire 12 DAC which appears as 6 soundcards in windows.  If the LEFT source channel is bi-amp'd, how do I assign the high pass filter output (tweeter) to the second channel on the 3rd soundcard and the low pass filter output (woofer) to the first channel?  This assumes the third soundcard outputs will be cabled to the two amplifiers.

In my setup, (2-way stereo) J-river does not label the output chanels the same as windows. So it may take some trial and error to figure out... For example my dac has channel ouputs 1,2,3,4.
from memory my
chnl 1 = left
chnl 2 = right
chnl 3 = surround Left
chnl 4 = surround Right

In PEQ: I first copy the Left & Right channels to the surround channels, then apply my x-overs ...
Hope this helps ...

[natehansen66]

If no one else does in the meantime, when I get home I'll post a tutorial that shows how to mix channels for an active crossover (if I don't forget!). I also use an Audiofire 12 so I'll be able to tell you the channel assignments.

[CraigNZ]

The AF12 can be configured in one of two modes: Stereo, Surround.  In Stereo configuration the 12 channels appear in windows as 6 stereo sound cards.  In Surround configuration the 12 channels are divided into two soundcards, one sound card has 8 channels and the other sound card has 4 channels.

One possible configuration is to use the 4 channel sound card for the bi-amp'd LEFT and RIGHT main speakers and then use the other sound card for the surround channels.

If doing a 3 way system then then 8 channel sound card would be used since the LEFT and RIGHT speakers wold require 6 audio channels.

[mojave]

When using ASIO output, the mode configuration and Windows settings don't matter. You should just be able to choose 12 channels in JRiver use it as a 12 channel soundcard. Natehansen66 will show you how.

[natehansen66]

OK, here's a reply I had for someone on another forum asking how to setup MC for an active speaker system:

The main thing in doing a crossover with J River is getting the channels routed properly. Go to the DSP Studio-Output Format. Select the number of channels that you need from the drop-down menu on the right. It sounds like you're doing 2-ways so 4 channels will work. Make sure "Mixing" is set to no up mixing or down mixing.

One thing you need to understand, is that the different sub-menus of the DSP Studio that are listed on the left can be moved up and down in order (except for Output Format and Volume Leveling, these are locked). This is important because these are processed in order from top to bottom. If it isn't already third from the top, move the Parametric Equalizer up under Volume Leveling. Then in the PEQ click Commands/Add/Mix Channels. This will allow you to tell JR which channel goes where, because until you tell it otherwise it only sends the signal to L & R. After you click "Mix Channels" choose Left for the "Source", and Center for the "Destination." For "Mode" select Copy. This will copy the Left signal to the Center channel. Now click "Commands" and add another mix channel filter, you'll see another one added to the list of filters. For this one choose Right for the "Source" and Subwoofer for the "Destination." Now you have 2 channels with a left signal and 2 with a right. I'd use the Left channel for your tweeter and the Center channel for your woofer. Your Right channel would then be your other tweeter and the Sub channel would be for your other woofer.

From there you can use whatever filters you like from the Commands button to do your eq/crossover, making sure you assign the filters to the correct channel. The filter list works like the DSP Studio sub menus in that it works in order from top down. You can drag filters up and down in the list. Make sure that any eq/crossover filters are below the channel mix filters in the list. Any filters you put ahead of the channel mix filters will be done globally to the L & R channels, which will affect all 4 channels.

Use ASIO, and set the AF12 to "Surround" in its settings.

The routing is as follows:

MC   AF12
Left         1
Right       2
Center     3
Sub         4
SL           7
SR           8
RL           5
RR           6
User 1      9
User 2      10

I've never tried to use the 11th and 12th channels..........

Edit: I was whining about the Wiki? A search for "Parametric Equalizer" brings up a link to the thread with all this info 

[CraigNZ]

Works perfectly!  Thanks heaps.

I ended up leaving the surround channels as is and 'copied' LEFT and RIGHT channels to 9 and 10.  I will put HPF outputs as LEFT and RIGHT and LPF outputs as 9 and 10.

I tested the configuration using the JRiver test tones and monitoring the AF12 front indicators.

[CraigNZ]

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.

I would also recommend that we setup a DSP section on the forum because I can see this is going to become a very popular topic and very advanced.  It would be convenient to have all the DSP related topics in one area.

[natehansen66]

You can do a dual channel measurement in REW to account for the latency of the measurement system if you want to look at phase. I can go into detail later if you'd like.

[natehansen66]

Do you have a measurement mic? Looking at how the filters work at the electrical level is good, but you need to see how they interact with the acoustic output of the drivers to do it right. Unless you've got flat response on either side of the xover freq for several octaves you'll never hit a theoretical transfer function without measurement.

[mwillems]

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.

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]

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.

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?

[mwillems]

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?

I also bi-amp and bass routing can be tricky, here are two solutions:

1) If you apply the LPF to 1 and 2 and the HPF to 9 and 10 (instead of the way you're currently doing it), channels 1 and 2 will have the bass for room correction to re-route.

2)  I don't use room correction for stereo bass routing, I just copy the left channel to the sub and then add a copy of the right channel to the sub channel and apply an appropriate LPF to the sub channel when I'm done.  

Also, I suspect the reason that you can't access channels 7 and 8 in JRiver is that 2.1 output format only outputs six channels (three of them silent).  If you want access to the seventh and eight channels in JRiver, you'll need to use an output format like "stereo in a 7.1 container" or similar.  

[sorepinky]

It is unclear how to apply the DSP Studio "Linkwitz-Riley filter".  It does not seem to present the necessary input fields.  Like whether you are applying the LP side of it or the HP side, or the slope of it.  Although LR24 is common, there is also LR48.  All it gives you is a frequency.  It seems to operate as an HP, but keying in certain numbers causes an apparent crash of the audio engine and then media server must be restarted.

[mwillems]

It is unclear how to apply the DSP Studio "Linkwitz-Riley filter".  It does not seem to present the necessary input fields.  Like whether you are applying the LP side of it or the HP side, or the slope of it.  Although LR24 is common, there is also LR48.  All it gives you is a frequency.  It seems to operate as an HP, but keying in certain numbers causes an apparent crash of the audio engine and then media server must be restarted.

The standalone Linkwitz-Riley filter isn't fully implemented; my advice is to cascade two butterworth filters of the appropriate order instead. The plain high pass and low pass filters are butterworths, so, for example, stacking two butterworth 12 low passes at the same frequency makes an LR24 low pass, two butterworth 24's make an LR 48, etc.

[charles0322]

Incredibly interesting thread. I am trying to wrap my head around this and will download the program to experiment with my current soundcard.

I am building a 4way stereo system and was planning to buy an Ashly Protea 4.8sp for about 1000$ to do all my routing for crossover slopes and amp sends.

I was looking around and found the Clarett 8 pre for much less than the Ashly.

I use a mac book pro with thunderbolt and really like the specs of the Clarett.

Is there any video tutorial of menus and settings for Media Center /JRiver?

Thanks!