Possible to check effect of Acourate filter with REW?

2519 Views 8 Replies 3 Participants Last post by 3ll3d00d, May 31, 2014

vpnogueira

Discussion Starter · May 25, 2014

Hello,

I am using REW v5.01 Beta 20 in windows 8.1. I use Acourate to generate FIR filters that are then used in the JRiver convolver.

Is it possible to measure the room response already corrected by the Acourate filter? I would like to measure it (keeping mic, etc, fixed) so I can compare the measurements without and with filter.

Thanks!

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EarlK

· #2 · May 26, 2014

vpnogueira said:
Hello,

I am using REW v5.01 Beta 20 in windows 8.1. I use Acourate to generate FIR filters that are then used in the JRiver convolver.

Is it possible to measure the room response already corrected by the Acourate filter? I would like to measure it (keeping mic, etc, fixed) so I can compare the measurements without and with filter.

Thanks!

Yes it's possible to run REW through Media Center to test the efficacy of your filters ( using your Accourate generated filters to convolve the REW test signal ) .

How to do this is best asked at their forum .

:sn:

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3ll3d00d

· #3 · May 26, 2014

Yes you can do this, exactly how depends on what hardware and software you have. For example I use asio line in with a virtual loopback in my mixer to route audio from Acourate to jriver, i then use jriver peq to move the signal to different channels.

You can also do this in Acourate alone by supplying a correction filter to the log sweep recorder.

If you ask over at interact then you will get some answers for sure (or search first, there are a number of such threads).

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vpnogueira

Discussion Starter · #4 · May 28, 2014 (Edited)

I received an email from Acourate yesterday mentioning that I could just put the filter in the Acourate logsweep recorder, like you said.

However, I would prefer to measure the sound already affected by the filter, running Jriver, using another software like REW, to take Acourate out of the loop (except for the filter).

I suppose in order to check just the frequency response I could play a pink noise file at JRiver with the filter in the convolver and use the RTA function of REW, but I wanted to find out a method to perform the regular REW measurement to see the impulse response, waterfall, etc.

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3ll3d00d

· #5 · May 28, 2014

vpnogueira said:
I received an email from Acourate yesterday mentioning that I could just put the filter in the Acourate logsweep recorder, like you said.

However, I would prefer to measure the sound already affected by the filter, running Jriver, using another software like REW, to take Acourate out of the loop (except for the filter).

I suppose in order to check just the frequency response I could play a pink noise file at JRiver with the filter in the convolver and use the RTA function of REW, but I wanted to find out a method to perform the regular REW measurement to see the impulse response, waterfall, etc.

This post - http://yabb.jriver.com/interact/index.php?topic=86792.msg594719#msg594719 - has my setup for routing rew output through JRiver. You need to post your setup to get a specific recommendation on how to do it.

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vpnogueira

Discussion Starter · #6 · May 29, 2014 (Edited)

My setup:

CAPS Zuma (windows 2012, JRiver using Acourate filter in the convolver, ASIO) -> Playback designs MPS-5 -> pair of Krell 750mcx -> speakers

Measurement equipment:

Macmini (with windows 8.1 and REW 5.01 beta20) <-> Roland quad-capture (with loopback in second channel for timing) -> line out to preamp
<- Earthworks M30

Anything else you need to know?

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3ll3d00d

· #7 · May 29, 2014 (Edited)

vpnogueira said:
My setup:

CAPS Zuma (windows 2012, JRiver using Acourate filter in the convolver, ASIO) -> Playback designs MPS-5 -> pair of Krell 750mcx -> speakers

Measurement equipment:

Macmini (with windows 8.1 and REW 5.01 beta20) <-> Roland quad-capture (with loopback in second channel for timing) -> line out to preamp
<- Earthworks M30

Anything else you need to know?

is it right that your measurement setup is completely separate to your playback chain? I don't understand how you're intending to get REW to playback through jriver in this case as REW doesn't have any external signal generator AIUI. To do this, you need REW to be able to route a signal through jriver. I'm not sure what "line out to preamp" refers to exactly but, if you don't have REW on the CAPS box, then you would need that line out to go to a line in on the CAPS and then route that into jriver.

Alternatively if you connected the quad capture to the CAPS then a quick read of the manual suggests you should be able to use asio line in much like I do. This means you would configure REW to accept input from the mic as usual but output would be to some asio output channel. For the sake of argument lets say you picked output 5. You would then open Asio Line In with channel offset = 3 and open it for 1 channel input. Note jriver uses a 0 based index so if your asio device has channels 1,2,3,4 then jriver sees 0,1,2,3 therefore saying offset = 3 basically tells jriver "read asio channel 4 as channel 1". Assuming this opens ok then open the dsp studio in jriver, turn off any other dsp modules, look at the analyser screen and send a sweep through it. You should see the trace go through the L channel. Once you see this then you can switch convolution back on and away you go.

I am assuming you are only using 2 output channels here hence have 2 spare on the roland. Google says your amps are monoblocks so I guess this is true.

A couple of foibles....

I've noticed that this setup produces 2 channel playback at times so I have to add a PEQ module to mute the L or R channel. I don't know why this is & I haven't investigated it further.

I've never found a way to provide a loopback timing reference in this setup, you would need to route that through convolution too otherwise the discrepancy in the delays between the 2 signals (I think) causes REW to get confused about the measurements (it sees the timing signal, sees no measurement signal due to the delay, errors about low measurement levels). If you need this function then I use holmimpulse & it's time lock feature for that.

If this doesn't give you enough info to get going then I think interact is a better place to ask as there are more people with more experience on this subject there.

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vpnogueira

Discussion Starter · #8 · May 30, 2014 (Edited)

Matt,

Thank you. You are clearly an expert.

I am using a separate system for measurement because I try to keep the Zuma for playback purposes only, using Windows Server 2012 with audiophile optimizer.

Based on what you said it seems I should install REW in the Caps Zuma so it would be easier to run the REW output through Jriver.

I didn't quite understand how can I have a timing reference, but I will try at Interact.

Thanks

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3ll3d00d

· #9 · May 31, 2014 (Edited)

vpnogueira said:
Matt,

Thank you. You are clearly an expert.

I am using a separate system for measurement because I try to keep the Zuma for playback purposes only, using Windows Server 2012 with audiophile optimizer.

Based on what you said it seems I should install REW in the Caps Zuma so it would be easier to run the REW output through Jriver.

I didn't quite understand how can I have a timing reference, but I will try at Interact.

Thanks

no problem. I think a timing reference is hard with convolution in play, I think you need to find a way to route that signal through the same convolution filter. I thought it weeks be possible to open 2 channels of asio line in, use the 2nd one for the timing reference and then route the output of that channel back into rew using my mixer app. It didn't seem to work though. Hence it's easier just to use holmimpulse for this tbh (which works well enough).

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