# More Savable Test Signals in the Generator



## mojave (Dec 30, 2006)

I currently use JRiver as my playback software. JRiver has a high quality parametric EQ that can be easily used with the filters generated by REW. However, the only way to currently test the filters with REW is to use the RTA feature and a Pink PN file. This doesn't give impulse response or other info from a regular measurement. The OmniMic measuring program provides all of its tones on a disc and allows one to do measured sweeps, etc. through any playback chain. Is it possible for REW to generate other tones that we can use to measure impulse response or can this be added?


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## Mitchco (Apr 12, 2011)

Here is how I measured, using REW, the before and after frequency response of the Audiolense created DRC filters, hosted in a convolution engine.

I have a Lynx L22 sound card that has both DAC and ADC using a native ASIO driver, and loopback capabilities: http://www.lynxstudio.com/lstreamloopback.html

I hosted convolverVST in a standalone app: http://www.hermannseib.com/english/savihost.htm and load the DRC filters in the convolverVST. 

Through the Lynx L22 loopback capabilities, I am able to compare DRC and no DRC. I am not saying this is the way to do it, but for me it was the easiest at the time. So…

Using a laptop, with REW loaded, I have the line out going to the analog line input of the Lynx card in my HTPC. Using the Lynx mixer, I am able to loopback the REW swept sine wave signal through the standalone hosted convolverVST and route it out to the mains, through the speakers and take the measurement of the filters on the 2nd PC (i.e. laptop).
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Then through the Lynx mixer, I can route the signal straight through and bypass the loopback. Here is the result of doing both before and after DRC. Before DRC is in purple, after is in blue:










I could come up with a diagram of the setup if that would help?

Why did I use a 2nd computer to measure with REW? I think it is an exclusive mode issue. If JRiver and/or REW uses ASIO in exclusive mode, then I can’t get at the Lynx ASIO driver in the standalone convolverVST as the ASIO driver is “locked out” by the other application.

I don’t know if running both REW and JRiver on the same computer, with exclusive mode, will let the Lynx ASIO driver be available to the two apps at the same time... seems unlikely.

It could very well be that I am doing it wrong 

Ideally, I would like to have REW send the swept sine way through JRiver's audio engine (with it's new and wonderful 64 bit Convolution engine!) with the mic hooked up to the ADC of the Lynx mixer and have REW capture the response (on the same computer). Then it is a click of a check box in JRiver to bypass the Convolution engine and can easily measure a before and after DRC response.

Hope that helps.


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## mojave (Dec 30, 2006)

Mitchco, have you tried the RTA method I posted about at JRiver. You thanked me for it in the convolution thread, but I didn't know if you had tried it yet.

If we could run a REW sweep through the JRiver DSP it would be a lot easier.


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## JohnM (Apr 11, 2006)

mojave said:


> Is it possible for REW to generate other tones that we can use to measure impulse response or can this be added?


It is on the list of things to do, but I'm not sure when I'll get to it, sorry.


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## Mitchco (Apr 12, 2011)

mojave said:


> Mitchco, have you tried the RTA method I posted about at JRiver. You thanked me for it in the convolution thread, but I didn't know if you had tried it yet.
> 
> If we could run a REW sweep through the JRiver DSP it would be a lot easier.


Aloha mojave! Initially, I thought your method was using the swept sine wave and then upon closer look realized it was with PN. I have the same concerns as hulkss here: http://yabb.jriver.com/interact/index.php?topic=69312.msg469867#msg469867

Next time I measure, I will try this method as well, but what I am really looking for is the impulse response, ETC, waterfalls, etc. features of REW.

For sure, if we could run the swept sine wave through JRiver DSP would be amazing!


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## mojave (Dec 30, 2006)

JohnM said:


> It is on the list of things to do, but I'm not sure when I'll get to it, sorry.


Is there a way JRiver could incorporate a sweep generator into their program that works with REW? This would allow those that use the Parametric EQ or JRiver's new convolution engine (with auto lip sync) to measure the results with REW. I'm sure the developers would work with you and this would alleviate you from implementing something in REW.


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## mojave (Dec 30, 2006)

In JRiver 17 build 17.0.19 they provided a WASAPI Loopback feature that allows one to route REW's output (and any external program) through JRiver. This is still experimental, but hopefully it stays. To use you must set your default soundcard to a different device than the one used by JRiver. You need to use the JAVA driver in REW and setup output to Default Device. In JRiver you activate the loopback by clicking File > Open URL and entering live://loopback. JRiver will now capture and route through its DSP chain whatever output was sent to the default device.

This means that one can use the Parametric EQ in JRiver with the filters generated by REW or use the convolution engine in JRiver and measure the actual response with REW!


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## mojave (Dec 30, 2006)

John, it sounds like from this thread that you are making this a priority. Would you be willing to allow JRiver to incorporate your test signals into their program for easier integration with REW? Thanks.


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