Impulse Response App, iMM6, & Roon Convolution

[Chris Barker]

I have installed AudioTool and loaded the CAL file for the iMM6 microphone when plugged into a Pixel 4a phone.

I am looking for a simple way to measure speakers and apply those measurements in Roon Music Software using it's DSP engine.

Ideally, I would like to capture an Impulse Response file since Roon will load an IR file and apply it to your speaker with a Convolution filter.

I bought the Impulse Response app that seemed to offer the feature I was looking for. I want to measure the speaker with IR and create a file to load into Roon. I did just that.

But, when playing back music with the loaded IR file, there is distortion which cannot be correct?

I have several questions.

What went wrong with my IR file and why is there distortion?

The IR file is limited to 44k. Roon will have to extrapolate this file when playing higher sample rate files. Is there a way to generate IR files with higher sample rates?

If the IR file is not possible, how do I generate the required settings for applying a manual PEQ values which Roon can also do.

Is there interest by the AudioTools team to work on a simple way to measure speakers using a cell phone with a iMM6 mic and send those settings to Roon?

Roon has a very powerful DSP but is barely used by most users (1%) because most do not know how to use or how it could improve their playback.

I would like to make a YouTube Video on my DIY HiFi Life channel that shows a simple and uncomplicated way to do this.

Thanks.

[Julian Bunn]

Hi Chris,

Answer/comments below:

On Mon, Mar 1, 2021 at 8:24 PM Chris Barker <ctbar...@gmail.com> wrote:

I have installed AudioTool and loaded the CAL file for the iMM6 microphone when plugged into a Pixel 4a phone.

I am looking for a simple way to measure speakers and apply those measurements in Roon Music Software using it's DSP engine.

Ideally, I would like to capture an Impulse Response file since Roon will load an IR file and apply it to your speaker with a Convolution filter.

I bought the Impulse Response app that seemed to offer the feature I was looking for. I want to measure the speaker with IR and create a file to load into Roon. I did just that.

But, when playing back music with the loaded IR file, there is distortion which cannot be correct?

I have several questions.

What went wrong with my IR file and why is there distortion?

I am not at all familiar with Roon, so I don't know what it is doing with the IR file you measured using Impulse Response. It may be that the data are not in the format they expect or support, but then one would expect to see an error message when loading the file.

It's also not clear to me what Roon is doing. If you measure the IR of your speaker, and then apply it to sound being played by that same speaker, aren't you magnifying the non-flat response, rather than eliminating it, which is what I suppose you want? Or does Roon invert the IR before applying it?

 

The IR file is limited to 44k. Roon will have to extrapolate this file when playing higher sample rate files. Is there a way to generate IR files with higher sample rates?

No, this is a limitation imposed because all phones support 44.1kHz sample rate, and that is the highest rate that can be guaranteed to work across all users' phones.

If the IR file is not possible, how do I generate the required settings for applying a manual PEQ values which Roon can also do.

I do not understand what a PEQ is. If you want to correct for the response of your speaker using AudioTool then one way would be to use some sort of EQ (like a graphic 1/3 octave equalizer) or more sophisticated per-frequency level adjustment, or other DSP-based device, and tune until AudioTool shows a flat response at the listening position.

Is there interest by the AudioTools team to work on a simple way to measure speakers using a cell phone with a iMM6 mic and send those settings to Roon?

This is beyond the scope of AudioTool, I'm afraid.

Roon has a very powerful DSP but is barely used by most users (1%) because most do not know how to use or how it could improve their playback.

I would like to make a YouTube Video on my DIY HiFi Life channel that shows a simple and uncomplicated way to do this.

That sounds great to me, but I'm not sure how simple it can be :-)

Julian

 

Thanks.

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