Idea on how to measure FR with Roon's DSP?


Using Roon’s DSP for some manual parametric EQ filters and would like to measure the system’s frequency response with the filters. Any ideas on how?

Would REW or other measurement software allow to export and play the test signal through an external player (i.e. Roon in my case) while measuring the response using a USB measurement mic?


Yes. I do that.
REW has a sweep generation function, somewhere, I don’t remembe4 where. You’ll find it, I did.

So I’ll understand the premise:
Sweep generation in REW creates a file (e.g. wav) to be played by another player (e.g. roon) while still measuring the output using the usb mic?

Use the singal generator inside REW to record a pink noise from 20Hz to 20000Hz. Save the file and play it with roon. While doing so use the RTA (real time analyser) function in REW to messure the response. Keep in mind that you are only able to messure the FR by this way. Other data like the impulse, RT60 or waterfall data are not recorded.

Thanks! :slight_smile:

So measuring phase issues is not possible?
If that’s the case then it is nice to have but not quite helpful for improving audio correctness. The reason being that FR can be measured independently, testing it again through the player will help validate the expected result but that’s it.
It is not the case with impulse and phase issues which might be induced BY the player’s eq filters (like high/low-pass) which we will be blind to and unable to correct without complete measuring through the DSP engine.

That’s as far as I understand it, please correct me if I’m missing something.

By this way phase measuring is not possible. You can only get an idea of what your FR is like with the filters set in the player’s DSP engine.

If you want to go deeper and have also a look at the phase and impulse I advice you to try room correction with REW and rephase.

Check out this great tutorial:

It might take some time to understand all of it but it’s worth it!

You’ll need REW beta 5.19 for the tutorial!

Very interesting!

Do you suggest replacing Roon’s PEQ filters I use for BM with a rePhase convolver loaded in Roon in order to guaranty linear phase?

I eventually chose Acourate, which analyzes phase/time response, and then generates a convolution that I loaded into Roon. Much better sounding results than I was able to achieve with REW. I know there are others.

Can Acourate be used for subwoofer integration (bass management)?
I’ve seen it got crossover section but can it generate content to the subwoofer (“LFE” in Roon’s DSP) channel?

There is an important trick: when generating the sweep file in REW, tell it to put timing signals in the file, necessary to sync the measurements in REW later.

I don’t think Acourate can generate the controls for bass management in Roon.
But you don’t need Acourate for that.
Roon’s channel mixer is fairly easy to set up, I think.

Already set up, here - Roon & Dirac integration again

So to clarify as far as you know the flow should be -

  1. Using Roon’s channel mixer to copy content from the fronts to the subwoofer channel
  2. (I believe one should add a -10db gain adjustment to the LFE after summing of the two channels)
  3. Using a convolution filter created with Acourate/REW/other to do the crossover (and other corrections)?

A lot of moving parts :slight_smile:

What happens when I play 5.1 content? What are the chances the same configuration using Roon’s DSP features for BM will transition correctly between stereo content and 5.1 (gain adjustment after summing is the main suspect IMHO).
@brian - Insight? Is proper BM planned?
I think that if BM is off the table then automated rules for zone/device switch (e.g. after detecting 5.1 content) might allow the use case with the current DSP features while adding additional flexibility / enabling other use cases.

Acourate is great for stereo but due to its high range of FIR filter taps the delay which is applied to signal makes it useless for multichannel audio, imho.

Linear phase and phase correction below 100Hz should be avioded as it can cause “pre-ringing”. Linear phase filters do always apply a greater delay to the signal than minimum phase filters.

There is no problem with FIR filters which are minimum phase as long you do correct the phase too.

Using rephase to generate the impulse reponse correction file for roon’s convolving engine is the right way to go.

I think you should set you speakers to small and activate your subs for stereo. Then do the mesurement in REW with the subs in the desired xover frequency (40,60,80Hz)… After that make the amplitude correction with REW eq function and time domain correction with rephase as it is done in the tutorial.

So more reason to implement auto zone switching or being able to have separate DSP settings based on content type.

I currently have Dirac Live for PC, that is why I need to create the sub channel (upmix 2.0 to 2.1) before Dirac and not using the pre/pro’s BM functions (small / large / etc).

As far as I understand doing as you suggest would be an alternative for Dirac, right?
I always thought that if I leave the comforts of Dirac (at least until they’ll implement BM internally which would fix this UX disaster) I would go the Acourate route. Or have I missed some advantage REW+rePhase have for my use case?

No, Acourate will do the same as the tutorial with REW and rephase.

The only advantage I see is that REW and rephase are free of charge while Acourate has its price…

Acourate itself is more comfortable of course.

I’m a friend of doing all corrections manually :wink:

We don’t have plans for a convenience-path for BM, but I think the building blocks are all there in our convolver text configuration support. Roon will pick the “best match” configuration file in your package. So for example, if you provide configurations for each sample rate at 2.0 and 5.1, it should automatically select based on content.

In that way you could set up 2.0 with bass management + 5.1 as a pass-through. You could do your Room correction as part of the same filters, or using a separate step. I think I would do it all together, personally.

I wasn’t aware of that - looks promising!
Gives me an incentive to go the convolver route.

Insight much appreciated, thank you! :stuck_out_tongue:


If you like to stay with Dirac (multichannel) and have also a proper BM then this device might be the right choice for you: (with BM plugin)

Thanks Lars!

I’ve been eyeballing minidsp’s product line for some time now, they have very good options.

As a strategy (and hobby) I am leaning towards consolidating more and more roles into the HTPC in software for flexibility and future proofing. Also as you might have noticed I am actively communicating any gaps I can identify with my use cases for any product I use trying to help this trend.