• WANTED: Happy members who like to discuss audio and other topics related to our interest. Desire to learn and share knowledge of science required as is 20 years of participation in forums (not all true). Come here to have fun, be ready to be teased and not take online life too seriously. We now measure and review equipment for free! Click here for details.

How to make room EQ with Volumio

Krunok

Major Contributor
Joined
Mar 25, 2018
Messages
4,600
Likes
2,972
Location
Zg, Cro
Current Volumio users may find this news exciting as recently BruteFIR convolution engine has been ported to Volumio platform. At the very beginning I must stress a fact that although BruteFIR is available at all Volumio platforms I do NOT recccomend using it with Raspberry PI (including newest 3 B+ model) in combination with USB DACs due to some constraints in networking and USB acrhitecture. Using RPI with SPDIF hat in combination with SPDIF input on DAC will work just fine.

I'm using Dell Wyse D50D fanless PC as a Volumio platform, but any PC will do (fanless platform is of course recommended).




BruteFIR install for Volumio can be found here: https://github.com/balbuze/volumio-plugins/tree/master/plugins/audio_interface/brutefir3

I recommend reboot after install. When you go to settings this is what you will see:



First thing you'll have to set to hear anything is the output format. I set it to "S32_LE" for my Topping D10 DAC.

96kHz sample rate is set by default, as is 65536 filter size, as recommended by @pos (author of rePhase FIR creation tool). In practice it turned out to work well, but you can of course adjust it to your liking.

BruteFIR uses 6dB of attenuation, additional attenuation can be adjusted on the setings screen, depending on the max gain used in your filters.

I used Room EQ Wizard (REW) for measuring. I will not elaborate measruement methods here as I'm not the expert in this field. @amirm already announced a write-up on the topic of measurement with REW so I'm sure you'll find all info there once he finds time to make it. Here I will only say that I used MMM measurement method described here. In REW you will be using RTA window for that. MiniDSP UMIK-1 mic is a fine tool for doing measurements.

So, this is what I got when I measured the response of my Castle Harlech S2 speakers at my listening position.




You'll need to export these measurements as text so you can import them into rePhase where you will be creating your filters:



Make sure you've set taps to 65536 (to match filter size in BruteFIR settings) and that you'll be using correct sample rate in rePhase.

Once your filter is generated you should put it in "/data/INTERNAL/brutefirfilters" directory of your Volumio unit (I'm using WinSCP tool for that), from where they can be selected in the BruteFIR settings screen.

This is what I got after repeating measurements at my listening position with filters active:



I also made a measurement 2 meters behind my listening position, which is app 6 meters from speakers:



As you can see the response there is not as linear as it is at my listening position but the response of left and right speaker is much more similar than it was at my listening position without filters so the filters are helping at that position as well.

When speaking subjectively I can say that I can now hear more details in many recordings I previosuly thought I knew very well. Also, bass got firmer and a little deeper. That goes for both listening positions, the sweet spot for which I optimised response and the position 2m behind it.

I would like to thank Pascal (aka balbuze) who made a great job of porting BruteFIR to Volumio platform.
I would also like to thank Thomas (@pos) not only for making such a great FIR creation tool as rePhase is but also for providing me with numerous advices how to create filters.
Finally, i would like to thank John Mulcahy, creator of REW, who helped me with acoustic timing reference measurements which are needed when you want to make log sweep with Volumio.
 
Last edited:
OP
Krunok

Krunok

Major Contributor
Joined
Mar 25, 2018
Messages
4,600
Likes
2,972
Location
Zg, Cro
Here are the same measurements with applied filter corrections with Var smoothing. In 1st post measurements are shown with 1/12 smoothing.
My question here would be which smoothing is considered optimal when creating filters?



 

verkion

Member
Joined
Feb 26, 2019
Messages
13
Likes
3
I know you used MMM for the measurements but was wondering if you (or anyone else) has tried to use the 9 Dirac positions, take full sweep measures at each, then vector average them in REW. This way, you can adjust for amplitude and phase. RTA doesn't give phase info I don't think.

Thanks!
verkion
 
OP
Krunok

Krunok

Major Contributor
Joined
Mar 25, 2018
Messages
4,600
Likes
2,972
Location
Zg, Cro
I know you used MMM for the measurements but was wondering if you (or anyone else) has tried to use the 9 Dirac positions, take full sweep measures at each, then vector average them in REW. This way, you can adjust for amplitude and phase. RTA doesn't give phase info I don't think.

Thanks!
verkion

Yes, i did..

https://www.audiosciencereview.com/...room-eq-dos-and-donts.6805/page-5#post-155426

Btw, there is no difference if you measure amplitude response with RTA vs 9 points average sweeps - you get the same result
RTA is simpler to make so I use it when I need only ampliture response.
 
Last edited:

verkion

Member
Joined
Feb 26, 2019
Messages
13
Likes
3
Yeah. That's true. RTA is quicker/much easier! Not entirely sure where/which sub-forum here to ask this, but how would you guys suggest I room correct for separate sub + stereo speakers? i.e. do I just measure speakers (which cutoff at 40Hz, -6dB) and then correct for them, measure the subwoofer, correct for it, then measure the two together and try to phase align them?

Or should I just measure sub+full range speakers together (left and right independently of course) and then try to correct based on that?

I've looked at Amir's threads about Room Correction but didn't see any specifics there on how to do this "properly." I could have missed it completely though...
 
OP
Krunok

Krunok

Major Contributor
Joined
Mar 25, 2018
Messages
4,600
Likes
2,972
Location
Zg, Cro
Or you should wait for @RayDunzl to explain how he did it. :)

But I'm pretty sure you have to start by measuring them separately. Based on that you can decide crossover point and adjust levels so they are equal.
Final check is to measure them playing together.
 

Feyire

Active Member
Joined
Mar 9, 2019
Messages
210
Likes
256
Location
Netherlands
Current Volumio users may find this news exciting as recently BruteFIR convolution engine has been ported to Volumio platform. At the very beginning I must stress a fact that although BruteFIR is available at all Volumio platforms I do NOT recccomend using it with Raspberry PI (including newest 3 B+ model) in combination with USB DACs due to some constraints in networking and USB acrhitecture. Using RPI with SPDIF hat in combination with SPDIF input on DAC will work just fine.
What about the Raspberry PI 4?
 

laidick

Active Member
Forum Donor
Joined
Apr 22, 2018
Messages
148
Likes
96
In burtefir, the filter size is 65536
In rephase, should I set tap to 65536 or the FFT length to 65536?
 

Soniclife

Major Contributor
Forum Donor
Joined
Apr 13, 2017
Messages
3,870
Likes
4,402
Location
UK
Here are the same measurements with applied filter corrections with Var smoothing. In 1st post measurements are shown with 1/12 smoothing.
My question here would be which smoothing is considered optimal when creating filters?



Did you ever find the answer to this?
I've been wondering the same, for initial measurements, and should you use the same smoothing for post EQ measurements, or change to use something like ERB to check you have got it right.
 

Xombul

Member
Forum Donor
Joined
Apr 1, 2019
Messages
83
Likes
74
Location
France
Hello, I need help with Volumio room correction DRC.
First, I would like to thank (in advance...) the developpers: creating an inexpensive solution for room equalization was just brilliant.
I am currently running Volumio DRC on a raspberry 3B+ and Allodigione ( coax)
Downloading the plugin was piece of cake, however the screen slightly different from the one presented by @Krunok.
I would like to make a test without filter first.

1) do I have to set up allodigione through brutefir?
2) Why this bloody AdafruitAdafruitMaxxxx comes in DAC Model?
3) Why I2S box is turned off after restart?

4) to make a test is it ok to select none for the left and right filters?
5) What is the recommended value for delay and the unit?
6) is it ok to have the same filter, for left and right?

I have also downloaded the tools.
7) Is it a good idea to use the pink noise generator with REW software? ( I could sell my extra long USB wire)
8) What are the recommended values in the first box advanced settings for the number of taps and the sampling frequency?
9) same questions with me sure with Rev <19
10) Can I convert a filter made with REW in a wave file and implement it in DRC?
Many thanks for the answers
 

TomB19

Active Member
Joined
Oct 13, 2019
Messages
135
Likes
92
I don't have the answer to your question so I apologize for not being directly helpful but I suggest you ask on the Volumio forum. There aren't many users on your level there but there are a couple and I've seen informative posts on the subject.

https://volumio.github.io/docs/Plugins_User_Manuals/brutefir/Drc_with_Volumio.html

I'm right behind you on Volumio DRC, so any info you share with your journey would be appreciated.
 

daftKow

New Member
Joined
Jan 11, 2021
Messages
2
Likes
0
Just stumbled across this, thank you! I read that the pi4 fixed the usb DAC issue, am I ok to use bruteFIR with it then? Strictly for Spotify Connect.

Edit: nvm I just saw the post above
 
Top Bottom