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.
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.
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