• WANTED: Happy members who like to discuss audio and other topics related to our interest. Desire to learn and share knowledge of science required. There are many reviews of audio hardware and expert members to help answer your questions. Click here to have your audio equipment measured for free!

Homebrew 'Dirac ART'

ppataki

Major Contributor
Joined
Aug 7, 2019
Messages
1,247
Likes
1,406
Location
Budapest
As I was reading about Dirac ART (né Dirac Unison) I really liked the idea to use the surround speakers to support the fronts for the bass (in case they go sufficiently low)
If I had to take a guess ART will not be available for PC anytime soon so I took a stab at trying to mimic it with the tools I am familiar with

All in all I think I succeeded so I thought I would share my experience here so those who have a 'compatible' system can enjoy this until (or if) ART is released for PC

I have a 4.0 system (pictures here) and my rears can go down to 25Hz - unfortunately in the current room setup they go only to 40Hz (more about that here) but that is sufficient for the purpose of filling in the dips caused by the L+R summation cancellations

Here is how my fronts' L+R summation looks like
(MLP measurement, 75dB, 265cm, used Dirac Live 3.5 for the per channel optimization and GrandEQ for further shelves)

1681299338225.png


My goal was to do something with that nasty dip between 50-60Hz

Here is how the L+R summation of my rear speakers look like:

1681299601758.png


They also have a dip there but let's see what we will get anyway....

Here is what I have done:

- set up Dirac Live 3.5 in Stereo mode
- created filters post-Dirac in the signal chain to copy the front channels to the rear channels and applied a low-pass filter at 100Hz for the rear channels
1681299664195.png


- measured the system with Dirac

This way when measuring L and R channels the rear L and R channels were active too but only between 40 and <100Hz

This is how the end result looks like:
(highlighted compared to the original LR summation)

1681299758676.png


It is not a huge improvement but it is definitely an audible improvement and I must say that it actually sounds great!!
(not just the measurement but also listening to it)

I have gone one step further and time and gain aligned the rear channels to the fronts and re-did all the above steps

1681299931761.png


Now this is what I got:
(highlighted vs the original)

1681299991377.png


Now this looks even better but actually when listening to it I tend to prefer the previous version (strangely enough)

So again I believe that this is something worth trying, I love the sound of it and I would encourage those who have a compatible system to give it a go.
You can find the mdat file here: https://drive.google.com/file/d/12cK0MCFBG8b0aNw985untX5uC552vS3f/view?usp=sharing

Any questions/comments are welcome and eagerly waiting for ART to be released for PC!
FYI @Flak
 

voodooless

Grand Contributor
Forum Donor
Joined
Jun 16, 2020
Messages
10,388
Likes
18,328
Location
Netherlands
Nice effort, but it's not exactly Dirac ART on the cheap. You just used your rears as subs to create a "normal" multi-sub system. Nothing wrong with this essentially though and I think it's a great idea :)

Just note that in many cases, in surround mixes, the low end will already be copied to the rears. It may cancel out your duplicated mains bass if the delay settings are not set up correctly.
 
OP
P

ppataki

Major Contributor
Joined
Aug 7, 2019
Messages
1,247
Likes
1,406
Location
Budapest
Thanks @voodooless

Just note that in many cases, in surround mixes, the low end will already be copied to the rears. It may cancel out your duplicated mains bass if the delay settings are not set up correctly.
I am using this setup for stereo music only - when watching movies (surround sound) I switch back to regular 4.0


EDIT:

You just used your rears as subs to create a "normal" multi-sub system

I think a main difference is that in a standard multi-sub (or single sub) setup you cut the lows from the mains - so there is a crossover involved
Here there is no crossover for the mains, they cover full range and the rears 'help' them in the bass range
Also this is stereo, not mono - by the way the next step for me is to try the same setup in mono (it is possible to 'monofy' the signal with a VST plugin below a certain frequency)
 
Last edited:

ernestcarl

Major Contributor
Joined
Sep 4, 2019
Messages
3,113
Likes
2,330
Location
Canada
A steeper low pass filter (mixed phase) could help avoid the cancellation above 90 Hz or so. Better perhaps (and yet more difficult to accomplish) would be to apply a per-channel phase and magnitude EQ.
 
OP
P

ppataki

Major Contributor
Joined
Aug 7, 2019
Messages
1,247
Likes
1,406
Location
Budapest
(it is possible to 'monofy' the signal with a VST plugin below a certain frequency)
I have tried this and I must say I am now totally blown away!!
Mono is magic! :)

This is what I got:

1681456296132.png


I managed to tame the dips pretty well below 100Hz!

This is how I did it:
there is a VST plugin called GMonoBass that can 'monofy' the signal below a certain frequency. I have set the plugin at 100Hz and applied it on all four channels after Dirac in the signal chain obviously.
And then optimized the system with Dirac like that

It doesn't just look great it also sounds excellent! No ringing whatsoever - this is by far THE best sound I managed to get in this room ever
I know I am losing some spatial information below 100Hz but after listening to many tracks where bass is panned to either sides I cannot hear any difference
 

abdo123

Master Contributor
Forum Donor
Joined
Nov 15, 2020
Messages
7,446
Likes
7,955
Location
Brussels, Belgium
I have tried this and I must say I am now totally blown away!!
Mono is magic! :)

This is what I got:

View attachment 279124

I managed to tame the dips pretty well below 100Hz!

This is how I did it:
there is a VST plugin called GMonoBass that can 'monofy' the signal below a certain frequency. I have set the plugin at 100Hz and applied it on all four channels after Dirac in the signal chain obviously.
And then optimized the system with Dirac like that

It doesn't just look great it also sounds excellent! No ringing whatsoever - this is by far THE best sound I managed to get in this room ever
I know I am losing some spatial information below 100Hz but after listening to many tracks where bass is panned to either sides I cannot hear any difference

Welcome to 4 subs setups
 

Zoomer

Senior Member
Joined
Oct 5, 2019
Messages
323
Likes
469
If you have Dirac mch with Bass Control it would be innaresting to compare ...
 
OP
P

ppataki

Major Contributor
Joined
Aug 7, 2019
Messages
1,247
Likes
1,406
Location
Budapest
If you have Dirac mch with Bass Control it would be innaresting to compare ...
Dirac Bass Control won't work, I have tried it
I could not switch off its crossover
The point here is that the fronts play full range and the rears help out with the bass (no crossover needed but just a low-pass for the rears)
 
OP
P

ppataki

Major Contributor
Joined
Aug 7, 2019
Messages
1,247
Likes
1,406
Location
Budapest
Just a recent update on this topic:

I have tried a purely linear phase approach (=low-pass filter on the rears and all shelf filters on all channels are linear phase using 12dB/octave slope) and actually that sounds the best so far!
It measures a bit worse than the previous approach but by ear this is the version I definitely love the most

Here is the totally flat measurement:

1684959013216.png


1684959039140.png


(negligible pre-ringing only)

1684959076587.png


(extremely low energy delay in the low-end - this is actually even a bit better than using just the front speakers)

And this is with the shelves applied (how I actually listen to it)

1684959169135.png


Regarding the stereo vs mono bass: I prefer to run the optimization with full stereo but then I apply low shelf cut filters on the side channels (ie. mid-side processing) to somewhat 'monofy' the low-end
Doing so decreases the ringing vs. using fully mono low-end (in my room at least)

I consider this exercise finished for now - I am super happy with the results, now this is how I listen to stereo music (obviously for movies I switch back to quadraphonic)
 
Top Bottom