Dirac Unison

Flak

Member
Nov 16, 2013
52
0
6
#1
The technology which has been previewed at January CES and tentatively named Unity has been finally trademarked as Dirac Unison.
It is not a product as of now, the tuning is really complex to release to the public so if/when we make it a product it will probably be for manufacturers, installers and pro markets only for very high-end systems.

Things are easier in a fixed environment (a predefined car model) with unlimited available measurements (i.e. 800 as you will see) so the first licensee to use Dirac Unison is the Volvo Car Group making the technology available in the all-new Volvo XC90 with a Bowers & Wilkins audio system.
The announcement is here: http://www.dirac.se/en/news-events/...irely-new-approach-to-sound-optimization.aspx

I can add the following from Michael Adenauer, former music producer and audio expert at Volvo Cars:

In the new XC90, the software has been used to re-create the exact acoustic qualities of Gothenburg Concert Hall, located in Volvo’s home town and home to the Gothenburg Symphony Orchestra, the National Orchestra of Sweden. A simple change in the centre touch screen that controls all the car’s features and the system will immediately alter its settings to mirror this concert hall, a recording studio or a stage.

“It took some 800 individual measurements in the Gothenburg Concert Hall before we captured the true richness of the acoustics,” said Mr Adenauer. “When it comes to the Studio Mode, it offers a precise and dry listening environment, similar to that which a recording engineer experiences in a studio. The Individual Stage mode offers the opportunity to control your position in a virtual venue through the innovative use of two sliders called ‘envelope’ and ‘intensity’. With these sliders you can move close to the stage, be surrounded by the musicians or place yourself out in the audience.”

Among the innovations in the new XC90 are the world’s first sub-woofer to be integrated into the body of the car rather than being a freestanding box that is simply bolted to it. Furthermore, this sub-woofer is also air ventilated – another world first – which means the air is expelled from an opening near the rear wheel-arch.
“The sub-woofer design is integrated in our new Scalable Product Architecture and is a world first in the automotive industry,” said Mr Adenauer. “This increases the subwoofer’s capacity to pulse more air, which enables extremely low bass tones all the way down to 20 Hz. In principle it turns the whole interior space in the car into a giant subwoofer.”

Ciao :) Flavio
 
Last edited:

Ron Kuper

New Member
Feb 21, 2014
8
0
0
#2
Hi Flavio,

Unison must be amazing.

I'm thinking - maybe take only one feature of it - "a completely new kind of bass management, which is automatically matched to the room and the loudspeakers" and make it into a consumer product?

Could be a heck of an upgrade module to Dirac Live!
 
Nov 16, 2013
52
0
6
#3
Hi Flavio,

Unison must be amazing.

I'm thinking - maybe take only one feature of it - "a completely new kind of bass management, which is automatically matched to the room and the loudspeakers" and make it into a consumer product?

Could be a heck of an upgrade module to Dirac Live!
Yes Ron :)

Flavio
 
Nov 16, 2013
52
0
6
#5
With reference to Dirac's Unison a very recent paper has been published by the Audio Engineering Society... it is dated February 10, 2015 :) and is available in full here:
http://www.aes.org/e-lib/browse.cfm?elib=17563

The following is an excerpt with relevant references:

"To obtain a specified target response in several measurement positions is a difficult task, particularly with individually designed filters.
First, as nearly all loudspeaker–room impulse responses exhibit excess phase (non-minimum phase) behavior [17, 25] the pre-compensator must be of so-called mixed phase type to correct for the excess phase distortion, i.e., the distortion components that are non-minimum phase.
Minimum phase filters, which are most commonly used, are generally insufficient for correcting such components.
Second, if a loudspeaker impulse response varies significantly between different measurement positions, as is typically the case in a normal room, then a single individual filter design for each speaker would, in general, not be sufficient to obtain good performance in all measurement positions.
A response may be attained that on average is close to the specifications, but there will always be remaining errors at each measurement position.
Hence, single-channel methods are most effective for compensating distortions that are common, or nearly common, to all positions in the region of interest.
Since audio systems of today generally include multiple loudspeaker channels, modern room correction methods propose the use of all, or at least a subset of, the available loudspeakers, see, e.g., [1, 2, 9, 12, 13, 18, 21, 23, 30–32].
In a recent publication, a Multiple-Input Multiple-Output(MIMO) approach to room compensation by the use of support loudspeakers was proposed and evaluated for a varying number of support loudspeakers [9].
It was shown that the effect of the room acoustics can be completely controlled up to a certain frequency, which is determined by factors such as, e.g., the number of loudspeakers, the size of the room and the sweet spot, and the granularity of the grid of measurement positions.
In the present paper we shall investigate how the MIMO framework can be used to variably control the contribution of the listening room acoustics throughout a spatial region where the listener is located.
By allowing the support loudspeakers to help the primary loudspeakers (e.g., the left and right speakers in a stereo system) to a higher or lesser degree, we can obtain a range of different equalizers that, to corresponding degrees, suppress the room acoustics while the direct sound of the primary loudspeakers is enhanced.
Consequently we are able to decrease the influence of the room in all spatial positions simultaneously, to an extent that can be determined by the user.
In the sequel we will refer to this concept as “Focus Control.”
The motivation for this type of variable room equalization can be manifold and depends on the role of the listener, on the audio material, and on the practical situation.
For example, a professional listener such as a mixing or mastering engineer can use it as a tool for carefully examining how various levels of listening room acoustics affect the perception of the material being produced.
At the consumer end, the preferences and needs of listeners may vary depending on the material being listened to.
If maximum intelligibility is desired for, e.g., a speech recording, then the maximum focus level (minimum level of listening room acoustics) is most likely preferable.
On the other hand, if the recording is a musical performance in a studio, involving a voice or an acoustic solo instrument, then it may be better not to remove too much of the listening room’s response, since the performance may then appear overly dry or dull, lacking the natural acoustic space normally associated with such performances"

REFERENCES
[1] P. Antsalo, M. Karjalainen, A. Makivirta, and V. Valimaki, “Comparison of Modal Equalizer Design Methods,” presented at the 114th Convention of the Audio Engineering Society (2003 Mar.), convention paper 5844.
[2] J. Backman, “Subwoofers in Rooms: Modal Analysis for Loudspeaker Placement,” presented at the 130th Convention of the Audio Engineering Society (2011 May), convention paper 8323.
[9] L.-J. Brannmark, A. Bahne, and A. Ahlen, “Compensation of Loudspeaker–Room Responses in a Robust MIMO Control Framework,” IEEE Transactions on Audio, Speech, and Language Processing, vol. 21, no. 6, pp. 1201–1216 (2013 June).
[12] A. Celestinos and S. Birkedal Nielsen, “Time Based Room Correction System for Low Frequencies Using Multiple Loudspeakers,” AES 32nd International Conference: DSP for Loudspeakers (2007 Sep.), conference paper 19.
[13] A. Celestinos and S. Birkedal Nielsen, “Controlled Acoustic Bass System (CABS)—A Method to Achieve Uniform Sound Field Distribution at Low Frequencies in Rectangular Rooms,” J. Audio Eng. Soc., vol. 56, pp. 915– 931 (2008 Nov.).
[17] M. O. Hawksford, “Digital Signal Processing Tools for Loudspeaker Evaluation and Discrete-Time Crossover Design,” J. Audio Eng. Soc., vol. 45, pp. 37–54 (1997 Jan./Feb.).
[18] M. O. Hawksford and A. J. Hill, “Wide-Area Psychoacoustic Correction for Problematic Room Modes Using Non-Linear Bass Synthesis,” presented at the 129th Convention of the Audio Engineering Society (2010 Nov.), convention paper 8313.
[21] M. Kolundzija, C. Faller, and M. Vetterli, “Multi- Channel Low-Frequency Room Equalization Using Perceptually Motivated Constrained Optimization,” in IEEE International Conference on Acoustics, Speech, and Signal Processing, ICASSP’12, Proceedings, pp. 533–536, Kyoto(2012 Mar.).
[23] A. Makivirta, P. Antsalo, M. Karjalainen, and V. Valimaki, “Modal Equalization of Loudspeaker–Room Responses at Low Frequencies,” J. Audio Eng. Soc., vol. 51, pp. 324–343 (2003 May).
[25] S. T. Neely and J. B. Allen, “Invertibility of a Room Impulse Response,” J. Acous. Soc. Am., vol. 66, no. 1, pp. 165–169 (1979 July).
[30] J. Vanderkooy, “Multi-Source Room Equalization: Reducing Room Resonances,” presented at the 123rd Convention of the Audio Engineering Society (2007 Oct.), convention paper 7262.
[31] J. Vanderkooy, “New Thoughts on Active Acoustic Absorbers,” presented at the 131st Convention of the Audio Engineering Society (2011 Oct.), convention paper 8458.
[32] T. Welti and A. Devantier, “Low-Frequency Optimization Using Multiple Subwoofers,” J. Audio Eng. Soc., vol. 54, pp. 347–364(2006 May).
 
Apr 3, 2010
15,814
2
0
Seattle, WA
#6
Ah yes. By chance I ran into that paper when I was researching something else and brought back good memories of seeing it work at CES last year. is this still aimed at automobile OEM business as opposed to consumer?
 
Nov 16, 2013
52
0
6
#7
Ah yes. By chance I ran into that paper when I was researching something else and brought back good memories of seeing it work at CES last year. is this still aimed at automobile OEM business as opposed to consumer?
Thanks Amirm,

I'm pleased to read that your memories of Unison are good, as is your question... what has changed since last year's CES and the most recent one is that Dirac Unison is now definitely aimed at consumers also (but no release date has been established yet)

Flavio
 
Nov 16, 2013
52
0
6
#9
The new Volvo XC90 looks great. It looks like it's a great value compared to Range Rover. Is unison tech in the upgraded B&W system?
I cannot double check because it's sunday but as far as I know BMW is using Dirac Live.

:) Flavio
 
Apr 3, 2010
15,814
2
0
Seattle, WA
#10
Thanks Amirm,

I'm pleased to read that your memories of Unison are good, as is your question... what has changed since last year's CES and the most recent one is that Dirac Unison is now definitely aimed at consumers also (but no release date has been established yet)

Flavio
Excellent!
 
Nov 16, 2013
52
0
6
#12
Almost three years have passed since I posted about Unison... but this may be the year we'll see it for home audio/theater-related products also
(page 2 in this interview: http://www.soundandvision.com/content/ridding-world-bad-sound#hCrdlULFF1JqVRil.97)

Details about Unison are available here: http://diracdocs.com/ISEAT15_Brannmark_Sternad.pdf

Retaining "the performance benefits of Dirac Unison while simultaneously creating an intuitive, not-too-technical calibration tool" is not a trivial task as explained here: http://www.dirac.com/dirac-blog/story-dirac-filterlab
that's the reason why it's taking so long :(

Ciao, Flavio
 

Mark Seaton

WBF Technical Expert (Speaker & Acoustics)
May 21, 2010
332
25
28
43
Chicago, IL
www.seatonsound.net
#13
Almost three years have passed since I posted about Unison... but this may be the year we'll see it for home audio/theater-related products also
(page 2 in this interview: http://www.soundandvision.com/content/ridding-world-bad-sound#hCrdlULFF1JqVRil.97)

Details about Unison are available here: http://diracdocs.com/ISEAT15_Brannmark_Sternad.pdf

Retaining "the performance benefits of Dirac Unison while simultaneously creating an intuitive, not-too-technical calibration tool" is not a trivial task as explained here: http://www.dirac.com/dirac-blog/story-dirac-filterlab
that's the reason why it's taking so long :(

Ciao, Flavio
Hi Flavio,

At CES 2016 I had suggested to a few in your room that one way to greatly show off the product, even if in limited capacity vs its full potential, would be a multiple subwoofer optimization tool. I figured this might also greatly reduce the number of variables and make something viable that most anyone can add to a system. Has there been any consideration for such a application of Dirac Unison, or will this start life only in multi-channel surround processors?

I am a big fan of the technology and very much look forward to seeing Unison available to enthusiasts.
 
Nov 16, 2013
52
0
6
#14
Hi Flavio,

At CES 2016 I had suggested to a few in your room that one way to greatly show off the product, even if in limited capacity vs its full potential, would be a multiple subwoofer optimization tool. I figured this might also greatly reduce the number of variables and make something viable that most anyone can add to a system. Has there been any consideration for such a application of Dirac Unison, or will this start life only in multi-channel surround processors?

I am a big fan of the technology and very much look forward to seeing Unison available to enthusiasts.
Hi Mark,

your suggestion, as expected :), is quite valid and reasonable... up to the point that we may decide to go that way in order to make Unison manageable by users that are less than very knowledgeable experts, it all depends on how much we will be able to automate during the next months.

Thanks for your well informed comments,
Flavio
 

audioguy

WBF Founding Member
Apr 21, 2010
2,765
34
48
Near Atlanta, GA but not too near!
#15
@FLAK This is not a Dirac Unison question but rather about measurement positions/locations for current Dirac. I do room calibrations for a large home theater retailer on their Datasat products (Trained by Datasat).) While the diagrams shown during the Dirac application are for the most part clear (one exception which I will ask in a moment), I have read a few different articles/opinions on slightly different approaches --- and actually tried all kinds of variations on mic positions.

Most end users for whom I do the calibrations are interested in at least one set of filters for the center seat sweet spot. So, when using the single chair model, it seems as if going further outside the boundaries of the sides of the chair gives better results (less chance of sharp peaks in the filters) than staying as the diagram might suggest. Do you have any specific recommendations that you have found work exceptionally well, given you have probably done a bazillion sets of measurements?

My other questions relate to the mic height position. Is the importance just to get measurements with the mic at various heights or are the "suggested" positions in the diagrams meaningful? One important reason I ask is that the lower mic positions seem to be below ear level which seems might be problematic for a Dolby Atmos surround system. For example, if the mic is in front of the seat and below ear level, it would likely not have line of site to the rear surrounds and/or rear Atmos speakers.

Your thoughts please.

Thanks
 
Nov 16, 2013
52
0
6
#16
Hi Audioguy,

I agree with your findings that in some instances going further outside the boundaries of the chair may give better results, it can happen that some overcorrection occurs so experimenting is always useful.

Having diversity in height is good and recommended.
However, the microphone should not be placed so that it is shadowed by the backrest unless the backrest is uncommonly high and can be expected to also shadow the listeners ears. This means that exactly what is appropriate depends from the furniture in the room.

http://www.gaylefurniture.com/wp-content/uploads/2016/06/high-back-armchair-1.jpg

For instance with the above type of seat it is unavoidable that the microphone is shadowed, as a result the measurements should be as well.
In general furniture does not necessarily shadow the ears from the surrounds and then the microphone should not be shadowed either.

Flavio
 

Flak

Member
Nov 16, 2013
52
0
6
#18
@FLAK ^^^^ Thanks for the response. How much, in your experience, variation in the height measurements is reasonable? 18"? Less? More?
Hi Audioguy :)

I'd use 18" above and below MLP as a minimum, eventually more but not less...

Flavio
 

audioguy

WBF Founding Member
Apr 21, 2010
2,765
34
48
Near Atlanta, GA but not too near!
#19
Hi Audioguy :)

I'd use 18" above and below MLP as a minimum, eventually more but not less...

Flavio
For a total of a 36" spread?

18" below the MLP will block rear surround and be so low that it would also block the side surrounds and 2 of the 4 ceiling speakers.

What am I missing?
 

Flak

Member
Nov 16, 2013
52
0
6
#20
For a total of a 36" spread?

18" below the MLP will block rear surround and be so low that it would also block the side surrounds and 2 of the 4 ceiling speakers.

What am I missing?
In that case you are correct and I stand corrected... in general I personally prefer a larger volume as in the sofa setting, I'm more into Stereo than Home Theater and follow a conservative approach to avoid any risk of eventual overcorrection but in the case that you mention where speakers are blocked then a smaller variation as you mention would be preferable.

Flavio
 

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