Table of Content
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Introduction
The purpose of this article is to provide advanced guidelines to ensure better results from an ART calibration.
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Keep in mind that ART processing is a mathematical concept. Just as with a mathematical equation, if the tool is given bad information, you will therefore experience a bad result. |
ART - In depth understanding
Reminder on what a Dirac Live ART calibration is made of:
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For any speaker, below 150hz, ART utilizes other speakers and/or subwoofers to support it and correct the speaker output.
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Supports frequency range
A crucial parameter to define is the frequency capacity range for each speaker.
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Table 1: Speaker Response based on datasheet
LFE management
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Manage the LFE with care. The LFE signal goes to the main SUB (first in the list), and we have to define support for this sub. The other subs are the most appropriate channels for this task, and using only your other subs to support the LFE could be sufficient. |
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While staying in the capable frequency range of your speakers, give the most latitudes you can to ART for it to work properly. Do not overconstray the support range and level, consider them as extreme limits, not what will be used in all cases. |
ART - Supports settings
Here we’ll go in details on how to set the supports settings in the Dirac Live interface.
The first parameter to set is the ART support range. But in practice, you will first decide which group will act as support for a given group.
Grouping speakers
The Dirac Live tool gives the opportunity to set groups of speakers. A group shares, for all speakers in it:
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Splitting speakers into more groups also allows for more granularity in the number of filters you can use in your ISP, but it also makes the configuration harder (more supports settings for each group).
Support range
The next phase will be to set the right supports range limits.
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In the “Considerations” chapter, we will define special cases this setting could be fine tuned, but for most cases we recommend to let your speakers support up to 150Hz.
Support level
The last setting you want to modify is the Support Level.
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As for Support Range, the Support Level is not a 1:1 operation, but rather a degree of liberty for ART, meaning that it may not always change the result of the calibration to the specified level, just set a maximum limit of use of a group for ART. |
Considerations
Directivity
Directivity is the capacity to localize an audio source in space. Immersive content is based on this to immerse you into a movie/content, but for low frequencies, it works differently.
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Support Range:
Reduce the higher frequency support limit. The lower you set it, the less for human physiology to determine the direction of arrival will be.Support Level:
Reduce the support level by increasing the value. This constraint on the level of the support filter leads to less or more energy in the support speaker. By reducing the level, you will reduce the perception of the direction of the signal’s arrival.
Coherence
We know that audio systems are usually symmetrical. This statement could lead you to define left support with less constraint than the right support for a left speaker (reverse is also true of course).
To do that you will need to separate your left and right speakers in individual groups and differently configure each support group regarding its position. To sum up this simply, speakers close to each other can help each other with a higher level as this is coherent localization wise. But do not forget that mirror speakers at opposite sides of the room also have a really good position to manage reflections (in regards to phase) to correct each other, so it is also a nice to have them correct each other. For example, both surround could be correcting themselves mutually.
SPL
Because energy is spread between speakers on their support frequency range, you will technically save SPL. This is true if speakers used as support have a homogeneous response in the support range. Then by tuning the support level, you will be able to spread the energy between your supports and in doing so remove excess load from the speaker to be corrected (this is often critical for the LFE).
However, most of the time this is not the case. Then the energy is spread through the speaker and its supports regarding their capacities in the room in term of magnitude and phase. This means that, if a speaker is the only one in the room to manage the frequency 53Hz for example, then all the energy regarding this frequency will be spread to this speaker. So you will, most of the time, end with an overall load that is split between your supports but with disparity. This will not ensure that your SPL is split between your subs for example. To overcome this issue and if you need more power in your room, you can physically group some subs to be considered as one speaker in the ISP. Physically, the power needed by each speaker will be divided by the number of speakers you group for a same SPL. The trade off you will face is the number of degrees of liberty in ART versus the maximum SPL you can manage with your speakers.
ART - Speaker settings
Front scene
In most cases, the front scene will need subwoofers to correct its lower frequency range. In addition to the subwoofers, we encourage to use speakers in the ear level to support the front scene low end reproduction as needed.
In any Home Cinema, the front scene is the most important set of speakers, meaning you should focus on correcting their frequency response first. They will benefit the most from being perfected as you will directly feel a new experience with ART.
The front scene is the second priority after the LFE to be considered for calibration and correction.
Center Speaker
In most Home Cinemas, the center speaker is quite critical. If you have enough speakers, we encourage you not to use the center as support for any speakers and use only sub and the front scene as support for the center. This will help to not overload a center speaker which have most of the time a very important signal to reproduce for the immersion.
Surround speakers
Every surround speaker should take the subs as support. This is a priority for low end response. Then you should add the ear level speakers as support because most of the time they are more capable than height or top speakers. Using the rules we defined earlier should provide a great response for each of these speakers.
Height and Top Speakers
Height and Top speakers can use any of the available speakers as support. You can try to focus using the front scene to help front heights and tops, and surrounds to help middles and back heights or top speakers.