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Background: Dirac Live 2 – calibration software for home use

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Dirac was already one of the best room correction solutions available. A thoroughly reworked version now makes the software more accessible to a larger audience. That's good, because at the same time more surround and stereo devices with Dirac appear on board. Arcam, NAD and Rotel, among others, recently embrace the new Dirac software. It is of course also usable with existing Dirac partners, such as miniDSP and Storm Audio.

In this article we look at the new version of Dirac for home use, Dirac Live 2.x. We have already written about this software of Swedish origin that is built into more and more audio products but that can also run separately on a PC. Both in the form of a background piece about what Dirac is and in the margin of tests of AV receivers as the Arcam AVR-550 and NAD T 758 v3 . Why do we now dedicate a longer piece to Dirac again? Because the software now has a substantial update to version 2. What is immediately noticeable is that the interface is fully adapted. That is nice, but at least as important is that Dirac now gets a new architecture so that in the future it can easily be expanded and improved with new modules that do something specific. The module approach sounds special, but you do not need those extra parts to get started with Dirac Live. The software is so completely functional and useful for the end user. A module has already been announced: Live Bass Management .

What is Dirac?

The first question is, of course, what is Dirac correct? Very simply, Dirac software is that you use the acoustic representation in a room so that your music and film sound better. That is really necessary in most cases. A room without problems and speakers that are really perfectly set up, you rarely encounter. Perhaps it is a dedicated cinema space that was designed by an expert. A typical living room or home theater almost always needs some software help.

Dirac is therefore a competitor for the calibration software found on AV receivers from Denon and Marantz (Audyssey), Yamaha (YPAO), Onkyo and Pioneer ( AccuEQ), Sony (DCAC), and others, and stereo devices such as the Micromega M-One M150 (MARS) or the Lyngdorf TDAI-3400 (RoomPerfect). It is certainly not the only solution to make sound sound good in your room.

For the sake of completeness, we have to mention that the Dirac software exists in yet other forms. It is used for example by car manufacturers such as Bentley (together with Naim), BMW (in the M series), Volvo and Rolls-Royce. Because Dirac has a strategic partnership with Harman, we suspect that this list will soon be much longer. Harman is the most important player in terms of automotive audio and systems, with partnerships around brand names such as Bowers & Wilkins and Bang & Olufsen. Dirac is also working hard to become a big name in the mobile segment. It has all sorts of software to improve the audio reproduction via smartphones and tablets. Finally, the firm also pays attention to virtual reality, with solutions for 3D Audio. It is a fascinating company, which recently did not happen to attract a lot of venture capital.

Another approach

A typical example of an acoustic problem that you can tackle with Dirac is a so-called room mode: a low frequency that shape of your room is strengthened. This causes a woolly bass that removes detail in the layer and possibly also makes things like dialogue and fine surround effects disappear. With an AV receiver, a typical calibration function will still do something: measure the distances between the different speakers and the listening position. After that the software will work out the differences in distances. This is done by slowing the speakers closer to something that is more distant. As a result, the sound effects and music of a soundtrack arrive at the right moment at your ears. This distance compensation is really useful. After all, in living rooms a situation with less optimally placed loudspeakers often occurs. For example, the stereo speakers are often closer than the center just below the TV screen. In summary: average calibration software intervenes on the frequency domain (by amplifying or suppressing certain frequencies) and on the time domain (by delaying speakers if necessary).

Dirac does all this too, but still a step further. It is also concerned with the impulse response. It is not entirely correct to say that this is the reverberation of a tone, as observed at the listening position, but it helps to understand the impulse response. Due to the characteristics of loudspeakers and the room, a tone does not just play. Certain frequencies may arrive at the listening position a little later, for example because bass still vibrates or because there are powerful reflections. It can also pass through the loudspeaker. A speaker with multiple drivers will – if it is well developed – be put together in such a way that the frequencies coming from the tweeter arrive at your ears at the same time as the midtones and the basses. But this phase coherence is not easy to achieve,

What's new?

Dirac really needed a new version. The software already dated from 2011, which you immediately saw at the interface (see below the old versus new interface). It was clearly designed by engineers and not by usability experts. As a result, the threshold for using Dirac was higher than with other calibration software. That was already the case anyway because you needed a computer to take measurements, instead just put a microphone on an AV receiver and then follow a step-by-step plan.

The new interface of Dirac Live 2.x we will soon see more in depth. But when it comes to making the software more accessible, we can already say that the mission has been successful. Thanks to the clear menus and graphic elements, for example, it becomes clearer how to measure. Important, because the measurements carried out according to the rules are the key to a correct correction at Dirac. Completely new is that the software can now also be used via a mobile app – although there are limitations to Dirac Live on a Mac or Windows machine.

The core of Dirac, the Dirac Audio Processor, is largely unchanged remained, says Dirac. The company does not solve an incredible amount of its algorithms, perhaps because it is fearful of competitors who take off with knowledge. However, Dirac says that the new software received a custom phase correction algorithm that makes stereo reproduction better. In the past the Audio Processor only looked at the phase coherence of individual loudspeakers, now it is also measured in pairs. This allows to create filters in which the phase response of a stereo pair is coordinated.

Testing with the new Dirac

We have tried the new Dirac version extensively during testing the Arcam AVR-850 . It was also the intention to test the impact for stereo on the basis of the brand new NAD C 658 which has been in our test room for a while, but unfortunately the firmware update that added the Dirac function was postponed as a result of which this was not possible . However, the update would be available within the foreseeable future. So be sure to read the review of this streaming pre-amplifier from NAD on Hifi.nl. The NAD is a special thing – and we suspect that the combination BluOS / Roon and Dirac will make it a very popular addition to the music systems of many hi-fi enthusiasts.

We also provide a test later in the spring the NAD M10, a compact but high-quality stereo amplifier with Dirac built-in. For this article, we performed all tests with the Dirac app on a MacBook Pro and on a Microsoft Surface Pro. It was also installed on an Android tablet and an iPad, but those mobile apps found no compatible audio devices. We asked Dirac how this came about, but unfortunately the company did not respond to our questions. Should there be a reaction, we will gladly add it to this article.

Getting started with Dirac Live 2.x

Dirac works in two phases: measuring and creating filters. Measuring is done in several places (a ninth is recommended). You need a measuring microphone for this. If you do not have a suitable Dirac compatible device, we would recommend a USB measuring microphone. We use the UMIK-1, a measuring microphone with USB connection that costs about 80 euros. You can purchase a more expensive model, but Dirac thinks the UMIK is good too. Which microphone you purchase, it is important that an individual calibration file is available from the manufacturer. This file describes the properties of the microphone, so that they do not count in the measurements.

In general, measuring at Dirac Live 2.x remains the same as before. The software first detects whether a compatible device is hanging on the network, after which you can choose the microphone. During the measurement itself, an extensive series of test tones is played by each speaker. In a surround setup it can be a collection of loudspeakers with very different sensitivities, and therefore you first need to find a volume level that is suitable for all speakers before measuring. You do that in a screen that is much brighter at Dirac Live 2.x than before. The method is simple: with each speaker you can play white noise, allowing you to adjust the volume so that a bar indicator turns green (not too loud, not too quiet). To match the speakers you have a master volume and a mic gain slide bar, but also an adjustment per channel. You start best by adjusting the least sensitive speaker (perhaps the rear-speakers or the height channels) and then the more sensitive speakers (perhaps left and right in front). The sensitive speakers will immediately receive a signal that is too loud, but you can then lower it at the speaker level.

Measuring itself is much more user-friendly than before. You can choose to measure more or more focused (depending on whether you listen with 1-2 people or a whole family). The app now clearly shows where you need to measure and it is possible to choose which measurement point to measure when. In total there are thirteen measuring points, but you can also work with less. You can also always go back and take a measurement again.

According to Dirac, the distance between the measuring points is not crucial, but it is important that you always keep the same distances. The 3D drawing in the app unfortunately does not make it quite clear that each measuring point is at an equal distance from another. A tip from a Dirac instructor we ever got was to indicate the measuring positions in advance with a piece of painter's tape. This way you are sure that you always measure in the right place. A microphone stand with a loose arm is also a skill. If everything is OK, then you are measuring for about 20-25 minutes with a 5.1.4 set-up. Background noise can be annoying, so it may be better to repeat a measurement if a large truck accidentally thunders during the measurement.

Making filters

With your measurement data you then create a filter that is transferred to your audio device after processing. sent. With the Arcam AVR-850 you can send one filter, but there are also devices with slots for multiple filters. But before you make a filter, you still have some work. A graphical representation shows the test data as a frequency display and as an impulse response. You can not change anything about the latter. Dirac optimizes the impulse response itself. However, you can manipulate frequency response.

The software will propose to adjust the measured frequency display so that it matches a target curve – that is, a frequency profile – that Dirac has devised. Everyone has an opinion about that target curve of Dirac; the consensus seems to be that the standard is too neutral and too drastic affects the character of the loudspeakers. Some audio manufacturers, such as NAD, therefore offer an alternative curve that will adapt the display to their house sound.

But you can also get started yourself by adjusting the target curve. You do this by creating a point on the target curve and increasing or decreasing it by a number of decibels. You will notice that you do not adjust that frequency, but that you make a hill or a valley that also affects surrounding frequencies. You can of course create several correction points. So you adjust the curve (the pink line on the image) in its entirety. (In theory you could make a fierce peak, but in reality the speaker driver would not only be able to reproduce that one frequency much louder because of its physical characteristics.)

A choice that some make is Dirac only to function to a certain frequency, for example 500 Hz. Room problems, such as room modes, are usually below this point. The advantage with this approach is that the character of your speaker is preserved in detail. An alternative is to bring the target curve at higher frequencies closer to the measured data. You may only weaken unwanted peaks, but you will retain the character.

Dirac lets you adjust the target curve per pair of speakers, with the exception of the center speaker and the subwoofer. Logical, because your surround and height channels are always a pair and should be the same type of speakers. But if you wish, you can also adjust individual speakers. This may be desirable, for example, if you have a sub-optimal set-up that involves a speaker in a bookcase or closer to a wall than the other speaker in the pair.

In short, this aspect of Dirac is quite complex. You already have to be an expert to create a filter that really sounds right as it should and that sounds as you like. Both things are not always right. In practice you will create filters several times, as part of your search for the best sound. An audio device that has slots for multiple filters and allows to switch between filters during listening is really useful.

Fortunately, you do not always have to measure again if you want to create a filter. You can use the data from one measurement session to create as many filters as you want – if you have thought about saving the data. That is why we advise you to do that measurement really well and then store it. The measurement is the foundation – do it well and thoroughly, and afterwards you can experiment with filters when you want.

And the results? You can read more about it in the tests of devices with Dirac. But in short: time and time again we hear a noticeably better result. Tighter – so a better impulse response – and often also more detailed and in balance. We find Dirac very strong to surround us. By addressing the speakers and the room, the positioning of effects in the room becomes more accurate. A moment that stayed with us was the race in 'Ready Player One', a fragment that we have always used for the last few months in surround tests, on a 5.1.2 set-up. During that race you often hear coins rolling (the money that players drop when they die in the virtual world); Suddenly we heard that sound right behind our heads – while we did not have surround back speakers. It was so realistic that we really looked up – even though we have seen this fragment dozens of times. 0

Conclusion

As far as we are concerned Dirac remains one of the best – if not the best – solution to improve sound reproduction. The fact that more and more manufacturers incorporate the software into their audio devices proves that we are not the only ones with that opinion. It remains a solution that requires time and knowledge to use correctly. Measuring takes longer and is more error-prone than with most calibration functions on AV receivers . Moreover, adjusting the target curve requires insight and patience to do well. But all that effort is really worth it. Dirac then provides a better, tighter and more transparent sound than before. Provided you create a good curve that tackles the problems without affecting the character of your speakers, that speaks. Indispensable for the critical listener, we find.

More information

Would you like to know more about the calibration of receivers and other home cinema equipment? Or do you want more tips and advice on buying and using this equipment? Then take a look at our home cinema information guide .

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