Since more and more companies are switching to Dirac Live in their receivers – Onkyo and Pioneer being two of the latest ones to do so – I thought it would be important to compare Dirac to Audyssey and YPAO. I don’t see a lot of reviewers or sites fully explaining the pros and cons of each technology. I also rarely see reviewers fully understanding how to set up Audyssey correctly to level the playing field. Lastly, I have a few gripes with Dirac Live that I would like to see addressed before it takes over the world.
Room Correction Technologies
Room correction started out at simply correcting for frequency response anomalies due to speaker and room interactions. This can be something as simple as graphic EQ (GEQ) or something a little more sophisticated called a Parametric Equaliser (PEQ).
However, correcting only the frequency response of a system won’t result in great sound. This is because phase and time-alignment issues caused by crossovers, room modes and first-order reflections will smear the original sound as it hits listener’s ears. What is more, using frequency-based corrections such as GEQ but especially PEQ can make these issues much worse affecting a system’s imaging.
This is why – for example – you never see YPAO making pin-point accurate changes with its PEQ system. If it did, it would affect imaging and steering in multi-channel soundtracks.
So modern room correction technologies focus on both phase and time-alignment issues as well as the frequency response and take the loudspeaker system and the room as one system while doing so. To do this, they use a mathematical tool called convolution and affect the impulse response of the loudspeaker in both the time and frequency domain.
While diving into convolution as well as FIR and IIR filters is outside the scope of this article, I hope this gets you started if you are interested in finding out more.
Dirac Live is laser focused on creating a clean impulse response at the listeners ears and I have to say it is the more advanced between the 3 technologies. They took their time to arrive at the algorithms they use to create the best imaging they possibly can and it shows. Let’s look at the pros and cons:
|1||Easy to create great sound – easy to use|
|2||The best imaging between the 3 technologies at the least effort|
|3||The standard frequency curve is good – without loudness compensation|
|4||Great with a single subwoofer|
|1||Still a lack of loudness compensation which in my opinion is critical to accurate cinema sound|
|2||Still a lack of advanced base management with the integration of 2 or more subwoofers|
So Dirac Live is simply excellent in creating pinpoint imaging and therefore helps with steering of multi-channel soundtracks. It is a truly impressive technology.
Dirac is also great in the subwoofer region – does as well as Audyssey and definitely much better than YPAO.
However, my main issue with it is the lack of advanced base management integrated into the package. It is something that equipment manufacturers have to integrate themselves – some do it more successfully than others. Secondly, and this is a huge one for me, there is no loudness compensation technologies like Audyssey Dynamic EQ / Dynamic Volume or YPAO Volume, which I think is absolutely critical for accurate cinema sound.
Instead, Dirac has gone towards creating a base “house curve” with a lifted low end and allows the user to do the same. This is a complete misunderstanding of how the human auditory system works and is going into the wrong approach. In fact, I find that a lack of research in this area is a step or two backwards compared to what THX and Audyssey has done. I would like to see them addressing it.
Read more about Loudness Compensation and why it is important here.
However, having said all that, loudness compensation is available as part of the THX or Dolby package in the form of THX Loudness Plus and Dolby Volume, which the receiver manufacturers could re-introduce and would be compatible with Dirac. This is what Onkyo seems to have done with the TX-RZ50 – bravo Onkyo.
Although the issue is that Dirac’s base curve is not quite there when loudness compensation is engaged and might need to be altered for it to work adequately. However, THX Loudness Plus is not quite as aggressive as Audyssey Dynamic EQ and Dynamic Volume in its default setting so it might work without major issues.
Update 24 Nov 21 – looking at the manual for the RZ50, unfortunately Dirac Live is disabled when THX listening modes are active. This is very disappointing in my opinion. The search continues for a receiver that can engage loudness compensation with Dirac Live.
YPAO R.S.C. uses a combination of FIR filtering, which is not shown on the front-end of the receiver and a layer of PEQ on top of that. The filtering is done to deal with room-modes, crossovers, phase and time-alignment issues. The PEQ is used in a broad fashion to correct the tonal balance between the speakers and the colouring introduced by the room. Let’s have a look at pros and cons:
|1||Easy to create great sound – easy to use|
|2||Good imaging and steering|
|3||The base frequency curve is good and suitable to use with or without loudness compensation|
|1||Still not great with subwoofers|
Yamaha’s approach to both the frequency response curve and loudness compensation / dynamic range compression is balanced. They don’t try and go overboard with either. Yamaha has weight to the sound and doesn’t try to overcorrect into too harsh or too mellow territory. Even their loudness compensation solution – YPAO Volume – is tuned conservatively to match most content: whether music or movies.
However, the biggest issue with YPAO is that it is still not great at calibrating subwoofers after all these years. I would recommend Yamaha get in touch with Audyssey for a crash course as it’s starting to border on ridiculous after all this time. YPAO regularly gets things wrong with subwoofers and over or under-corrects. Therefore great subwoofer positioning is required to get the most out of YPAO. The only saving grace here is that YPAO allows you to copy one of their frequency curves to a manual slot while keeping both the FIR filters and the PEQ filters. In the manual slot, the PEQ filters become editable and with proper equipment allows you to correct issues in the subwoofer calibration.
To get the very best out of YPAO, refer to YPAO – The Lost Manual.
Audyssey’s heritage comes from THX (Tom Holman eXperiment), Tom Holman being one of the founders of Audyssey. Audyssey is based on very sound research that takes into consideration the need for impulse response, tonal characteristics as well as the science of cinema sound and that of the human auditory system.
However, where Audyssey has fallen down has been with the design of the algorithms that balance imaging with frequency based corrections and that the system was designed with the reverberation characteristics of their single test-room.
This unfortunately makes Audyssey less user-friendly to set up and requires careful setup of room, and careful choice of microphone positions. To add insult to injury, the default microphone positions provided in almost all the manuals result in an unideal sound. Let’s look at pros and cons:
|1||Great sound – but only if set up correctly|
|2||Great imaging and steering – but only if set up correctly|
|3||Very much aiming at reference – but only achieved if Dynamic EQ and Volume are engaged|
|4||The most advanced Loudness Compensation and Dynamic Range Compression algorithm on the market – besting even THX and Dolby.|
|5||Unparalleled base management – phase and time-alignment of multiple subwoofers|
|1||To get great sound requires work- work that most people won’t or can’t actually do:|
– careful setup of room
– careful positioning of microphone
|2||Ultimately, tries to present itself as user friendly but isn’t quite there at the level of YPAO or Dirac Live as mishaps in setup can result in harshness and fatiguing sound.|
I am 100% on board with what Audyssey is trying to achieve: reference sound based on sound research. What I have found with Audyssey however is that they didn’t improve their algorithms when users faced issues. Instead, they came up with the Audyssey mobile app that allows users to create their own house curve. While this is useful if you are unable to get great sound in your room, it kind of ignores the problem. The main issue being that Audyssey’s ultimate search for reference sound requires it to tackle the white elephant in the room: RT60. That is that reverberation characteristics of the listening space will alter the energy in the high frequencies and therefore how sound is perceived.
Having said this, if the room is set up correctly, and microphone positions are carefully chosen Audyssey can sound almost as great as Dirac Live can – and offers a more complete package. However, I think very few people have ever heard Audyssey at its best. This is why I have written Secrets of Audyssey so more people can experience it. If you have an Audyssey receiver, I would highly recommend you get and follow the guide to the letter.
Which Technology is Best?
I am afraid there is no perfect technology. Each needs improvement.
Audyssey needs to keep improving its research and algorithms, especially when it comes to reverberation characteristics of listening spaces. Also, the balancing of imaging and frequency response should not have to be so hard with regards to microphone positioning or need Audyssey Pro and 10+ mic positions.
Dirac Live MUST implement some sort of loudness compensation and dynamic range compression to be taken seriously by the home cinema semi-pros and pros. Also, base management needs (much) more work.
Yamaha must lay down its pride and have a chat with Audyssey or alternatively, get someone who understands base management and correction. YPAO R.S.C. needs to do much better with subs and not just yearly incremental improvement otherwise it will never be taken seriously.
A Note on Reference Mixes
This likely requires an article of its own, but it needs to be mentioned. Unfortunately, more and more movie companies are putting out sound mixes – especially on streaming services – that are mixed for TVs and sound bars. This is at a time where more and more people are getting high-end home cinemas installed. Unfortunately, these new mixes are heavily dynamically compressed to the point that they are difficult to listen to on a large system.
Disney and Apple are the main culprits here, but Netflix has done similar mixes also. Unfortunately, this new state of affairs is completely unacceptable – especially as physical media is slowly going away. However, Disney has put these mixes on physical media as well, which is borderline criminal. All the hard work that the movie industry – as well as Dolby and THX – did from the 70s onwards to standardise cinema sound is being thrown out the window so that watching movies on TVs is acceptable.
The correct solution would be to implement loudness compensation and dynamic range compression within the streaming applications – as opposed to nuking the original soundtrack for the movie. The other option is to offer two mixes: one for TVs and soundbars, and one for dedicated home cinema systems.
Otherwise, this is going to be slowly swinging the other way and getting the other half of their customers upset. If you are as unhappy with the sound quality of content on Disney+ as I am, please put a complaint in directly to Disney. If this is not resolved by them within the next few years, I will stop my subscription and boycott content that is not mixed to an appropriate quality. I would encourage you to do the same.
Otherwise, this is going to result in the Wild Wild West of cinema sound before standardisation, and will throw us back 40 years. I am surprised that we even have to call this out for a studio as well regarded as Disney but there we are. I am very worried what they will do with all the 20th Century Fox content they have acquired. Let’s hope they heed our complaints and do something about it.