Poussin (artist name) welcomes us in his studio to present us the different parts of his work as a sound engineer in his different activities such as mixing, Dolby Atmos Mix, Mastering and Audio Preservation.
Poussin’s Digital Encoding System Studio exists since 2000 and is specialized in :
- the digitization of tape preservation, more than 20,000 tapes have been digitized
- multichannel concert mixing with more than 400 concerts mixed, from 5.1 to Dolby Atmos, for DVD, bluray and cinema.
- Multichannel music mixing since the beginning on SACD, DVD, Bluray, cinema
- Mixing and mastering in stereo, digital or analog
- The expertise of formats since Dolby Digital and DTS, then Dolby TrueHD and DTS HDMA, and also Atmos and SACD for a few years.
Here is the second part of the tour, you can find the first part of the tour here, with the presentation of analog tape recorders, from the calibration, the reading to the digitization of 1/4 to 2 inch tapes.
The next step in the digitization process is the restoration of the digitized tapes.
Restoration
The restoration will use the digitized tapes, the obtained files are in high resolution 24 bits 192 kHz not compressed, this resolution allows to record all the nuances of the tape. These files constitute the backup for the patrimony.
The first treatment consists in removing the small peaks which can be present on the tape, we treat the whole of the tracks of the tape (from 4 to 48 tracks according to the albums) to obtain the maximum quality.
When recording, the type of tape used, the recording level (0 dB, +3 dB, +6 dB) and the use of a noise reducer (Dolby A, Dolby SR or DBX) will affect the noise floor of the tape. Without a noise reducer, the background noise can be more or less loud. It may be necessary to reduce the background noise. But, it is not a systematic and automatic treatment. Even a very good noise reducer can impact the signal and remove small details that are on the edge of noise. And in this case, it is better to keep some noise to not deteriorate the music.
Now that the music is digitized and restored, The music can be used to reissue albums, as for example with Serge Gainsbourg, the high resolution files generated by Poussin were used by Abbey Road Studio for the release of box sets with the vinyls cut in half speed. These files are also used to mix in Dolby Atmos.
Before detailing the mixing in Dolby Atmos, we start with the presentation of the Dolby Atmos Music certified studio.
The Dolby Atmos studio
The Studio 1 Atmos is equipped with Dolby Atmos 9.1.8, which means 9 floor level speakers and 8 top speakers, with a subwoofer channel.
Speakers
The speakers used are Dynaudio for the 9 speakers and 8 Tannoy coaxial speakers for the top. The dynaudio speakers used are :
AIR 25 for the front : three-way active monitor with two 10″ woofers (amp 2x300w), 5.5″ midrange (amp 300w) and 1.1 soft dome tweeter (amp 300w) with crossover frequency at 400 Hz and 2400 Hz (full DSP managed). They are used with the AES digital input.
AIR 20 for the surround: three-way semi-active monitor with 10″ woofers (200w), 5.5″ midrange and 1.1 soft dome tweeter (amp 200w for midrange and tweeter) with crossover frequency at 390 Hz (DSP managed) and 2600 Hz. They are used with the AES digital input.
AIR 6 for the other surround: two-way active monitor with 6″ woofers (amp 200w) and 1.1 soft dome tweeter (amp 200w) with crossover frequency at 2150 Hz (DSP managed). They are used with the AES digital input.
Tannoy DVS 6-WH, these coaxial speakers were chosen by Poussin for their coherence of diffusion with the coaxial loudspeaker. These 8 speakers are powered by 2 LAB Gruppen E Serie 10:4 4*200 watts amps (with analog imput).
2 x AIR BASE 24 for the subwoofers : AIR BASE 24 – Active subwoofer with 2x 12″ woofer (amp 700w), frequency response 20 Hz – 200 Hz +/- 3 dB. It is used with the AES digital input.
Console and worlflow
Now that the speakers are presented, we can continue with the presentation of the other materials.
The mixing console is a fully digital SSL C200HD which is capable of handling up to 512 I/O (inputs, outputs). The console can work up to a sampling rate of 96 kHz with 96 channel of processing. With the option DAW for the Pro Tools. 4 carte Madi, 2 carte AES, 6 carte DSP.
Avid Pro Tools is the heart of the digital system, it manages the audio tracks and the mixes. It is installed on a MAC PRO and uses the SSL C200 console for automation (Pro Tools control from the console with automatic adjustment of the level faders and the console directly modifies the changes in Pro Tools). The Mac Pro is equipped with 3 HDX digital audio cards.
The Dolby Atmos Renderer of the Mastering Suite is the central core to allow monitoring in Dolby Atmos. It manages all the Atmos channels and objects to reproduce them according to the Studio configuration in 9.1.8. It also allows binaural monitoring for headphone listening. The Renderer runs on a Mac Pro Inter Xeon 16 cores with 96 GB of RAM with RME card.
JBL Intonato is a Monitor Management and Tuning System. It allows you to calibrate all the speakers with a bass management and an egualization of each speaker to have a coherent rendering. It also manages the delays applied to each speaker to have a homogeneous and coherent diffusion of the 18 speakers. The Monitor Management not only allows you to manage the listening level, but also to isolate a speaker or a group of speakers to better analyze the mix. It can work with digital inputs (AES) and digital (AES) or analog outputs. The system is qualified for a reference level of 85 dB. The control box allows you to adjust the sound level and also to isolate the channels (surround, top, stereo….) for a control listening.
SSL XLogic Delta-Link MADI HD converts the digital format coming from the Pro Tools HDX cards to the MADI format. Each Delta Link is capable for handling 2 MADI ports with 128 (2×64) channels at 24 bits and 48 kHz. There is one Deltal Link to handle the 128 channels of Dolby Atmos (see explanations below), and 2 Delta Links to send 256 channels in 24-bit and 48kHz or 128 channels in 24-bit and 96kHz to the console SSL.
The Marantz prampli can decode Dolby Atmos tracks broadcast on Apple Music for example to have a musical rendering of the files available to users. Poussin can optimize its mixes by taking into account the constraints of streaming.
Here is the audio workflow of the studio. All connections are digital, except for the TOP speaker outputs which are analog outputs from the JBL Intonato to feed the LAB Gruppen amplifiers.
There are two modes of operation for the studio:
- The Atmos mode (left side of the diagram) which goes through Dolby rendered.
- The Stereo or 5.1 or 7.1 mode (right side of the diagram) which connects the Pro Tools to the SSL C200 console.
The diagram above shows only a part of the studio, many other equipments are not included in the diagram.
How works Dolby Atmos
The Dolby Atmos has 128 audio channels which can be organized according to 2 types of sound data:
- The BED which is configured in 7.1.2 and which corresponds to a fixed configuration of the speakers, it is an extension of the 7.1 which we know with 2 TOP speakers.
- The sound objects contain a mono sound track. They can be placed in the 3D space in a fixed or dynamic way. They are independent of the arrangement of the speakers. There can be up to 118 sound objects.
The rendering of these sound objects is calculated by the Dolby Atmos Renderer according to the configuration of the speakers from the smallest to the largest system (64 speakers).
It is the sound engineer who decides how to distribute the music tracks among the objects.
The Dolby Atmos presents different information:
This area represents the use of the channels. In purple we find the 10 channels constituting the BED in 7.1.2 (channel 1 to 10). Below, we find the 118 possible objects, in blue the used and active objects.
This area represents the available speakers with their disposition. It is from this information that the objects will be interpreted to be reproduced on the speakers in 9.1.8 configuration.
This zone indicates the output level of each speaker, here in 9.1.8 configuration, as well as the loudness level.
This area represents the processor load of the Mac Pro and the use of the 3 HDX sound cards.
The last zone represents all the sound objects and the bed present in the sound reproduction space. We can follow the movement of each object in real time with its sound level.
Mixing in Dolby Atmos
Now, we can return on our examples of albums of Serges Gainsbourg. With the album L’Homme à la tête de chou, Poussin has 24 tracks which will be remixed to be disposed in the sound space to benefit from the opening of the Dolby Atmos. But, it should not be forgotten that Poussin works on albums which were already mixed in stereo and thus known. It is necessary to make a work which respects these albums while bringing an opening of the 3D sound spatialization. The work is done track by track.
The first step is to listen to the original stereo mix, to listen to all the instruments, to note the panning (which can change during the song), the reverbs used and other effects. This first analysis will allow to reposition all the tracks to find the spirit of the original mix. It is from this base that Poussin will add the specialization of the sound by working on the opening of the sound scene, by seeking to immerse us more in the music. To do this, Poussin will configure the different channels available in Dolby Atmos and also replace the classic reverbs by 3D reverberations working in Dolby Atmos. This allows to build a more enveloping sound universe. But, throughout this process, the comparison between the original stereo version and the Dolby Atmos version is done to make sure to respect the same sound distribution.
No question to move an instrument to the left, if it is on the right in the original mix. This comparison is done on headphones between the original stereo version and the binaural Dolby Atmos version, or on speaker between the stereo and the 9.1.8. This comparison is important to keep the original distribution with a more important opening of the sound scene. Here is an example between binaural and stereo.
Sound mixing in Dolby Atmos is different from stereo mixing. Indeed, for stereo mixing, you can choose to position a track on the right, in the center or on the left depending on the panning, add effects, reverb. For Dolby Atmos, you have to think about sound objects and define them. A track on a tape is converted into one or more sound objects depending on its content (instruments, voices, etc.). These sound objects are worked in 3D to obtain the desired spatial sound rendering. Poussin has been familiar with multichannel music mixing (5.1, 7.1) for 20 years and since the beginning of Atmos Music a few years ago. It’s all this experience that allows him to convert albums that were recorded on 24-track tapes as well as on 16, 8 or even 4-track tapes to Dolby Atmos.
Here are two other examples made with an 8 track multi-track tape and a 4 track tape. The result obtained is surprising when you think that the tape dates from 1962 and 1970!
Why is the result so good? This is due to the fact that the original multitrack tapes are used for playback and digitization as described in the first part of the report. Multitrack tapes are less used than stereo masters. These stereo master tapes have been used for more than 50 years to make vinyls, cassettes, CDs, remasterings, reissues. They are more damaged than the multitrack versions. But it also depends on the quality of the original tapes.
During the presentation of the digitization of Serge Gainsbourg’s album N°4, we had specified that there were two tapes, the first one recorded in the studio contained the 8 original songs of the album, the second one contains 4 songs added during the reissues of the album. This second tape was recorded in the studio in England. If we compare these 2 recordings, we notice that the tape of the original tracks is perfect, the voice is clear and present, while on the additional tracks, there is saturation of the voice, as shown in these two examples.
In this case, there is no secret, you have to make do with the existing material, and it is difficult to correct defects like this. But fortunately, the majority of the recordings are of excellent quality.
To deliver the result of the ATMOS mix, a file in AMD format (Audio Definition Model) is generated. This one contains the BED and the objects with the spatialization indications, all this information is not compressed. In addition to the ADM file, the original stereo version, and the binaural version are also provided.
The ADM file produced is then compressed in DD+ for distribution by the platforms. The question is: are there any major differences between this DD+ file and the ADM file?
We compare in the studio, between the master and the version broadcast by Apple Music. The difference is obvious, the result is good, but we lose a little in dynamics, in precision of spatialization, in nuance in the musical return. How to explain this difference?
It’s quite simple to understand. Let’s take an example of a song, for 4 minutes of music an ADM file weighs more than 1 Gb, the ADM file is an uncompressed file containing the bed and the objects in 24 bits 48 khz. The corresponding DD+ file is encoded in 768 kb/s and obtains a file of 20 Mb. There is a ratio of more than 50 between the two files. There is no secret, the encoding in DD+ compresses the sound with an important loss of information to obtain this compression ratio. It is normal to have differences in the listening. To reduce the impact on the sound rendering, Poussin optimizes the use of the BED and the objects to obtain the best possible rendering after compression in DD+.
The alternative would be to use DD TrueHD with compression is lossy. The bit rate of Dolby True HD is not comparable to that of DD+, which easily goes up to 6000kb/s and even 10000kb/s. With DD TrueHD we find a rendering closer to the studio master. To realize this, the review of the album The Tipping Point compares the Atmos streaming version at 768 kb/s and the Bluray audio version at 6600 kb/s).
Let’s continue with Atmos mixing, but for the broadcasting of concerts in theaters. We will take as an example the concert of Bercy 2003 of Johnny Halliday.
Poussin did the Dolby Atmos mix of this concert. Here, no tapes as multitrack source, but a digital Pro Tools recording of more than 60 tracks. The 60 tracks contain the voices, instruments and ambience capture. Poussin used all these tracks to recreate the Dolby Atmos Mix, the Dolby Atmos mix contains the BED and 30 objects. We find the same principle as for the mixing of the previous examples, but with the added constraint of being consistent with the images of the concert. That’s why the studio is also equipped with a video projector. We were able to listen to the Dolby Atmos master in Pro Tools of several samples of the concert, the rendering is stunning, Poussin points out that the capture is very good, with a very beautiful rendering of the voice. This can be heard perfectly when listening, with a superb atmosphere that immerses us in the concert and an incredible rendering of Jonhny’s voice, he is really in front of us, we have the impression of being on scene right in front of him and feeling his presence. This rendering in Dolby Atmos is really extraordinary in terms of quality and immersion. To realize the rendering, with the previously mentioned limitations of the DD+ compressed format, the concert is also available in streaming on Apple, Amazon and Tidal. The ideal is to listen to it on a 7.1.4 system. For compatibility with 7.1 and 5.1, Poussin started by doing a 7.1 mix which served as the basis for the mix to Atmos and the manual downmix to 5.1.
Let’s detail the Atmos mix with the Mylene Farmer concert : Live 2019. Jérome Devoise did the Dolby Atmos mix of this concert for a broadcast in theaters and on the UltraHD bluray media. The Dolby Atmos mix contains the BED and more 30 objects. The realization of Atmos sound tracks for the cinema is more complex.
The mix was done at Studio DES, and there is an additional validation step, the mix must then be validated by Dolby in a cinema auditorium. The validation was done in the Digital Factory auditorium which is equipped with Dolby Atmos with a 25.2.16 cinema configuration.
The film is projected with its complete soundtrack and the Dolby engineer checks the criteria to validate the Dolby Atmos mix. When the mix is validated, a specific Dolby Atmos encoding for cinema is made. It is this version that was used for the projection of the concert film in the cinema.
This Dolby Atmos mix was also used for the release of the concert on Bluray UltraHD (first french concert in UltraHD and Dolby Atmos).
The track is encoded in Dolby Digital True HD, which guarantees the most faithful reproduction compared to the Dolby Atmos master. This Dolby Atmos track is not available for streaming today. The bluray has 5.1, 7.1 and Atmos tracks.
SACD mastering
Poussin also performs special mastering requests such as for Barbara‘s album Bobino 1967 on SACD. The request was very precise, the customer gave the examples of editions by indicating the desired sound or not. The objective is to make a SACD from the final analog mix, to make the mastering in analog to record it in DSD for a distribution in Japan in SACD. SACD is still a very popular format in Japan where many high-end SACD decks exist. To realize this mastering Poussin started with a 1/4 inch tape at 38 CM/S without noise reduction and mastered with an analog chain made of MANLEY (Mastering version).
A treatment was made at the level of the equalization, a light compression to obtain a natural rendering of the voice and the music.
The digitization and processing was done on SADiE Series 5 dedicated to the creation of masters for SACD. SADiE works directly in the DSD format from recording to SACD master creation.
Bluray Audio mastering
In the 2010s, many album editions were made in the Audio Bluray format.
Poussin made masters for the Audio Bluray. He has worked on various albums such as Songs In The Key Of Life by Stevie Wonder (2013), The Look Of Love by Diana Krall (2013) and Bob Marley & The Wailers_Legend [ The Definitive Remasters ] (2013).
For these Audio Blurays, Poussin did the mastering, giving the best sound rendering for each album. The mastering was done in 24 bits 96 kHz. From this stereo master provided by Poussin, an authoring of the audio bluray was done with a Dolby Digital True HD and DTS Master Audio encoding. The Audio Bluray has the same audio track with 3 formats, the PCM corresponding to the initial master and the Dolby and DTS encoded versions.
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