Bob Stuart, creator of MQA, talks in detail about this revolutionary British technology that sets a new standard in capturing, delivering and reproducing digital audio.
MQA is a superb technology for distributing high-quality recordings. Our goal is to bring listeners the sound of the studio and older recordings from the Archive. MQA has sophisticated tools and methods to recover recordings from all eras including cylinder or shellac, analogue tape or digital right up to modern 768 kHz PCM or quad DSD.
Our viewpoint is that ‘Resolution’ is a concept of Perception, best interpreted in the analogue domain. This pioneering insight is better aligned to listening experience than to digital domain definitions of quality. As a result, we don’t include or exclude recorded material on the basis of digital file format or parameters such as sample rate or bit depth. Instead, we focus on temporal resolution, noise stability and analogue blur. 
Provenance and technical standards are completely different things. A music file can be altered after artist release, irrespective of the technology used. Provenance is indicated when MQA is played back.
- The MQA ‘Studio’ (blue light) gives confirmation directly from mastering engineers, producers or artists to their listeners. MQA Studio authenticates that the sound you are hearing is exactly as played in the studio when the music was completed and, by implication, that this is also the definitive version of the recording at that point in time.
- A second level, ‘MQA’ (green light) is available to indicate that although the stream is genuine, provenance may be uncertain or that it is not yet the final release.
Questions on Provenance
Q1. Where does MQA encoding take place?
A1. Music can be encoded as MQA in the studio, in a label’s supply chain or in specific circumstances on behalf of a retailer or service provider.
Q2. What should be encoded as MQA Studio?
A2. The MQA Studio authentication should be reserved for new or remastered recordings prepared after studio preview or, for recordings where the rights holder is able to definitively assert that the source is the original release.
By implication, the further down the supply chain encoding happens, the harder it is to be certain of provenance and so recordings may only be encoded as MQA Studio when provenance is explicitly supported and provided by the content owner. Where there is doubt over the chain of custody, music should be encoded as MQA.
Q3. What is the original release?
A3. Generally, in the production process, a final mix/mastering is agreed between artist, producer and mastering engineers. Often this version precedes distribution releases – some of which may include further processing such as: EQ for LP; Mastering for iTunes (MFIT) or for CD; or format conversion to provide choice in for High-Res download, etc. This can mean that the original project may use different (lower or higher) sampling rate or bit depth than versions in the distribution chain. Conversely, a vinyl or MFIT release may be the only approved version.
Q4. Does MQA perform technical analysis of files?
A4. Our ingest and encoding processes make a number of checks on incoming audio to help avoid errors such as malformed or inconsistent files from being distributed. The encoder also performs a deep technical analysis and is on the look-out for certain tell-tale characteristics.
Q5. Do you reject upsampling?
A5. We do look for egregious or accidental upsampling and raise a query, but this is not a straightforward issue:
- It is virtually impossible to use spectral analysis to absolutely determine if a music file has been simply upsampled in the supply chain – there are several sophisticated upsamplers that attempt to obfuscate their use, however we do our best.
- A modern recording or remaster may employ processing or effects at higher sample rates in some (but not all) of the stems or instruments and it is standard practice to shuttle recordings from digital to analogue and back again (sometimes at a higher rate) to access specific tools.
- Some plug-in effects introduce so-called ‘brick-wall’ or even aliasing effects. Such files may give the impression of having been upsampled even though they actually contain genuine high-rate data.
MQA is concerned with one thing only: ‘Is this the definitive version signed off by the artist, producer or mastering team?’
Q6. What about re-releases?
A6. Occasionally an artist will re-visit an album and use more up-to-date tools in the studio. That is their prerogative and our job is to make sure the final result is delivered faithfully.
Q7. What about download standards
A7. Some retailers apply standards based on technical numbers such as sample rate or bit depth. However, these standards are not strongly correlated with provenance nor indicate the number of generations between the file and the original recording. For example, a file being 24-bit does not imply it is an original master.
Q8. How does MQA provenance differ from DEG or JAS specifications?
A8. The JAS specification and logo program apply to playback hardware. To carry the logo, equipment must be able to handle digital inputs up to 96 kHz 24bit and to have an analogue bandwidth to at least 40 kHz.
The DEG logo program for High-Resolution digital music requires the original release to be in DSD or PCM with a minimum of 48 kHz and 20 bits.
MQA technology focuses on temporal resolution, channel noise stability and end-to-end blur in analogue domain. MQA system encoders and decoders never impact a recording’s dynamic range.
MQA provenance recognises that great music may only be available in early analogue or early digital or Redbook CD format; such recordings, if vouched for by the rights holder, can be marked MQA Studio and enjoy the profound sonic benefits of the MQA chain.