I believe this has to be a Q&A turnaround record... Many many thanks to Bob for answering these questions so quickly and so thoroughly!

Sorry if your question didn't make the list: we had to prune anything we felt was not close enough to MQA subject matter, not related to product roadmaps, had already been answered, or could be answered from existing knowledge. As it turned out, we managed to squeeze in more than 10 questions, and Bob answered *nearly* all of them.

Question material in red.
Bob's answers in italics.


Added by Bob


Q0. What is MQA?

A0. As will become clear in our answers, MQA is one of the technologies in Meridian's Versatile Distribution system. MQA is also our 'umbrella' term for the suite of technologies and underlying audio coding philosophy, which itself goes beyond recording. Master Quality Authenticated captures the ethos of the enterprise and the MQA stream is central to distribution.

The MQA technologies include: Archive extraction and creation, forensic and recording tools; advanced A/D and D/A conversion; Encapsulation to a kernel; MQA lossless coding; MQL (triply-compatible lossless bandwidth-extension) lossless compression; Playback Rendering. A glossary will follow.



The MQA encoding process and distribution of MQA media


Q1. Clearly, artists using larger recording studios will benefit from MQA. Given the need to keep sensitive cryptographic keys secure, will MQA be available to smaller (even home) recording artists who cannot afford expensive studio time, either directly, or via an "MQA encapsulation" service?

A1. There are several parts to this answer, technical and policy.

1. The MQA syntax supports a hierarchy of authentication keys using strong encryption. The encryption protects the encoding/decoding instructions, various metadata and verification of both lossless digital transmission from studio to decoder and 'beyond digital lossless', it authenticates the analogue-to-analogue path -- which is a major step forward in sound quality.

2. At the lowest level the keys verify that the stream is genuinely MQA. This is important for the full benefit of Authentication to be realised and we hope that facility will ignite new and enriched ways for artists to communicate with fans and for listeners to appreciate 'the real thing'. MQA is neither a DRM nor conditional-access system; listeners can still enjoy the music without a decoder in a variety of legacy playback scenarios, in actual CD quality. However the keys protect the ecosystem.

3. The hierarchy of keys, in principle allow us to have streams which are verifiable for different things, ranging from, e.g. genuine MQA in a local ecosystem, to a fully-authenticated path from artist/studio to the listener. This highest level we call 'MQA Studio'. In principle these levels can be displayed on a UI and licensed decoders are required to indicate this. In the middle are levels of authentication that can be applied by a distribution house, mastering studio, broadcast, etc.

4. How intermediate keys will be used is not fully settled and we are in consultation with music industry partners.

5. We fully expect to have a variety of options available for smaller-scale encoding requirements but can't comment just yet. Suffice it to say that the MQA initiative is supported by music companies and it is our intention to make access very inclusive and convenient.



Q2. Can MQA files be written/distributed as red book CDs and, if so, is this an expected distribution medium? (Small artists love to sell their material at gigs.) Or are streaming and downloads expected to dominate MQA distribution?

A2. Another question with technical and policy intertwined!

1. The MQA encoding process can be applied to any PCM file of more than 12-bits. So 44.1 kHz 16 bit can be losslessly conveyed using MQA along with metadata and encoder and decoder parameters. If the stream has been Encapsulated then the decoding and rendering parameters are also included in the stream.

2. A 1x MQL file (e.g. from an 88, 176, 352kHz master) can also be placed on a CD by truncating the file at 16-bits. In this case we see the third compatibility option; if the 24-bit MQL file is truncated, an MQA decoder will reconstruct the baseband losslessly, while audio above 22kHz will be a lossy reproduction - giving a very important intermediate envelope-preserving result between CD and 2x lossless.

3. So there is a great opportunity to create CDs that sound significantly better than basic CD and which are fully backward compatible.

4. A normal CD player will handle the MQA stream perfectly and can be fitted with a decoder or feed an outboard decoder/DAC. Note, that the same holds true for an MQA/L file streamed over a legacy 1x 16-bit interface (such as Airplay).

5. Will anyone make CDs encoded with MQA? We shall see. Meridian's 808v5 will be upgraded to include the decoder.

6. Obviously the recordings have to be made or converted first to 44.1k family.



MQA quality questions


As posted by JB: "MQA is a fully compatible file because its core audio information can be played on all current systems/products that are able to play a CD file. Moreover MQA enables this core audio data to deliver a sound that is better than a standard CD file played on the same device."

Q3. Please will you explain how this is possible? i.e. Broadly speaking, what has been done to make a 1x sample rate file better?


A3. An MQA file is inherently pre-apodised and so the legacy DAC is less aggravated by the content. In addition, the MQA proprietary quantisation and dither processes provide improved results. If the file encounters a decoder then the quality is raised further.


Q4. Size of download and limited existence of outstanding 192/24 releases aside(!), is there any significant difference in audio quality between MQA and a well-produced 192/24?

A4. The MQA solution is very efficient of transmission data and also capable of extreme quality in archive and distribution. We can answer this in two ways.

1. Yes, the difference is substantial and important. The improvement comes from the Encapsulation/Rendering processes that are about an order-of-magnitude better in preserving critical timing and amplitude information. We hear this clearly because it achieves actual Resolution (the ability to resolve details and components). This improvement is impossible to do in an open system. Whilst we acknowledge that the need for a decoder is a (short-term until DAC chips include it) complication, there is no way to accomplish this without connecting the final rendering to the analogue input process. MQA is 'beyond digital' and therefore 'beyond lossless'.

2. Yes. If, in the studio we connect a state-of-the-art 192kHz ADC to the microphone feed and then monitor its output on a conventional DAC, there is a loss of quality. MQA in contrast loses nothing - we are currently limited by the microphone. This is why so many producers, artists and mastering engineers are thrilled with MQA. It actually delivers the sound of the studio, and at a relatively low bitrate.



Time resolution of HiFi systems


We'd all love to own SE loudspeakers, but this is not possible for everyone. Many of us have non-SE DSP loudspeakers (either SpeakerLink and/or coaxial MHR) with the older aluminium dome tweeter.

Q5. How close can these non-SE loudspeakers get to the "magical" 5-10s discrimination of the ear? i.e. What is the typical and/or range of resolving ability of non-SE DSP's in the time domain and how does it compare to the SEs?


A5. First we reject the hypothesis in the question: "We'd all love to own SE loudspeakers, but this is not possible for everyone." [Ed: LOL]

1. MQA's system-wide lack of pre- and post-echo, stable background and improved amplitude handling shows up clearly on most systems.

2. The SE has three things: Be[ryllium] tweeter which is necessary to get to the 10s resolution with no pre/post echo; 192k operation of the differential converters; wider bandwidth analogue stages. These changes came out of the MQA development process as we pushed for a complete chain that could reach the transparency of the microphone feed. We have yet to encounter a studio with clearer-sounding monitors.

3. Meridian's DSP speakers are much closer than an analogue system in this regard because in the analogue system, temporal blur accumulates in an arbitrary assembly of DAC, Preamp, Power amp, cable, passive crossover, loudspeaker, group-delay and lack of time-alignment.

4. Non-SE systems have twice the temporal blur on leading edges and some post-ring in the tweeter, however that is more than good enough to hear the benefits of MQA very clearly - just not to get the ultimate.



Q6. We appreciate that how MHR and Meridian DACs work are secrets. However, with an MQA source and new loudspeaker firmware if required, will non-SE MHR-capable DSP loudspeakers deliver greater time resolution with a *decoded* 96k MQA stream than they will with the same *un*-decoded 96k MQA stream? i.e. time resolution improvements over and above the inherent (apodizing) improvements in the un-decoded MQA file. Is this effectively the long promised "firmware update to enable 192k [or better]"?

A6. Yes and possibly! But we don't comment on future product plans smile But you have come to know we always try to support our customers beyond industry standards.


Many of us have analogue loudspeaker systems or headphones. To date, most HiFi manufacturers have been considerably less "enlightened" than Meridian when it comes to the importance of time resolution throughout the chain; there simply aren't going to be measurements of time domain resolution available for the consumer to judge whether or not equipment is "MQA ready". As RH commented, an extended ultrasonic response *might* indicate a commensurate impulse response, but it might not! Conversely, just because an in-ear headphone has a published 20kHz frequency response doesn't imply that the transducers, in isolation of the housing, don't have a fast impulse response.

A7 i. "Many of us have analogue loudspeaker systems". Well, there's never been a better reason to make a concerted move to something much better!!

A7 ii. "Many of us have headphones." The Prime Headphone Amplifier, which has a very wide bandwidth and compact impulse response, is getting MQA decoding by firmware update. How cool is that!



Q7a. How can we evaluate the time resolution of these systems? Would Meridian be able to produce some test MQA material for determining if analogue equipment has adequate time resolution for MQA? E.g. Using the same master, starting with a deliberately smeared time response, and gradually increasing the time resolution up to the full MQA experience; so if you can keep hearing an improvement, then your analogue equipment has good enough time resolution at each stage. Could this also be done with non-MQA files?

A7a. We don't think this is manageable, there are too many variables. We need an awareness campaign -- see next question.


Q7b. Can you comment (in general terms) on the time resolution of analogue equipment? (preamps, power amps, loudspeakers (tweeters, electrostatics) and headphones of various types (dynamic, electrostatic, in-ear, etc.))?

A7b. In general the audio industry has taken an isolated view and not considered the end-end system response. In our recent AES paper on listening to filters we pointed out that a cascade of apparently blameless components, e.g each with a response to 30kHz, could aggregate to an 80us blur and defeat listening tests. What is needed is an industry recognition that time is more important and a sensible measure for a specification. We worked with the Japan Audio Society (JAS) on this and are evolving and evangelising better standards. e.g., to earn the Hi-Res sticker in Japan, an analogue component has to respond beyond 45kHz - thereby ruling out the majority of headphones, many amplifiers and most loudspeakers. There is no choice; it's how we hear and there needs to be a shift in thinking about system design. Just demand the answer.


Compatibility of MQA with pre-MQA Meridian systems


JB posted the following: "As SpeakerLink and MHR have a data transfer speed of 4.6 Mbps and MQA never exceeds 2 Mbps, even at the highest studio quality, then all Meridian DSP loudspeakers since 1999 (when MHR was introduced) are compatible with MQA. <snip> At the moment what you have is 96/24 over MHR. We will be delivering MQA over MHR.

Accepting that an MQA source/decoder is going to be necessary at some point in our systems:

Q8. Can any pre-MQA Meridian processor process the MHR output from an MQA source? i.e. Can you put, say, a G68 or an 861v8 (for room correction, time alignment, DSP presets, etc.), *in between* an MQA MHR source and MHR-capable loudspeakers and not lose the MQA benefits that would exist if the source was connected directly to the loudspeakers? Similarly, would something like a 562V.3, which does not modify the signal, pass an MQA MHR signal (without loss of benefits) to two pairs of MHR-capable loudspeakers (via the main and copy outputs)?


A8.

1. This is similar to Q6.

2. An MQA signal can be passed through any device that effectively is a bypass. A surround processor, except in bypass, changes the data and will revert the MQA to CD-quality if it does not have a decoder.

3. An MQA decoder in a complex system such as a surround processor, naturally divides into its decoder and renderer (including DAC manager) sections with processing in between such as upscaling and bass management. Providing there is a secure communication between these parts they can be in different processors, chips or even different boxes. MHR/SpeakerLink happens to include syntax that permits this with authenticity. However The fact that something is possible doesn't mean we have a shareable plan to do it, or that we necessarily commit to go back through the last 20-years product range for software updates. Watch this space.

4. I can't remember if 562V is MHR-capable!



Other uses of MQA


Q9. If we accept that MQA is superior to other "Hi-Res" recordings, will MQA have a role to play in developing the quality of home cinema sound (or commercial cinema come to that)?

A9. It's absolutely possible but we think unlikely in the near term. We have already taken on a monumental task with the music industry. Having said that, we hope that by educating on the principles behind MQA and encouraging improved DAC/ADC structures that the tide will rise for us all.


Q10. Could MQA be used for live capture and transmission of music (or other) events? Presumably the bandwidth may be too much for everyday broadcasting today, but what about MQA as a future broadcast standard?

A10. Definitely. Although it's not necessarily pre-processed to the same extent, audio can be encapsulated on the fly, especially if you know what's coming (in a statistical sense). Conceptually there is then no difference between streaming and broadcast. One of the keys is for live broadcast.


Questions 11 and 12


Q11a. Will analogue inputs also get the MQA treatment? i.e. DAC correction for the ADC in a Meridian processor.

A11a. The concepts of MQA teach us how to make better systems. Having said that, Meridian already did a great job with many sources. MQA is fantastic for capturing from 78 or vinyl, the surface noise and scratches are completely decoupled smile


Q11b. Will existing 176k and 192k material (via Sooloos/ID4x or USB input) be encapsulated so as to preserve the extra resolution?

A11b. We have an exciting roadmap for the Sooloos product range but do not share roadmaps!


Q12. Is the Trademarked "MQL" an alternative name that was considered for MQA or something "not to be commented on?

A12. See A0. MQL is a stream syntax including MQA; MQA is a stream on its own. More on this later.
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