A question about EQ and TIDAL Masters (MQA)

Is EQ in AS applied to a TIDAL Masters (MQA) song? I guess not as it would break the MQA signalling to my external MQA DAC, but I’d like to understand what happens with EQ (Audio Units) if I play an MQA track in AS. Is the EQ bypassed in this case?

I have no experience with MQA. And don’t know how AS handles this either. But this seems to me to be a matter of testing.

Make an extreme EQ setting so you can hear the difference.

I can imagine that it matters how you set the settings to the DAC. If you set this as ‘not MQA’ then EQ could just be applied. As a decoder or renderer then EQ will not be applied?..?..

It turns out that AS disables EQ processing for MQA tracks (which I guess is the correct thing to do). I looked at the processing chain and it showed no processing for TIDAL Masters (MQA) songs, but did show my EQ being applied for regular FLAC songs.

Actually, I’m not sure if it makes sense that a file format determines whether it’s appropriate that you apply an EQ or correction.

But hey, I’m biased about MQA. I don’t understand what’s so good about it.

From what I understand, MQA has its own filters.

Maybe not possible now in Studio, but it should possible to do EQ to MQA tracks, provided:

  1. Studio saves the rendering info to forward to the MQA renderer (i.e. DAC).

  2. EQ is done after the MQA core decoder in Studio does the first “unfold”.

Roon does this!

Yes, this would be a good feature to have. Does Roon have some sort of agreement with MQA to retrieve the MQA signalling information, perform EQ, and then ‘inject’ the MQA signalling information back into the data stream post-EQ?

Note that without EQ, Roon would have to retrieve the MQA rendering information, do the MQA core decoding and then ‘inject’ the MQA rendering information back into the data stream for the renderer*. Saving and injecting the rendering info back into the data stream is likely the job of the MQA core decoder. Thus, the process is not much different with or without EQ. The signalling injected is merely the rendering info, indicating which trivial upsampling, using one of 16 predefined MQA filters, the DAC should do, and the original sample rate.

  • The DAC must support rendering operation from an MQA core decoder (88.2/96kHz) signal. (Not all DACs do.)

I don’t know if there’s a specific agreement with MQA Ltd related to EQ. There is already an agreement/contract to pay royalties on the MQA core decoder, The same is also true for Audirvana.

This is a quote from Roon:

First, Roon will decode the MQA file or stream it to an MQA Core stream. This produces a PCM audio stream at 88.2kHz or 96kHz which contains MQA signaling information that your DAC needs to render the MQA signal properly. Then Roon preserves the signaling information (setting it aside for safekeeping), applies DSP to the audio portion, and then restores the signaling information. This re-embeds it into the stream so that your DAC can complete the rendering process.

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So Roon applies DSP on the first 17bits. (It can do anything with that signal) And than restores bit 18-24 and now the DAC handles the file like an MQA?

No. The rendering info is in one bit. The lower 8 bits containing the compressed high frequencies are decoded and combined with the other frequencies producing a PCM audio stream at 88.2kHz or 96kHz which contains (the one bit of) MQA rendering information. The DSP is applied to the audio portion after the decoding.