The meaning of resolution rates?

Roon Software Discussion
1

I’ve recently purchased a Meridian 218 that I am using successfully with Roon. Yesterday I had an exchange with my salesperson at the local dealership and wonder if others can add more information. Many thanks!

The dialogue began with my asking about the following from a review of the 218. (I have placed the dealer’s answers in BOLD type.

"While the 218 handles high-res audio files up to 192kHz/24-bit, only the analog output is treated to the full suite of Meridian audio processing as well as the MQA decoding. Interestingly, while the coaxial output supports 192kHz, it is limited to 96kHz by default, and the higher resolution must be enabled in an advanced configuration page.”

Could you please explain the first sentence and tell me how to enable the 192kHz support in the second?

The digital output, which you are not using, is limited by default to 96kHz.

Tell me if I’ve got this right.

  1. The Meridian receives a digital input from either the albums I have imported on to my USB external drive or from a Tidal file when I stream one. – Correct.

  2. That digital input is determined by the original recording. So when I choose a Hi-Rez album I have bought from HD Tracks for example, that input is either 88.2 kHz, 96 kHz or 192 kHz, depending on what I purchased. - “Hi-Rez” would technically be anything above 16/44.1. So you could have a 16/48, 24/44.1, 24/48 and then all the ones you mentioned.

  3. On music I have imported from CD using Apple Lossless settings the digital input is generally 44.1 kHz. – Yes. That will always be 16/44.1 (you do need to also pay attention to the sampling rate however, which is the 128kbps, 320kbps, 1411kbps and above. Anything less than 1411kbps is less than CD quality even though it is still 16/44.1.

  4. The Meridian takes that signal and outputs it as an analogue signal. – Correct. Through the DAC architecture, the 218 takes whatever hi-rez signal you are sending it and converts it to the analog version of that. On the Digital output (again, which you aren’t using), it will downsample anything above 96kHz and play everything else at or below that naturally.

Let’s take the example of the Tidal album I am listening to right now:

http://www.2l.no/pages/album/106.html Magnificat on the label 2L

I am playing the MQA enabled version. The blue light is on, on the Meridian 218.

Roon tells me the Source is: “Tidal FLAC 44.1kHz 24 bit 2ch, MQA 352.8 kHz”

What exactly does that mean I am hearing? I do not know the answer to that. The Roon guys may be able to answer that question for you, but I’m not sure.

2

If you are using the analog output of your 218, the MQA track is being unfolded to the maximum rate your DAC is able to handle. The DAC inside the 218 is capable of processing up to 192kHz, so in this case the MQA file will be unfolded to 176.4kHz.

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3

@RBM in the case of the 2L file I cited, why 176.4 and not 192? If the file itself (irrespective of the the DAC) is capable of 352.8?

4

AFAIK It will play at the native rate, 384 will be played at 192 by your DAC but 352.8 will be 176.4.

.sjb

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5

Got it! Thanks!!

6

It depends on the bitrate of the original file: MQA files come in FLAC containers at either 44.1kHz or 48kHz. These unfold/upsample at 2x, 4x or 8x rates.

In this case, your DAC maxes out at 4x and the originating file is 44.1khz, so it unfolds to 4x44.1=176.4kHz. Likewise, MQA files at 48kHz will unfold to 192kHz in the 218.

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7

I would asume that the 352.8 listed in Tidal information line is the original file’s sampling resolution as reported in the embedded header information of the MQA file.

So with your file, the first MQA pass will “unfold” the file to either 88.2 or 96 resolution depending (88.2 for 44.1 files and 96 for 48 files). During the second stage, it will up-sample and filter, up to the resolution dictated by the purchased file and the playback hardware. In your case, it is 176.4 which is a multiple of 44.1, which was the base file resolution.

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8

I have a similar question for FLAC, not MQA. Is the 218 limited to 96 kHz using Roon? Roon shows 176 kHz files being downconverted to 96 from 176.

9

Yes, the Sooloos streaming implementation in the 218 is limited to 96k. There is no Sooloos streaming device >96k, period.

10

Thanks, makes sense. New to Roon and Meridian, didn’t realize Roon used Sooloos implementation.

11

Unfortunately has to if it wishes to stream to Meridian Sooloos networked audio endpoints.
It would ha e been fantastic if Meridian could have adopted RAAT on Sooloos.

That said, I believe the new Meridian 210 streamer does support RAAT but frustratingly still limited to 96KHz.