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AudioQuest adds MQA Support to Dragonflies via firmware


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So out of this discussion comes an obvious question for AQ: Is " 'full decode' on the current gen DF roadmap with a firmware update?" The answer to this question could/should be the determining factor for a consumer purchase decision.

 

I'm looking at the decoder from the Bluesound firmware, and there is no way it can fit on the Dragonfly microcontroller.

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Some general remarks regarding MQA decoding:

 

- from reading a bunch of the patents, its clear the first unfold, if required, is the most computationaĺly intensive part of MQA. This is the almost lossless unfold from 48 to 96 kHz.

 

- The lossy unfolding (from 96 to 192 kHz and beyond) is mathematically related to upsampling with some custom reconstruction filters. Every DAC already has the hardware to do this sort of thing.

 

- The final DAC deblur thing is I think a particular reconstruction filter.

 

- All this to say that it makes sense that computationaĺly starved dacs might have to rely on a software unfold for the first unfolding.

 

- It shouldn't in theory make any difference in sound quality whether the first unfold is done in hw or sw. But who knows?

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I'm sure there will be many more software MQA players soon. No reason for there not to be. The software decoder is only doing one unfold, anyway - nothing else. So, for instance 24/44.1 to 24 88.2. All the rest of the MQA decoding is done in HW.

BTW, it's been hinted that with MQA files being sent to the Dragonfly as max sample rates of 88 and 96, that you will actually be able to play MQA unfolded to 176 and 192 on the Dragonfly. Why? Because the limitation of the Dragonfly is the USB receiver chip that can't go above 96, and not the Dac itself.

 

If that was the case that the dragonfly could play internally at 176 or 196, it would have to do internal unfolding. But I thought that was the limitation, that it can't do the unfolding. So I don't think it'll really get to play songs at above 96khz and get the full data as what the explorer 2 could.

 

Now the MQA dac compensation process may have the Dac running at the 4x rates for playback for improved temporal performance and different digital filtering, but the raw source data reaching it will be the max 96khz version unless it can do internal unfolding, in which case there is no need for a software decoder anyway.

 

Hope that makes sense.

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The Explorer2 has an XMOS chip which is considerably more capable. It would still be a tight fit though.

 

The first explorer had an xmos chip too but apparently not powerful enough for MQA which is why there was an explorer2 with a higher performance xmos chip created.

 

The explorer used about 150ma playing while the explorer 2 about 230ma, with the analog hardware being mostly the same. So that power is probably mainly for running the more powerful xmos chip.

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If that was the case that the dragonfly could play internally at 176 or 196, it would have to do internal unfolding. But I thought that was the limitation, that it can't do the unfolding. So I don't think it'll really get to play songs at above 96khz and get the full data as what the explorer 2 could.

 

Now the MQA dac compensation process may have the Dac running at the 4x rates for playback for improved temporal performance and different digital filtering, but the raw source data reaching it will be the max 96khz version unless it can do internal unfolding, in which case there is no need for a software decoder anyway.

 

Hope that makes sense.

 

Its the other way around. The easy part is the internal unfolding. The hard part if the first fold unfold. Hence the Dragonfly will.do the additional unfolds and deblur but relies on a software decoder to do the heavy lifting.

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Hi Miguelito.

 

Funny you should ask.

 

Two nights ago I selected several albums using the Tidal - "What's New / Masters" selection process on my MAC Air and checked the "passthrough" selection for my Explorer2 DAC. Under both checked and unchecked the blue light on my explorer did NOT come on as it is supposed to - it simply showed as a white light.

 

Not sure what is going on as I do not pretend to be a technical guru. If anyone could shed some "light" on what I could possibly be doing wrong it would be appreciated.

 

 

 

Ajax

 

Two possibility come to mind.

 

1. You didn't use "exclusive mode" so the dac isn't getting bit perfect data.

 

2. You didn't update your explorer 2 to firmware 1717 which is needed for MQA support.

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Its the other way around. The easy part is the internal unfolding. The hard part if the first fold unfold. Hence the Dragonfly will.do the additional folds and deblur but relies on a software decoder to do the heavy lifting.

 

If that's the case, it's good news for dragonfly owners.

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If that was the case that the dragonfly could play internally at 176 or 196, it would have to do internal unfolding. But I thought that was the limitation, that it can't do the unfolding. So I don't think it'll really get to play songs at above 96khz and get the full data as what the explorer 2 could.

 

Now the MQA dac compensation process may have the Dac running at the 4x rates for playback for improved temporal performance and different digital filtering, but the raw source data reaching it will be the max 96khz version unless it can do internal unfolding, in which case there is no need for a software decoder anyway.

 

Hope that makes sense.

Not exactly.

 

Comments From Bob Stuart

The strength of MQA is that one file can be played back in a wide variety of situations by the customer.

 

The three presentations you discussed: No decode; MQA Core; Full decode are all previewed in the studio. Each is optimally set up for that presentation (with appropriate de-ringing).

 

MQA Core (which comes out of the soft decoder or digital outputs) carries the additional information necessary for an MQA Renderer (eg Dragonfly) or a full Decoder (eg MSB, Brinkman, Mytek, Meridian) to 'finish the job downstream'.

 

Full software decode is not possible because the DAC must be known and characterized. MQA is an analog to analog process.

 

Read more at MQA Decoding Explained | AudioStream

 

What is being said by some is that the 88 or 96 limit of the Dragonfly is the USB input, not the DAC itself inside the Dragonfly (after the input).

Apparently the Dragonfly works with MQA software in playback that does the first unfold. (say 24/48 ot 24/96 or 24 44.1 to 24/88.2). This takes some load off the Dragonfly, which "only" has to apply the MQA deblurring that's been encoded into the Dragonfly firmware. The implication was made that the actual DAC inside the Dragonfly CAN playback 176 and 192, and that since the MQA system often has those higher rates folded into the file that appears to be a 96 or 88 file to the Dragonfly at it's inputs, the Dragonfly could unfold them to 176 or 192.

 

"Full decoders" can do all the unfolding and deblurring, which is why when you use an MQA DAC with Tidal, you tell Tidal to "bypass" MQA decoding. The Tidal MQA decoding is the first unfold.

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What is being said by some is that the 88 or 96 limit of the Dragonfly is the USB input, not the DAC itself inside the Dragonfly (after the input).

Apparently the Dragonfly works with MQA software in playback that does the first unfold. (say 24/48 ot 24/96 or 24 44.1 to 24/88.2). This takes some load off the Dragonfly, which "only" has to apply the MQA deblurring that's been encoded into the Dragonfly firmware. The implication was made that the actual DAC inside the Dragonfly CAN playback 176 and 192, and that since the MQA system often has those higher rates folded into the file that appears to be a 96 or 88 file to the Dragonfly at it's inputs, the Dragonfly could unfold them to 176 or 192.

 

If the microcontroller is too slow to simply pass 192 kHz straight through to the DAC chip, how could it possibly be fast enough to upsample, by any algorithm, anything to that rate?

 

The ESS DAC chip itself obviously handles higher rates. The trouble is getting the data to it.

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Not that I'm enamored of MQA's terms, but these conversations get really confusing. I propose that we begin to use the terms "MQA Core", "MQA Renderer", and "full decoding" instead of confusing terms like "first unfolding", "second unfolding", "de-blurring", "software decoding", etc.

 

I'd be delighted if Bob Stuart stopped inventing new names for things on a weekly basis.

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If the microcontroller is too slow to simply pass 192 kHz straight through to the DAC chip, how could it possibly be fast enough to upsample, by any algorithm, anything to that rate?

 

The ESS DAC chip itself obviously handles higher rates. The trouble is getting the data to it.

 

The DAC's designer has gone on record that the 96 Khz limitation is more due to compatibility than hardware constraints. Its a USB DAC thing, to do with drivers etc.

 

The Dragonfly has enough power inside, and a capable enough internal DAC, to do MQA unfolding to at least 192kHz, given that it has been fed an MQA signal that has already been software decoded to the MQA Core.

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The DAC's designer has gone on record that the 96 Khz limitation is more due to compatibility than hardware constraints. Its a USB DAC thing, to do with drivers etc.

 

The Dragonfly has enough power inside, and a capable enough internal DAC, to do MQA unfolding to at least 192kHz, given that it has been fed an MQA signal that has already been software decoded to the MQA Core.

It's an 80 MHz CPU with 32 KB RAM. You won't be doing a lot of processing with that.

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It's an 80 MHz CPU with 32 KB RAM. You won't be doing a lot of processing with that.

 

You keep stating that, but AudioQuest have confirmed it *will* support higher resolutions using MQA.

 

I guess we'll see when the update comes out.

John Walker - IT Executive

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When the update arrives and someone measures the sample rate at the DAC pins.

 

Of course! I know you won't trust the little lights ;) LOL

John Walker - IT Executive

Headphone - SonicTransporter i9 running Roon Server > Netgear Orbi > Blue Jeans Cable Ethernet > mRendu Roon endpoint > Topping D90 > Topping A90d > Dan Clark Expanse / HiFiMan H6SE v2 / HiFiman Arya Stealth

Home Theater / Music -SonicTransporter i9 running Roon Server > Netgear Orbi > Blue Jeans Cable HDMI > Denon X3700h > Anthem Amp for front channels > Revel F208-based 5.2.4 Atmos speaker system

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To add even more to this conversation and answering a few other questions from above:

 

-Explorer 2 definitely does full MQA decoding, has since early last year with the 1717 firmware.

 

-It has been alluded to that the Explorer 2 runs internally at 384khz in MQA deblur mode (what the dac chip is capable of) even though it can only support up to 192khz MQA decode.

 

If the Dragonfly can playback 192khz stuff even though the usb interface is only 96khz, it wouldn't be out of the question for the Explorer 2 to be able to natively play 384khz material even though it's interface is limited to 192khz. I doubt it does this though or it'd be advertised.

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