Chord Electronics Qutest DAC - Official Thread
Jan 11, 2018 at 12:41 AM Post #91 of 6,705
I think you are right, and the fact Chord all out refuse to answer my questions both here and on facebook suggests the Qutest, like the Mojo, will use DoP for Mac DSD transmission, (rather than native transmission with an ASIO driver) meaning the DSD128/256 drop outs issue will remain so I will not be purchasing this or any other chord DAC.
I talked to Chord about this issue as I do not use a Mac; apparently ASIO is not supported on iOS. The issue of dropouts is the source sending faulty data; when the DAC sees a fault in the DoP format I used to have a full mute, thus making the dropout obvious. However, I have fine tuned the treatment of faulty data, so that now a hard mute is not created, and you may hear a tiny tick when the source transmits faulty data. In practice it is very hard to detect now. But the treatment still means that DSD changes does not create clicks and pops. It took quite a lot of effort to mute when DSD changed, but to be tolerant of small errors in the data.
 
Jan 11, 2018 at 1:45 AM Post #92 of 6,705
I talked to Chord about this issue as I do not use a Mac; apparently ASIO is not supported on iOS. The issue of dropouts is the source sending faulty data; when the DAC sees a fault in the DoP format I used to have a full mute, thus making the dropout obvious. However, I have fine tuned the treatment of faulty data, so that now a hard mute is not created, and you may hear a tiny tick when the source transmits faulty data. In practice it is very hard to detect now. But the treatment still means that DSD changes does not create clicks and pops. It took quite a lot of effort to mute when DSD changed, but to be tolerant of small errors in the data.

Not very clear to be honest,

a) I have used other DSD Dacs and they have not exhibited this drop outs problem, so surely it's the way the Mojo or Qutest works with OS X, rather than "the source sending faulty data", which implies it's somehow a problem with my mac or software or files, rather than the Chord Electronics equipment...

b) Still Chord refuses to answer the simple question - will the Qutest transmit DSD on a mac natively or via DoP (assuming the DSD will be native DSD either way, rather than a PCM conversion)?

c) Exasound have implemented ASIO drivers with OS X (if not iOS), so native DSD transmission on a mac is possible
 
Jan 11, 2018 at 2:12 AM Post #93 of 6,705
Has BNC input but no coax input? Bummer
 
Jan 11, 2018 at 2:23 AM Post #94 of 6,705
Has BNC input but no coax input? Bummer

BNC is coaxial, but with a BNC connector instead of an RCA connector. An RCA to BNC adaptor should be fine.
 
Jan 11, 2018 at 2:54 AM Post #96 of 6,705
what's the tap length of the mojo?

Around the same as the Hugo2 and Qutest, but run at half speed for equivalent performance to Hugo1.

Sources:

Actually it's about twice as many as Hugo but run at half the speed giving approximately the same number crunching power in terms of DSP ..... We have mentioned this before, but didn't want to put much focus on it as this is a small only part of the over design of Rob's overall topology
it was always our intention to try to match the performance of Hugo To do this without using as much power as Hugo. Therefore Rob used more DSP cores but run differently to match the performance of Hugo but at far lower power demands. JF
 
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Jan 11, 2018 at 3:51 AM Post #97 of 6,705
Eagerly awaiting to hear the Qutest on my setup. Hugo 2 performance at a lower price? Yes please!
 
Jan 11, 2018 at 5:58 AM Post #100 of 6,705
since

it's slower does that mean the sound is worse? is there more latency?

For latency I don’t think so, although that’s a question for Rob I would think. I like the sound of the Mojo but haven’t heard the Hugo1. The Mojo measures better but some users prefer the brighter sound of the Hugo. Both have the same power output and 4e Pulse Array. At the end of the day it’s not just the TAP length that influences the sound.

Might want to compare the Mojo and Hugo in their respective threads so this one stays on topic with the Qutest.
 
Jan 11, 2018 at 6:54 AM Post #101 of 6,705
b) Still Chord refuses to answer the simple question - will the Qutest transmit DSD on a mac natively or via DoP (assuming the DSD will be native DSD either way, rather than a PCM conversion)?

The Qutest doesn't not transmit anything digital, it only receives it. Your question is really: Can a Mac send DSD?

The answer is: There isn't any native DSD support in MacOS. You need software that can transmit DSD such as Audirvana Plus or Roon. Such software doesn't have to use DoP though, but can send DSD directly. DoP is used to fool hardware into treating DSD as if it were PCM, allowing easy transmission, even though the actual data is not PCM at all.
 
Jan 11, 2018 at 7:00 AM Post #102 of 6,705
I think this is a similar concept behind NAD's digital direct amplifiers. Of course their digital process is different than Chord's but same idea.

Where I think that type of tech has the potential to shine is in active speakers with direct digital active cross overs.

The Kef LS50 Wireless (I think) does something similar with active crossovers, dsp phase correction and such.

I think a potential fantasy product could be a Chord/KEF collaborative LS50 wireless that uses Chord's tech for the digital stuff. Could be a world beater. But I digress.

The entire point of a power amp would be to drive passive speakers with it, not active ones.

If the upcoming power pulse array products are DACs with the power amp in the DAC's analog output stage (similar to prior Chord DAC/amps, but with a lot more power on tap...pun intended), that means they would not be able to be paired with any other DAC, including any by Chord. (Though I presume you would be able to connect DDCs like the Blu MkII to improve the sound.) This complicates matters. But since they are going to be more expensive and I don't know when they will be available, perhaps I will get a Qutest anyway in the meantime.

I took a brief look at the NAD products you mentioned. How do they work? Are they DACs with the amplification in the DAC's analog output stage? If so, this is the first time I'm hearing of a product like this that's not a Chord one. If not, why is it called direct digital?

Does the Qutest remember the selected output voltage when you power it off and on?

Yes:

To set the OP voltage you press the two buttons together when it's starting up - display in rainbow mode - then qutest will remain in that level. Pressing the buttons together will change the brightness of the display when in normal or working mode.
 
Jan 11, 2018 at 7:17 AM Post #104 of 6,705
that means they would not be able to be paired with any other DAC, including any by Chord.

Actually, the digital power amp has been discussed extensively in the DAVE thread intended to use the dual quad coaxial output, but I’m still fuzzy on the details regarding the DAVE’s role with the digital power amp.
 
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Jan 11, 2018 at 7:20 AM Post #105 of 6,705
since

it's slower does that mean the sound is worse? is there more latency?

No. It simply uses the DSP cores at 104 MHz rather than at 208 MHz, in order to save power. Mojo design is all about saving power, in order to save battery life and because the unit is small, so can't dissipate the heat. You can design a WTA filter of a given tap length with a number of DSP cores at 104 MHz - if you then run the cores at 208 MHz you simply need half the number of cores - the filter performance is identical.
 

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