Chord Qutest

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I suspect he Qutest all be the best DAC under $5K for those who do not need balanced output or volume control (or may be able to use software VC).  I just recommended it to my brother as a really great upgrade for his setup.

 

I hope we will still see a new Hugo TT, as volume control and balanced outputs are needed by many audiophiles, including myself, and i prefer onboard power supplies (and please no battery/supercap nonsense)...

 

Without the TT Chord is missing a critical price point between DAVE-Qutest for a home system DAC (non-portable)

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10 hours ago, firedog said:

Wow, big statement conidering the new iFi DSD Pro was announced and it does have the features "missing" from the Chord, among others. Maybe lets wait till people hear them to decide which DAC is best. 

Qutest uses the same design as Hugo2, so there is no need to hear it, it has already been heard.  My statement was clear, that it is all that for those who do not need other "features".  

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4 minutes ago, firedog said:

Still quite an assumption. How many times have we seen "it's the same, but" and it turns out not to be as good?

Not an assumption, the sound quality of the H2 is well documented and the Qutest uses the same architecture.  The only difference pertaining to sound quality will be power supply, and with the Qutest one is able to use the power supply of their choice, which actually means better than H2 sound quality will be possible if a really good LPS is used...

I am going to build a really trick PS for my brother's unit...

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I am not sure what they mean there, there is a separate micro USB jack for the power supply: do they mean to say it can also be powered from the USB jack used for the audio input?  I would suspect not, but do not pretend to know.

In any case, I will build a sweet "perfect" linear power supply to gift to my brother with a USB jack on it so it is super easy for him to incorporate with his unit (no stupid adapters or anything, all he will need is a standard USB-microUSB cable for power).

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3 minutes ago, mozes said:

To me Hugo 2 is more versatile with a volume control, headphone amp and desktop mode. You can also use it to drive high efficiency speakers!

Right, I would say the beauty of the Qutest is that it gives one the performance of the H2, for less money, for those who do not need extra features.  I need volume control and balanced outputs, for example, so it is not for me, but my brother has an nice integrated amp with single ended inputs, it is perfect for him.  And it does not use batteries which are no advantage and just a plain hassle in my experience.

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There is no technical reason to say that galvanic isolation of the USB is a detriment to sound quality, quite the opposite is true.

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Isolated USB inputs inside a DAC are a completely different thing than an ISO regen. They are a good things and when done right only will improve sound quality (that is why they are used).

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38 minutes ago, ElviaCaprice said:

What if it's not needed because the USB stream is clean, would it then be a detriment to SQ?  

From all I read and from other companies avoiding GI, I can't help but think it can also be a detriment.  Thus no free lunch.

Nothing is clean.  When it is done right there is no detriment, only gains.  Some companies are lazy and look for excuses.  The USB receiver itself is not clean and needs to be isolated from the DAC circuitry.

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2 hours ago, ElviaCaprice said:

Never.  I don't stream.  Closed system.  Don't even allow a network connection to taint my server system.  For comparison, I see all the problems they ran into for the sCLK-EX trifecta system.  Turns out there is alot more going on with ethernet and wifi network connections.  Not interested in that mess.  Have my simple USB sCLK-EX server system playing perfectly for these ears.  Keep it simple!!

  Server=>DAC=>Speakers  

If I wanted to, I do have a reclocked sCLK-EX point on the LAN for streaming to the server if I ever get the itch.  Nah, what for?

That is a bunch of nonsense.  By your own admission you have no experience, so I would suggest, perhaps, not commenting on something you have no experience of.

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9 hours ago, ElviaCaprice said:

I was asked and I gave my opinion.  Just as you have.  I also disagree with you on the galvanic isolation or at least am not yet convinced that there is a free lunch.

You would do well to educate on the actual technical aspects of such things.  Spreading beliefs which have no basis in technical reality is a dis-service to the community.

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38 minutes ago, ElviaCaprice said:

I find our testing thru live listening, comparison goes far further in educated experience/help than any back seat technical science explanations, which do far more dis-service to the community.

I have no problems with listening evaluations when combined informed technical understanding.  But complete lack of understanding of either approach will steer people wrong.

 

A well implemented isolated USB input is proper engineering has no possible negative impact on sound quality.  If you think it does have a negative impact, you are just wrong, it is not a matter of opinion or listening.

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3 minutes ago, ElviaCaprice said:

On this, I have no experience to compare, so it may well be as you say.  But I am skeptical.

What is the source of this skepticism?

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5 minutes ago, ElviaCaprice said:

Various postings from John Swenson here on the forum.

I work with JS, and I have never heard him say anything negative regarding the proper implementation of a USB interface in a DAC.  Perhaps you have mis-interpreted him...

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20 minutes ago, ElviaCaprice said:

Various postings from John Swenson here on the forum.

I work with JS, and I have never heard him say anything negative regarding the proper implementation of a USB interface in a DAC.  Perhaps you have mis-interpreted him...

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17 minutes ago, ElviaCaprice said:

Is possible?  Like I said, I have no listening experience to suggest it doesn't work properly.  But JS did do some extensive posting on GI and how it can differ greatly in actual application.  There have been other postings from Alex on GI in application with the ISO Regen and it's issues.  Also there have been posts from Roy in consultation with SOtM engineers and how they view GI negatively and thus you never see them use GI but instead prefer filtering.

What I am talking about has no relationship to ISO-Regen, I am talking about an isolated USB receiver section in a DAC: in such an interface the USB signal is not running through isolators, the I2S signal is.  Here is the technical description (for example our USB receiver will be an XMOS chip):

 

USB input-XMOS chip, powered from USB 5VDC-I2S-isolators-Reclocking and masterclock(s), powered from dedicated "clean" power supply-I2S-DAC chip.

 

In this example, the jitter inherent in the the output of the XMOS chip is removed on the "clean" side, by direct reclock from the masterclock, right before the I2S lines input to the DAC chip (DAC chip for example only, could be discrete DAC, whatever).  This approach insures jitter at the DAC chip is as low as possible.  This approach also reduces processor noise from the XMOS chip and USB source, keeping it away from the masterclocks and DAC.

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1 minute ago, ElviaCaprice said:

And that gets to the crux of the matter.  Does the reclocking by the masterclock remove all the negative effects caused by the GI?  

Yes.  That is the entire point.  The only "negative effect" is jitter.  By re-clocking direct from a local, free-running, masterclock jitter at the DAC chip is reduced to that which is inherent in the masterclock, plus slight additions for parasitic elements etc. (which would be present no matter what).

If you do not believe in the effectiveness of re-clocking, you might as well not believe in USB audio either, as it relies on clocking the samples out of a buffer via a clock: if you believe this cannot be done well, then basically forget about digital audio entirely.

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In the I2S data there are only two things, the data, and the jitter.  The data is either present or it is not.  If data is lost there will be an audible "tic" or dropout.  As far as the I2S data is concerned that is the only possibility (if there is a "problem").  as long as one does not have a "tic" or dropout, the data is not corrupted.

Jitter is a separate issue and has already been discussed.

There is no "subtle data integrity loss" which could result in a sonic change, you either have continuous music, indicating no data problem, or you have "tics" or dropouts, nothing in between.

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1 hour ago, ElviaCaprice said:

It doesn't have to be either black or white, only.  I just don't agree with this mentality and all of yesterdays science won't convince me otherwise.  We can argue all day and it will come down to this.  

Yes it does, this is not a "mentality" it is a technical fact.  I will not argue it, as it is inarguable.  Sorry no "alternate facts" here.

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21 minutes ago, ElviaCaprice said:

Are you really that full of yourself?  The concept of zero, a set, a point and two parallel lines never intersect  are not technical facts.  They are accepted truths, unproven.  

I look forward to innovative scientific findings, not back seat coaching.

I am in the front seat.  Just because we may not understand all things in audio from a technical perspective is no reason to dismiss the things we actually do fully understand.

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1 hour ago, beerandmusic said:

 

This is very interesting to me.  I wasn't aware of that.  Are you suggesting that if i am playing native dsd 256 and that if i don't hear any "tics or dropouts" that I can assume that every bit of information was processed correctly?

 

I always thought that bits could be lost and we will miss some actual sonics, details, depth, or other "non-perfect" playback.  I didn't know that if bits were lost due to clocking, noise, or whathave you, that you would always here a tic or something....i have never ever heard any "tics" or dropouts, so i guess that is a good thing.

 

Is what you are saying "known as fact" that all engineers agree with, or is that just your belief?

 

Yes, if you do not hear any little "tics" or dropouts, there is no lost data.  Almost all computer audio products in common use by computer audiophiles will not ever have any data loss.  The same cannot be said, for say, Bluetooth (most of us who have ever used Bluetooth music transfer have heard "tics" and dropouts, right?)  Same is true for Ethernet and USB.

 

Sound quality differences are not about data loss, or data integrity problems, all sound quality differences are related to noise issues affecting digital audio clocks, DAC chips, and the analog sections of DACs.

 

Addendum:  It does not mean that the data was processed correctly, if what you mean by processed is converted to analog.  It means that all the data got through the interface to the DAC, where sonic problems happen is in the conversion to analog.

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Any data problem, dropped samples, will result in an audible "tic" or dropout.  There is not subtle degradation of sonics caused by data integrity problems, as there is no error correction: any missing sample will be missing, and result in a "tic" or dropout.

The very earliest USB audio interfaces had these problems, and dropouts were common, but these problems were solved long ago.

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No.  The better the masterclock (specifically the lower the phase noise of the clock) at the DAC chip, the more accurate the conversion.  For any given masterclock, any noise present will degrade its performance, so will vibration.

So best performance will be realized with the best clock, powered by the best power supply, with 0 noise present, and no vibrations, and perfect coupling to the DAC chip's clock input pin.  Everything matters, and of course, there is no such thing as perfection.  All clocks have some phase noise, all power supplies have some noise, every circuit layout has some parasitic problems, and some vibration is always present.  Best performance is realized by reducing all of these factors.

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The point is, reducing noise is exactly what high end audio is about, it is not easy, or affordable to do so.  Same thing with clocks, even a $1500 NDK DuCoLon ovenized clock still has significant phase noise.  everything matters, the more attention which is paid to these details, the better performance gets, but it costs more to do so.

Besides these factors, you have the design of the digital filter(s) and the dAC conversion it self is never perfect, and then you have the analog output section which is also far from perfect.

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12 hours ago, opus101 said:

 

Since the I2S isn't perfectly isolated, you also have a commonly-overlooked third aspect to consider - common-mode noise currents in the ground wire.

 

Note - these ground currents are by no means a problem for the digital circuitry, they're way below the level needed to corrupt data. But they end up corrupting the analog signal in many cases.

There is no "ground wire" in this scenario.  There is no ground connection from the USB receiver side to the DAC side.  Not sure what you mean?  Of course the "isolation" may not be "perfect", and may have some capacitive coupling.  

In my system, there is no ground continuity between the USB ground, and the ground of the DAC. 

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Nope, I am talking about I2S.  But the ground from the USB receiver is isolated, that is the point.  The I2S lines are:

 

1. data

2. word clock

3. bit clock

4. masterclock

+ground

 

With isolation on the I2S lines, !,2, and 3 come from the USB receiver through the isolators, 4 comes from the clean side of the interface and goes through the isolator to the USB receiver.  Ground is isolated form the USB receiver side to the clean side.