Chord Electronics Qutest D/A processor Measurements

Sidebar 3: Measurements

I measured the Chord Electronics Qutest using my Audio Precision SYS2722 system (see the January 2008 "As We See It"), using both the Audio Precision's optical and electrical digital outputs and USB data sourced from my MacBook Pro running on battery power with Pure Music 3.0 playing WAV and AIFF test-tone files.

Apple's USB Prober utility identified the Chord as "Qutest" from "Chord Electronics Ltd," with the serial number "413-001." The Qutest's USB port operated in the optimal isochronous asynchronous mode. Apple's AudioMIDI utility revealed that, via USB, the Qutest accepted 32-bit integer data sampled at all rates from 32 to 768kHz. The optical input locked to datastreams with sample rates up to 96kHz (192kHz is listed in the specifications), the coaxial S/PDIF inputs to streams of up to 192kHz-sampled data.

A 1kHz digital signal at 0dBFS resulted in an output level of 3.01V into 100k ohms with the output level set to "3V," 2.01V with it set to "2V," and 1.01V with it set to "1V." (Except where indicated, all the measurements were taken with the maximum output level set to 3V.) The output impedance was an extraordinarily low 0.4 ohm at 20Hz and 1kHz, rising to 0.9 ohm at 20kHz, and the analog outputs preserved absolute polarity (ie, were non-inverting).

The Chord's impulse response with 44.1kHz data and the Incisive Neutral reconstruction filter (Filter button glows white, fig.1) indicates that this filter is a conventional linear-phase type, with a large amount of time-symmetrical ringing to either side of the single sample at 0dBFS. The Incisive Neutral HF roll-off filter's impulse (Filter glows green, not shown) was similar, while the Warm filter's impulse response (Filter glows orange) was still a linear-phase type, but with asymmetrical ringing (fig.2). The Warm HF roll-off filter (Filter glows red, not shown) was also asymmetrical, but with more ringing before the single high sample than after.

1218ChoQutfig01.jpg

Fig.1 Chord Qutest, Incisive Neutral filter, impulse response (one sample at 0dBFS, 44.1kHz sampling, 4ms time window).

1218ChoQutfig02.jpg

Fig.2 Chord Qutest, Warm filter, impulse response (one sample at 0dBFS, 44.1kHz sampling, 4ms time window).

With 44.1kHz-sampled white noise (footnote 1) and the Incisive Neutral filter (fig.3, red and magenta traces), the Qutest's response rolled off extremely sharply above 20kHz, reaching full stop-band suppression by half the sample rate (vertical green line). An aliased image at 25kHz of a full-scale tone at 19.1kHz (blue and cyan traces) can't therefore be seen. The second and third harmonics of the 19.1kHz tone are visible above the ultrasonic noise floor, though both are very low in level, at just below –90dB (0.003%) and –100dB (0.001%), respectively. Repeating this test with the other three filters gave identical results, though the Warm HF roll-off filter had a very slight droop in its white-noise response just before 20kHz (fig.4).

1218ChoQutfig03.jpg

Fig.3 Chord Qutest, Incisive Neutral filter, wideband spectrum of white noise at –4dBFS (left channel red, right magenta) and 19.1kHz tone at 0dBFS (left blue, right cyan), with data sampled at 44.1kHz (20dB/vertical div.).

1218ChoQutfig04.jpg

Fig.4 Chord Qutest, Warm HF filter, wideband spectrum of white noise at –4dBFS (left channel red, right magenta) and 19.1kHz tone at 0dBFS (left blue, right cyan), with data sampled at 44.1kHz (20dB/vertical div.).

When I examined the Chord's frequency response with S/PDIF data at 44.1, 96, and 192kHz, the 44.1kHz output dropped like a stone above 19.5kHz (fig.5, gray and green traces). The responses at the two higher sample rates followed the same shape, flat to 20kHz, with then a slow rolloff, disturbed by a sharp drop at each Nyquist frequency (cyan, magenta, blue, and red traces). With the two HF roll-off filters (fig.6), the output with all three sample rates was down by 1dB just below 20kHz. Channel separation was superb, at >120dB in both directions below 3kHz, and still 115dB at 20kHz (fig.7).

1218ChoQutfig05.jpg

Fig.5 Chord Qutest, Incisive Neutral filter, frequency response at –12dBFS into 100k ohms with data sampled at: 44.1kHz (left channel green, right gray), 96kHz (left cyan, right magenta), 192kHz (left blue, right red) (1dB/vertical div.).

1218ChoQutfig06.jpg

Fig.6 Chord Qutest, Warm HF roll-off filter, frequency response at –12dBFS into 100k ohms with data sampled at: 44.1kHz (left channel green, right gray), 96kHz (left cyan, right magenta), 192kHz (left blue, right red) (1dB/vertical div.).

1218ChoQutfig07.jpg

Fig.7 Chord Qutest, channel separation, ref. 3V into 100k ohms (L–R blue, R–L red, 5dB/vertical div.).

The low-frequency noise floor was both low in level and free from any power-supply–related artifacts (fig.8). When I increased the bit depth from 16 to 24 with a dithered 1kHz tone at –90dBFS (fig.9), the noise floor dropped by almost 30dB, meaning that the Qutest offers almost 21 bits' worth of resolution, which is close to the state of the art. With undithered data representing a tone at exactly –90.31dBFS (fig.10), the three DC voltage levels described by the data were well resolved, the waveform was perfectly symmetrical, and the very low noise level allowed the filter's linear-phase ringing to be seen. With undithered 24-bit data, the result was a superbly clean sinewave (fig.11).

1218ChoQutfig08.jpg

Fig.8 Chord Qutest, spectrum (0Hz–1kHz) of dithered 1kHz tone at 0dBFS (20dB/vertical div.).

1218ChoQutfig09.jpg

Fig.9 Chord Qutest, spectrum with noise and spuriae of dithered 1kHz tone at –90dBFS with: 16-bit data (left channel cyan, right magenta), 24-bit data (left blue, right red) (20dB/vertical div.).

1218ChoQutfig10.jpg

Fig.10 Chord Qutest, Incisive Neutral filter, waveform of undithered 1kHz sinewave at –90.31dBFS, 16-bit TosLink data (left channel blue, right red).

1218ChoQutfig11.jpg

Fig.11 Chord Qutest, Incisive Neutral filter, waveform of undithered 1kHz sinewave at –90.31dBFS, 16-bit TosLink data (left channel blue, right red).

Harmonic distortion was extremely low in level into the punishing 600 ohm load (fig.12). The second harmonic in this graph lies at a roots-of-the-universe –120dB (0.0001%) in both channels! Intermodulation distortion was similarly vanishingly low in level with all four filters (fig.13). Tested for its rejection of word-clock jitter with 16-bit TosLink data, the Qutest turned in superb performance: all odd-order harmonics of the LSB-level, low-frequency squarewave were at the correct levels (fig.14, sloping green line). With 24-bit J-Test data (fig.15), no jitter-related sidebands were present.

1218ChoQutfig12.jpg

Fig.12 Chord Qutest, spectrum of 50Hz sinewave, DC–1kHz, at 0dBFS into 600 ohms (left channel blue, right red; linear frequency scale).

1218ChoQutfig13.jpg

Fig.13 Chord Qutest, Incisive Neutral filter, HF intermodulation spectrum, DC–30kHz, 19+20kHz at 0dBFS into 100k ohms, 44.1kHz data (left channel blue, right red; linear frequency scale).

1218ChoQutfig14.jpg

Fig.14 Chord Qutest, high-resolution jitter spectrum of analog output signal, 11.025kHz at –6dBFS, sampled at 44.1kHz with LSB toggled at 229Hz: 16-bit TosLink data (left channel blue, right red). Center frequency of trace, 11.025kHz; frequency range, ±3.5kHz.

1218ChoQutfig15.jpg

Fig.15 Chord Qutest, high-resolution jitter spectrum of analog output signal, 11.025kHz at –6dBFS, sampled at 44.1kHz with LSB toggled at 229Hz: 24-bit TosLink data (left channel blue, right red). Center frequency of trace, 11.025kHz; frequency range, ±3.5kHz.

Even without taking into account its small size, the fact that it's powered by a 5V wall wart, and its relatively affordable price, Chord's Qutest offers state-of-the-art measured performance.—John Atkinson



Footnote 1: My thanks to Jürgen Reis of MBL for suggesting this test to me.
COMPANY INFO
Chord Electronics Ltd.
US distributor: Bluebird Music Ltd.
275 Woodward Avenue
Buffalo, NY 14217
(416) 638-8207
ARTICLE CONTENTS

COMMENTS
grussgott's picture

would be great to hear your thoughts compared to the Yggy and RME ADI-2

MZKM's picture

Hi John,

Something I’ve noticed for a while now, but in your wideband spectrum of white noise measurement, Fig. 3 & Fig. 4 in this case, it states -4dBFS, but doesn’t the graph show it at -40dBFS?

John Atkinson's picture
MZKM wrote:
Something I’ve noticed for a while now, but in your wideband spectrum of white noise measurement, Fig. 3 & Fig. 4 in this case, it states -4dBFS, but doesn’t the graph show it at -40dBFS?

In analyses like these, the individual levels of each FFT bin or spectral component are not the same as the signal level. That is equal to the RMS sum of the FFT bins. Each spectral component of the noise signal lies around -40dBFS but together they add up to -4dBFS.

John Atkinson
Editor, Stereophile

Bogolu Haranath's picture

May I suggest reviewing the new Benchmark HPA4 headphone amp/pre-amp? ......... Specs say 256 step volume control and, the head-amp specs also look excellent ......... You could compare it with the passive volume control, you are currently using :-) ...........

John Atkinson's picture
Bogolu Haranath wrote:
May I suggest reviewing the new Benchmark HPA4 headphone amp/pre-amp?

Great suggestion, I'll get on it.

John Atkinson
Editor, Stereophile

Bogolu Haranath's picture

Great ........ Looking forward for the review :-) .........

Bogolu Haranath's picture

May I also suggest reviewing Auralic Polaris? :-) ...........

Integrated amp for the 21st century :-) ............

Kurt@Andersen's picture

Dear John

I could be very cool to have historial "competition review" between the hitorical outstanding BB PCM 1704** dac (derived from PCM63/1702 dating all way back to mid 80 ties) and how this brilliant Burr Brown R2R technology have found its way into modern FPGA implementations in Denafrips Terminator and Soekris 1541 who both are cutting edge implementaions of this fundamental Signed Magnitude R2R ladder, with clever reclocking and femto level clock oscillators to eliminate jitter, etc etc.

Thanks Kurt

tonykaz's picture

When one sounds a tad better is it because of the Interconnects?, the difference in Interconnects?, the associated equipment's interface preferences, the physical location of magnetic fields or what???

I've done this same test yielding day to day performance flips. Am I Neurotic? Are all of us Neurotic? My Esoteric Audio Store Ownership experience provided convincing evidence that Audiophiles are a combination of Neurotic & Psychotic behaviors. ( which is probably why families/wives eventually condemn us to the dam Basement ).

Dave Wasserman ( Stereo Exchange ) just did an Audiophiliac Video about his Decades as a Used Equipment Specialist. He reveals the underlying foundation of our audiophile Hobby. It's a Must-See!

Dam it, that Chord Stuff is nice, probably nicer than the PS Audio stuff but PS is one of our few local outfits. We gotta nod to Paul McGowan, don't we?, I sure do! And... we gotta nod to Schiit despite their shitty name, phew, when are they gonna changeover to Stoddard & Moffat? ( isn't S&M naughty enough for them and their youngish, tatted-up customer base?)

We're just around the corner from everything being Class D, no look'n back but there will STILL be the White-Nuckle Grip on Analog from a tiny group tenaciously holding/collecting/hoarding and loving their Fossil Fuel Based, Ozone killing music Format and their Class A Hot Box Electronics, god love em. Harley-Davidson just announced their new Line of Electric Motorcycles ( not made in USA )

Chord is gorgeous stuff, especially if a person lives somewhere in the British Empire, has there ever been a more beautiful Hi-Fi ? It just seems like a person can't go wrong choosing Chord.

Tony in Michigan

Bogolu Haranath's picture

JA can't seem to cut the 'Chord' :-) ............

May be JA could review the new Chord Hugo2 and Hugo TT2 ........ and review the new Meze Empyrean 'phones with the Chords and compare them with his Audeze LCD-X headphones? :-) ............

foxhall's picture

I'm listening to the Angela Hewitt CD right now. Hyperion recordings are often remarkable as you have written numerous times.

tonykaz's picture

I experienced her playing JSBach, she seemed to play effortlessly and seemed to make the playing sound like two Pianos, Phew!

If a person has to live in England and only listens to the near infinite range of Hyperion Recordings they should own a CHORD Music System, it would make rainy days Heavenly. ( even on a 50 foot Narrowboat )

Tony in Michigan

spacehound's picture

Thank you for the review. It's good to see comparisons.
Though Shannon's 1948 work is not a "thesis", it is a theorem, thus as proven as Pythagoras' triangles, and so is not susceptible to dispute or MQA's "rejection".

However:
Having owned several DACs from £100 to £18,000 since I started 'computer' audio in 2010 I have come to a simple conclusion.
I now will NOT purchase any DAC that uses an 'off the shelf' DAC chip such as the various Sabre, Wolfson, etc chips. Not only are such chips purposefully designed to be cheap enough to be used in portable digital radios, TVs, music centres, car audio, etc, they mean the DAC designer is merely implementing other peoples's ideas as best they can, sometime charging thousands of dollars for a box that depends on a five dollar heart.

And the Chords, DCS, and PS Audio ones sound so much better. Also the superiority of even the £400 Chord Mojo over the 'standard chip' sort is instantly obvious on first hearing, though its ergonomics are not best suited to a 'home' system and its battery longevity is suspect.

Were I starting today, from my experience with the Mojo, the Qutest would be my 'go to' DAC regardless of price, even if unheard before purchase.

Mentt's picture

Be aware that Chord DAC sound is not for everybody. Had original Chord Hugo for couple months and sold it. Had Chord qutest for 6 weeks and sold it. To my taste sound was to much sterile and without emotions. Now I am happy with ciunas ISO DAC

spacehound's picture

They can sound a little 'sterile'. But I believe you are hearing Chord's 'accuracy to the source' (which of course is some kind of recording) rather than introduced harmonics and other distortions. And accuracy, not "I personally like it" is what high fidelity means. We don't pay thousands for 'nice'. Though I would like a Kondo Ongaku amp :)

Mentt's picture

For sure it is not about accuracy as Chord DACs have own particular signature = Chord DACs are not neutral

spacehound's picture

That they are as 'neutral' as anyone gets.
However, as we can never know how the recording studio intended any given piece of music to sound, and even they are limited by their equipment, it remains a 'belief' as does yours :)

I'm not qualified to judge their 'pulse array' DAC process but their subsequent 'many taps' (in this case 48,000 rather than a typical 128) filter process makes a lot of sense.

Mentt's picture

You are judging DAC performance based on number of “taps”? Really? Have you even heard the Chord DAC in question?

spacehound's picture

Here's an analogy:
You want to record the length and shape of the UK's coastline.
With only 128 pins to stick in you will get a very inaccurate result. With 48,000 pins you will do it far more accurately.

As I said I am not sufficiently mathematically qualified to judge their 'pulse array' DAC part.

Ears are useless to judge the 'goodness' of this stuff as we have no reference, not being present in the studios when the recordings were made. Ears only tell us whether we like it or not, which has zero to do with high fidelity.
So all we can do is go for a measured flat frequency response of DAC, amp, and speakers and hope. Don't forget the 'time domain' is merely the inverse of the frequency response so a measurement of either one is sufficient.

No I haven't heard the Qutest but I do own a Mojo, a Dave, and a DCS Rossini. They all sound much the same and I assume the Qutest will fall between the Mojo and the Dave. I started with an 'el cheapo' Cambridge Audio Dacmagic. It sounds much livelier than the other three thus initially more involving, but after a while just sounds a mess.

Mentt's picture

Don’t see point of your argument . Either you like the DAC sound signature or you don’t. It is insane to buy DAC for thousands of dollars only because reviewers like it or that it supposedly to be neutral or whatever

spacehound's picture

Just saying where I am coming from. Others can of course come from a different place, it's their money and their enjoyment.

Also don't ever believe that logic is an important 'driver' of human behaviour :)

As for reviewers, in any field, not just hi-fi, they can be a helpful guide as to what is worth following up, though one's actual purchases are your own decision.

Bogolu Haranath's picture

"The pendulum of the mind alternates between sense and nonsense ..... not between right and wrong" ....... Carl Jung :-) .........

w1000i's picture

If the rest of the system is not neutral, the DAC neutrals will not fix that but exposes that.
The best way to jedge DACs is with headphones. You can sawp headphones and they are single drivers with more transparency and less mechanically complicated and without room issues.

Bogolu Haranath's picture

I agree 100% :-) ............

tonykaz's picture

isn't it impossible to agree 100% ?

But, then again, Agent Orrange followers seem to agree 100% with everything he says, lies and all. Hmm.

R you that famous Radiologist my Cardiologist talks about?

Tony in Michigan

Bogolu Haranath's picture

May be, may be not :-) .........

spacehound's picture

...a lack of neutrality in other parts of the system is good.
A lack of neutrality is a fault and you can't fix it by introducing another fault somewhere else.

Bogolu Haranath's picture

So, how many wrong things we have to do to make it right? :-) ............

spacehound's picture

In fact after many years I have come to the point of almost giving up on 'specialist' hifi. As have most sane human beings, as demonstrated by there being less and less dedicated hifi shops.

I have reached a point where I am happy with what I have and unless something breaks and can't be repaired I don't visualise any more significant (= expensive) purchases.

I'm in the UK. Cambridge Audio does well, as does the unrelated Arcam (A R Cambridge). Naim also, at least the less expensive parts of their range. But to 99% of UK 'fairly well-off' households all the rest are very small, Chord included. Meridian sales are so small as to be invisible.

'High Street' names such as Sony, Yamaha, Denon, etc. have become so good with their AV receivers that very few people bother with anything else, except maybe Monitor Audio and B&W speakers, which are available in many UK high street stores. Such receivers used in 'direct' mode are fine for two channel stereo too.

Bogolu Haranath's picture

Check out ATC self-powered loudspeakers .......... Several UK audiophile magazines have reviewed them very favorably ....... One of the 'other' audiophile magazines in USA has favorably reviewed them recently ......... ATC self-powered speaker models are somewhat expensive :-) ...........

Bogolu Haranath's picture

You could also check the self-powered wi-fi capable KEF LS series models ......... also, the new self-powered Elac Navis is another contender ......... The KEF and Navis are not very expensive :-) ..........

If you want to get into 'smart speakers' (which obey your voice commands), you can check the Apple HomePod, Google Home Max and Amazon Echo models ....... The downside is, those (darn) 'smart speakers' will be listening to you all the time, unless you turn them off :-) ............

johnnythunder's picture

is how I characterize CHORD. Very fast. Very clean. Huge power reserves. Leading edge of transients emphasized. Deep bass. Probably great with Orbital played loud in a British flat during a party with glowsticks. Perfect to be played at Hi Fi shows using Clapton's live acoustic Layla. Not for me but I'm like Herb and prefer my audio equipment to have more "meat on the bones." I feel equipment like this is sometimes very exciting to listen to at first but long term has a high fatigue factor.

Sibelius's picture

I am quite sure this DAC sounds very well as all I have heard about Chord's DACs are good comments regarding their sound. Unfortunately, they insist on this industrial design line. To my eyes, they resemble toys, or game consoles.They are not Qute, even less Qutest. I cannot live with what are to my eyes ridiculous looks and therefore this happens to be their main drawback. Of course tastes are tastes and I assume there are thousands of satisfied consumers who approve their controversial design. Moreover, who are willing to pay for them.

spacehound's picture

Chord have an irritating tendency to let their physical design ideas get in the way of their functionality.
I have had a Mojo for about two years and if I want to know the sample rate I still, after all this time, have to look at the box it came in to equate the colour of the button with the sample rate. (44.1 is red and DSD is white though there is no way of telling whether it's DSD64, DSD128, etc. I have to check the box to determine all the others.)
It's even worse with the Qutest, they do the same with the filters too.
I suppose they are trying to be 'clever'. FAIL.

Bogolu Haranath's picture

So, colorblind audiophiles can't use it :-) ...........

Sibelius's picture

Neither functional, then. Also, I really do not get the magnifying glass concept. I would understand a loupe in order to see a machine moving inside, such as in an automatic watch. But I do not think a microchip is interesting enough as to need to see it inside my DAC.

johnnythunder's picture

Skittles.

johnnythunder's picture

I agree. I think their equipment is some of the most ostentatious, misguided, over-complicated industrial design in audio today. To each their own obviously, but the only thing it looks better next to is a Rega Isis style of god know what its supposed to look like style of design. Let me know if I'm leaving something uglier out.

jorgen's picture

tested by John would be very interesting!

Charles E Flynn's picture

“Chord Electronics FPGA DAC Technology Explained” (Video: 5 min. 27 sec.) at https://www.youtube.com/watch?v=hCYUujl1zTM&t=11s .

hollowman's picture

I was just looking thru two early-90s Stereophile issues (Dec. 1992; Mar. 1993) ... not a single analog/phono review or article (tho' I did see an Acoustic Sounds ad with LPs and equip.). Some tube gear. And MANY multibit DACs or CDPs -- reviews, articles, ads, classifieds.
I have a late-1980s aftermarket-modified Philips CDP, with the classic TDA1541A and SAA7220 (4x DF) chipset. It is better sounding than all more-modern DACs in my collection (that feature delta-sigma).
Indeed, those early-90s Stereophiles were full of glowing reviews of Arcams and MSBs and Naims ... all using that classic Philips platform.

I have some non-oversampling (multibit) gear, too. And it has that whatchamacallit sound charc. that appeals to some. Not me. BUT, I'll take well-done NOS over poorly-done DS any day.

My suggestion for JA and other Stereophile reviewers is to go into their attic or basement storage ... and dig out legacy gear. And use THEM as a basis of comparisons against Chord, Border Patrol, Benchmark, etc.

Oh ... JA ... please webify that 1995 Fabio article. He had VERY high-end $$$ system based on a Krell CDP. No phono, no tubes.

spacehound's picture

….the poor ergonomics of some Chord DACs don't matter in actual use, which is listening, not testing.
Take the Qutest filters. Most people will find the one they like best and stick to it. Let's say you find that you like the 'green' one best. Having selected it once, the next time you switch it on it will also be green as it remembers the last setting. Even if you want to try different filters all the time it is not the filter specification that matters, it is whether you like the result or not. And it's just as easy to remember "this sounds most to my liking on the blue filter" as it is to remember the "quick rolloff HF filter".

And as for sample rates, you play what you have, some of which will be 44.1, some 96, or whatever. The only time you actually need to know it is in the initial setup or your player, such as JRiver or Tidal MQA/non-MQA, for example. It's the player and/or the recording that sets the sample rate, not the DAC. Once setup to play the recordings at their 'native' rate (or, for example, if you prefer some upsampling rate) you don't need to know what the rate actually is anymore. You are listening to "Beethoven's Ninth", not "44.1" or "MQA".

tonykaz's picture

What's poor ?

Seems a luxury arrangement to have Color, lights, mystical Spheres and exotic metal packaging.

Would customers pay Premium Prices for something dreadful?

Chord's uniqueness is a Statement, isn't it?

Kinda like an Audiophile tattoo proclaiming something Architectural and Social Level about it's Owner.

It's almost like Chihuly Art Glass Objects.

I have to approve & admire the daring Owners.

Tony in Michigan

johnnythunder's picture

feeling is better than apathy or purely style-less products like Bryston. I actually don't mind the look of the little DACs - quirky as they are. I've been tempted by some of the good reviews but those reviews come from people (usually British) who like the overall Chord "house sound" of clarity and detail. A warm fleshy sound gets me every time and sounds like live music from a great seat in the middle of the orchestra or a back in the balcony where the sound is blended and sometimes diffuse in a good way. Chord, ATC stuff sounds like my head is in the speaker.

hollowman's picture

I've never owned, touched much less heard a Chord product. Nevertheless, I like the overall "Apple-like" product design.
For example, with the form factor of DAVE (and similar DACs going back to 2001), Chord managed to squeeze in all components (incl. a switching PS) into a nice, compact unit. It's not a big, heavy thing like many high-end DACs.

Bogolu Haranath's picture

Chord designs kinda look like the space ship in the Spielberg film 'Close encounters of the third kind' :-) .........

krahbeknudsen's picture

Dear JA,

Thank you for another great review. As the PS Audio DS is very much a moving target due to regular firmware updates it would be helpful if Stereophile would always specify which FW version was used when comparing this DAC in reviews.

Thanks!

Ali's picture

Love it or hate this Qutest, just use it with external USB battery power bank; more detail...getting it closer to dCS.

X