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The Chord DAC bandwagon

webster said:
My experience when I purchased a Qutest was that it needed a while to reveal its qualities fully.
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For sure, subtle differences require extended listening to "rise to the surface". I expect I will come to appreciate them.
However I'm also a believer in quick first impressions, and this is a used unit so no 'burn in factor'.
 
eastone said:
Ah, I see, perhaps that explains it. I have a late 2012 Mac Mini, the last user-upgradeable ones apparently, not that I’ve ever got round to doing so!

I really got that ‘wow’ moment with the Metrum Musette. The Chord was very different for sure, but not for me. I recently got an ifi Zen Dac for the bedroom office, now that was a ‘wow’ moment for a £130 DAC. Really laughably good for the price, if lacking a little in ‘refinement’.
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I thought the iFi Zen Blue was great with digital out (and PSU upgrade). The DAC itself, not great, but I think the DAC in the Zen DAC is better.
 
Amber Audio said:
That’s what I look for when I get a new piece of kit, doesn’t happen that often, recently the dCS Bartok and Cadenza Bronze both gave me that feeling and the grin when you know you’ve made a good move.
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...I'm grinning now, adding the DC3 LPSU makes quite a difference (the PSU does cost as much as the DAC so you'd hope so), as does upsampling on the Mac mini. Recommended!
 
Amber Audio said:
Does any Hi-Fi DAC use in-house designed silicon?
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EMM Labs design and build their proprietary DAC's. More on this from Ed Meitner in this video -


"Why design your own DAC and what's wrong with commercial chips?"

"I want to have my freedom. I want to be able to decide what do I want to do with it. And I also do want to change every two years. Not that there's something wrong with chips, there is a place for it, but the place is not in the high end audio business where the philosophy and the whole idea behind is to further the state of the art. So, what do we do? Ok. And it's paid of for us. We have total control over everything in our equipment. And that was the goal I wanted."
 
Cesare said:
First up, i'm a professional DSP engineer, not a chip designer, or FPGA programmer, so I can cover some of this, but not all of it.

The FPGA can be used as a DAC simply because it can produce a bitstream, a fast switching digital output which by varying the amount of high and low bits can represent voltages by the bit density (PDM - see here https://en.wikipedia.org/wiki/Pulse-density_modulation)

For 16 bit audio at 44.1Khz, without clever noise shaping, you need to basically double the sample rate for each bit, so 15 bit @ 88.2Khz can represent the same voltages as 16bit @ 44.1Khz, so at a basic level, you can get 16/44.1Khz quality with a 1/1.4Ghz signal (44.1 * 2^15). Basically, 32768 * oversampling. This will have a flat noise floor across the audio spectrum below the level of the 16 bit data. Now we can improve on this by shaping the noise, which is the delta/sigma approach (feeding back the error to change the output bit) and by doing this we can shift the noise up about the original 22.05Khz nyquist frequency, and by doing this, achieve the same results without needing such a massive oversampling factor. There's lots of strategies, with different computational costs, and other tradeoffs, but the philips bitstream setup achieved the same quality with 64* oversampling, which is a much more manageable 1/2.8Mhz).

Now for higher bit depths, and higher sampling rates you need to increase the frequency, but you get the idea.

The FPGAs operate in the 200Mhz or so range (the larger ones are slower, the smaller ones faster). So, flipping an output bit at 200Mhz gives us plenty of wiggle room to generate high sample rate and high bit depth audio using the same philips delta/sigma approach that has been well explored. I imagine the chord box is performing high order noise shaping, and obviously it's long length FIR filtering too, but this is all easy stuff for an FPGA, actually, it's easy stuff for any computer.

The overall output quality will then be determined by the clock source for the FPGA, so a high quality stable clock will be needed to avoid modulation type errors creeping into the output.
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Another question, if I may.

From what I understand, modern DAC chips are quite sophisticated, employing multiple techniques to achieve their performance. They do include considerable amount of processing power, multiple filter options and often an analog components as well.

Can all of the above be performed in a generic FPGA?
 
eastone said:
I recently got an ifi Zen Dac for the bedroom office, now that was a ‘wow’ moment for a £130 DAC. Really laughably good for the price, if lacking a little in ‘refinement’.
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Have to agree... am also using one in my home office. Though I'm running it through a pre-amp now, I had even spent some time with it direct to the amp. Surprisingly decent there too.
 
I have a Chord TT2 and am very happy with it as an integrated DAC-headphone amp. I like how it eliminates an unnecessary extra box, and is not a ridiculous size and weight. I also like the unique design, especially the glowing coloured orb.

As far as sound quality goes it is my opinion you can’t really comment much about the sound of a DAC without taking into account the source. A DAC is the equivalent of a phono preamp in an analogue rig. Many would argue that having the best phono preamp in the world doesn’t matter much if the turntable is crap. My view is that the source is also the most important component in a digital rig.
 
Thats the absolute counter of my opinion. If the dac is perfect you can feed it any old crap. Laptop, rpi, fancy server, if the dac is impervious to noise and source timing then it makes no difference.
 
andrewd said:
I have a Chord TT2 and am very happy with it as an integrated DAC-headphone amp. I like how it eliminates an unnecessary extra box, and is not a ridiculous size and weight. I also like the unique design, especially the glowing coloured orb.

As far as sound quality goes it is my opinion you can’t really comment much about the sound of a DAC without taking into account the source. A DAC is the equivalent of a phono preamp in an analogue rig. Many would argue that having the best phono preamp in the world doesn’t matter much if the turntable is crap. My view is that the source is also the most important component in a digital rig.
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What is your source?
 
eastone said:
What is your source?
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The audio server. Of course the quality of the recording and mastering is even more important.
This is my opinion based on experience with a reasonable number of audio servers. I am not going to get into a bits are bits debate if anyone is in that camp.
 
sq225917 said:
Thats the absolute counter of my opinion. If the dac is perfect you can feed it any old crap. Laptop, rpi, fancy server, if the dac is impervious to noise and source timing then it makes no difference.
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That is a common opinion, but I have the opposite view based on experience with different servers. This subject used to cause heated debates in years gone by, less so in recent years as more people have had real world experience with well designed high end servers.
 
Amber Audio said:
The EX runs HQ Player? Must have a bit of poke about it or is it an NAA?
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You can run HQP server or NAA embedded and they come pre-installed. Since Chord DAC’s work natively in PCM I use 16xPCM upscaling with a 2M-tap sinc filter. The EX barely breaks a sweat running at about 7% CPU load. Its a different story if you have a DAC that works natively in PWM (most other DACs), these would benefit from DSD upsampling which is significantly more compute-intensive, so perhaps a stretch for the EX if you push the upscaling to the max.
 
I run HQ Player on a PC and pointed my Auralic G2 to it. Running ROON on a NUC ROCK.

We’re locked down till end March so aim to try a few different configs, I’ve taken the Auralic out for now, not sold it yet, replaced it with a dCS. Have a couple other DACs to mess with and was toying with the idea of building a DIY Audio Server. HQ Player is a bit ugly but does the business.
 
Chunk McDaniel said:
Don't mix up measurements with what we hear as music. Everything that equates to a good musical presentation cannot be measured by a piece of lab equipment and plotted on a graph. Some things cannot be measured and everyones perception of what they hear can be wildly different. While measurements tell us how a dac chip, pfga or r2r ladder performs with certain fixed criteria it does not tell the whole story or give a complete picture. Our ears and emotions fill in the blanks.
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Measurements are there to tell how faithfully a piece of kit reproduces the original sound. The validity of these measurements are confirmed by empirical science. Naturally they cannot predict exactly what you prefer. Nor are they meant to do that.
 
andrewd said:
I have a Chord TT2 and am very happy with it as an integrated DAC-headphone amp. I like how it eliminates an unnecessary extra box, and is not a ridiculous size and weight. I also like the unique design, especially the glowing coloured orb.

As far as sound quality goes it is my opinion you can’t really comment much about the sound of a DAC without taking into account the source. A DAC is the equivalent of a phono preamp in an analogue rig. Many would argue that having the best phono preamp in the world doesn’t matter much if the turntable is crap. My view is that the source is also the most important component in a digital rig.
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One of the biggest problems in digital audio is that people still try to understand its workings with ideas borrowed from analog audio. In addition, the source first ideology was one of the greatest errors in audio history.
 
Octavian said:
One of the biggest problems in digital audio is that people still try to understand its workings with ideas borrowed from analog audio. In addition, the source first ideology was one of the greatest errors in audio history.
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I am offering my experience based on actually owning and listening to various equipment. I am not getting into a bits are bits argument. It has been done to death before.
 
Octavian said:
One of the biggest problems in digital audio is that people still try to understand its workings with ideas borrowed from analog audio. In addition, the source first ideology was one of the greatest errors in audio history.
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I just dug out my 2012 MacBookPro and compared it to the 2020 M1 Mini. Via USB to the Qutest, the 2020 machine wins hands down. The difference is as much as a different level of DAC. Even though the Mini is plugged into my hifi block and the MPB is running off its battery.

Better to avoid ideology on either side of the debate, otherwise it ends up as a self fulfilling prophesy (or circular argument...).
 
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