NDX and Chord Hugo
Posted by: Foxman50 on 18 April 2014
I have been contemplating adding a DAC to my NDX/XPS2 to see (or should that be hear) what it can bring to the party. And so thought it about time i made inroads into Having a few home demos. After looking around at products that are within my budget i came across the Chord Hugo DAC.
Although it is meant to be a portable headphone unit, it can be used as a full line level fixed DAC.
The dealer lent me a TQ black digital coax lead, which have twist grip plugs. This was required as the present batch of Hugo's have a case design fault that wont allow any decent cable to fit, soon to be rectified. Thankfully the TQ just manages to hang on to the coax port.
Once all connected and gone through the minimal setup procedure of the Hugo, what does the red LED mean again, i left it to warm up for half an hour.
Poured a beer and sat down for an evenings listening.
What was that, where did that come from, that's what that instrument is. OMG, as my little'n would say, Where is it getting all this detail from.
After spending last night and today with it, all i can say is that it has totally transformed my system from top to bottom. I never considered my NDX to be veiled or shut in, not even sure that's the correct terms. All i can say is its opened up the sound stage and space around instruments. Everything I've put through it has had my toes, feet and legs tapping away to the music.
Even putting the toe tapping, the resolution the clarity to one side, what its greatest achievement for me has been in making albums that I've had trouble listening too enjoyable now.
One added bonus is that it has made the XPS redundant. I cannot hear any difference with it in or out of the system.
While i thought a DAC may make a change in the degree of the jump from ND5 to NDX, i was not prepared for this. Anyone looking at adding a PSU to there NDX may want to check this unit out first.
For me this has to be the bargain of the year.
Stop the presses! There is a piece of audio gear Richard hasn't heard (or better, doesn't own!) 
Your encyclopedic knowledge of all things audio has never ceased to amaze me. (When you knew my Denon tuner model number from looking at the picture I knew you had a serious "problem" 
Heck, I don't even remember it!)
According to one source, the Hugo's designer claims the brain samples sound in real time every 4 microseconds (4/1,000,000 of a second).
This appears to be the big claim. It is not mentioned on the Chord website for reasons unknown. Perhaps advertising standards. Who knows? Anyhow, lets examine this central claim in more detail. Clearly everything hinges on it.
Yamaha, the people who make state-of-the-art recording equipment and grand pianos, say a time delay of 30 milliseconds (30/1000 of a second or 30,000 microseconds) is imperceptible to the human ear in audio replay. Source here in the temporal masking section http://www.yamahaproaudio.com/...hapter4/03_auditory/
The Yamaha piece can be corroborated with another high quality source. This time from the hearing aid department at German engineering company Siemens
"when [the delay is] longer yet (more than 40ms) the auditory information may fall out of synchronization with the visual information." Note they mean milliseconds not microseconds!
http://hearing.siemens.com/Res...blob=publicationFile
So, is the Chord designer right and both Yamaha and Siemens wrong? Not just wrong but 7,500 times out in their measurement as 30,000 microseconds is 7,500 times longer than 4 microseconds.
Is there a more simple explanation? Simply that 4 microseconds is a mistake and what was meant to be said was say 4 milliseconds. Both might be written as 4ms in error. 
Seriously though, hearing latency texts appear to suggest 4-10 milliseconds as a target for latency. Was the 4 microseconds just a mistake?
According to one source, the Hugo's designer claims the brain samples sound in real time every 4 microseconds (4/1,000,000 of a second).
This appears to be the big claim. It is not mentioned on the Chord website for reasons unknown. Perhaps advertising standards. Who knows? Anyhow, lets examine this central claim in more detail. Clearly everything hinges on it.
Yamaha, the people who make state-of-the-art recording equipment and grand pianos say a time delay of 30 milliseconds (30/1000 of a second or 30,000 microseconds) is imperceptible to the human ear. Source here in the temporal masking section http://www.yamahaproaudio.com/...hapter4/03_auditory/
The Yamaha piece can be corroborated with another high quality source. This time from the hearing aid department at German engineering company Siemens
"when [the delay is] longer yet (more than 40ms) the auditory information may fall out of synchronization with the visual information."
http://hearing.siemens.com/Res...blob=publicationFile
So, is the Chord designer right and both Yamaha and Siemens wrong? Not just wrong but 7,500 times out in their measurement as 30,000 microseconds is 7,500 times longer than 4 microseconds.
Is there a more simple explanation? Simply that 4 microseconds is a mistake and what was meant to be said was say 4 milliseconds. Both might be written as 4ms in error.
You are confusing the ability to discern the timing differences between two event streams (on different sense organs) from the best-case resolution at the brain cortex (the Kunchur limit, if estimated at 4uS, about 250 kHz) on one of them.
30mS is the generally-accepted* number above which delays in video program material are clearly perceptible–but this is only about 33.3Hz; clearly the frequency response of our own hearing extends to nearly 1000x (or greater) that amount.
One other thing to consider is that our brains can generate a tone of a fundamental frequency from its upper harmonics, so that a 15kHz tone can easily be interpolated by providing a 45 kHz 2nd and 75 kHz 4th harmonic at the correct levels - using similar armchair maths, this doesn't give us (using the 250kHz, 4uS upper limit) much more than a best-case, 50kHz usable aural bandwidth (150kHz 2nd / 250kHz 4th harmonic), even though we can perceive the upper harmonics (which may be more useful for spatialization, etc. than previously believed).
* ITU BT1359 (1998)
** - The Yamaha Pro Audio paper you refer to specifies the Kunchur limit at 6uS, which has now been modified (by Milind Kunchur himself) to less than 5uS. There is a very succinct Hi-Fi Critic article (Spring 2009) summarizing his research as it applies to consumer audio.
According to one source, the Hugo's designer claims the brain samples sound in real time every 4 microseconds (4/1,000,000 of a second).
This appears to be the big claim. It is not mentioned on the Chord website for reasons unknown. Perhaps advertising standards. Who knows? Anyhow, lets examine this central claim in more detail. Clearly everything hinges on it.
Yamaha, the people who make state-of-the-art recording equipment and grand pianos say a time delay of 30 milliseconds (30/1000 of a second or 30,000 microseconds) is imperceptible to the human ear. Source here in the temporal masking section http://www.yamahaproaudio.com/...hapter4/03_auditory/
The Yamaha piece can be corroborated with another high quality source. This time from the hearing aid department at German engineering company Siemens
"when [the delay is] longer yet (more than 40ms) the auditory information may fall out of synchronization with the visual information."
http://hearing.siemens.com/Res...blob=publicationFile
So, is the Chord designer right and both Yamaha and Siemens wrong? Not just wrong but 7,500 times out in their measurement as 30,000 microseconds is 7,500 times longer than 4 microseconds.
Is there a more simple explanation? Simply that 4 microseconds is a mistake and what was meant to be said was say 4 milliseconds. Both might be written as 4ms in error.
You are confusing the ability to discern the timing differences between two event streams (on different sense organs) from the best-case resolution at the brain cortex (the Kunchur limit, if estimated at 4uS, about 250 kHz) on one of them.
Not sure about that. The Yamaha paper clearly shows two sets of speakers which would produce a 30 millisecond timing difference and says the difference in the two is imperceptible. If this is the case then two snare hits less than 30 milliseconds apart would also be inseparable.
Re Kunchur, Yamaha say "The brain uses the time difference between the left ear and the right ear information to evaluate the horizontal position of the sound source." Unsure then if Kunchur in their context is relevant to our debate given two channels in front of you i.e. the standard home hi-fi format.
Re Kunchur, Yamaha also say "Signals arriving from sources located in front of the head (0-degree angle) arrive perfectly in time". So, based on limited understanding, I think Kunchur is interesting but perhaps a distraction in the context of home hi-fi. Very much a distraction in explaining why this 4 microseconds claim is so vital.