wasnotwasnotwas
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I'm not sure, but I think this is an affirmation of Amir's measurements without saying as much? Either way, thanks for engaging.
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CEntrance Hifi-M8 V2 Review (DAC and headphone amplifier)
- Thread starter amirm
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I'm not sure, but I think this is an affirmation of Amir's measurements without saying as much? Either way, thanks for engaging.
Not really. As the paper spells out, noise and distortion are different. But SINAD doesn't split one out from the other. We have never disputed the THD measurement and it's been on our website all along. Noise is the where there is currently insufficient data.
Amir wants to measure background noise separately from distortion, but he couldn't do so as the driver on our website was old. Amir needs an updated ASIO driver that will enable him to perform this measurement. The new driver version is currently in internal beta test and will come soon.
Amir wants to measure background noise separately from distortion, but he couldn't do so as the driver on our website was old. Amir needs an updated ASIO driver that will enable him to perform this measurement. The new driver version is currently in internal beta test and will come soon.
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bhat
Member
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"Criminal" is a strong accusation if anyone decided to take it literally.
Please read again:
NOISE (AKA RESOLUTION) IS BETTER THAN MEASURED.
Amir couldn't measure the noise and stated that more than once.
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We did, on page 12. Please let us know what specifically you are looking for.
bhat
Member
Apologies. I glanced over the graph on page 12 which showed the dynamic range to be less than 96db. After reading it again, I see that was due to the driver issue.
bhat
Member
Can you please post your measurements here or your website? noise, THD, multitone for both hot and cold sides
OP
- Thread Starter
- #270
I have given you a number of links and references to what we are looking for. Not sure what is confusing about it. Can you produce a set of measurements like these? https://www.audiosciencereview.com/...qudelix-5k-bluetooth-dac-headphone-amp.17386/
OP
- Thread Starter
- #271
But you can since you have the driver. What is the reason for not running that test and reporting it as I have run?
Thank you. No problem at all.
Frankly just available manpower. We are carefully splitting our time between making measurements to satisfy this community and shipping product to paying customers. No disrespect, the last couple of weeks have been quite busy and nobody has cancelled the covid restrictions for the simultaneous number of people in the office. Latest driver dropped 2 days ago. We need to run it through its paces, send to beta testers, approve it and then we would be in the position to make these tests. It all takes time.
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This has been one heck of an inquiry indeed. From day one I felt that something wasn't right so I wanted to figure it out and stay in communication. As we were up in the mountains with no reliable internet service for a week, that wasn't easy. Talk about perfect timing and a ruined vacation... but customer commitment comes first.
Our internal measurements are not performed the way Amir performs measurements, so we needed to create apples to apples conditions. AP handbook differs in some of its recommendations, but it's not worth getting into that rabbit hole now.
Since getting back after thanksgiving, we engaged with our staff to make new measurements and run tests. All the while, we had to juggle shipping and covid distancing, so quite a dance all around.
Here is what we know so far:
- Initially I wasn't clear what the issue was (THD, noise, power). This Wednesday it finally dawned on me -- I had forgotten that the digital gain pot is the immovable object. In all fairness, we designed the product two years ago and since then designed many others, so it wasn't fresh in my mind anymore (I wear many hats, cannot remember everything).
- Realizing this caused me to sit down, retrace the design decisions and write this paper, which I published today, if anything as a memo to myself (and anyone else who would care to read it). The end result: HiFi-M8 THD will remain at 0.004%. That will not change unless we wire across the digital pot. I suspect people do want volume control, so that's not a likely mod. Otherwise, we can easily bring distortion another decimal point down.
- Regarding noise, first there is the driver, which is in progress. And then, there is also the output level, about which there is a bit of a debate around the office. Amir wants to measure the output at 2V, which assumes that the output is a line output. But HiFi-M8 is not a desktop DAC and it doesn't have a line output. It has 4 headphone outputs, all different. Which one is fair to choose as a line output? And if we have to dial down from FS in digital domain to achieve 2V, would we be artificially limiting dynamic range? We are at a crossroads on this at the moment. Hope clarity will emerge with additional discussions.
- Lastly, regarding power, HiFi-M8 behaves better than DACport HD, which was recommended on this forum. And yet HiFi-M8 was failed. Amir was frustrated with the driver, but subjectivity shouldn't enter into his judgements, so there must be something else. Did he not have the woefully inefficient Dan Clark headphones earlier? We don't have them, so we cannot check with them. We check with LCD2, etc. and by the time you hear any distortion it's so loud, your ears hurt. Should you really be listening (and evaluating) at those levels?
In summary, we are happy to continue the inquiry (time permitting) and trust that clarity will emerge. At this point we know that THD will not improve. We may or may not continue with power as the effort to match the experimental conditions is starting to become a serious resource drain vis-a-vie other standing commitments. We still believe that noise (aka dynamic range, aka resolution) will improve once the driver is ready.
EDIT: Time permitting, we have been reading up on this forum, to study Amir's process and to understand the general discourse. We hadn't been here much before and it's a rather large resource at this point (how does he even have the time?)
Knowing what we know now, we should plan to design future products to make it easier to evaluate them within this framework (hint: 2V output). Having to jump through these same hoops again is definitely not an attractive proposition.
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@radioman the writeup is appreciated! So the main contributor of THD is the volume control chip, which was chosen to have very low noise and power consumption. The issues with other better performing devices seems to mainly be power consumption, correct? Why then does your device have a class A amplifier stage? How big of a power impact would a better chip really be percentage wise? How much is lost on those LED’s on average?
STAMINA mode would not be possible, dropping the run time to about 4 hrs, which we would consider inadequate. LEDs are not the problem - they run very efficient and on top of that can be gradually turned off with the brightness control, down to zero contribution.
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So, @amirm did you ever get their measurements, other than the one graph posted earlier (that was carefully truncated before the harmonics and any image problems)? Project files? Measurements of the returned unit?
Or have we finally decided that there's problems in the implementation and there's nothing broken in the sample you tested?
Or have we finally decided that there's problems in the implementation and there's nothing broken in the sample you tested?
Excellent, looking forward to trying it out!
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