NuForce uDAC-2 Drama (detailed measurements)
Mar 11, 2011 at 8:51 PM Post #121 of 208
First of all I would like to say hello to everyone, this is my first post. I have been following this thread from the beginning and would like to say a few words from the perspective of one of the [size=x-small][size=x-small]"relatively new and growing number of [/size][/size][size=x-small][size=x-small]consumers that are using computers for the playback of (mostly) MP3 music files." I decided to post here versus headphoneaddict's impressions thread due to relevance to the discussion. [/size][/size]
 
[size=x-small][size=x-small]While I am not new to PC audio, I am relatively new at looking for ways to improve it. Since my kids moved out of the house I have more time for things I enjoy, and now have the opportunity to use my old Sennheiser HD700 headphones. They are 10 years old but practically brand new! Onboard audio just didn't cut it for me anymore so I started to research soundcards and USB DACs. Tried the Behringer UCA-202 that nwavguy mentioned in his review for the uDAC-2 because it was cheap and recommended by several people on the hydrogenaudio website. It was a definite improvement over the onboard audio but would not drive the HD700 to an adequate volume. So next I bought the uDAC-2 based on Amazon and Crutchfield reviews. I am not very good at describing how audio equipment sounds but I know what I like, and I really enjoy the uDAC-2. It has a nice warm tone as headphoneaddict described in his impressions, but is still very detailed. I use it with my headphones on different PCs and connected via the RCA out to a Harman Kardon HK3390 stereo receiver in my office. I can listen to it for hours without fatigue. That's how I measure good sound. If there is any clipping going on I haven't heard it. I also do not hear a channel imbalance with the HD700.[/size][/size]
 
[size=x-small][size=x-small]@jasonl: I don't get the impression that nwavguy is working for a competitor and is trying to cause NuForce harm. He is telling it like he sees it. I don't believe measurements would cause someone who likes the sound of the uDAC-2 to stop using it or recommending it to others. [/size][/size]
 
[size=x-small][size=x-small]@nwavguy: I see that you are trying to educate the buyer on what's he's getting and appreciate that. I wouldn't waste your time with a comeback to NuForce's response. You told your side of the story and NuForce has told theirs. [/size][/size]
 
[size=x-small][size=x-small]BTW, head-fi is an awesome website![/size][/size]
 
Mar 11, 2011 at 8:52 PM Post #122 of 208
@SP Wild, I tried a couple of different ones in each model to make sure I didn't have a "bad" one the first time...  Turns out I didn't.  Frankly, I could care less (but lots of people might and rightfully so) of what it might have cost, in the pursuit of "musical enjoyment."  Interesting journey, but can't really say head-fi has "helped."
 
Mar 11, 2011 at 8:54 PM Post #123 of 208


Quote:
I would please like some input from others who have been following this thread. I can approach the lengthy NuForce response several different ways. I could:
  • Just let it end here. I've tried to make my concerns about the product, and NuForce's earlier response and position known already.
  • Respond to a few of what I consider the more potentially misleading points in their long response.
  • Respond with a similar level of detail to what they've provided.


Vote for option 1.  We all know where both sides stand.  Nothing else to gain by further discussion on this particular matter.
 
Quote:
So from the Stereophile review on the first sample of the Nuforce CD player sample we might infer evidence to support either
 
(a) that a CD player with very high jitter ( 3 plus ns) and other poor noise and distortion measurements can actually sound subjectively good or
(b) that Stereophiles listener is stone deaf ?
 
This is far from the first time that John Atkinson has been bemused and pondered why his subjective reviewers liked a product that was actually pretty low fi.
 
If a then jitter does not look like a real issue after all ?
 
If b then perhaps their recomendations ought to be taken with a pinch of salt
 
As Stereophile has this neurotic tension between being a predominantly highly subjectivist magazine but are also obsessed over the degrading effects of jitter, how do they square this ?
 
Fascinating...
 



Stuff like this is why I am subscribed to you, Nick. 
biggrin.gif

 
Quote:
^ Fascinating post. Touché!

Probably the most useful thing to come out of this thread.  A good note to end on I think. 
 
 
 
Mar 11, 2011 at 9:46 PM Post #124 of 208
Yes. I think if we can learn from this debate, keep our cool, and discuss about it with an open mind, that will be beneficial to all.
Here's our take on the jitter issues.
Can we hear the difference before and after? Yes.
When CDP-8 was first developed, one of our investors (retired technology company CEO, long time audiophile), who has a top of the line Meridian system, commented that it was equal in performance (clarity, resolution, dynamic etc) as his $15,000 player system.  We also compared CDP-8 with other top of the line players. And CDP-8 sounded better.
We did other measurements but not the jitters.
 
That's what Wes Phillips and many others concluded as well.  For those of you who are skeptical, please give these experience audiophiles benefit of the doubt. Lets not start to dismiss each others opinion.  Just as this debate has taught us, we are both right. The distortion is there, but does it matter, and in what way.
Some audiophile magazine don't want to get into measurement, and it works for them and their readers. Some such as Stereophile do both, sometimes it works, but sometimes it becomes a source of ridicule! What is going on here? Wes Phillips is known to be very consistent with his assessment of equipment. And Stereophile's measurement is correct.
Right after the 1st pilot production went out, we hired a technician with a lot of measurement experience to look at Icon HDP (which was still under development). The DAC in CDP-8 went into HDP. And this guy noticed some ground noise at one part of the circuit of CDP-8. So we decided that it is worth fixing for the full production units.
That's where the discrepancies occurred. Wes Philips got one of the 1st pilot production units.
 
One of our senior engineer could probably write another long technical paper on jitters but simple observation tells me that jitters measurement does matter, but that the particular jitter measurement does not affect listening experience much.  The improved CDP-8, when compared with the "highly praised" pilot CDP-8, sounded better.  Sure, we can hear it.
Wes Phillips is right. Stereophile's measurement is correct. We could have done a better job in the first place. Even before it was pointed out by Stereophile, we decided to fix it for the full production.  We are all passionate about sound quality and will keep an open mind.  If some measurement does matter, we will adopt it.
I think sometimes consumer's first reaction to a product's problem is to start blaming the company of some malicious and evil intent or incompetency. Lets not forget that most of us at one point or another work for some company. We all take pride in our work, but mistakes will happen. Some mistakes are serious enough that a recall is necessary, some mistakes are simply accepted as a product's weakness and area for improvement in the next version. For the CDP-8 partial ground noise issue (which affected the jitter measurement, the fundamental digital circuit design is fine), before it was discovered by Stereophile, we decided to bite the bullet and put it into production, and offer free replacement daughter board for all the units shipped. We really care about what the customer is getting.
 
Speaking about measurement, I doubt anyone measure the switching frequency of class-D amplifier.  Ah ha, this result has profound effect on listening experience. It is much more significant than distortion, noise floor, FR or jitters.  So here we go, how come nobody publish such data, are they all incompetent? No. Does the manufacturers know about this effect? I am sure most of them do. Well, since this is a data that can not be easily changed (most companies adopt off-the-shelf modules or ICs), there is no point publishing it. Well, I sounded like self serving because our amplifier has a very high switching frequency. For class-D amp, analog input signal is converted to pulse width (that's why it is called PWM, pulse width modulation), the switching frequency of the pulses obviously affect the resolution.
 
So, audio listening perception is very complex and there are a lot to learn.  We can not be so biased and close minded.
If anyone of you are in the bay area, stop by our office to listen to what I described above. If you have a high-end system and is skeptical of Wes Philips hearing, we can send you a CDP-8 with jitter to compare against your existing player or against computer + Benchmark DAC-1 (or whatever DAC you have). You can then hear the improved CDP-8.
 
 
Quote:
So from the Stereophile review on the first sample of the Nuforce CD player sample we might infer evidence to support either
 
(a) that a CD player with very high jitter ( 3 plus ns) and other poor noise and distortion measurements can actually sound subjectively good or
(b) that Stereophiles listener is stone deaf ?
 
This is far from the first time that John Atkinson has been bemused and pondered why his subjective reviewers liked a product that was actually pretty low fi.
 
If a then jitter does not look like a real issue after all ?
 
If b then perhaps their recomendations ought to be taken with a pinch of salt
 
As Stereophile has this neurotic tension between being a predominantly highly subjectivist magazine but are also obsessed over the degrading effects of jitter, how do they square this ?
 
Fascinating...
 
 
 



 
 
Mar 11, 2011 at 10:20 PM Post #125 of 208


Quote:
So from the Stereophile review on the first sample of the Nuforce CD player sample we might infer evidence to support either
 
(a) that a CD player with very high jitter ( 3 plus ns) and other poor noise and distortion measurements can actually sound subjectively good or
(b) that Stereophiles listener is stone deaf ?
 
This is far from the first time that John Atkinson has been bemused and pondered why his subjective reviewers liked a product that was actually pretty low fi.
 
If a then jitter does not look like a real issue after all ?
 
If b then perhaps their recomendations ought to be taken with a pinch of salt
 
As Stereophile has this neurotic tension between being a predominantly highly subjectivist magazine but are also obsessed over the degrading effects of jitter, how do they square this ?
 
Fascinating...
 
 
 


Weren't you saying before jitter at that level is supposedly inaudible? If so, your low-fi comment is moot. You're not starting to use evidence to support contradictory positions suddenly are you?
 
 
Mar 11, 2011 at 10:27 PM Post #126 of 208


Quote:
@SP Wild, I tried a couple of different ones in each model to make sure I didn't have a "bad" one the first time...  Turns out I didn't.  Frankly, I could care less (but lots of people might and rightfully so) of what it might have cost, in the pursuit of "musical enjoyment."  Interesting journey, but can't really say head-fi has "helped."


Bulmanxxi,
I hope my latest post about CDP-8, etc give you an balance view that not all companies are out there selling snake oil.  We and many others (such as SNTHOLIDAY) can tell the difference.
But there are people who can't.  I don't take offense when you said that in your post that you can't tell crap from uDAC-2, uDAC, Icon Mobile etc.  And it must have cost us a lot of money to keep sending you products (free shipping, no restocking). But that's ok.  Just don't say that we have evil intent etc :).  Nobody is hauling money to the bank.  This is a very touch and competitive business and we will be lucky if we make a decent profit to grow the company and bring out more interesting products. There are a few customers who also return products and sincerely gave us feedback that they can't tell the difference.  To me, solving this problem is more important. That's why we spent a lot of effort and money to put together the audio concept demo tracks http://www.nuforce.com/hp/media/Nuforce%20Demo1/index.php. Hey, if a non technical consumer can use these demo tracks to differentiate between good and bad sounding audio, even if he/she don't end up buying our products, so be it. 
I understand that no matter what we tried, some people can never tell the difference. But making a difference in audio is our passion and our mission. Sounded corny, but I am almost 50 and if I can make a real difference in my career, it brings a nice closure to it. I am still an engineer at heart.  Solving puzzle is our life.
 
 
Mar 12, 2011 at 10:33 AM Post #128 of 208


 
Quote:
Weren't you saying before jitter at that level is supposedly inaudible? If so, your low-fi comment is moot. You're not starting to use evidence to support contradictory positions suddenly are you?
 


The empirical evidence we have suggests that jitter at this level is inaudible and has done so for the last 12 years, though the precise threshold of audibility wrt different spectra is fluid, but many audiophiles and audiophile magazines and manufacturers of digital kit and add-ons like jitter reducers, reclockers and so on stolidly maintain that jitter is such a big problem that a few ps make a big difference.
 
At the forefront of the consumer magazine branch of this ideological position is Stereophile whose reviewers including Atkinson, Fremer and Harley maintain a consistent jitter is evil and audible position.
 
Thus we should expect that one of their most experienced reviewers would effortlessly pick up on such egregiously high levels of jitter. It is unfair to single Wes Philips on this, you can find other SP reviewers faling to detect massive jitter in several other products.
 
 
 
 
Mar 12, 2011 at 1:38 PM Post #129 of 208
Jason, you are my hero. No kidding.
 
Quote:
Originally Posted by jasonl /img/forum/go_quote.gif

Bulmanxxi,
 
I hope my latest post about CDP-8, etc give you an balance view that not all companies are out there selling snake oil.  We and many others (such as SNTHOLIDAY) can tell the difference.
 
But there are people who can't.  I don't take offense when you said that in your post that you can't tell crap from uDAC-2, uDAC, Icon Mobile etc.  And it must have cost us a lot of money to keep sending you products (free shipping, no restocking). But that's ok.  Just don't say that we have evil intent etc :).  Nobody is hauling money to the bank.  This is a very touch and competitive business and we will be lucky if we make a decent profit to grow the company and bring out more interesting products. There are a few customers who also return products and sincerely gave us feedback that they can't tell the difference.  To me, solving this problem is more important. That's why we spent a lot of effort and money to put together the audio concept demo tracks http://www.nuforce.com/hp/media/Nuforce%20Demo1/index.php. Hey, if a non technical consumer can use these demo tracks to differentiate between good and bad sounding audio, even if he/she don't end up buying our products, so be it. 
 
I understand that no matter what we tried, some people can never tell the difference. But making a difference in audio is our passion and our mission. Sounded corny, but I am almost 50 and if I can make a real difference in my career, it brings a nice closure to it. I am still an engineer at heart.  Solving puzzle is our life.



 
 
Mar 12, 2011 at 1:44 PM Post #130 of 208
nwavguy,
 
I can honestly tell the same to you. You and jasonl were rude sometimes, but both of you did expanded community knowledge base by your dispute, nevertheless. All of us are going our head-fi way and knowledges are important. Thank you.
 
Mar 12, 2011 at 1:51 PM Post #131 of 208
bulmanxxi,
 
I backed up your posts to my disk, they are great, really. But I like to tell you something on your equipments list / history. I do not see any good source there. And this may be a reason of your disappointment. I spend some time / money here to learn "source first" lesson well.
 
Quote:
WOW!!!  Head-fi?!  More like head-in-the-sand.org to be polite that is...  I have bought plenty of crap HYPED UP on here, just to be duly disappointed.  Want a list?  uDac, uDac-2, Icon Mobile, Earsonics SM3, Grado Gr8, Grado Gr10, Grad HF-2, Grado MS1, Koss Porta Pro, Ray Samuels Shadow, iBasso D4, Amarra, etc.  The disappointment is not based on SQ only, but cost, features, convenience, improvement, etc.



 
 
Mar 12, 2011 at 2:54 PM Post #132 of 208
SnTholiday,
 
are you sure your cans are HD700? I do not know them, and I googled and got a conradictionary results - http://images.google.com/images?hl=en&gbv=2&tbs=isch%3A1&sa=1&q=sennheiser+hd700&aq=f&aqi=g1&aql=&oq=.
 
 
 
Mar 12, 2011 at 5:58 PM Post #133 of 208

 
Quote:
Nwavguy, do what you think is right and don't let NuForce intimidate you with their personal attacks. As stated previously, all NuForce is doing now is damage control, and their so called "rebuttal" spends more time questioning your competence and discussing subjective matters. NuForce lost my respect the moment they started quietly changing specs on their uDAC page. Personally, I would like to see your analysis on other gear popular on HeadFi. uDAC is not worth all this time anymore, the cat is already out of the bag. 
smily_headphones1.gif

 
 

Thanks Gevorg. And thank you to everyone else who's expressed their encouragement for what I've tried to do. I do plan to keep analyzing other gear. I recently posted a review of the FiiO E5 headphone amp for example.
 
Some of you want me to keep going, some want me to just address the bigger points, and some say give it up. So I'll try to compromise...
 
Here are, for now, some of my brief observations:
 
1 - They spent the most time trying to suggest that anything under 1% THD is perfectly acceptable and inaudible. The audibility of distortion in a complex issue and I've said many times how much is audible is difficult to anwer. They argue it's always masked, but that's not true. Anyone can hear even 0.5% THD on a sine wave for example. Even 0.1% is somewhat audible under some conditions. But there are too many variables to set the threshold in any general way.
 
2 - They ignored the fact their distortion compromise only improves the noise performance, by at most, 1 dB -- or about 1%. This is a really trivial improvement. If you take some low level but audible noise, and boost or cut it by 1 dB, you'll be hard pressed to tell anything changed. A single dB, by definition, is the smallest change most humans can even detect. So why compromose the distortion performance in such a big way for such a small gain in noise?
 
3 - They glossed over the fact 4+ dB of frequency response deviation is audible. And, in fact, my listening test has already demonstrated that. People have easily picked out the sample using the SuperFi headpones that cause the same 4+ dB of variation.
 
4 - The whole short circuit protection excuse for their excessively high output impedance doesn't pass the test of being reasonable. Lots of IC's that work really well, and are used in lots of really well loved headphone amps, are already short circuit protected. Even the $20 FiiO E5 amp has a near zero output impedance and is not harmed by short circuits. So if FiiO can do it in a $20 product, but NuForce can't figure out how to do it in a $130 product, something seems to be wrong with their argument. And, it's also worth noting, all the high-end headphone products I know of, like Benchmark for example, also have near zero output impedances--for good reason.
 
5 - They ignored the whole gain issue and that the headphone and line outputs of their product clip at about 60% of the full volume setting. This is arguably a poor design for the vast majority of their customers.
 
6 - They ignored the horrible volume tracking issue that's long been, and continues to be a problem with the product. It's my single biggest complaint and many others have posted similar concerns.
 
7 - When I judge a product, I judge it against similar products and what's considered "typical" in the industry as a whole. And if the $30 Behringer volume control can work vastly better, why can't NuForce fix theirs? And even if you argue the levels of distortion, high frequency distortion, and jitter in the uDAC-2 are not audible, they're also not typical. Lots of other products, even ones as cheap as the $30 Behringer DAC and the $30 Sansa Clip+ blow the uDAC-2 away in these areas. So their argument, to me, still doesn't explain why they can't at least be in the same league performance wise as much cheaper devices?
 
8 - I have not tried to distort the Stereophile article as NuForce has said. The FACTS are: Their product measured exceptionally poorly compared to typical products in a few areas. Their response indicated they had never even thought to make the measurements. Rather than claim, as they have here, the poor performance was justified, they attempted to fix the problems and submited another product for review. My main point was that A) This has happened before with NuForce, and B) They don't seem to believe in making typical measurements even for their $1500 products. I don't think that's distorting anything.
 
Sorry if there are any typos in this, or other errors, but as I explained earlier I don't have much time to respond at the moment. And I really don't want to keep beating this dead horse if I don't have to.
 
Mar 12, 2011 at 6:42 PM Post #135 of 208


Quote:
 
Sorry if there are any typos in this, or other errors, but as I explained earlier I don't have much time to respond at the moment. And I really don't want to keep beating this dead horse if I don't have to.

 
deadhorse.gif

 
 
 

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