[review] NuPrime uDSD
May 8, 2015 at 2:08 AM Thread Starter Post #1 of 53

Armaegis

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To start, here are the features/specs from the website:
http://nuprimeaudio.com/index.php/product/dac-headphone-amps/portable-dacs/udsd
 
Features:
  1. 24-bit/384kHz and native DSD 256 support
  2. Discrete USB audio receiver and D/A converter, with coaxial S/PDIF (24bit/192kHz) output
  3. Coaxial output can also stream DoP (DSD64) for long distance transmission of DSD from computer
  4. Asynchronous transfer mode for doubled jitter-reduction at data input and over-sampling filter stages
  5. High-performance headphone amplifier (balanced design)
  6. High voltage 2V analog output (fixed volume direct DAC output)
  7. Coaxial S/PDIF output
  8. High-quality analog volume control
  9. Diminutive size 
  10. USB powered, no external power supply required
  11. Works with Windows 7/8 and Mac OS.  
Specifications
  1. Input:
    1. USB 1.1, 2.0, compatible.
  2. Outputs:
    1. Analog Stereo RCA Out.
    2. Digital Coaxial Out.
    3. Headphone Amplifier Out (3.5 mm-jack socket).
  3. USB sampling rates: 44.1,48,88.2,96,176.4,192,352.8,384KHz and DSD 2.8,5.6,11.2MHz.
  4. Bit resolution: 16-24-bits.
  5. Output: Analog RCA 2V rms (DAC out).
  6. Headphone output: max 140mW x 2 @ 32 ohm.
  7. Dynamic range: 98dB.
  8. S/N ratio: 112 dB.
  9. THD+N < 0.01%.
  10. Power: USB-Bus powered, 150mA/5V.
 
I'm adding these since they weren't on the site:
  1. Dimensions: 23x57x101mm
  2. weight: 150g
 

 
For comparison/reference, here's my review of the NuForce uDAC-3 from only a year and half ago. My how time and technology flies eh?
http://www.head-fi.org/t/693047/review-nuforce-udac-3
 
 
A bit of background
 
Those of you who've been observant may have noticed that there's a guy on the forums by the name of @jasonl who's been promoting a few different products from different companies, yet the title under his name doesn't match any of them. So what gives? Well to get there, I'll tell everyone a short story.
 
Once upon a time there was a company called NuForce. They mostly played around in the hifi world and made a pretty good name for themselves, particularly with their patented class-D amps which were derived from their own R&D and not licensed/built from OEM modules like most others on the market. They eventually branched into desktop gear with the Icon family of amps, and their Icon Mobile was an early player in the portable battery powered usb dac/amp scene. This was their start into the head-fi world, along with some iems, but it was the uDAC which really put Nuforce into the headphone spotlight. There was hype, there was anti-hype, but hey no such thing as bad publicity right?
 
Looking back it almost seems comical that there'd be so much fuss, but you have to realize that there weren't nearly as many options even just a scant few years ago. Anyhow, the uDAC eventually gave way to the uDAC-2, and later again eventually the uDAC-3. Meanwhile, Nuforce also expanded into more headphone specific desktop gear with more Icon family gear and then the larger “100” series.
 
And then Nuforce was bought by Optoma, a projector company. Weird right?
 
So anyhow, Jasom Lim (co-founder and former CEO of NuForce) left and created Heap Venture. What is that exactly? I emailed Jason and this is straight from the horse's mouth:
 
Heap Venture manages brand, product strategy, global sales and marketing on behalf of its strategic partners. Heap Venture’s partners can be an OEM factory, a startup or a retailer who prefers to have someone manages the business for them.
NuPrime, Encore and Celsus Sound are all different companies who formed long term partnership with Heap Venture.
 
NuPrime is becoming a full fledged consumer electronics company with new products coming out literally every month. Celsus will focus more on portable products and wireless speakers. Encore will be transforming into a brand with extreme value for the money.

 
So NuPrime is not a rebadged NuForce. However, just to add slightly to the confusion, NuPrime did acquire the rights to the high end product line from NuForce (nothing headphone related). Beyond that though, they are not affiliated.
 
That now brings us to the uDSD, which in effect is a direct competitor to the uDAC-3. I feel as though this is perhaps Jason's subtle somersaulting avian to NuForce, but those are my words, not his.
 
Anyhow, storytime's done. Let's move on.
 
 
Build quality
 
Nice and solid build. Roughly twice the size of the uDac3 and much heavier (150g vs 81g). It's still small, but isn't nearly as pocketable as the uDac3.
 
Brushed/stylized surface finish that doesn't seem to show scratches and doesn't smudge easily. High quality rca jacks on the back. All in all it feels like a premium little component.
 
I like the use of a usb-B jack. I have a million usb printer cables lying around, and it allows for the use of boutique cables as well. It's a bit odd that the usb jack is on the side though. I suppose this was a consequence to styling the case longer rather than wide. This could potentially make it slightly awkward to fit all your cables in if you are planning on having the uDSD tucked into a small rack, but that's not really the purpose of having the uDSD now is it?
 
 
Internals
 
I didn't open it.
 
But really, I asked and they said their policy is to not mention the specific components as they wish their product to be judged based on the implementation not what yaddayadda chip is inside.
 
But really, I poked a bit and they did tell that it is an XMOS based usb receiver and the dac is Sabre based. People who really want to know can dig and probably find it mentioned online somewhere.
 
 
Features/compatibility
 
Driver installation (Windows) was relatively straight forward. Install the driver, plug in the device, bippity boop it does the rest from there. I did find this new driver a big improvement over the older Nuforce drivers because it would auto detect/output the source bitrate, whereas the old one required manually choosing.
 
I did have some inconsistent behaviour when using the uDSD with the Wyrd. First was that I had to install the driver twice (once with, and once without the Wyrd in the path). Second is that early on the headphone output wouldn't work when connected through the Wyrd, but lately it's been fine. Anyhow, that's just something random to note. Everything is fine otherwise.
 
The uDSD powers on simply by turning the volume pot. Self-explanatory.
 
The coax output operates even if the uDSD isn't turned on. Apparently it can do DSD from the coax using something called DoP streaming... but I don't currently have the appropriate gear on hand to test that (I'm not really a fan of dsd either, but that's a discussion for another day).
 
Analog RCA outputs are 2V line level (not volume controlled, unlike the uDAC-3) and auto-mute when headphones are plugged in. The analog outputs do not function unless the uDSD is turned on.
 
There's no turn on/off thump at all from either the RCA or headphone outputs.
 
 
Performance as a DAC
 
vs HDP (fed coax from uDSD) - because this was the easiest one to compare against
- uDSD is smoother, HDP is more aggressive and seems to pull out those microdetails a tiny bit better, but at the cost of being a tiny bit hard at the edges in the treble range
- add the Wyrd into the chain and the uDSD detailing gets just a bit better than the HDP
- but the HDP renders bass textures slightly better and makes it feel more immersive and impactful
 
vs uDAC-3
- uDac3 is flabby in comparison, weak subbase from lineouts
- mids and upper are better than the bass, but not as clear as the uDSD or HDP
- nitpicking: the uDSD is a tiny tiny smidge edgier
 
 
Performance as a SPDIF bridge
- I like it better than the Peachtree X1, which seems to add a hard edge to everything
- better clarity than the uDAC-3; it's close but the uDAC-3 is still a bit flabby
 
 
Performance as Headamp
 
It took me a bit of head scratching to wrap my head around this one. I've been playing with ridiculously high powered amps hooked up to an HE-6 for so long that it took me a while to scale my ears back down to the realm of portable gear. Even then, I couldn't quite figure it out. It's not super resolving, nor punchy, nor anything, but I kinda forget about it. It is quite clean though. Nice plucking on guitar strings. I hate using the word “neutral”, but it's apt here.
 
Headphones used: Hifiman HE-6, Sennheiser HD598 & HD25-13, Oppo PM-3, Fostex T50rp (modded), Celsus Gramo One, Vsonic GR07, V-Moda XS, whatever else I could find really
 
vs uDAC-3
- can immediately tell the uDSD is stronger and a cleaner through the whole range
- it's not a matter of energy or detail, just a sense of a haze that is lifted
 
vs HDP
- almost on par with the HDP headphone out on technical ability
- HDP has more power overall, better subbass presence because of that
- with the Wyrd I would say uDSD has slightly better detail across the board
 
vs FiiO e10 (not the e10k version)
- The FiiO is a groovy little number that happily and unabashedly sits in low/mid-fi land. It doesn't try to be more, and you don't really care either. It's a bit mushy, but thumpy and fun.
- The uDSD on the other hand strives to be more, and thus begins to suffer from the hifisnobbery effect. It's like my brain recognized that and goes “hey this is pretty good... I better start nitpicking at it”. Like it's pretentious and I want to find fault somewhere. Except I can't really.
 
vs Schiit Vali
- Vali has more gain and power
- but Vali adds a lot of energy and its own flavour into the sound
 
 
 
Closing thoughts
 
It's a really fantastic multi-tool. It was great when auditioning new gear and I didn't want to install drivers. Took it to a local shop and just fed the Moon Neo 430HA from the coax. I had an Oppo HA-1 on loan and I fed it coax and RCA simultaneously so I could evaluate and switch inputs directly. I could plug in a headphone directly then jump to another amp which was being fed from the lineouts. So many options!
 
When I went from uDAC2 to the uDAC3, I felt there was a smidge of an improvement but not really worth spending the money on if you already had the uDAC2. Going from the uDAC3 to the uDSD is a more noticeable step than going from the 2 to 3. Worth the expenditure? Well that's always a tricky matter when one is making small incremental upgrades. I'd give a hesitant yes here. If the only dac/amps you have are in the sub-$100 range, the uDSD is a great piece of kit and I'd highly recommend it as your next step. If you already have toys in the ~$200-300 range, I think the uDSD is strongly competitive but not quite groundbreaking on (ie: it's good, but you already have something in this bracket, save up for the next tier).
 
Except waitaminnit, NuPrime is offering a trade-in program to knock $50 off the price of the uDSD, bringing it down to a very nice $129 price point. That's pretty darned tootin' sweet! See here for details:
http://www.sonicunity.com/collections/nuprime-audio/products/udsd
At that price it's the same as the uDAC-3 and kicks it squarely in the spongebob squarepants. Absolutely worth it if you're budgeting for the $200 range.
 
May 8, 2015 at 2:09 AM Post #2 of 53

Armaegis

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I'm not a photographer who can make gear look pretty. Some guys will use a backdrop, glossy table, fancy lighting, filters, photoshop, etc. Me, I've got an old point & shoot camera that's older than my underwear, a dining room table, and a ceiling light that needs half its bulbs replaced.
 
 
 

Yeah that's my ruler from elementary school a million years ago. I'm amazed I still have it. I think it was a gift from my piano teacher.
 

From left to right:
Peachtree X1 (usb to spdif bridge)
NuPrime uDSD
NuForce uDAC-3
 
 

My other ruler is a metre stick. No silly imperal system here.
top to bottom: uDAC-3, uDSD, X1
 

It's a threesome with everybody's holes are facing up. The bigger ones mean better quality right? If nothing else, they fit tighter.
left to right: uDAC-3, uDSD, X1
 

Here's my desk. A messy desk. A manly desk. Behind me is the bear that I wrestled and turned into a rug.
The puny uDSD sits in the middle atop a Schiit Wyrd, feeding coax into my HDP.
 

That gouge on my hand is from the bear. 'Tis but a scratch.
 
May 8, 2015 at 1:02 PM Post #3 of 53

h1f1add1cted

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Thanks for the write up I have some questions:
 
I guess you provide ASIO drivers for e.g. foobar2000 (with all needed plugins like SACD etc) that we can play native DSD256?
 
The device itself has no power switch and get powered on if you start your PC, because its USB powered? Or do I need to power on and power off the device manually alwas after I shut down my system? Because I want to use it for my music server -> uDSD dac -> RCA -> amp
 
If I only use the RCA output straight to my amp, I don't need to use the volume knob to 100% because it's a fixed line out?
 
Do you have any measurements from the vendor about the dac?
 
Do you have a timeline for offical launch in Germany? Can't find any details.
 
May 8, 2015 at 1:15 PM Post #4 of 53

Armaegis

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I installed the driver and didn't have to do anything else to play DSD files.
 
The power switch is integrated into the volume pot. There's a click right at the beginning. If you leave it on, it *should* power on when the computer boots... but this is a funny thing with different computers and how the usb works, so I can't say yes with full confidence (but this will also be the issue with nearly any usb device). I can say that it has been working for me so far when I shut down and unplug from my laptop but leave the power switch on.
 
Yes the RCA output is fixed. The volume pot has no effect on it as stated in my review.
 
Measurements as stated in the other uDSD thread...
 
Yes it is correct - 140mW into 32 Ohm
 
The size:
Height:  23 mm
Width:   57 mm 
Depth:   101.3 mm
 
It will work if the USB power is supplied by a hub.

 
You will have to ask @jasonl for European launch dates.
 
May 8, 2015 at 1:49 PM Post #6 of 53

h1f1add1cted

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  I installed the driver and didn't have to do anything else to play DSD files.
 
  Measurements as stated in the other uDSD thread...
 
 
You will have to ask JasonL for European launch dates.

 
Which music player software you are using? Thats new for me that you don't need to configure anything for native DSD playback. I own a ifi micro iDSD and I need to configure under foobar2000 some little settings and after that I played some DFF files with DSD128 or DSD256 nativly without problems.
 
I mean no specs like output power, that I already know, I mean real independent measurements, like with RMAA and others of the dac section and the RCA output, headphone output and so on.
 
Thanks for asking the release dates.
 
May 8, 2015 at 1:56 PM Post #7 of 53

Armaegis

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I am using JRiver Media Center.
 
I have not done any independant measurements.
 
I'm quite confident the RCA outputs are 2V just by comparison with my othe dacs, but no I didn't actually measure it.
 
I've used RMAA in the past, but taking those measurements in a vacuum with no useable reference points is kinda pointless.
 
If someone really wants I can pull out the multimeter and some resistors to calculate the output impedance... *shrug* no promises if I can do that soon.
 
May 9, 2015 at 8:08 AM Post #8 of 53

h1f1add1cted

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Thanks for the information, I really appreciate it. Now hopefully can buy one soon here in Germany.
 
/edit finally I found it in a German shop for 199 Euros :)
 
Is there no offcial spec about the 3,5mm output what output impedance is used? Do you need calculate it? This is my last open question before I oder thanks.
 
May 10, 2015 at 4:52 PM Post #9 of 53

Armaegis

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Ok, so I've done a couple quick measurements. Keep in mind, these are mostly static measurements done with resistors, with a cheap multimeter. As such, I would not call these results "accurate".
 
A quick calculation to start, from the specs we're given 140mW into a 32ohm load. Work backwards from P = VV/R and that gives us a max Vrms = 2.1166V
 
Measuring max output from the uDSD output gives me ~2.6V (but I don't known if it clips here)
 
For a reference point, I set it down to roughly 2.0 V for my measurements.
 
Measuring across the following loads, I got these voltages:
no load = 2.0 V
560 ohm = 2.0 V
180 ohm = 1.9 V
50 ohm = 1.7 V
32 ohm = 1.8 V
24 ohm = 1.6 V
 
So right away we can see that the low accuracy of my multimeter is giving a lot of wobble there (seriously... the first decimal is sketchy)
 
If we treat the output impedance in the simplest scenario as an inline resistor which forms a resistor divider with your headphone load, the equation is
Vout = Vin * [R/(R+Z)] where Vout is what we measured, Vin is out input, R is the load and Z is the output impedance
 
Go backwards to solve Z = R*Vin/Vout - R
560 ohm... 0 ohm
180 ohm... 9.47 ohm
50 ohm... 8.83 ohm
32 ohm... 3.56 ohm
24 ohm... 6.00 ohm
 
 
Take that for what it's worth. Keep in mind:
- cheap multiimeter with low accuracy
- resistance is not the same as impedance
- I'm assuming that we can treat the output Z as a simple resistor divider
- go read my HAP-100 review where I calculated negative output impedance. Yeah you can't trust what you see in these numbers because active devices muck up readings that are expecting a static-ish output
 
 
Oh and just for extra fun, I measured resistance from output channel to ground as 6.1 ohms, and 10.8ohm bridging L to R. Subtract roughly 0.8ohm to account for the probe wires. BUT if I turn the uDSD off, I get no reading. So whoops I guess there really is active circuitry there and we can't treat it like a resistor to ground like my assumptions above. But hey, those are the numbers I got. Do with them as you will.
 
Jul 4, 2015 at 1:26 PM Post #13 of 53

Armaegis

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I used to have the e10 (don't remember if it was the k version or not) but have not compared them directly. From memory though, the FiiO is a nice piece of kit for the price but I'd put it along the lines of the uDac1. The uDSD is really a step up.
 
Aug 8, 2015 at 11:01 AM Post #15 of 53

Armaegis

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  Thanks for the review, if it doesnt take forever (or a higher price) i will maybe get one for my workplace.

 
If you have an old dac sitting around, you should take advantage of the trade-in deal.
 

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