# nuforce icon uDAC-2 in the nude



## rjm003

Hard to figure out which is the right forum, here or computer audio. Anyhow, if anyone was wondering (as I was) what the insides of the little beastie look like, wonder no longer:
   

   
  Revealed: a pretty dense layout, most SMT, with a daughterboard for the volume control and headphone section. At least five ICs, plus voltage regulators. A number of passives on the reverse side of the boards, too. Quite a feat of engineering, packing it all such a tiny volume. I'm pretty pleased with my purchase.


----------



## Fantoon

Seems decent


----------



## rjm003

I've noticed Nuforce taking some flak in these forums for not disclosing which chips it uses. fwiw the ICs in the uDAC-2 have what appear to be custom markings with "nu" (for nuforce?) printed on them, a date code, and some other alphanumerics which turns up squat in Google.
   
  That get's a fat "no comment" from me. At this price point they can do whatever they like: I have very low expectations regarding the actual cost of the chips and and I won't complain if the decide to protect their I.P. like this. Good circuit design matters as much or more anyway.
   
  some other misc notes:
   
  A single length of red wire as a jumper suggests some last minute revision, or an unsolvable routing issue.
   
  The two large orange capacitors are curious. They are 2.2uF 50V polar electrolytics marked "L.L". All the other caps are SMT types, and rated for much lower voltage, 16V or less. Why go out of your way to use these big and bulky radial caps with such a low capacitance value? Beats me. A pair of 10uF 16V SMT caps sit nearby.


----------



## MadCow

Well I just ordered a red uDAC-2 myself. Looks pretty interesting, and I hope they've fixed/improved on the channel imbalance issue that I've read about since I plan to use them with my IEMs.


----------



## rjm003

Yeah, a number of people were unhappy with that. I've had no problems with my uDAC-2 with 16ohm 104dB Denon AH-C700's.


----------



## tranhieu

Does the sound get distorted in this version whenever the pot's cranked up? I never turn it higher than 1/2 the whole turn.


----------



## techenvy

hey thanks we appreciate this.  any idea what dac cip she uses?
   
  thanks


----------



## Chikolad

An amazing product!
  Received it 2 days ago, and after those days of burn-in I have to say I'm completely amazed at what this little thing can do to my sound.
  I have a very low quality interconnect cable so the sound is pretty bad when I hook it up to my X-Can, but I'm really flabbergasted at how well it can drive my GS1000 right through its headphone out. MUCH better than the X-CAN's USB input.
  Can't wait to find out what it can do through its line-out and my X-CAN with a proper cable.
   
  Worth every penny!


----------



## Fantoon

It's one of the newest Sabre Dacs, i think this information is posted in the first uDac version thread
  
  Quote: 





techenvy said:


> hey thanks we appreciate this.  any idea what dac cip she uses?
> 
> thanks


----------



## moocow111

Quote: 





tranhieu said:


> Does the sound get distorted in this version whenever the pot's cranked up? I never turn it higher than 1/2 the whole turn.


 

 I don't think it does. I tried it yesterday with Born in the USA, it sounded just great at 3/4 volume.


----------



## rjm003

Quote: 





techenvy said:


> hey thanks we appreciate this.  any idea what dac cip she uses?
> 
> thanks


 
   

  I'd be willing to bet money it's a rebadged ESS ES9022.
   
http://www.esstech.com/PDF/ES9022_PF_090731.pdf
   
   
  (16SOP package: check, 2Vrms output: check, no DC blocking capacitor: check, minimal components: check, decent specs: check, single supply 3.3V DC operating voltage: check.)
   
  I feel I'm on a roll. Let's take a guess at the headphone amp: most likely the MAXIM MAX4411 or possibly the MAX4409. 
   
http://datasheets.maxim-ic.com/en/ds/MAX4409.pdf
http://datasheets.maxim-ic.com/en/ds/MAX4411-MAX4411B.pdf
   
  DC coupled output: check, 80 mWpc at 16 ohm: check. 20 pin 4x4mm package, check. 3.3 VDC single supply operating voltage: check.
   
  re: distortion at high volume. "cranking it" can sometimes harden the sound, depending on program material. Typical for it's class (portable audio) and pretty much unavoidable given the low supply voltages (+3.3V, -3.3V from charge pump circuit).


----------



## tranhieu

Thanks, perhaps I got a defective unit, but a friend of mine also experiences the same problem. It's a great little unit with a nasty pot though.
  
  Quote: 





moocow111 said:


> I don't think it does. I tried it yesterday with Born in the USA, it sounded just great at 3/4 volume.


----------



## usf09

Had to exchange my first one due to a channel imbalance favoring the right side slightly...second one works perfectly though, great sound quality for such a small, inexpensive unit...
   
  Side note though, if you do return it for an exchange, keep the USB cable and stuff. I sent all of that back, and they just sent me a uDac2 unit in bubble wrap. Not a big deal since I have a ton of USB A-B cables lying around...also they didn't return the box or anything, so if I want to sell it later, I'm screwed, but they didn't give me any hassle with the exchange, and the new uDac2 works great, really happy with it...


----------



## rjm003

To clarify, the uDAC-2 has a different pot from the original, and does not have any problems with channel imbalance, etc.
   
  FWIW the uDAC-2 has an improved headphone amp.
   
  Setting the volume level to 3/4 is likely to cause clipping in either product, unless the original recording is of an unusually low level. No reason to think the unit is defective.
   
  Assume program material peaks are -6 dB, so 1 Vrms of the 2 Vrms line output from the DAC. Assume the headphone amp has a gain of 6dB (MAX4411B). If the volume exceeds -6 dB (3/4 turn), the output signal will exceed 1 Vrms.  The clipping point for the amp with 16 ohm headphones, 80 mW, is 1.1 Vrms.
   
  80 mW is also in excess of 140 dB for most headphones. Keep it safe out there kids.
   
   
   
  Quote: 





tranhieu said:


> Thanks, perhaps I got a defective unit, but a friend of mine also experiences the same problem. It's a great little unit with a nasty pot though.


----------



## jasonl

We pride ourselves at providing high performance DAC/HP amp at very affordable prices.  Certain manufacturers we worked with provide slightly modified versions of their products, even with modified firmware for Nuforce, and that allows Nuforce to offer performance that far exceeds the sum of the parts.
   
  By the way, we like your comment on the circuit, even though not all are correct. You know your stuff


----------



## Chikolad

Quote: 





jasonl said:


> We pride ourselves at providing high performance DAC/HP amp at very affordable prices.  Certain manufacturers we worked with provide slightly modified versions of their products, even with modified firmware for Nuforce, and that allows Nuforce to offer performance that far exceeds the sum of the parts.
> 
> By the way, we like your comment on the circuit, even though not all are correct. You know your stuff


 

 Do I sense a job offer coming?


----------



## rjm003

Thanks for the kind words. I'm impressed that you have the buying power to get your own custom chip labels, let alone your own firmware. Of course going that route is going to attract some level of speculation.
	

	
	
		
		

		
		
	


	



   
  Your uDAC-2 is clearly a very polished product and is a joy to use. I wish you every success with it.
   
   
  Quote: 





jasonl said:


> We pride ourselves at providing high performance DAC/HP amp at very affordable prices.  Certain manufacturers we worked with provide slightly modified versions of their products, even with modified firmware for Nuforce, and that allows Nuforce to offer performance that far exceeds the sum of the parts.
> 
> By the way, we like your comment on the circuit, even though not all are correct. You know your stuff


----------



## jasonl

We are a very small company. Being a high performance company has its advantage where some suppliers are keen to work with us because they can use us as a reference. uDAC and OPPO BDP-83SE Nuforce Edition were displayed at ESS's demo room at CES last year. I am not implying that we use customized chip from ESS.


----------



## MadCow

My uDAC-2 just arrived a few minutes ago; extremely speedy service considering that it travelled nearly half the globe in order to get here. Looks like I'll be busy tonight.


----------



## Squa7ch

I just ordered a uDAC-2, can't wait for it to get here 
	

	
	
		
		

		
		
	


	




.


----------



## shaddix

had to exchange mine b/c of hissing, hopefully they will send it back with the box/cable/manual etc.......


----------



## rasmushorn

Quote: 





squa7ch said:


> I just ordered a uDAC-2, can't wait for it to get here
> 
> 
> 
> ...


 

 I did the same. I heard the uDAC at a meet in Berlin and it had a very surprising synergy with my Grado SR325i. I went home and ordered the uDAC-2 hoping it will sound just as good - maybe better?
   
  From what I can read the DAC-section is better in the uDAC-2. So does anyone know if the AMP-section is the same in the uDAC as in the uDAC-2 ?


----------



## Lil' Knight

The uDAC-2 has improved headamp section.


----------



## rasmushorn

Quote: 





lil' knight said:


> The uDAC-2 has improved headamp section.


 

 I hope improved does not mean different sound signature??? Has anyone done a comparison between the uDAC and the uDAC-2 ?


----------



## Lil' Knight

Quote: 





rasmushorn said:


> I hope improved does not mean different sound signature??? Has anyone done a comparison between the uDAC and the uDAC-2 ?


 

 No idea because I haven't ordered the uDAC-2.I doubt it would change a lot though. Did you check out the uDAC-2 thread?


----------



## rasmushorn

Quote: 





lil' knight said:


> No idea because I haven't ordered the uDAC-2.I doubt it would change a lot though. Did you check out the uDAC-2 thread?


 

 Aahhh - thanks! I didn't even know a uDAC-2-thread existed 
	

	
	
		
		

		
		
	


	




 (I thought this was the one.)


----------



## rjm003

I've had the uDAC-2 long enough now to be able to review it with some confidence. Let's give it a shot.
   
  Preamble: It's $129, well into impulse buy territory for most audiophiles. All you need to know is whether it does what it's supposed to (it does) and whether it sounds decent (it does)... the rest is petty details. However if you want the nitty gritty, read on.
   
  For $129, it justifies itself on functionality of a 24bit 96kHz capable USB-spdif converter alone. Every thing else is a bonus.
   
  The line out is more correctly a preamp out, as the output level is adjusted by the volume control. It's not a USB DAC, but rather a USB DAC+preamp. This could be a feature or an annoyance depending on what you propose to use the line out for.
   
  Finally there is the headphone amplifier, which automatically switches off the preamp output when a headphone is plugged into the socket. This switching could again be considered a feature or an annoyance.
   
  If you stick to using it as as the volume control in minimalist PC sound system, either with headphones or external power amp and speakers, the way it's configured is intuitive and straightforward.
   
  When the uDac is plugged into a Windows PC the OS automatically detects the device and routes the audio to it, turning off the default audio device. So it is "plug and listen", zero hassle.
   
   
  Perhaps though it is "peace of mind" that is the most useful feature of the uDac-2: With this tiny little box you are _guaranteed_ a consistent audio experience, regardless of whatever computer you happen to be using. For me this counts for a lot.
   
  Case studies.
   
  Case 1. Denon AH-C260 IEH (16 ohms, ~$40), uDac-2 vs. Realtek ALC272 HDaudio codec (Samsung n310 netbook)
   
  I wanted to begin this by concluding that with inexpensive headphones like these low end Denons there really want any audible difference - but the fact of the matter is that music sounded more realistic and was far more enjoyable through the uDac. The AH-260 has fairly limited frequency response and a mid-bass hump to compensate, but is a nice enough sounding headphone overall. 
   
   
  Case 2. Denon AH-C700 IEH (16 ohms, ~$150), uDac-2 vs. Realtek ALC272 HDaudio codec (Samsung n310 netbook)
   
  The AH-C700 has a much wider frequency response, and as a result the comparison between the uDAC and the netbook's headphone out was more complicated. Yes, the uDac was more realistic, more hi-fi... but the higher resolution headphones were able to detect some roughness in the treble, roughness which increased with playback volume of the uDac. The ALC272 was mushy, but comparatively smooth.
   
  Case 3. Sennheiser HD-600 (300 ohms, ~$300) uDac-2 headphone out vs. uDac-2 preamp out into Twilight 6CG7/FET mu-stage headphone amplifier.
   
  The uDac-2 headphone amp with the HD-600 gave a result typical of the HD-600 paired with low voltage solid state headphone amps: reasonably ok but lacking the "grip" needed to get the best from these 'phones. No bass response, small, collapsed soundstage. Treble was smooth though. The preamp out to the mu-stage, with the two volume controls set at arbitrary values, put the headphone amp of the uDac in it's place with authority. The good news to take from this though is that the preamp out of the uDac is fine, excellent even, and it's not insult to the uDac to say it can't drive HD-600's. Very few headphone amps in the world today can.
   
  Conclusion
   
  Seems the headphone amp is a little starved for current. Otherwise full marks.


----------



## radonsg

Using it with my imac, it is auto detected.
  1 thing to note, default setting is only 16bit. I manually change it to 24bit.
   
  Working nicely with my sr60i & soundmagic pl30, can feel the increase in bass.


----------



## pejayjay

Very nice rjm.
   
  It's (yet another) on my list of things to buy..


----------



## korek

Hello,
   
  could you please post the details about udac2 volume pot?
  I have udac1 and I'd like to replace the pot.
   
  I know that it differs in the on/off functionality ... perhaps the pinout is different as well.
  Haven't opened my udac1 yet.


----------



## USCdeacon

Quote: 





radonsg said:


> Using it with my imac, it is auto detected.
> 1 thing to note, default setting is only 16bit. I manually change it to 24bit.
> 
> Working nicely with my sr60i & soundmagic pl30, can feel the increase in bass.


 


  hey radonsg, how did you manually change it to 24bit?  And does changing it to 24bit matter if most of my music is ALAC/16bit?  (On the first uDAC by the way).  Thanks!


----------



## rjm003

Quote: 





uscdeacon said:


> hey radonsg, how did you manually change it to 24bit?  And does changing it to 24bit matter if most of my music is ALAC/16bit?  (On the first uDAC by the way).  Thanks!


 


  It's a setting on your computer and depends on which OS you are using. For Vista/Windows 7, it's the "manage audio devices" dialog, click on the playback device, select the advanced tab, and change the default format from 2 channel 16 bit 48 kHz to 2 channel 24 bit 96kHz.
   
  It's not clear to me what if any effect this has when playing back 16bit 44.1kHz media. I do know that if can degrade sound quality if Windows internally converts from 44.1kHz to 48 kHz because it thinks the output device can only handle 48khz.


----------

