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:

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

 

[moocow111]

Quote:

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:

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:

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:

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