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[REVIEW] - UDac3 - Good things do come in small packages - Page 2

post #16 of 27

Hi guys, hey Brooko, looks like our findings for the most part are in agreement.

 

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post #17 of 27
Thread Starter 

Nice review Arly.  Yes - similar thoughts.

 

Just noticed a couple of things in the last few days.

 

  1. Had my first driver instability - basically stopped playing.  Was just a simple matter of unplugging and replugging.  Could well have been a Windows fault rather than the uDac-3.  Up until now it's been rock solid.  Might install the actual NuForce driver at work though and see if that avoids any more issues.  This has only been a oncer so far though - so it's been remarkably stable.
     
  2. I've noticed with the DT880s it very occasionally heats up.  It's nothing to worry about - as it simply gets a little warm.  So far only happens if I leave the DT880s plugged in, and have the uDac-3 on, but the music paused for a longer period of time.  Again - nothing startling - just something to note.

 

I'm still using this evey day at worjk BTW - and absolutely loving it :)

 

It has me kind of intrigued now to see what else is in NuForce's line-up.

post #18 of 27

Thanks for the kind words Brooko. I've had the unit for a good 5 months and I've yet to have any problems. I've also noticed that my unit will get warm when I'm driving my Alpha Dog or Paradox but its nothing that really worries me. It takes a good hour to get warm and its far from hot so I don't worry about it. Truth be known I've been using the uDAC-3 more as a desktop solution with my C/IEM's. I really like how it makes my C/IEM's sound.

post #19 of 27
Quote:

Originally Posted by Brooko View Post

 

 

SO WHAT IS THE UDAC-3?

The uDac-3 is an extremely small (a little larger than a zippo lighter) high resolution USB powered DAC ...

 

TECHNICAL SPECIFICATIONS

 The table below lists most of the relevant specifications.

Input :

USB 1.1, 2.0 compatible

Native Bit Rate :

32, 44.1, 48, 88.2, 96 kHz, 24-bit

Output (line out) :

Analog RCA output = 2Vrms

Dynamic Range :

90 dB

S/N Ratio :

98 dB

THD+N :

0.05%

Digital Output :

Coaxial RCA 75-Ohm

Headphone Output :

80 mW x 2 @ 16-Ohm

Power :

USB Bus Powered, 80 mA/5V

Dimensions :

68 x 38 x 21 mm

 

 

 

If the line out is really 2 Vrms from a 5V USB-powered device in such a small footprint, it would be quite impressive. A pure sine wave with 2V rms has a peak to peak amplitude of  5.66 V, which certainly exceeds the USB standard's allowance for 5V +/- 0.25V for complying devices. I have to admit that I'm a bit skeptical that the device can actually achieve the 2Vrms that's specified on the website; rather, I expect that the output is 4V peak to peak (or 1.41 Vrms).

 

If Brooko or wolfgang could chime in regarding the output levels of the analog out; specifically, if the little guy can really muster outputs beyond the limits of the input voltage. I'd be very interested in how NuForce achieved high quality boosted voltage rails---I have some small form-factor projects that would benefit from voltage rails > +/- 2.5V! Certainly, it's a specification that would set the udac3 ahead of the other usb-powered DACs that I'm currently aware of.

 

Cheers

post #20 of 27
Thread Starter 
Quote:
Originally Posted by ab initio View Post
 

 

If the line out is really 2 Vrms from a 5V USB-powered device in such a small footprint, it would be quite impressive. A pure sine wave with 2V rms has a peak to peak amplitude of  5.66 V, which certainly exceeds the USB standard's allowance for 5V +/- 0.25V for complying devices. I have to admit that I'm a bit skeptical that the device can actually achieve the 2Vrms that's specified on the website; rather, I expect that the output is 4V peak to peak (or 1.41 Vrms).

 

If Brooko or wolfgang could chime in regarding the output levels of the analog out; specifically, if the little guy can really muster outputs beyond the limits of the input voltage. I'd be very interested in how NuForce achieved high quality boosted voltage rails---I have some small form-factor projects that would benefit from voltage rails > +/- 2.5V! Certainly, it's a specification that would set the udac3 ahead of the other usb-powered DACs that I'm currently aware of.

 

Cheers

 

Wolfgang knows about the thread - so I'll let him answer the technical questions.  I wouldn't expect too much though - especially if it is proprietary info.  Even when asking which DAC chip they used, they weren't exactly forthcoming.  Pity really as the unit really does sound quite good.

 

The figures I quoted were direct from their site / packaging.

 

I will say this though - the little guys does output a nice amount of power.  Has no problem with the Beyers (250 ohm DT880) or the Senns (HD600) - although to be fair, neither of them are really that hard to drive.

post #21 of 27
Thanks.....do you know if the RCA analog output is variable with the ability to plug directly into powered speakers?

Also, can this unit be "tricked" into working with iPad/CCK with a powered USB hub?
post #22 of 27
Thread Starter 
Quote:
Originally Posted by Robster1958 View Post

Thanks.....do you know if the RCA analog output is variable with the ability to plug directly into powered speakers?

Also, can this unit be "tricked" into working with iPad/CCK with a powered USB hub?

The RCA out is variable - but the gain (using the pot) is only about 6db.

I tried the iPad/CCK and it didn't work. If you can "jury-rig" a powered hub and have it work, I'd really appreciate if you can let me know how.
post #23 of 27
Thread Starter 

Update - just found out from Wolfgang that the Headphone Out impedance on the UDac-3 is 5.3 ohms.  Higher than I would have expected - but would be an acceptable damping combo with everything 40 ohms and up - and to be fair, most 32ohm +.

 

I didn't really have any issues with my IEMs either.

post #24 of 27
Quote:
Originally Posted by cyph3r View Post

Great review and Interesting piece of kit. Do you know what DAC chip is inside?


It uses an ESS ES9023.

 

Also, while the SA9027 is Async capable, it does not appear they are using it in Async mode, just plane adaptive mode (I have not seen a picture

of the bottom of the digital board though...maybe they are hiding the clocks under there..?).

post #25 of 27
Quote:
Originally Posted by Avro_Arrow View Post


It uses an ESS ES9023.

Also, while the SA9027 is Async capable, it does not appear they are using it in Async mode, just plane adaptive mode (I have not seen a picture
of the bottom of the digital board though...maybe they are hiding the clocks under there..?).

Thanks Avro. well that explains the compact setup, the ESS9023 has an integrated opamp. Reasonable choice for good sound and size. Clock? ES9023 uses i2s as input. The master clock probably is provided by an oscillator under the board. Dont know mayve there is apossibility to get a signal from the usb-i2s chip (xmos?).
post #26 of 27
Quote:
Originally Posted by Avro_Arrow View Post
 


It uses an ESS ES9023.

 

Also, while the SA9027 is Async capable, it does not appear they are using it in Async mode, just plane adaptive mode (I have not seen a picture

of the bottom of the digital board though...maybe they are hiding the clocks under there..?).

 

It is in async mode. A while back, I actually ran some test over the USB to confirm that the uDAC3 is configured as async.

post #27 of 27
Quote:
Originally Posted by cyph3r View Post


Thanks Avro. well that explains the compact setup, the ESS9023 has an integrated opamp. Reasonable choice for good sound and size. Clock? ES9023 uses i2s as input. The master clock probably is provided by an oscillator under the board. Dont know mayve there is apossibility to get a signal from the usb-i2s chip (xmos?).


The USB to I2S is a SaviAudio SA9027.

 

Does anyone have a picture of the underside of the digital board?

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