[mr-teatime]

hello,

i noticed a slight difference in the volume balance of the left and right channel of the udac (on headphone and rca output). the left channel is a little bit louder than the right – with low output volume more recognisable than with higher (obviously).
has anyone else recognised this issue? is this an issue or kind of normal due to production conditions? anything one can do about it (apart from manipulating source balance (e.g. in itunes) or amplifier)?

apart from that i‘m more than happy with the device!

best,
teatime

[betweentheears]

I noticed the same left side prominance, but only at the very lowest volume posible. Once volume is adjusted to listening levels it is balanced. That would be the only negative in my experience with the little wonder.

[mr-teatime]

i‘ve had time to do some tests: feeding the signal from rca output back into the macbook. created sine waves using ableton live and used a spectrum analyzer to visualize  the signal from the rca out. throughout the whole volume range the left channel is kind of one bar louder. the impact of this imbalance is of course not that noticeable in higher volumes (3+1 vs 12+1).
as betweentheears mentioned, there is also one point on the lowest end of the volume control, where only the left channel is playing, but this effect already disappears when you put the volume one dot up.

cheers

[NotoriousBIG_PJ]

My uDac (black) and my friend from works uDac (red) are both slightly louder on the left side. Nuforce is kindly sending me a replacement. I hope it does not have the same problem.

Biggie.

[mr-teatime]

@NotoriousBIG_PJ
thanks for letting us know – and keep us posted with results ...

funny enough: a left channel dominance makes the music sounding more pushing (at least for me) – try it yourself and flip the channels – when the right side is louder, it feels kind of hesitant ...
all about psychology?

[Kenobi]

funny enough: a left channel dominance makes the music sounding more pushing (at least for me) – try it yourself and flip the channels – when the right side is louder, it feels kind of hesitant ...
all about psychology?


MrTeaTime,

Its also possible your left and right ears are not at the same sensitivity level--at least for myself.  My right ear is now deprived of the highest registers in the frequency band due to excessive phone use which I instinctively relegated to this ear.  I now have learned to balance things out and have my left ears cover most of this chore.  However, the left ear still allows for better high frequency reception and enjoyment.  More air and sparkle whereas the right ear is somewhat muted and muffled in comparison.  So, be sure to use both ears equally if possible and don't develop a habit of using one more than the other before its too late.

Kenobi 

[i10neorg]

My uDac (black) and my friend from works uDac (red) are both slightly louder on the left side. Nuforce is kindly sending me a replacement. I hope it does not have the same problem.

I have the same channel imbalance issue and am waiting to hear the the issue is resolved with the replacement, before requesting a replacement myself.

The response to the support ticket I opened at their help desk was not very inspiring:

Hello,
I apologize for not clarifying my view. There are many factors involving the imbalanced channels of the Udac. The mechanic of every Udac cannot be perfect, the volume control might have some deviation curves. Second, a rather sensitive headphone can amplify the above problem. In addition, there is a possibility that the Dac and the headphone don't match. I've done some reading myself just now, and I have found only a minority is experiencing this problem. So there might be a good chance that you receive a less deviate Udac through replacement. Thank You for your time.

Best Regards,
Logan
NuForce

[nuforce-casey]

The transducers have much higher channel tracking issues.  You can read the various measurement presented in some headphones/earphones measurements: http://www.headphoneinfo.com/d/reviews.htm

Tracking
Headphones have one channel for each ear, so it is vital for good performance that both sides are identical.

Our test system produces the graph below, which shows the tracking across the frequency range of 80 to 2kHz. If the line is at 0 percent, that indicates the sound at that frequency is identical in both channels. If it goes above that line, the left channel is stronger, and if it goes below, the right channel is is putting out more.

Bose QuietComfort3 (over ear as an example)


Apple 3G In Ear (the free iPhone earphones)


Shure SE530 (one of the best L/R tracking)


Vmoda Vibe Duo (really bad!)



Monster Turbines (quite bad)






The volume control at the low volume setting still tracks within 1dB, however, check your earphone's performance - almost all IEMs except the very top-end models exhibit significant deviation between L and R buds.



 

[i10neorg]

The transducers have much higher channel tracking issues.  You can read the various measurement presented in some headphones/earphones measurements: http://www.headphoneinfo.com/d/reviews.htm

Monster Turbines (quite bad)

Thank you for the information, nuforce-casey, but please understand that the characteristic you've shared is not the issue we're experiencing.

Looking at the channel tracking testing you've referenced, I found no mention of the overall volume level used while testing.  The problem we're describing is very specific to low volume only (as set on the volume knob of the uDAC).

Furthermore, the channel deviations described by the tests you've passed on are in the higher (above human voice) frequencies only (>3kHz).  The problem we're describing is as broadband an effect as simply making a (R/L) balance adjustment.

The volume control at the low volume setting still tracks within 1dB, however, check your earphone's performance - almost all IEMs except the very top-end models exhibit significant deviation between L and R buds.

I tested my faulty uDAC with both decent and cheap headphones, over the head and in ear.  Exactly the same problem regardless of headphone.  It's not just a difference between the channels at certain frequncies--as the volume is reduced to the quietest levels, the sound moves to a single (same in both earphones) channel before the overall volume goes to zero.

The problem does not exist on my laptop's headphone out jack.  The channel imbalance at low volumes we're describing is a problem with the uDAC.  And it's pronounced.

[betweentheears]

My experience with volume diferential is from 7:00 the off position to 8:15-8:30. After that R/L balance is achived..in my ears anyway. Even with my sensitive IEM's {TF10's} I find I listen at a level beyond 10:00 so the imbalance I hear is a non issue.

[nuforce-casey]

Thank you for the information, nuforce-casey, but please understand that the characteristic you've shared is not the issue we're experiencing.

Looking at the channel tracking testing you've referenced, I found no mention of the overall volume level used while testing.  The problem we're describing is very specific to low volume only (as set on the volume knob of the uDAC).

Furthermore, the channel deviations described by the tests you've passed on are in the higher (above human voice) frequencies only (>3kHz).  The problem we're describing is as broadband an effect as simply making a (R/L) balance adjustment.

I tested my faulty uDAC with both decent and cheap headphones, over the head and in ear.  Exactly the same problem regardless of headphone.  It's not just a difference between the channels at certain frequncies--as the volume is reduced to the quietest levels, the sound moves to a single (same in both earphones) channel before the overall volume goes to zero.

The problem does not exist on my laptop's headphone out jack.  The channel imbalance at low volumes we're describing is a problem with the uDAC.  And it's pronounced.

On those chart examples, you should see that the volume deviation (Monster Turbine) is consistent over the low frequency at -2dB, and the Vmoda +3dB.  The wide swing at high frequencies are actually not that easy to hear, because they swing between R and L with very limited (notched) frequency bands.  I want to show were the gentle, nearly straight lines that falls between 20 to 1kHz in those examples.

That said, Nuforce would gladly exchange the uDAC and I would be interested to measure the returned unit.  You should send a note to our helpdesk.

[Double-C]

Icon AMP owner here (newly). I was just about to post this exact issue as I too am experiencing where my left channel produces no sound at low volumes.

[i10neorg]

My experience with volume diferential is from 7:00 the off position to 8:15-8:30. After that R/L balance is achived..in my ears anyway.

Similar for me.  At 9:00 one channel begins falling faster than the other, by 8:30 it feels almost all in one channel, and from 8:00 to 7:00 (off), only silence.

Even with my sensitive IEM's {TF10's} I find I listen at a level beyond 10:00 so the imbalance I hear is a non issue.

Unfortunately, it is a real issue for me, sometimes wanting to be around 8:45.

Furthermore, the channel deviations described by the tests you've passed on are in the higher (above human voice) frequencies only (>3kHz).  The problem we're describing is as broadband an effect as simply making a (R/L) balance adjustment.

On those chart examples, you should see that the volume deviation (Monster Turbine) is consistent over the low frequency at -2dB, and the Vmoda +3dB.  The wide swing at high frequencies are actually not that easy to hear, because they swing between R and L with very limited (notched) frequency bands.

I believe that is how I understood the graphs as well, and I don't think I've said anything to suggest otherwise.

Looking at the channel tracking testing you've referenced, I found no mention of the overall volume level used while testing.  The problem we're describing is very specific to low volume only (as set on the volume knob of the uDAC).

I want to show were the gentle, nearly straight lines that falls between 20 to 1kHz in those examples.

But without data over a range of volumes, it's impossible for the analysis you've referenced to capture the issue we're experiencing.

Even if the their analysis happened at the problem volume level (say, 8:00 to 9:00 on the uDAC), what we're experiencing would look like a mostly horizontal line (equal volume reduction across all frequencies) and very far from 0 (a very different graph).  We aren't just talking about a handful of dBs difference here, at the right volume you almost exclusively hear only a single channel.

That said, Nuforce would gladly exchange the uDAC and I would be interested to measure the returned unit.  You should send a note to our helpdesk.

A week ago I sent a note to your helpdesk, Call/Ticket ID: 1305.  I had been holding off returning my uDAC to hear if NotoriousBIG_PJ's replacement fixed the issue.  But knowing now my return will allow you to experience the issue for yourselves, I think I'll do so.

[i10neorg]

I had been holding off returning my uDAC to hear if NotoriousBIG_PJ's replacement fixed the issue.  But knowing now my return will allow you to experience the issue for yourselves, I think I'll do so.

Unfortunately, I'm experiencing the same low volume channel balance problem with a replacement uDAC.

Here's a quote from the reply from the NuForce helpdesk, 2010-03-15:

I tested the one that you sent back, there was slight differences compared to a functional one. I am not sure why the replacement Udac was defective as well, because we don't get much customers complaining about this issue. Sorry for the trouble, please return the unit in the following manner. We will process your refund promptly once we receive it.

Thanks,
Logan
NuForce

I'll be keeping the unit, it's useful to me for usb to coaxial spidf.  Picking up some higher impedance phones would let me listen at low volume past the low volume channel balance problem.  Otherwise, moderate volumes and above, they're fine.

Other than there being a problem at all, my experience with NuForce was positive: open, responsive, and accommodating.

[rustydoglim]

After analyzing the issue, we published this article:

http://www.nuforce.com/hp/support/analog-volume-graph.html

And since then we have informed our support staff that such issue related to Icon uDAC is to be expected -
 from 6 to 9 o'clock, the volume pot is only responsible for approx. 1% of the attenuation range (i.e. 99% of resistance of the pot). Tolerance wise, it's not achievable to be 0.5dB accurate between channels, since a small difference would have resulted in 2-3dB of mismatch easily.

But we will still give 100% refund if customer can not accept this level of performance for uDAC.  It is not that such performance can not be achieved:
- many entry level product uses DIGITAL VOLUME CONTROL and you don't get such discrepancies at low volume
- for high-end product, the analog volume control can be very precise.

Icon uDAC uses a high-end volume pot to get the performance we need, but the cost and space constrain does not allow us to tune the channel balance at very low volume level.

[rudy99]

how does the usb udac compare to the usb hd ampdac  th hdp i think


thanks