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Tiny DAC, Big Sound, Evolved – Stoner Acoustics UD100 / UD110 / UD120 - Page 73

post #1081 of 1089

Running an analog output stage on 3.3V is vanishingly unlikely to be delivering state of the art performance. For a start caps at 4V rated working really suck, so the power supply is a major challenge.

post #1082 of 1089
Thread Starter 
Quote:
Originally Posted by Sapientiam View Post
 

Running an analog output stage on 3.3V is vanishingly unlikely to be delivering state of the art performance. For a start caps at 4V rated working really suck, so the power supply is a major challenge.

 

...fortunately we have 5V on USB? Then again, the DAC we are talking here has internal charge pump and capable of spilling out line-level 2.1Vrms signal without any extra parts. It is not some 'state of the art' DAC that required NASA qualified engineer to design its power supply.

post #1083 of 1089

Ah there's the rub - we don't always have 5V on USB, that's the nominal voltage and it can go lower. Hence the need for local regulation to a lower voltage. Gino's comments that it 'can't be that good' were in the context of looking for something state of the art I believe. Not to knock this DAC which looks excellent given the low cost and small size.

 

Internal charge pumps are convenient but all IC charge pumps tend to have rather high output impedance, which is a limitation on SQ.

post #1084 of 1089

Can you clarify how the line output impedance going into the amp impacts SQ?  What would be the normal input impedance for line level on an amp?

post #1085 of 1089
Thread Starter 
Quote:
Originally Posted by Sapientiam View Post
 

Ah there's the rub - we don't always have 5V on USB, that's the nominal voltage and it can go lower. Hence the need for local regulation to a lower voltage. Gino's comments that it 'can't be that good' were in the context of looking for something state of the art I believe. Not to knock this DAC which looks excellent given the low cost and small size.

 

Internal charge pumps are convenient but all IC charge pumps tend to have rather high output impedance, which is a limitation on SQ.

 

Not to knock on Gino either, but it is kind of odd to comment about state of the art DAC which is not what this thread is about. At least I have not seen anyone claiming any DAC discussed in this thread to be state of the art. That's the discussion best reserved on the high-end or DIY forum.

 

Quote:
Originally Posted by fritobugger View Post
 

Can you clarify how the line output impedance going into the amp impacts SQ?  What would be the normal input impedance for line level on an amp?

 

DAC is not supposed to 'drive' the amp and should only acts as a pure voltage source. To have that, usually we want the output impedance of the DAC to be at least around 1/10 of the input impedance of the amp. Input impedance of the amp can vary by a lot, but usually we are talking a few thousand ohm, so we tend to see DAC's output impedance on a few hundreds ohm. Most DAC is not designed to output a lot of current, and if it does driving a load, it will not behave at its best and we will see performance decreases.

post #1086 of 1089
The driving impedance primarily affects SQ because it sags the power supply of the driving amp to some degree. The upshot is - the higher the driven impedance (I would suggest aiming for over 47kohms with normal CD levels) the better the sound.
post #1087 of 1089
post #1088 of 1089

http://stoneracoustics.blogspot.com/

 

I would have preferred with built-in dac. Now I have to use USB OTG cable to UD110v2, and from the output of the dac to the input of the amp. It could go straight from the smarpthone (Note 3) to the dac and amp.


Edited by satsurfer - Today at 3:44 am
post #1089 of 1089

Belgian huh? yay!

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