Node 2i Loudness

Beantwortet

ric982

• 15. Dezember 2020 01:47
• Bearbeitet

Not sure anyone can clear this up but ....

I wanted to compare the Node 2i DAC to my Channel Island VDA-2 DAC.

I've got two areas of confusion. One relates to loudness and the other to sound quality.

Lets start with the loudness area in this post.

So I set up the following two paths to my amp:

Wi-fi -> Node 2i -> Coax -> VDA-2 DAC -> PreAmp/Amp CH 1 Balanced Input (XLR)
Wi-fi -> Node 2i -> RCA                          -> PreAmp/Amp CH2 Unbalanced Input (RCA)

For a fair comparison, the two paths need to be normalized to the same loudness level. As described below, I can adjust my amp to get equivalent loudness, but I'm trying to understand quantitatively where the difference is coming from.

Neither DAC supports the other input type so I don't have a choice to match these. I have the Node 2i set to "Fixed Volume". The VDA-2 has no volume controls.  I'm noticing to get roughly the same loudness levels, I'm having to increase amp volume on the unbalanced input about 6-8 dB. The amp manual describes its display as "Volume". I was checking the loudness dB levels with a phone app to match them up, so I should be in the ball part for accurately setting the amp to match the loudness levels. 

I've seen other posts that say that the Node 2i seems to need more Gain to match other sources (not sure whether they are balanced or unbalanced from the posts). I'm wondering what part of this could be due to balanced vs unbalanced inputs. 

Assuming the amp does not compensate for the input type, my thinking is something like:
RCA unbalanced - should be -10 dBV -> 0.316 Vrms - should be 0.447V peak voltage
XLR balanced - should be +4 dBu -> 1.228 Vrms- should be 3.147V peak to peak (differential signal)

20 log10 (3.472/0.447) = 17.8 dB which doesn't go with my 7 dB of correction.

Am I looking at this wrong?

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• Offizieller Kommentar

  

  Sam R.

  • 15. Dezember 2020 20:34

  Hello,

  Two things I would look at here: balanced vs unbalanced, as you said, but also digital vs analog. 

  The VDA-2 is doing the analog to digital conversion in your first scenario. Depending on the DAC chip and a number of DSP processes, that may be the source of some of increased loudness, though I imagine it would be a difficult time pinpointing wherein that exactly it is. I've heard people describe the NODE's DAC as very neutral. 

  Also, balanced connections (the cables especially) are designed to preserve/shield the connection from interference. The unbalanced connection may be losing some signal on the run. 

  Regards,
  Sam R.
• 

  ric982

  • 16. Dezember 2020 21:35
  • Bearbeitet

  Thanks Sam.
  
  I've noticed that the VDA-2 seems hot compared to what's coming out of my TV monitor - maybe about +6dB - but again that is unbalanced so could still be balanced vs unbalanced.

  The cables are short - say 2 ft. I'd buy that unbalanced is more susceptible to noise (on a much longer cable), but probably not that it is loosing signal level.
  
  It's probably not too important why they are different. I was hoping someone would pop up and say - hey - the level's your are assuming are wrong or that I did something wrong in the calculation.

  My first guess is that the amp does compensate for balanced vs unbalanced, my calculation was correct (though the amp compensates for this),  and that the VDA-2 vs the Node 2i are about 6 dB different for whatever reason. I'll let it go at that.

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