Only "half of the machine" used when using single-ended on a fully balanced DAC?

[kongwee]

And in that case you really *are* only using half of the machine. And probably no audible difference. So suddenly you want half your money back!

I can heard the difference more than gain drop, can't solved by level and EQing. More importantly if there is any hum or buzz, keeping differential path fully differential will eliminate the guess work. XLR connectors must be as Neutrik as possible. For me who do stuff for DAW and sometime need to man mixers. Differential all the way as much as possible. This is work not science.

 

[MrBingley]

Just bumping an older thread to share some info.

I was wondering about the XLR vs RCA output on a R-2R DAC from Denafrips. The Venus II.

I could clearly hear a difference between the two connections but wondered what exactly was going on so I emailed the distributer. It turns out RCA only uses the positive signal from pin 3 of the XLR connection so you are only getting half the processing power of this 4 ladder DAC.

BUT - the reason for the sound quality difference on my 300B SET tube amplifier is that it uses a balanced input board (2 opamps) to merge the XLR signal back to single ended and it does sound significantly better that the half signal from RCA,

So the question that needs to be asked is both how does the DAC create the single ended signal and how does your amp translate the XLR signal (unless it is a fully balanced amplifier). Both need to be known before deciding if RCA may be equivalent to XLR in sound quality. But many times it will not be.

 

[radix]

Just bumping an older thread to share some info.

I was wondering about the XLR vs RCA output on a R-2R DAC from Denafrips. The Venus II.

I could clearly hear a difference between the two connections but wondered what exactly was going on so I emailed the distributer. It turns out RCA only uses the positive signal from pin 3 of the XLR connection so you are only getting half the processing power of this 4 ladder DAC.

BUT - the reason for the sound quality difference on my 300B SET tube amplifier is that it uses a balanced input board (2 opamps) to merge the XLR signal back to single ended and it does sound significantly better that the half signal from RCA,

So the question that needs to be asked is both how does the DAC create the single ended signal and how does your amp translate the XLR signal (unless it is a fully balanced amplifier). Both need to be known before deciding if RCA may be equivalent to XLR in sound quality. But many times it will not be.

The RCA signal is the same signal as the XLR. Assuming you do not have massive noise, the balanced amp still cancels common mode noise you pick up on the signal and shield.

The amp will take the difference of the + and - signals. This means you get 2x signal and 0 common noise. That is, if your signal XLR is +A and -A, then the amp will get (+A - -A) = +2A as the signal. Any common noise N will be (N - N) = 0.

One reason you might hear a difference is XLR is you get 2x the voltage. it's just louder. If you level match your speakers (i.e. with a volt meter) between the balanced and unbalanced, the difference will likely go away.

The XLR and RCA might expect difference input impedances. Some units, when they take the RCA from pin 3 use a separate driver op amp for it, some just take it straight from there.

 

[MrBingley]

The RCA signal is the same signal as the XLR. Assuming you do not have massive noise, the balanced amp still cancels common mode noise you pick up on the signal and shield.

The amp will take the difference of the + and - signals. This means you get 2x signal and 0 common noise. That is, if your signal XLR is +A and -A, then the amp will get (+A - -A) = +2A as the signal. Any common noise N will be (N - N) = 0.

One reason you might hear a difference is XLR is you get 2x the voltage. it's just louder. If you level match your speakers (i.e. with a volt meter) between the balanced and unbalanced, the difference will likely go away.

The XLR and RCA might expect difference input impedances. Some units, when they take the RCA from pin 3 use a separate driver op amp for it, some just take it straight from there.

Thanks for the reply. But my ears certainly tell me the XLR is giving more dynamics and detail than the RCA output when volume level is adjusted to balance each output. The RCA is softer and rounder sounding with diminished details in the highs.

Whether that is the effect of the balanced input board in the amp adjusting the impedance of the signal to the tubes or that the cumulative + and - signals from the XLR are providing a cleaner and more detailed signal than just the positive signal on its own or something else is going on I cannot say for certain. And it may very well be more noticeable with my particular equipment than say a solid state setup.

In either case the distributor encourages using the XLR output on the DAC for best sound reproduction.

I appreciate you taking the time to respond.

 

[radix]

Thanks for the reply. But my ears certainly tell me the XLR is giving more dynamics and detail than the RCA output when volume level is adjusted to balance each output. The RCA is softer and rounder sounding with diminished details in the highs.

How did you adjust the volume between RCA and XLR? You do need to measure it at the output of the amp or at the speaker. The ear has different frequency response based on the volume, and relatively small difference can be heard as different response.

I doubt there is any audible difference in the output of the DAC between XLR and RCA. Maybe the amp does something strange? I'm not sure about the specific model you have.

I'd suggest trying to equalize the volume with a 1 khz tone to an RMS volt meter on the amp output, using the DAC volume control, and then swap between then to the amp. if you only have 1 DAC and are trying to compare the XLR vs RCA, that would be a bit of a problem as you would need to re-calibrate between each listening and you'd likely forget the sound you heard by the time you could switch.

Overall, the XLR input is likely a better choice as it will give you a much hotter signal, so you need less amplification for the same output volume.