Balanced But Not Fully Balanced


I own a preamp which has both balanced and single ended jacks. I assumed that since I was using the balanced jacks I was getting the benefit of a balanced circuit. I have just now realized that just having balanced plug-ins doesn't mean your preamp (or any other component) is "balanced." Just wondering what sonic compromises are being made with equipment which has balanced inputs and outputs but changes the signal to single ended as it passes through it. If you are using the balanced outputs, what good is that if the signal going into this jack is single ended? I don't understand what good is it to offer equipment with balanced capability only to revert to single ended signals. Is this just a gimmick to sell equipment or is there some advantage to not making the circuitry "fully balanced?"
frepec
@gdhal
Hi Hal,

As you are aware, the Oppo player is clearly described as featuring "a true differential signal path all the way from the DAC to the 3-pin XLR connector." And as you indicated the Emotiva ERC-3 purports to be similar in that respect. However despite the ERC-3 being referred to as a "Differential Reference (TM) CD Player/Digital Transport," and despite suggestions in its manual that its balanced analog output is "generally preferred," IMO there is enough ambiguity in its descriptive literature to leave me at least a little bit uncertain as to whether its analog signal path is in fact fully balanced. Also, we have no way of knowing "a priori" whether the net result of the tradeoffs I referred to in my post above dated 9-20-2012 would work in favor of the balanced or unbalanced inputs of the M6si integrated amp.

So the only way to be confident of the answer to your question would be to try both players both ways. Which it sounds like you’ve already done, with similar results in each case. But if in fact there is any difference, given that the M6si has only a single XLR input, and given that the Oppo can be said with certainty to have a fully balanced analog signal path, my guess would be that the best odds of obtaining optimal results would be if you were to connect the Oppo via XLR and the Emotiva via RCA.

Best regards,
-- Al

@almarg and @stringreen 

Understood. Thanks!

Bringing back this 8-year old thread that has been dormant for 3-years.

I have two components that I know are fully balanced, and two others in my secondary system that I suspect are not, despite them having XLR connectors. I plan to ask the pointed question of the manufacturer of those components, as suggested.

My question though: Is it typically a tip-off that a component is NOT fully balanced if the XLR input or output connectors for left and right channel are close to one another on one side of the component (say both on othe right side, rear faceplate), as opposed to being spaced from one another and generally on opposite (left and right) sides of the component? In that connector-same-side situation, is it reason to suspect that the internals are not a fully balanced topology?

For balanced designs it makes sense to me that for separation the layout may keep the circuitry on either side of chassis and in that manner also have the corresponding connector on the respective side. Or am I reading too much into this?
Not necessarily.  Look at Musical Fidelity M8xi.  That is a fully balanced unit which is a true dual mono amp and even has separate power supplies for the two side of the amp and the XLRs are paired right next to each other.  It's a design choice like anything else.  

If it is unbalanced, sound quality will be dictated by the quality of transformer used to convert the signal unless your system is noisy or you have ground issues.  If it is an unbalanced amp, odds are the RCAs will sound better than the XLRs.  Especially if it is tube based gear.  
My question though: Is it typically a tip-off that a component is NOT fully balanced if the XLR input or output connectors for left and right channel are close to one another on one side of the component (say both on othe right side, rear faceplate), as opposed to being spaced from one another and generally on opposite (left and right) sides of the component?
No!  They can be side by side with no worries.