Understanding Balanced Audio (video)

[MRC01]

... The convention for interfacing balanced to unbalanced is to leave the (-) balanced output floating and just route shield and (+) output to the RCA ground and (+) input respectively. ... Opinions vary a bit on how to connect a single-ended output to a balanced input and it somewhat depends upon the circuit configuration of the balanced input. You connect RCA (+) to balanced input (+), then decide whether to connect RCA (-, ground) to the balanced (-) input, shield, or both.

Thank you for responding Don! I hadn't thought on using an adapter ...

That works, but you may get elevated noise or distortion, as balanced signal paths rely on differential signalling to reject common mode junk, so may have worse performance when only 1 signal pin is connected. This affects some balanced equipment more than others, depending on how they're designed. Example: the Schiit Magnius.

 

[Xii-Nyth]

Question, which I believe it was addressed slightly. Are TRS connection / plugs (like form a mixer or pre-amp) balanced?

aren't those the optical ones that look like rca? so they are digital? or am thinking of something else entirely

if they are those ones I guess technically not since its a single reference ground, but as long as it has a tolerance of 49% (or ~33% to avoid a floating range) it would be able to tell whats a 1 or 0 so it doesn't matter

in a perfect world any load device could just have any converters and amps built in and we just transfer all data over wifi instead of a cable, anyone who tells you there is signal interference is pretty much not telling the truth since its not like our devices constantly get sent incorrect bits over wifi since that would cause them to crash or make errors all the time

only problem is then you can't (easily) reuse the same hardware, and it would add weight to the devices. but theoretically there will one day be a perfect headphone so you will only need to buy something once, and the fully integrated components and circuitry could theoretically less dense than air.

Going further people would just have direct digital to neuron converters in the heads and I highly doubt there will be people claiming it sounds better when they plug into a wall with their \|7 2200000 [Gen 8 quantum currency] AudioQuest III synthetic carbon-plasma cables (carbon shielding at absolute 0, wiring at 3000 C, achieved with differential energy technology to block out noise) inspired by human mythology

if you see one of the guys just use scissors on his cable

 

[DonH56]

TRS = tip-ring-sleeve and are used for many purposes, including sending stereo signals to headphones, balanced signals to other components, and effects loops in mixers and pro signal processing units. They are not optical. They are often used in place of XLRs to save space and for quick connections (not locking).

From a quick search (I use Sweetwater a lot so it came up first in my search): https://www.sweetwater.com/sweetcare/articles/whats-the-difference-between-ts-and-trs-cables/

 

[Xii-Nyth]

TRS = tip-ring-send and are used for many purposes, including sending stereo signals to headphones, balanced signals to other components, and effects loops in mixers and pro signal processing units. They are not optical. They are often used in place of XLRs to save space and for quick connections (not locking).

From a quick search (I use Sweetwater a lot so it came up first in my search): https://www.sweetwater.com/sweetcare/articles/whats-the-difference-between-ts-and-trs-cables/

oh haha, never considered those had a name!

 

[JP]

Have always seen it called tip, ring, sleeve.

 

[DonH56]

Have always seen it called tip, ring, sleeve.

"Sleeve" yes, that is the usual nomenclature, sorry. Had a mixing console on my mind so "send" crept in. Corrected.

 

[Robbo99999]

I just watched this video & got a question. Did Amir say you need balanced inputs to avoid ground loops? Does this mean that a balanced DAC/amp (all-in-one device) that is connected via USB to a PC will not be immune to ground loops when using the balanced output of the DAC/amp (because USB input is not classed as a balanced input, I don't know)? I was thinking along the lines of a DAC/amp like the Fosi DS2 for instance which is marketed as a balanced headphone dongle mainly.

 

[amirm]

It must be late at night as I don't understand your question. Balanced output is useful if you are going to connect unit to an amplifier. Inverted, you want an amplifier with balanced input.

 

[Robbo99999]

It must be late at night as I don't understand your question. Balanced output is useful if you are going to connect unit to an amplifier. Inverted, you want an amplifier with balanced input.

Ha, yes, I see what you mean (I think). The balanced out of the FOSI DS2 connected to a seperate balanced amplifier on it's balanced inputs would remove ground loops. So, if for example I hooked up the balanced output of the Fosi DS2 to the balanced inputs of my JBL 308p speakers then that would be ground loop protected? And what about if I hook up balanced headphones directly to the balanced output of the Fosi DS2, is that ground loop protected? (EDIT: On reflection I'm thinking the headphone example is inherently not open to ground loop issues.)

 

[amirm]

That's correct. Note that this is 99% the case.

 

[Robbo99999]

That's correct. Note that this is 99% the case.

For the headphone example connected directly would you need balanced headphone to avoid ground loops or any headphone connected to any dongle which is connected via USB is not open to ground loop issues? (Just to be sure on the last point I mentioned in my previous post)

 

[antcollinet]

For the headphone example connected directly would you need balanced headphone to avoid ground loops or any headphone connected to any dongle which is connected via USB is not open to ground loop issues? (Just to be sure on the last point I mentioned in my previous post)

Headphones (like passive speakers) have no ground connection - so ground currents won't pass through the headphone/speaker cable. Hence you can use balanced or unbalanced headphones/interconnect for your phones.

Balanced 'phone connections can give a small (probably inaudible) benefit in channel separation - but this has nothing to do with ground loops.

 

[Robbo99999]

Headphones (like passive speakers) have no ground connection - so ground currents won't pass through the headphone/speaker cable. Hence you can use balanced or unbalanced headphones/interconnect for your phones.

Balanced 'phone connections can give a small (probably inaudible) benefit in channel separation - but this has nothing to do with ground loops.

Right, so balanced DACS/amps in terms of ground loop eradication are only useful and "necessary" in situation where you have other amps or active speakers connected further down the chain, in which cases you use the balanced input connections of said amps and speakers (whilst headphones & passive speakers won't benefit from any ground loop aspect).

 

[antcollinet]

Right, so balanced DACS/amps in terms of ground loop eradication are only useful and "necessary" in situation where you have other amps or active speakers connected further down the chain, in which cases you use the balanced input connections of said amps and speakers (whilst headphones & passive speakers won't benefit from any ground loop aspect).

Pretty much.

If you have ground loop noise current, then it "gets on to" the signal "along the length of" an unbalanced ANALOGUE interconnect.

While digital cables can conduct ground loop currents along their ground connection, there will be no noise added to the signal (unless the ground current noise gets so bad it corrupts the digital signal, but then you'll get dropouts and clicks, not an audible version of the ground current noise)

So in the case you have a PC connected via USB to the DAC, the PC noise can conuduct via the USB cable to the DAC, then on through the analogue connection to pre-amp or amp (or active speakers), then back to earth via the ground connection of pre-amp or amp. It is on the receiving end of the analogue connection that the noise gets added to the signal with an unbalanced connection. The longer the analogue connector, the more noise there will be (it is related to the ground impedance between the two devices**) This is why there is more frequently an issue with analogue connected powered/active speakers or subwoofers.

With balanced connections, the noise gets added to both the positive and negative signal, so when the negative is subtracted from the positive the noise cancels out.

So you can solve ground loop noise either by using balanced interconnect (for all analogue connections in the chain) - OR by breaking the loop by using a USB isolator, or a TOSLINK connection from PC to DAC. A cheap USB to Toslink converter will do the job nicely.

With digital connections to integrated amps, or to powered speakers, there is rarely (if ever) a problem since any analogue interconnect between DAC and AMP only exists internally to the amp and is too short to have a problem. Further, proper internal ground design can straightforwardly eliminate the issue.


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**hence analogue interconnect with better/lower impedance ground/shield can also reduce the problem - though not eliminate it.