Understanding Balanced Audio (video)

[amirm]

I have been meaning to write an article for a while on what balanced audio means. Alas, have not had time so I thought I do a video on it instead. Hopefully for people who are new at this, it clarifies different things we call "balanced" and benefits it can provide:

Hope you find it useful.

 

[phoenixsong]

I like how the main points have been made simple and clear. Also, hopefully the explanation on balanced>unbalanced adapters at the end will save some people from destroying their equipment

Now I can't wait for a tutorial on input/output impedance!

 

[HerbertThePervert]

Thanks for the great video!

I add this because i often hear people complain about the lack of XLR outs for example on home theatre processors:

You can convert RCA Outputs to balanced using just a single resistor. The most important part of the CMNR is the two signal conductors (3 wire cable) having the the same impedance. Measure your devices output impedance and connect the "-" with a resistor (value=output impedance) to rca ground. You do not get higher output but the noise rejection is greatly improved. For voltage gain and differential output you can use a dirt cheap DRV134 board.


As you mentioned in the video, differential is something different and often mixed up with balanced.

 

[diddley]

yep thanks again Amir

 

[HTNut1975]

Amir, I’m absolutely loving these videos! This is good stuff that’s going to last for us laypersons in the group.

 

[PeteL]

Thank you. Very to the point and easy to understand.

 

[Ismapics]

Hello Amir: Thanks for another great video that installs knowledge (software) in our brains. Also illustrates that there are plenty of YT Reviewers that don't know the technical aspects and their reviews of these show. Can you consider a video debunking Directional RCA, please. In you do in that same one address using silver, vs copper. Cheers

 

[sq225917]

Differential, a signal that swings positive and negative in a mirror image on two separate signal phase.

Balanced, impedance matched inputs/circuit legs, usually to accommodate a differential signal input, generator/ source.

SE, a signal that is referenced to a nominal ground, zero volt reference.

Balanced Headphones, capable of being driven by a differential signal source.

Headphone companies really shot the pooch with this description. You'd think they would fix this nomenclature error. Of course places like headfi just perpetuate the mistake.

 

[Atanasi]

Sometimes a balanced headphone output is used to drive balanced line inputs. This is most straightforward with a 4.4mm connector, which includes the ground wire. If the headphone amp is implemented in the usual way, it would be balance in the line-level sense.

 

[PeteL]

Sometimes a balanced headphone output is used to drive balanced line inputs. This is most straightforward with a 4.4mm connector, which includes the ground wire. If the headphone amp is implemented in the usual way, it would be balance in the line-level sense.

But why would you want to do that?

 

[Deleted member 2944]

You can convert RCA Outputs to balanced using just a single resistor. The most important part of the CMNR is the two signal conductors (3 wire cable) having the the same impedance. Measure your devices output impedance and connect the "-" with a resistor (value=output impedance) to rca ground. You do not get higher output but the noise rejection is greatly improved. For voltage gain and differential output you can use a dirt cheap DRV134 board.
As you mentioned in the video, differential is something different and often mixed up with balanced.

Yes indeed.

Amir makes the same mistake in premise that so many audio types do. Balanced interfacing is primarily about the source impedance(s) being equal and has essentially nothing to do with equal impedances in the load device. It's perfectly possible to have a destination device with unequal input resistances (or even gain) on both polarities and still have a proper, balanced, interface.

An active differential-signaling scheme is not required for a balanced interface.

Dave.

 

[PeteL]

Yes indeed.

Amir makes the same mistake in premise that so many audio types do. Balanced interfacing is primarily about the source impedance(s) being equal and has essentially nothing to do with equal impedances in the load device. It's perfectly possible to have a destination device with unequal input resistances (or even gain) on both polarities and still have a proper, balanced, interface.

An active differential-signaling scheme is not required for a balanced interface.

Dave.

May you point me where he says that it's about equal impedance in the load device? I "kinda" get your point, but also note that Amir chose to not focus on CMNR, pointing that the actual benefit is minimal with short cable lengths, so yes the explanation is incomplete, but I've failed to catch actual "mistakes", but maybe I didn't catch that.

 

[Atanasi]

But why would you want to do that?

When there's no separate line output, like with dongles or portable devices.

 

[Deleted member 2944]

May you point me where he says that it's about equal impedance in the load device?

He doesn't mention it. That's my point.
The key aspect in balanced interfacing is the equal impedance in both legs of the source device.
Amir seems much more interested in the input configuration of the load device.

The key (balanced) distinction here between input and output interfaces he doesn't mention at all. Which seems curious to me since the video is titled "understanding balanced audio."

Dave.

 

[Nango]

Now I can't wait for a tutorial on input/output impedance!

On output impedance and others: http://archimago.blogspot.com/2021/03/measurementsmusings-headphone-impedance.html?m=1

 

[PeteL]

He doesn't mention it. That's my point.
The key aspect in balanced interfacing is the equal impedance in both legs of the source device.
Amir seems much more interested in the input configuration of the load device.

The key (balanced) distinction here between input and output interfaces he doesn't mention at all. Which seems curious to me since the video is titled "understanding balanced audio."

Dave.

Yeah, but then it's just semantics, if we go there even the term balanced input printed on devices is debatable, you can only have a balanced "connection" not a balanced input.

 

[Thomas savage]

Your crushing the YouTube videos Amirm , a great way for you to get content published and put across a more human side thats harder to do on these text based mediums.

Amirm , uncal audio ha ha

 

[Deleted member 2944]

Yeah, but then it's just semantics, if we go there even the term balanced input printed on devices is debatable, you can only have a balanced "connection" not a balanced input.

Semantics? No, these are actual interfacing issues that could exhibit in real-world systems.
Amir seems primarily interested in the alleviating of ground loops aspect of this, but there are other aspects as well.

This video seems aimed at less experienced audio types, and in that sense it's probably fine and dandy. But there is much more to this topic than he hit on. Anyways, it's not a big deal. It's just something I would have expected Amir to elaborate on.
"Balanced audio" is a premise that a couple of audio hardware manufacturers have placed their whole business model on.

Dave.

 

[phoenixsong]

On output impedance and others: http://archimago.blogspot.com/2021/03/measurementsmusings-headphone-impedance.html?m=1

Thanks for the link! However, I was hoping for information on impedance matching between devices too, not just for headphones (heard of the 1/8 rule before for that)

 

[Ismapics]

I have been meaning to write an article for a while on what balanced audio means. Alas, have not had time so I thought I do a video on it instead. Hopefully for people who are new at this, it clarifies different things we call "balanced" and benefits it can provide:

Hope you find it useful.

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