I don't wish to seem disrespectful or argumentative, but there are quite a few technical errors in that video!

He confuses balanced vs single-ended vs symmetrical, which is a common enough error, but if you are going to present a video about interconnections I do think you owe it to your audience to be precise. He also completely misrepresents how a balanced interface works! (at least he understands the difference between polarity and phase!)
 
There are lots of really good resources that describe audio interconnections various levels of tech speak, I'd recommend Rane, Jensen Transformers or Audio Systems Group as good starting points.
 
The really short version:
A balanced source presents an equal impedance from each of two signal conductors to a common reference, most often ground. It is not necessary that both signal conductors carry a signal, but if they do they do need to be  of opposite polarity, as described in the video.

The benefit here comes from that  equal impedance to common - any external noise will be impressed equally to both conductors, making it much easier for a balanced input to subtract the common signal.
 
A balanced input can be a difference amplifier or a transformer, the key specification is the common mode rejection ratio, a fancy way of representing how well the input stage rejects any signal common to the two input pins. It works perfectly well if the desired signal is on one or both pins.
 
Here is a really cool trick that works really well when connecting a single-ended  source to a (properly) balanced input
- connect the source signal pin to the high side of the input
- connect shield from the source - through a resistor that is approximately equal to the source impedance - to the low side of the input. This creates a balanced source.
- you can even use the shield on a coaxial cable, but a twisted pair will work better.
 
But I digress...
 
It is  equally important to remember that the shield on a shielded cable has no affect on magnetic fields, which is the field generated by 60 Hz noise makers. It is very effective in shielding the signal conductors from high frequency interference. The cable twist is feature that reduces the effect of magnetic fields, and it is REALLY effective.
 
Most folks don't give it a lot of thought, but loudspeaker wiring can be (and often is) balanced, no not the active, line level stuff, we're talking the high power, low impedance output from an amplifier.

This is not all that complicated, but is a plethora of inaccurate information all over the internet, and it can be difficult to sort it all out.

As far as where to get cables (any audio cables really) I  highly recommend building them yourself. Not only will you save a little money, you'll be able to repair them should they have problems. It is not difficult at all to do so.

But if you really don't wish to, then any reputable audio supply house can provide different grades of assembled cables. I like Full Compass, but there are many out there. If you have a local music store (not one of the big box chains) you can also likely get good cables at reasonable prices.

wst3
I don't wish to seem disrespectful or argumentative, but there are quite a few technical errors in that video!

He confuses balanced vs single-ended vs symmetrical, which is a common enough error, but if you are going to present a video about interconnections I do think you owe it to your audience to be precise. He also completely misrepresents how a balanced interface works! (at least he understands the difference between polarity and phase!)
 
There are lots of really good resources that describe audio interconnections various levels of tech speak, I'd recommend Rane, Jensen Transformers or Audio Systems Group as good starting points.
 
The really short version:
A balanced source presents an equal impedance from each of two signal conductors to a common reference, most often ground. It is not necessary that both signal conductors carry a signal, but if they do they do need to be  of opposite polarity, as described in the video.

The benefit here comes from that  equal impedance to common - any external noise will be impressed equally to both conductors, making it much easier for a balanced input to subtract the common signal.
 
A balanced input can be a difference amplifier or a transformer, the key specification is the common mode rejection ratio, a fancy way of representing how well the input stage rejects any signal common to the two input pins. It works perfectly well if the desired signal is on one or both pins.
 
Here is a really cool trick that works really well when connecting a single-ended  source to a (properly) balanced input
- connect the source signal pin to the high side of the input
- connect shield from the source - through a resistor that is approximately equal to the source impedance - to the low side of the input. This creates a balanced source.
- you can even use the shield on a coaxial cable, but a twisted pair will work better.
 
But I digress...
 
It is  equally important to remember that the shield on a shielded cable has no affect on magnetic fields, which is the field generated by 60 Hz noise makers. It is very effective in shielding the signal conductors from high frequency interference. The cable twist is feature that reduces the effect of magnetic fields, and it is REALLY effective.
 
Most folks don't give it a lot of thought, but loudspeaker wiring can be (and often is) balanced, no not the active, line level stuff, we're talking the high power, low impedance output from an amplifier.

This is not all that complicated, but is a plethora of inaccurate information all over the internet, and it can be difficult to sort it all out.

As far as where to get cables (any audio cables really) I  highly recommend building them yourself. Not only will you save a little money, you'll be able to repair them should they have problems. It is not difficult at all to do so.

But if you really don't wish to, then any reputable audio supply house can provide different grades of assembled cables. I like Full Compass, but there are many out there. If you have a local music store (not one of the big box chains) you can also likely get good cables at reasonable prices.

Good info, wst3!
 
Back in the day, when I was making my own cables, I used to make twisted pair cables with multistrand wire of the appropriate gauge. I'd cut two equal lengths, knot one end of the pair of wires, get someone to hold the knotted end in a right-angle needle nose pliers and I'd lock the other end of the pair in a power drill, stand far enough away to make the pair of wires taut, and slowly drill my way to a twisted pair. Worked great. The resulting cable was easy to route.

wst3
I don't wish to seem disrespectful or argumentative, but there are quite a few technical errors in that video!

He confuses balanced vs single-ended vs symmetrical, which is a common enough error, but if you are going to present a video about interconnections I do think you owe it to your audience to be precise. He also completely misrepresents how a balanced interface works! (at least he understands the difference between polarity and phase!)
 
There are lots of really good resources that describe audio interconnections various levels of tech speak, I'd recommend Rane, Jensen Transformers or Audio Systems Group as good starting points.
 
The really short version:
A balanced source presents an equal impedance from each of two signal conductors to a common reference, most often ground. It is not necessary that both signal conductors carry a signal, but if they do they do need to be  of opposite polarity, as described in the video.

The benefit here comes from that  equal impedance to common - any external noise will be impressed equally to both conductors, making it much easier for a balanced input to subtract the common signal.
 
A balanced input can be a difference amplifier or a transformer, the key specification is the common mode rejection ratio, a fancy way of representing how well the input stage rejects any signal common to the two input pins. It works perfectly well if the desired signal is on one or both pins.
 
Here is a really cool trick that works really well when connecting a single-ended  source to a (properly) balanced input
- connect the source signal pin to the high side of the input
- connect shield from the source - through a resistor that is approximately equal to the source impedance - to the low side of the input. This creates a balanced source.
- you can even use the shield on a coaxial cable, but a twisted pair will work better.
 
But I digress...
 
It is  equally important to remember that the shield on a shielded cable has no affect on magnetic fields, which is the field generated by 60 Hz noise makers. It is very effective in shielding the signal conductors from high frequency interference. The cable twist is feature that reduces the effect of magnetic fields, and it is REALLY effective.
 
Most folks don't give it a lot of thought, but loudspeaker wiring can be (and often is) balanced, no not the active, line level stuff, we're talking the high power, low impedance output from an amplifier.

This is not all that complicated, but is a plethora of inaccurate information all over the internet, and it can be difficult to sort it all out.

As far as where to get cables (any audio cables really) I  highly recommend building them yourself. Not only will you save a little money, you'll be able to repair them should they have problems. It is not difficult at all to do so.

But if you really don't wish to, then any reputable audio supply house can provide different grades of assembled cables. I like Full Compass, but there are many out there. If you have a local music store (not one of the big box chains) you can also likely get good cables at reasonable prices.

Good info, wst3!
 
Back in the day, when I was making my own cables, I used to make twisted pair cables with multistrand wire of the appropriate gauge. I'd cut two equal lengths, knot one end of the pair of wires, get someone to hold the knotted end in a right-angle needle nose pliers and I'd lock the other end of the pair in a power drill, stand far enough away to make the pair of wires taut, and slowly drill my way to a twisted pair. Worked great. The resulting cable was easy to route.

TheMaartian
Good info, wst3!
 
Back in the day, when I was making my own cables, I used to make twisted pair cables with multistrand wire of the appropriate gauge. I'd cut two equal lengths, knot one end of the pair of wires, get someone to hold the knotted end in a right-angle needle nose pliers and I'd lock the other end of the pair in a power drill, stand far enough away to make the pair of wires taut, and slowly drill my way to a twisted pair. Worked great. The resulting cable was easy to route.

I used to do that for power wiring, but now there are several companies that sell twisted pair power cables... so I trade cheap for lazy<G>!

I know the OP needed a Balanced connection to powered speakers. I was only trying to clarify what an actual speaker cable is for those who may not understand this. Many don't. I have had to point this out many times when helping Churches straighten out issues with their sound systems. The logic is if the connection fits, use it. 
The title of this thread is misleading as there is no such thing when audio people communicate as a balanced speaker cable. It's a nit picky thing but I think it's relevant to use the proper terminology as much as possible around here.
 
The other one I nit pick about is the term Sound Card when we talk about audio interfaces.  

Cactus Music
I know the OP needed a Balanced connection to powered speakers. I was only trying to clarify what an actual speaker cable is for those who may not understand this. Many don't. I have had to point this out many times when helping Churches straighten out issues with their sound systems. The logic is if the connection fits, use it. 
The title of this thread is misleading as there is no such thing when audio people communicate as a balanced speaker cable. It's a nit picky thing but I think it's relevant to use the proper terminology as much as possible around here.
 
The other one I nit pick about is the term Sound Card when we talk about audio interfaces.  

Actually there is no such thing as a balanced cable. There are balanced sources, and there are balanced inputs, the cable itself is not balanced.
 
However, there are many amplifiers that do not connect one side of the output to a common reference, so both pins will present the same impedance with respect to  common, making them balanced  sources.

AND, very few (if any?) loudspeakers connect one side to a common reference, making them balanced inputs.

That doesn't make the speaker cable balanced, but it does mean the circuit is.

Signal balance and symmetry are one of the most misunderstood topics in audio, right up there with twisted pairs, shielding, and the dreaded "Pin-1" problem<G>!

wst3
 
...Actually there is no such thing as a balanced cable. There are balanced sources, and there are balanced inputs, the cable itself is not balanced....

I agree with what you have posted on this thread, but disagree with the above statement. A TRS "Balanced" cable contains 2 conductors plus shield that is used to conduct differential signals between balanced sources and balanced inputs. An TS "Unbalanced" cable will not work with Balanced Sources/Inputs since three conductors are required to work with this scheme. (As an Analog Integrated Circuit Design Engineer, I've designed differential amplifiers with a high CMRR.)
 
A Cat 5E cable is another example of a "Balanced Cable" where 4 sets of "twisted" pairs that transmit digital signals of opposite polaritry. The twisting of the wires means both wires will "pick up" electrical noise but will be rejected by the inputs since the one of the signals gets inverted and summed. Thus the noise is cancelled by subtraction.
 
Walt 
 

Hi Walt,
 
I'm afraid you have not swayed me<G>... a cable can not be inherently balanced or unbalanced (more properly single-ended?). A cable can have some number of conductors, and if there is only one signal conductor and a shield that it can not be used to connect a balanced source to a balanced input.

By way of analogy, a simple operational amplifier can measure the difference between the "+" and "-" input pins, which makes it a difference amplifier, but it is NOT a balanced input because the inverting and non-inverting inputs present a VERY different impedance with respect to common, and when you add feedback it changes again. Yet a lot of companies sell devices with nothing but a simple op-amp as the input, and they call them balanced.

Does that make sense? I'm not trying to be difficult, but as an industry audio engineers have become remarkably sloppy in their use of terminology that was once well understood.

 
Hi Bill,
 
First of all I don't think you're being difficult. We're just having a good technical discussion, and this how people (myself included) learn. In some cases, people find they are really in complete agreement but didn’t understand where the other person was trying to convey, i.e.
 

wst3
 …cable can not be inherently balanced or unbalanced (more properly single-ended?)…

 
Not sure what you mean here? A TRS cable is a three conductor cable that can be used as a stereo cable or balanced cable. Google “TRS balanced cable”.
 

wst3
…if there is only one signal conductor and a shield that it can not be used to connect a balanced source to a balanced input…

I agree, you must use a balanced cable.
 

wst3
By way of analogy, a simple operational amplifier can measure the difference between the "+" and "-" input pins, which makes it a difference amplifier, 

While a simple operational amplifier can measure the difference between the “+” and “-“ inputs, without an embedding network the output voltage cannot be predicted since the open-loop gain varies significantly from device to device and is too high to be of any use.
 

wst3
…but it is NOT a balanced input because the inverting and non-inverting inputs present a VERY different impedance with respect to common…

If you look at a schematic of a typical Op-Amp, you’ll see that the inputs are identical albeit out of phase. The input impedance for each input is simply the Beta of the input transistor times the re + RE of the input transistor which is very high (and higher due to Beta) and since components in I.C.s are inherently matched, the Zin of both inputs should be almost identical.
 

wst3
..and when you add feedback it changes again…

 
You can add 4 resistors to an op-amp and make it a crude diff-amp, but the resistors lower the input resistance and takes away for the advantage of an op-amp, i.e. high input impedance.
 

wst3 
...Yet a lot of companies sell devices with nothing but a simple op-amp as the input, and they call them balanced...

Can you give me a Manufacturer and part number? I'm interested.
 
Thanks,
 
Walt
 

Hi again Walt,
 
I suspect we're going to have to agree to disagree on the cable thing, but some last minute thoughts are interspersed...
 

WallyG
 
Hi Bill,
 
First of all I don't think you're being difficult. We're just having a good technical discussion, and this how people (myself included) learn. In some cases, people find they are really in complete agreement but didn’t understand where the other person was trying to convey, i.e.

 
Agreed, it is all about language, and words (who knew) do matter<G>!
 

wst3
 …cable can not be inherently balanced or unbalanced (more properly single-ended?)…

 

WallyGNot sure what you mean here? A TRS cable is a three conductor cable that can be used as a stereo cable or balanced cable. Google “TRS balanced cable”.

So what would you call a cable of shielded twisted pair construction when used to connect a single-ended source to a single-ended input? How about a single-ended source to a balanced input? My point, which may be nothing more than semantics, is that the cable does not posses the characteristic of being balanced or not. It depends entirely on how it is used.
 

wst3
By way of analogy, a simple operational amplifier can measure the difference between the "+" and "-" input pins, which makes it a difference amplifier, 

WallyGWhile a simple operational amplifier can measure the difference between the “+” and “-“ inputs, without an embedding network the output voltage cannot be predicted since the open-loop gain varies significantly from device to device and is too high to be of any use.

There are uses, but then I'd really be picking nits, so yes, without a feedback network the opamp is of little use to audio.
 

wst3
…but it is NOT a balanced input because the inverting and non-inverting inputs present a VERY different impedance with respect to common…

WallyGIf you look at a schematic of a typical Op-Amp, you’ll see that the inputs are identical albeit out of phase. The input impedance for each input is simply the Beta of the input transistor times the re + RE of the input transistor which is very high (and higher due to Beta) and since components in I.C.s are inherently matched, the Zin of both inputs should be almost identical.

Without the feedback network some opamps do have identical input Z, some don't. However, as you pointed out, in most audio circuits you are going to apply negative feedback, and that changes the effective input Z of the inverting input. They are no longer equal, and CMMR will decrease.

The better solution is to use two opamp stages as buffers, and feed them to the diff amp. Most of the time I see this referred to as an instrumentation amplifier, although I'm not sure that's a universal name.
 

wst3
..and when you add feedback it changes again…

 

WallyGYou can add 4 resistors to an op-amp and make it a crude diff-amp, but the resistors lower the input resistance and takes away for the advantage of an op-amp, i.e. high input impedance.

We agree!
 

wst3 
...Yet a lot of companies sell devices with nothing but a simple op-amp as the input, and they call them balanced...

WallyGCan you give me a Manufacturer and part number? I'm interested.

I can't really - I worked for a couple of them. I fought tooth and nail to do away with designs like that, along with bringing pin 1 into the enclosure and wimpy power supplies. Sometimes I won those battles<G>, but I can't really brag about the wins without exposing the losses...

Take care,
 
Bill