A little more about balanced and differential amplifiers....

[KeithL]

Here's a short description about the difference between "balanced" and "differential"...

The term "balanced" in general refers to a situation where two cables, or two amplifier channels, carry copies of the audio signal that are equal but out of phase.

- the term "balanced" generally refers to amplifiers or signal paths ("a fully balanced amplifier"; "a balanced input or output"; "a balanced signal path"; "a balanced cable")

The term "differential" refers to a situation where you have two inputs or connections, and differences between them are amplified or passed, while signals that are common to the two are ignored.
- the term "differential" generally refers to a type of circuit

So, for example, a balanced cable carries two identical, but out of phase, versions of the same audio signal.
When you then connect this balanced cable to a balanced input it is usually passed to a differential circuit.
This differential circuit keeps the desired signal - by passing and amplifying the difference between the signal on the two input lines ( when you subtract the inverted signal from the non-inverted signal you get 2x the signal).
And the differential circuit discards most noise picked up by the wires ( any noise picked up in transit is likely to be the same on both wires - so, when you subtract one from the other, most of the noise is cancelled out).

HOWEVER, a differential circuit is also used internally in almost all modern amplifiers, even on the unbalanced inputs, to compare a portion of the output signal to the input signal (as part of how NFB works).
So, when you have a balanced input, but each of the input lines is already connected to its own differential input circuit, the whole thing can fairly be described as "dual differential".
And, if you have a balanced amplifier, and each of the two amplifier channels has a balanced input, and each of those input lines is connected to its own differential input circuit, you can fairly call it "quad differential".

It's also important that what we're talking about is "function blocks" - which is a fancy way of saying "what stuff does".
For example, most modern amplifiers have "an active differential input circuit", which is quite easily recognized on a schematic.
However, the balanced transformer inputs on vintage microphone preamps, and are still used in some equipment today, are a very effective form of PASSIVE differential input circuit.
(They are no longer commonly used because they have several important disadvantages.)

An engineer will simply look at the schematic and notice where various balanced connections and differential circuits are used.
HOWEVER, while the term "balanced connection" is pretty much standard, the terms you use to attempt to describe the other stuff to a non-engineer aren't....
Therefore, we do our best to use terms that are both descriptive of what's actually going on, and that sound cool in the marketing literature.
The takeaway is that, if you find all this terribly confusing, then you shouldn't really worry about it quite so much.....

All that really matters is the results it produces in a given situation and how it all sounds... right?

[mick]

Jul 26, 2019 9:42:37 GMT -5 KeithL said:

Here's a short description about the difference between "balanced" and "differential"...

The term "balanced" in general refers to a situation where two cables, or two amplifier channels, carry copies of the audio signal that are equal but out of phase.

- the term "balanced" generally refers to amplifiers or signal paths ("a fully balanced amplifier"; "a balanced input or output"; "a balanced signal path"; "a balanced cable")

The term "differential" refers to a situation where you have two inputs or connections, and differences between them are amplified or passed, while signals that are common to the two are ignored.
- the term "differential" generally refers to a type of circuit

So, for example, a balanced cable carries two identical, but out of phase, versions of the same audio signal.
When you then connect this balanced cable to a balanced input it is usually passed to a differential circuit.
This differential circuit keeps the desired signal - by passing and amplifying the difference between the signal on the two input lines ( when you subtract the inverted signal from the non-inverted signal you get 2x the signal).
And the differential circuit discards most noise picked up by the wires ( any noise picked up in transit is likely to be the same on both wires - so, when you subtract one from the other, most of the noise is cancelled out).

HOWEVER, a differential circuit is also used internally in almost all modern amplifiers, even on the unbalanced inputs, to compare a portion of the output signal to the input signal (as part of how NFB works).
So, when you have a balanced input, but each of the input lines is already connected to its own differential input circuit, the whole thing can fairly be described as "dual differential".
And, if you have a balanced amplifier, and each of the two amplifier channels has a balanced input, and each of those input lines is connected to its own differential input circuit, you can fairly call it "quad differential".

It's also important that what we're talking about is "function blocks" - which is a fancy way of saying "what stuff does".
For example, most modern amplifiers have "an active differential input circuit", which is quite easily recognized on a schematic.
However, the balanced transformer inputs on vintage microphone preamps, and are still used in some equipment today, are a very effective form of PASSIVE differential input circuit.
(They are no longer commonly used because they have several important disadvantages.)

An engineer will simply look at the schematic and notice where various balanced connections and differential circuits are used.
HOWEVER, while the term "balanced connection" is pretty much standard, the terms you use to attempt to describe the other stuff to a non-engineer aren't....
Therefore, we do our best to use terms that are both descriptive of what's actually going on, and that sound cool in the marketing literature.
The takeaway is that, if you find all this terribly confusing, then you shouldn't really worry about it quite so much.....

All that really matters is the results it produces in a given situation and how it all sounds... right?

Thank you for your post Kieth but your confusing the hell out of me. lol Using the Emo product page can you list which is which please, as this will make easier for me to understand to making a choices.

[richb]

In theory, the purpose of these circuits is to increase signal to noise and reduce distortions.
There are specifications for these on Emotiva amps but not for the RMC-1.

Will you be providing performance specifications for the new line of processors that includes,linearity, output voltage, and signal to noise with and without processing engaged?

- Rich

[garbulky]

What he's saying is there are amps that have XLR inputs which are pretty common. These inputs are balanced but not the outputs.

But a fully balanced amp (quad differential according to Emotiva). Which means that it remains balanced from output to input. It's not a small difference. It basically requires TWO amps per channel which is nearly twice the circuitry. So doing fully balanced is EXPENSIVE. And so that is important. Usually a fully balanced amp would be advertised as being fully balanced because it didn't happen by accident because it costs twice the material in amps. In terms of measurable performance - there is I believe a 6 db increase of signal to noise ratio. Also fully balanced means that each channel produces two signals out of phase with each other. When they combine they cancel the distortions picked up within the gear.
If you have a fully balanced chain (like your DAC and preamp is fully balanced) then all the way through your chain these distortions get cancelled.

So fully balanced Emotiva amps
XPA-1 L gen 1 and 2, XPA-1 gen 1 and 2. XPA-1 DR-1, DR-2, DR-3. Emotiva PA-1.

Emotiva fully balanced gear:
Emotiva RMC-1 (some configurations vary in number of channels balanced), XMC-1 (front channels), XSP-1 gen 1 and 2, XDA-1, XDA-2, Emotiva DC-1. ERC-1, ERC-2, ERC-3, ERC-4.

Amps that are not fully balanced but have XLR inputs
Emotiva HC-1, XPA gen 3. XPA-2 gen 1 and 2, XPA-3 gen 1 and 2 XPA-5 gen 1 and 2, XPA-7 gen 2.
And also all the older amp line that had XLR inputs that was not the XPA-1 gen 1.

As for audible results? Well in double blind tests, I think it would be hard for anybody to tell the two apart. I prefer fully balanced amps because they also tend to be overbuilt and I really like the look and aesthetic to them. It's not surprising to me that the best amps I've heard have all been fully balanced amps. But I've heard some darn good non fully balanced amps too. I don't think an amp HAS to be fully balanced to be the best. For instance a non fully balanced XPA-2 gen 2 imo outperforms a fully balanced XPA-1 L monoblock pair.

[mick]

Jul 26, 2019 11:42:17 GMT -5 garbulky said:

What he's saying is there are amps that have XLR inputs which are pretty common. These inputs are balanced but not the outputs.

But a fully balanced amp (quad differential according to Emotiva). Which means that it remains balanced from output to input. It's not a small difference. It basically requires TWO amps per channel which is nearly twice the circuitry. So doing fully balanced is EXPENSIVE. And so that is important. Usually a fully balanced amp would be advertised as being fully balanced because it didn't happen by accident because it costs twice the material in amps. In terms of measurable performance - there is I believe a 6 db increase of signal to noise ratio. Also fully balanced means that each channel produces two signals out of phase with each other. When they combine they cancel the distortions picked up within the gear.
If you have a fully balanced chain (like your DAC and preamp is fully balanced) then all the way through your chain these distortions get cancelled.

So fully balanced Emotiva amps
XPA-1 L gen 1 and 2, XPA-1 gen 1 and 2. XPA-1 DR-1, DR-2, DR-3. Emotiva PA-1.

Emotiva fully balanced gear:
Emotiva RMC-1 (some configurations vary in number of channels balanced), XMC-1 (front channels), XSP-1 gen 1 and 2, XDA-1, XDA-2, Emotiva DC-1. ERC-1, ERC-2, ERC-3, ERC-4.

Amps that are not fully balanced but have XLR inputs
Emotiva HC-1, XPA gen 3. XPA-2 gen 1 and 2, XPA-3 gen 1 and 2 XPA-5 gen 1 and 2, XPA-7 gen 2.
And also all the older amp line that had XLR inputs that was not the XPA-1 gen 1.

As for audible results? Well in double blind tests, I think it would be hard for anybody to tell the two apart. I prefer fully balanced amps because they also tend to be overbuilt and I really like the look and aesthetic to them. It's not surprising to me that the best amps I've heard have all been fully balanced amps. But I've heard some darn good non fully balanced amps too. I don't think an amp HAS to be fully balanced to be the best. For instance a non fully balanced XPA-2 gen 2 imo outperforms a fully balanced XPA-1 L monoblock pair.

Thank you, is there a difference between fully balanced and differential as you mentioned Xpa 1L as being fully balanced?
Please bear with me with the question. as i feel i could learn from this thread.

[donh50]

Going from single-ended to differential provides 3 dB increase in SNR. The signal is doubled, and noise also increases, but assuming the noise is uncorrelated (unrelated) in the two channels then it only rises by 3 dB so you get a net increase of 3 dB in SNR.

[mick]

Ok .... now, so, lets a assume i trade up to a RMC-1L and i may or may not install 16 speakers.

At the moment i have 5x XPA-1L amps and 1x XPA-5 gen2 is the XPA-5 the weak link in this chain? in other words are the 1L's and the XPA-5 a miss match?

sorry but i'm going to ask my questions slowly so i can get it into my thick head

[garbulky]

Jul 26, 2019 13:19:33 GMT -5 mick said:

Ok .... now, so, lets a assume i trade up to a RMC-1L and i may or may not install 16 speakers.

At the moment i have 5x XPA-1L amps and 1x XPA-5 gen2 is the XPA-5 the weak link in this chain? in other words are the 1L's and the XPA-5 a miss match?

sorry but i'm going to ask my questions slowly so i can get it into my thick head

There isn’t a weak link or mismatch. Technically since they are different amps they are slightly mismatched but not having anything to do with being balanced. They should work perfectly together.

As for your other question the xpa1l is fully balanced (aka quad differential). The xpa5 is not fully balanced but is differential is on the inputs. (Dual differential). But not the output.
If you are interested in a way to go fully balanced on all channels and still keep the price low I can’t think of a better option than a whole bunch of Emotiva pa1 amplifiers which are fully balanced.
But your current setup is very good imo.

[mick]

Jul 26, 2019 13:24:29 GMT -5 garbulky said:

Jul 26, 2019 13:19:33 GMT -5 mick said:

Ok .... now, so, lets a assume i trade up to a RMC-1L and i may or may not install 16 speakers.

At the moment i have 5x XPA-1L amps and 1x XPA-5 gen2 is the XPA-5 the weak link in this chain? in other words are the 1L's and the XPA-5 a miss match?

sorry but i'm going to ask my questions slowly so i can get it into my thick head

There isn’t a weak link. As for your other question the xpa1l is fully balanced (aka quad differential). The xpa5 is not fully balanced but is differential is on the inputs. (Dual differential). But not the output. The xpa1l has two amps per channel. The xpa5 has one per channel.
If you are interested in a way to go fully balanced on all channels and still keep the price low I can’t think of a better option than a whole bunch of Emotiva pa1 amplifiers which are fully balanced

Sorry i should have said i will use all XLR cables, not sure if this matters or not.

"The xpa1l has two amps per channel." i get it .. i get it, i now understand this part now, there are two internal amp's in the 1L's AMP learning.  

Does it matter in the chain of the amps if some are quad and some are dual? 

[KeithL]

What matters between components is whether you have a balanced connection or not.

And, if you want a "fully balanced system" then all of your components must offer a fully balanced signal path and they must all be connected together with balanced connections.

(A fully balanced system MUST use all balanced connections... and all balanced components... but not all systems that use balanced connections are fully balanced.)

Note that a piece of gear, like a preamp, could have balanced inputs and outputs, yet still not have a fully balanced internal signal path (it's not that uncommon).

In that case, you would get all of the benefits of balanced connections, which are the more important of the two, but would miss out on a few of the benefits of having a fully balanced system.

Things like "dual differential" and "quad differential" refer to specific types of circuitry inside the individual components and how certain things are done internally.

They all relate to the performance of the individual piece of gear... so there's no specific need to "match them" on different components.

Jul 26, 2019 13:39:49 GMT -5 mick said:

Jul 26, 2019 13:24:29 GMT -5 garbulky said:

There isn’t a weak link. As for your other question the xpa1l is fully balanced (aka quad differential). The xpa5 is not fully balanced but is differential is on the inputs. (Dual differential). But not the output. The xpa1l has two amps per channel. The xpa5 has one per channel.
If you are interested in a way to go fully balanced on all channels and still keep the price low I can’t think of a better option than a whole bunch of Emotiva pa1 amplifiers which are fully balanced

Sorry i should have said i will use all XLR cables, not sure if this matters or not.

"The xpa1l has two amps per channel." i get it .. i get it, i now understand this part now, there are two internal amp's in the 1L's AMP learning.  

Does it matter in the chain of the amps if some are quad and some are dual? 

[KeithL]

I do need to correct you on one small thing....

"Quad differential" actually refers to the input circuitry.... and does not specifically address that the main part of the amplifier is fully balanced or that the output is balanced.

Jul 26, 2019 13:24:29 GMT -5 garbulky said:

Jul 26, 2019 13:19:33 GMT -5 mick said:

Ok .... now, so, lets a assume i trade up to a RMC-1L and i may or may not install 16 speakers.

At the moment i have 5x XPA-1L amps and 1x XPA-5 gen2 is the XPA-5 the weak link in this chain? in other words are the 1L's and the XPA-5 a miss match?

sorry but i'm going to ask my questions slowly so i can get it into my thick head

There isn’t a weak link or mismatch. Technically since they are different amps they are slightly mismatched but not having anything to do with being balanced. They should work perfectly together.

As for your other question the xpa1l is fully balanced (aka quad differential). The xpa5 is not fully balanced but is differential is on the inputs. (Dual differential). But not the output.
If you are interested in a way to go fully balanced on all channels and still keep the price low I can’t think of a better option than a whole bunch of Emotiva pa1 amplifiers which are fully balanced.
But your current setup is very good imo.

[mick]

Jul 26, 2019 14:02:34 GMT -5 KeithL said:

What matters between components is whether you have a balanced connection or not.

And, if you want a "fully balanced system" then all of your components must offer a fully balanced signal path and they must all be connected together with balanced connections.

(A fully balanced system MUST use all balanced connections... and all balanced components... but not all systems that use balanced connections are fully balanced.)

Note that a piece of gear, like a preamp, could have balanced inputs and outputs, yet still not have a fully balanced internal signal path (it's not that uncommon).

In that case, you would get all of the benefits of balanced connections, which are the more important of the two, but would miss out on a few of the benefits of having a fully balanced system.

Things like "dual differential" and "quad differential" refer to specific types of circuitry inside the individual components and how certain things are done internally.

They all relate to the performance of the individual piece of gear... so there's no specific need to "match them" on different components.

Jul 26, 2019 13:39:49 GMT -5 mick said:

Sorry i should have said i will use all XLR cables, not sure if this matters or not.

"The xpa1l has two amps per channel." i get it .. i get it, i now understand this part now, there are two internal amp's in the 1L's AMP learning.  

Does it matter in the chain of the amps if some are quad and some are dual? 

Ok, starting to get the hang of things,      XLR to XLR is balanced But XLR to RCA is not?

How many speakers does it take to have a good Atmos system, and i dont want to have 16 speakers as i don't have the room?

In what configuration makes a good Atoms system? I think this is my last question unless you throw me a curve ball  

[KeithL]

You've basically got it right.

A balanced CONNECTION uses two signal leads, one carrying a (signal+) signal, the other a (signal-) signal, plus usually a ground.

The benefit of a balanced connection is that any noise picked up by the cable, especially hum, tends to be cancelled out.

An XLR connector has three wires, two signal leads and a ground, and so can carry a balanced connection.

On all Emotiva gear, when you see an XLR analog input or output, it is fully balanced.

(It is possible to use an XLR connector for an unbalanced connection by simply not connecting one of the wires... and occasionally someone does it that way... but not us.)

An RCA connector has one signal lead (signal+) plus a ground, and so CANNOT carry a balanced connection.

Therefore any connection that involves an RCA connector at one or both ends is NOT a balanced connection.

(You can technically squeeze a two-wire balanced connection through an ungrounded RCA connector... but that's really non-standard and you're unlikely to ever see one.)

Jul 26, 2019 14:24:31 GMT -5 mick said:

Jul 26, 2019 14:02:34 GMT -5 KeithL said:

What matters between components is whether you have a balanced connection or not.

And, if you want a "fully balanced system" then all of your components must offer a fully balanced signal path and they must all be connected together with balanced connections.

(A fully balanced system MUST use all balanced connections... and all balanced components... but not all systems that use balanced connections are fully balanced.)

Note that a piece of gear, like a preamp, could have balanced inputs and outputs, yet still not have a fully balanced internal signal path (it's not that uncommon).

In that case, you would get all of the benefits of balanced connections, which are the more important of the two, but would miss out on a few of the benefits of having a fully balanced system.

Things like "dual differential" and "quad differential" refer to specific types of circuitry inside the individual components and how certain things are done internally.

They all relate to the performance of the individual piece of gear... so there's no specific need to "match them" on different components.

Ok, starting to get the hang of things,      XLR to XLR is balanced But XLR to RCA is not?

How many speakers does it take to have a good Atmos system, and i dont want to have 16 speakers as i don't have the room?

In what configuration makes a good Atoms system? I think this is my last question unless you throw me a curve ball  

[geeqner]

In my Pre-Purchase "Research" for a new 2-Channel Preamplifier - I've been learning a bit about this issue as well

From what it sounds like:

BALANCED CIRCUITS:
Are a particularly nice way to reduce noise / improve the Signal-To-Noise (S/N) Ratio within various Audio Signal Amplification and/or Processing circuits.
They appear to have the most / greatest advantage over Non-Balanced equivalent circuits where the Input Signal is very miniscule.
Essentially, whatever is the SAME (usually noise of various types) in Both Sides of a Balanced Circuit gets nulled-out while whatever is DIFFERENT gets amplified / passed-on to the next stage.
The trade-off is that Balanced Circuits are usually significantly more complex (more components) and require greater "attention to detail" in their design and execution.

There are other schools of thought where some designers believe in minimizing the quantity of components and keeping the signal paths as short as possible (SIMPLICITY) produces less opportunities for noise to get-in and/or to be produced by the components.

BALANCED (ANALOG)CONNECTIONS:
Similar to Balanced Circuits - There are (2) Separate wires that are SEPARATED FROM GROUND carrying the signal from one end to the other.
At the "Receiving End" the signals are run-through a type of Comparitor Circuit.
Any Electrical Noise that is able to get through the shielding on the cable will usually produce the SAME noise in BOTH wires.
This circuit is able to null-out (ignore) any such noise signals that are the same in both wires, producing a very LOW noise floor.

Also, because GROUND (Earth Ground or Chassis Ground) is separated from the "Signal" conductors - they help to minimize ground loops / ground "hum" noises between components.
(Balanced Connections are usually only bonded to Ground at ONE End - "Ground" IS NOT used as one of the "Signal" Conductors like it is within a typical RCA type unbalance cable)

If you are running line-level (CD Analog Out or Pre-Out to an Amplifier In) over a SHORT distance, the advantages of a Balanced Connection over un-balanced are not as great, provided that high-quality cables and connectors are used at both ends.  But all things being equal - Balanced offers less opportunity for noise and better isolation against grounding issues.

Balance Circuits provide the greatest advantage when signals need to be transmitted over relatively long distances
[such as a Stage Microphone at a Concert being connected, via a multi-channel "snake cable" to a mixing console in the Sound Booth, and then back to the Speakers flanking the Stage through a different set of wires in the snake.  Here the Balanced Connection handles the VERY Low-Level Signal output from the mics and keeps them from interfering with eachother (cross-talk) and with the Speaker Feeds via numerous Balanced Circuits]  [Similar to the situation in more complex Home Theater Systems where you "movie-junkies" have an F-Ton of channels going between your Receiver / Decoder and your Amplifiers...]

[Or when you would rather put your shiny new Monoblock Amplifiers within 3 feet of your speakers and run a Balanced (Usually XLR Type Connector) Cable from your Pre-Amp, across the room to where you will be putting your Amp for that speaker.  Going that sort of distance with an RCA Cable (Un-Balanced) would probably not be a good idea]

[KeithL]

I'll look into making up a table that shows some useful compraisons:

- which of our products have fully balanced inputs and fully balanced outputs

- which of our amps are internally fully balanced designs

However, I am NOT going to include things like "dual differential" and "quad differential".

The reason I'm excluding them is that they are NOT "features" that you should be using to decide whether one amplifier is better than another.

We came up with a somewhat unique sort of differential connection that works really well in some of our amplifier designs - and we decided to refer to it as a "quad differential input".

However, that doesn't mean that it would necessarily benefit our other amplifiers, or that you should avoid buying those that don't use it.

Jul 26, 2019 10:18:31 GMT -5 mick said:

Jul 26, 2019 9:42:37 GMT -5 KeithL said:

Here's a short description about the difference between "balanced" and "differential"...

The term "balanced" in general refers to a situation where two cables, or two amplifier channels, carry copies of the audio signal that are equal but out of phase.

- the term "balanced" generally refers to amplifiers or signal paths ("a fully balanced amplifier"; "a balanced input or output"; "a balanced signal path"; "a balanced cable")

The term "differential" refers to a situation where you have two inputs or connections, and differences between them are amplified or passed, while signals that are common to the two are ignored.
- the term "differential" generally refers to a type of circuit

So, for example, a balanced cable carries two identical, but out of phase, versions of the same audio signal.
When you then connect this balanced cable to a balanced input it is usually passed to a differential circuit.
This differential circuit keeps the desired signal - by passing and amplifying the difference between the signal on the two input lines ( when you subtract the inverted signal from the non-inverted signal you get 2x the signal).
And the differential circuit discards most noise picked up by the wires ( any noise picked up in transit is likely to be the same on both wires - so, when you subtract one from the other, most of the noise is cancelled out).

HOWEVER, a differential circuit is also used internally in almost all modern amplifiers, even on the unbalanced inputs, to compare a portion of the output signal to the input signal (as part of how NFB works).
So, when you have a balanced input, but each of the input lines is already connected to its own differential input circuit, the whole thing can fairly be described as "dual differential".
And, if you have a balanced amplifier, and each of the two amplifier channels has a balanced input, and each of those input lines is connected to its own differential input circuit, you can fairly call it "quad differential".

It's also important that what we're talking about is "function blocks" - which is a fancy way of saying "what stuff does".
For example, most modern amplifiers have "an active differential input circuit", which is quite easily recognized on a schematic.
However, the balanced transformer inputs on vintage microphone preamps, and are still used in some equipment today, are a very effective form of PASSIVE differential input circuit.
(They are no longer commonly used because they have several important disadvantages.)

An engineer will simply look at the schematic and notice where various balanced connections and differential circuits are used.
HOWEVER, while the term "balanced connection" is pretty much standard, the terms you use to attempt to describe the other stuff to a non-engineer aren't....
Therefore, we do our best to use terms that are both descriptive of what's actually going on, and that sound cool in the marketing literature.
The takeaway is that, if you find all this terribly confusing, then you shouldn't really worry about it quite so much.....

All that really matters is the results it produces in a given situation and how it all sounds... right?

Thank you for your post Kieth but your confusing the hell out of me. lol Using the Emo product page can you list which is which please, as this will make easier for me to understand to making a choices.

[KeithL]

That all looks right to me....

However, let me add one or two things....

In a balanced connection, the two signal wires are normally twisted together as a pair, which helps ensure that they are equally exposed to outside noise sources.

For example, if the pair is run next to another cable, which is a source of noise, the individual wires take turns being next to it, which helps ensure that they pick up the noise equally.

And, from the point of view of the signal lines, any noise that is present on the ground line is "equally in both channels - relatively speaking:, and so is rejected along with other common mode noise.

And, incidentally, where you described "a type of comparator circuit"........

That circuit is an amplifier with a  differential input (which is designed to amplify and pass the difference between two input signals while rejecting anything that is common to both.

(And that's the "differential input" we are referring to when we talk about a differential input on a balanced input.)

Jul 26, 2019 15:36:39 GMT -5 geeqner said:

In my Pre-Purchase "Research" for a new 2-Channel Preamplifier - I've been learning a bit about this issue as well

From what it sounds like:

BALANCED CIRCUITS:
Are a particularly nice way to reduce noise / improve the Signal-To-Noise (S/N) Ratio within various Audio Signal Amplification and/or Processing circuits.
They appear to have the most / greatest advantage over Non-Balanced equivalent circuits where the Input Signal is very miniscule.
Essentially, whatever is the SAME (usually noise of various types) in Both Sides of a Balanced Circuit gets nulled-out while whatever is DIFFERENT gets amplified / passed-on to the next stage.
The trade-off is that Balanced Circuits are usually significantly more complex (more components) and require greater "attention to detail" in their design and execution.

There are other schools of thought where some designers believe in minimizing the quantity of components and keeping the signal paths as short as possible (SIMPLICITY) produces less opportunities for noise to get-in and/or to be produced by the components.

BALANCED (ANALOG)CONNECTIONS:
Similar to Balanced Circuits - There are (2) Separate wires that are SEPARATED FROM GROUND carrying the signal from one end to the other.
At the "Receiving End" the signals are run-through a type of Comparitor Circuit.
Any Electrical Noise that is able to get through the shielding on the cable will usually produce the SAME noise in BOTH wires.
This circuit is able to null-out (ignore) any such noise signals that are the same in both wires, producing a very LOW noise floor.

Also, because GROUND (Earth Ground or Chassis Ground) is separated from the "Signal" conductors - they help to minimize ground loops / ground "hum" noises between components.
(Balanced Connections are usually only bonded to Ground at ONE End - "Ground" IS NOT used as one of the "Signal" Conductors like it is within a typical RCA type unbalance cable)

If you are running line-level (CD Analog Out or Pre-Out to an Amplifier In) over a SHORT distance, the advantages of a Balanced Connection over un-balanced are not as great, provided that high-quality cables and connectors are used at both ends.  But all things being equal - Balanced offers less opportunity for noise and better isolation against grounding issues.

Balance Circuits provide the greatest advantage when signals need to be transmitted over relatively long distances
[such as a Stage Microphone at a Concert being connected, via a multi-channel "snake cable" to a mixing console in the Sound Booth, and then back to the Speakers flanking the Stage through a different set of wires in the snake.  Here the Balanced Connection handles the VERY Low-Level Signal output from the mics and keeps them from interfering with eachother (cross-talk) and with the Speaker Feeds via numerous Balanced Circuits]  [Similar to the situation in more complex Home Theater Systems where you "movie-junkies" have an F-Ton of channels going between your Receiver / Decoder and your Amplifiers...]

[Or when you would rather put your shiny new Monoblock Amplifiers within 3 feet of your speakers and run a Balanced (Usually XLR Type Connector) Cable from your Pre-Amp, across the room to where you will be putting your Amp for that speaker.  Going that sort of distance with an RCA Cable (Un-Balanced) would probably not be a good idea]

[vcautokid]

Then in some designs though starting balanced differential you may go through summers, winters and falls. No wait just summers and or phase splitters for unbalanced. Why was this subject even started LOL? I suppose it is fun but yeah allot of gear at Emotiva is/was reference or quad differential. One of the nice to haves. Do you have to have it without fail? Don't know about that, but options are always nice. I don't lose too much sleep on it really.

[donh50]

Cross-posted from the other thread:

FWIWFM a fully-differential circuit provides higher common-mode noise rejection, 3 dB better SNR, and cancellation of even-order distortion terms, among other things. It also facilitates isolating the signal path from earth (safety) ground to break ground loops. You are unlikely to hear a difference unless you have problems. I went with differential lines to my rear subs because they are long lines and the subs are on separate power circuits so noise and ground loops were a concern. I have plumbed my XMC-1 to my XPA-n amplifiers (PAs, y'a know ) using RCA and XLR connections and not noticed a difference after calibrating for gain and all that jazz.

A basic overview: www.audiosciencereview.com/forum/index.php?threads/differential-single-ended-balanced-unbalanced-and-all-that-jazz.1352/
Ground loops with a side comment about differential operation: www.audiosciencereview.com/forum/index.php?threads/ground-loops-101.7162/

HTH - Don

[mick]

Jul 26, 2019 15:05:42 GMT -5 KeithL said:

You've basically got it right.

A balanced CONNECTION uses two signal leads, one carrying a (signal+) signal, the other a (signal-) signal, plus usually a ground.

The benefit of a balanced connection is that any noise picked up by the cable, especially hum, tends to be cancelled out.

An XLR connector has three wires, two signal leads and a ground, and so can carry a balanced connection.

On all Emotiva gear, when you see an XLR analog input or output, it is fully balanced.

(It is possible to use an XLR connector for an unbalanced connection by simply not connecting one of the wires... and occasionally someone does it that way... but not us.)

An RCA connector has one signal lead (signal+) plus a ground, and so CANNOT carry a balanced connection.

Therefore any connection that involves an RCA connector at one or both ends is NOT a balanced connection.

(You can technically squeeze a two-wire balanced connection through an ungrounded RCA connector... but that's really non-standard and you're unlikely to ever see one.)

Jul 26, 2019 14:24:31 GMT -5 mick said:

Ok, starting to get the hang of things,      XLR to XLR is balanced But XLR to RCA is not?

How many speakers does it take to have a good Atmos system, and i dont want to have 16 speakers as i don't have the room?

In what configuration makes a good Atoms system? I think this is my last question unless you throw me a curve ball  

Thanks Kieth, i think i got it.

[mick]

Jul 26, 2019 15:53:43 GMT -5 KeithL said:

I'll look into making up a table that shows some useful compraisons:

- which of our products have fully balanced inputs and fully balanced outputs

- which of our amps are internally fully balanced designs

However, I am NOT going to include things like "dual differential" and "quad differential".

The reason I'm excluding them is that they are NOT "features" that you should be using to decide whether one amplifier is better than another.

We came up with a somewhat unique sort of differential connection that works really well in some of our amplifier designs - and we decided to refer to it as a "quad differential input".

However, that doesn't mean that it would necessarily benefit our other amplifiers, or that you should avoid buying those that don't use it.

Jul 26, 2019 10:18:31 GMT -5 mick said:

Thank you for your post Kieth but your confusing the hell out of me. lol Using the Emo product page can you list which is which please, as this will make easier for me to understand to making a choices.

I think the table would be very helpful Kieth, for me any way.