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Is there any advantage to unbalanced connections?
Old 27th May 2006
  #1
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jgrif08's Avatar
 

Is there any advantage to unbalanced connections?

I understand what the difference is between balanced and unbalanced cables. Im just wondering if there are any situations in which an unbalanced cable is prefferable / necessary over a balanced one?

I think I remember someone saying that insert cables are unbalanced, with the ground acting as a return for the signal, is that correct? are both balanced and unbalanced cables capable of sending a signal back and forth?
Old 27th May 2006
  #2
mds
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For all intents and purposes balanced is always better than unbalanced on a theoretical level. Sometimes balanced is not necessary, like in a control signal. Send/Return cables are unbalanced for ease of use and space considerations(single jack), not because it wouldn't be better if both signals were balanced. In practice it doesn't always matter a whole lot, but on less than the shortest runs balanced is the preferred approach.

Mike
Old 28th May 2006
  #3
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vernier's Avatar
Quote:
Im just wondering if there are any situations in which an unbalanced cable is prefferable / necessary over a balanced one?
Prefferably when you want a cleaner, better signal ..as does the top mastering guys. Balanced serves one purpose, when you must run honkin' long lines.
Old 28th May 2006
  #4
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Actually, for short runs (like a couple feet) running unbalanced is actually cleaner & 'better' since you won't have electronic or transformer balancing amps in the signal path if they aren't needed.

Most of the big mastering houses run unbalanced connections throughout their rooms since most of those runs are 3-5 feet or less.

The downside to running totally unbalanced is that the chance of picking up stray fields (RFI is huge!) and noise shoots up dramaticly on long runs.

You also lose 6dB of gain when you switch from balanced to unbalanced.
Old 28th May 2006
  #5
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Quote:
Originally Posted by mds
Send/Return cables are unbalanced for ease of use and space considerations(single jack), not because it wouldn't be better if both signals were balanced.
Mike
So could a balanced cable be used as a Send/Return as well? Or in order to use a single cable as a Send/Return does the cable have to be unbalanced?
Old 28th May 2006
  #6
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Quote:
Originally Posted by jgrif08
So could a balanced cable be used as a Send/Return as well? Or in order to use a single cable as a Send/Return does the cable have to be unbalanced?
A single cable insert is TRS (tip/ring/sleeve) at the insert end, then it Y's out to 2 leads that are 2 Tip/Ring. There is no way to make this balanced. To make it balanced you need separate send / return jacks that are each 3 conductor jacks (TRS). Balanced inserts (seperate send / return jacks) are usually only seen on the bigger high end boards.

BTW, balancing is basically done outside of the mixer and outboard gear, within the mixer or outboard, the signal is unbalanced.



Fleaman
Old 28th May 2006
  #7
Gear Nut
 

Quote:
Originally Posted by Jay Kahrs
You also lose 6dB of gain when you switch from balanced to unbalanced.
Is this true regardless of cable length?
Old 28th May 2006
  #8
Gon
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Quote:
Originally Posted by jeak
Is this true regardless of cable length?
The gain is caused by applying common mode rejection - when you sum two correlated signals, the result is 6dB louder.

This also has another positive effect: noise in the signal itself will be summed uncorelated, which will make it 3dB louder, but the actual signal is summed corelated, which will make it 6dB louder. This means that balanced transmissions have an inherent 6dB - 3 dB = 3dB better SNR than unbalanced, in addition to rejecting noise that has potentially been induced in the transmission run.
Old 28th May 2006
  #9
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Quote:
Originally Posted by Jay Kahrs
Actually, for short runs (like a couple feet) running unbalanced is actually cleaner & 'better' since you won't have electronic or transformer balancing amps in the signal path if they aren't needed.
only if the devices have independent unbalanced inputs and outputs. as most devices only have a single output stage it wont serve any benefit.
Old 28th May 2006
  #10
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kurt's Avatar
Quote:
Originally Posted by Jay Kahrs
Most of the big mastering houses run unbalanced connections throughout their rooms since most of those runs are 3-5 feet or less.

Please name ONE! Professional piece of gear without balanced I/Otutt
Old 28th May 2006
  #11
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midiman123's Avatar
 

Quote:
Originally Posted by kurt

Please name ONE! Professional piece of gear without balanced I/Otutt
Alan Smart C1...?

KK
Old 28th May 2006
  #12
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Quote:
So could a balanced cable be used as a Send/Return as well? Or in order to use a single cable as a Send/Return does the cable have to be unbalanced?
i believe the answer to this is YES! only both devices should have send+return (input/output in the case of outboard) on one jack... e.g. you can use one balanced cable to connect an unbalanced insert point on a mixer to the fmr rnc/rnla... most outboard gear tends to have separate input and output jacls, unlike the rnc.

self.
Old 28th May 2006
  #13
Registered User
 

I have always wondered why my Origin STT-1 provieds unbalanced outputs in addition to balanced ones. Then I read Buzz Audio preamps have unblanced outputs on their pre's to provide the "best" audio quality.

Hugh Robjohns from SOS mag (a tech buff) confirmed that an unbalnced output is technically better quality - if you use a short cable run.

Trebor
Old 28th May 2006
  #14
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Quote:
Originally Posted by Gon
This also has another positive effect: noise in the signal itself will be summed uncorelated, which will make it 3dB louder, but the actual signal is summed corelated, which will make it 6dB louder. This means that balanced transmissions have an inherent 6dB - 3 dB = 3dB better SNR than unbalanced, in addition to rejecting noise that has potentially been induced in the transmission run..
Wonderful! So by passing a signal repeatedly through a balanced connection we can reach any SNR we want.

This is of course not true. The only improvement vis-a-vis single-ended transmission concerns noise induced on the transmission line.

-synthoid
Old 28th May 2006
  #15
Gon
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Quote:
Originally Posted by synthoid
Wonderful! So by passing a signal repeatedly through a balanced connection we can reach any SNR we want.

This is of course not true. The only improvement vis-a-vis single-ended transmission concerns noise induced on the transmission line.
Sorry, I guess I wasn't quite clear. What I meant was that a balanced transmission has 3dB better SNR than an equivalent unbalanced transmission, given otherwise ideal conditions. Of course, using a balanced line won't result in lowering the noise floor inherent in the program material, but the line itself has better SNR than an unbalanced one.

This is due to the fact that while the signal in the lines is summed corelated (+6dB), any thermal noise in the curcuitry is summed uncorelated (+3dB).

Of course, in real world applications, the effect will vary.
Old 28th May 2006
  #16
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Balanced cables and circuits came to us from the phone company because they obviously run rediculously long cables from point to point. They also use a twisted pair which will run a LONG way without a sheild.

Almost every piece of equipment made with a balanced input and output converts the signal to an un-balanced signal at the input and back on the output.
Almost every console ever made has an input circuit that accepts a balanced signal and converts it to an un-balanced signal. This is done with either a transformer or an op-amp functioning as a differential amplifier. Once inside the console the signal remains un-balanced. It only makes sense that the insert would be un-balanced as well because it would require either another pair of transformers or two additional opamps. The reasoning is that insert cables are not going to run that far. This same idea is used in patchbays. A Neve 8128 that I once lived with for years had an "active" patchbay that I never quite figured out (I was too busy fixing other crap in it all the time!) If you know how this design worked please keep it it to yourself because I sold that hunk of iron years ago and the guy I sold it to no longer has it either, so it's out of my life!

I too have heard that mastering people use un-balanced cables in their rigs. Because they are using short runs they can do this, but you can run short lenghs without any trouble yourself. Since they have a chain of several pieces of gear their thinking is that un-balanced will eliminate the associated transformer or differential amplifier stage. In essence what they are doing is "building" the equivelent of an un-balnced console.

An advantage with transformers is that they physically isolate pieces from one another, but still pass the signal.

Danny Brown
Old 28th May 2006
  #17
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skygod's Avatar
Quote:
Originally Posted by vernier
Prefferably when you want a cleaner, better signal ..as does the top mastering guys. Balanced serves one purpose, when you must run honkin' long lines.
But even if you run balanced lines longer than 25 feet tutt you will start losing top end and midrange depending on the gauge of the lines. Some years ago I saw posted on Crown or Crest or some other live amplification website discussing this with detailed charts of signal losses and power losses by wire gauge x length of cable runs. Thats why we have Countryman DIs and REDDI DIs and de Maria DIs etc boosting the signal for long cable runs to maintain signal sonic and power (if applicable) integrity. It all boils down to a transparent clean boost active or passive. Then there is the ground issue of unbalanced lines which should not be a major concern in a RFI controlled studio environment. But I cannot confirm or refute this because I have never traveled inside of a cable run as an electron to experience this first hand. I am relying solely on the external resulting affected evidence based on the forces of nature that superimposed itself upon such an electron in its travels throughout this vast universe, or micro universe, depending on your perspective of universal definitions of inter/intra relationships between electrons and their carriers through the space-time-continuum.
Old 28th May 2006
  #18
mds
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Quote:
Originally Posted by skygod
...I have never traveled inside of a cable run as an electron to experience this first hand. I am relying solely on the external resulting affected evidence based on the forces of nature that superimposed itself upon such an electron in its travels throughout this vast universe, or micro universe, depending on your perspective of universal definitions of inter/intra relationships between electrons and their carriers through the space-time-continuum.
Woah....
Old 29th May 2006
  #19
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Very helpful responses. Thanks everyone
Figure I'll ask another simple question here in this same thread.... Im almost embarrased to ask:

What exactly is the difference between speaker and instrument cable? Is it just that speaker cable carries power? Of am I off base here?

Just another one of those things I should have paid more attention to in school
Old 29th May 2006
  #20
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Fleaman's Avatar
 

Speaker cable carries a high current/amp signal, so it is heavy gauge, like a power cable.

Instrument cable or line level interconnects are low milliamp low voltage and very thin gauge.
Old 29th May 2006
  #21
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Bigbang's Avatar
 

Quote:
Originally Posted by Jay Kahrs
Most of the big mastering houses run unbalanced
This is what Manley Labs says about the mastering consoles they build:

Most of the consoles we have built have been unbalanced. We can certainly build balanced but we don't usually recommend going that way as it adds to the number of electronic parts that can influence the sound.
Old 9th July 2006
  #22
Gear Head
 

Speaker cables use individual solid-core or stranded wires to run signals and returns.

Instrument cables are shielded with the return conductor being wrapped around the sending conductor.
Old 9th July 2006
  #23
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Is a 17' unbalanced run from my synths to my A/D not a good idea? Should I get some sort of stereo DI and place near the synths, then run balanced out of the DI? Or is this a non-issue?
Old 9th July 2006
  #24
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Unbalanced ins/outs are a fairly recent "invention" in our business. While I agree that an unbalanced interface *might* sound better due to the simpler circuitry, the main reason it became popular was cost cutting.

The original MCI JH-400 series console was probably the first "otherwise professional" unit I can recall which had any unbalanced I/O...for the channel inserts (which also ran at -6 dBu...yet another corner being cut). In that same general era, Teac/Tascam went totally unbalanced so they could sell desks and decks WAY below the prices of Ampex, Studer, etc.

One compromise is to have an unbalanced (or "impedance balanced") output stage with a decent balanced input.

Bri
Old 9th July 2006
  #25
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Quote:
Please name ONE! Professional piece of gear without balanced I/O

Helios Type69 is unbalanced. Apparently the engineers liked the sound better than when they balanced it.
Old 9th July 2006
  #26
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The Avalon Design 20xx series has unbalanced as well as balanced outputs. I don't see why it should be unbelievable that eliminating the differential driver and receiver at the ends of the transmission line would improve the signal quality under some circumstances. Do you think that it would be better to used balanced (i.e., differential) connections on every PCB trace inside the gear? Of course not. the same thing goes for short cable runs.

-synthoid
Old 9th July 2006
  #27
Gear Maniac
 

Quote:
Originally Posted by kats
Helios Type69 is unbalanced. Apparently the engineers liked the sound better than when they balanced it.
Hi All,

First off I love the site. Been reading it for a while but this is my first post.

I was told that the focusrite red range stuff is actually unbalanced (I dont use them myself). Though they have xlr connections, not all three pins are wired inside the unit. Can anybody confirm or deny this? Does anybody wanna open one and have a peek?

Cheers,

ofsaints
Old 9th July 2006
  #28
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Quote:
Originally Posted by ofsaints
Hi All,

First off I love the site. Been reading it for a while but this is my first post.

I was told that the focusrite red range stuff is actually unbalanced (I dont use them myself). Though they have xlr connections, not all three pins are wired inside the unit. Can anybody confirm or deny this? Does anybody wanna open one and have a peek?

Cheers,

ofsaints
i can tell you from use that it is balanced and from seeing the inside it has large output transformers
Old 9th July 2006
  #29
Motown legend
 
Bob Olhsson's Avatar
 

Once again, it really depends entirely on implementation.

Doing balanced well is never cheap so there have been a number of "pro-sumer" products that indeed sounded better with their unbalanced outputs. During the late 1960s it became all the rage to modify gear by removing the transformers and this could sound better.

Today, I find it's a moving target, a question of specific gear plugged into specific other gear. All things being equal, balanced at least seems more idiot-proof.
Old 9th July 2006
  #30
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max cooper's Avatar
 

Quote:
Originally Posted by Bob Olhsson
During the late 1960s it became all the rage to modify gear by removing the transformers and this could sound better.
I think we've come full circle as there are a few bits of pricey hifi gear with balanced ouputs. Makes me snicker.
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