balanced-unbalanced

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dmbfan1981

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i had a few quick questions...what is the difference between balanced and unbalanced. when would you want to use each and not use each. what are the pros and cons.

also...what is the difference between +4 and -10

I am going to be running from the balanced outputs of a mixer into my emu 0404 but do not know if they are balanced or unbalanced. will it hurt anything if they are not balanced as well?

sorry if this is all stupid questions.
 
hmmm..... where to begin.

Balanced vs. Unbalanced has to do with how the cables function. Balanced uses a ground wire and two signal wires. The two signals (from the same source) are in phase-inversion. When the cable is connected to a balanced input these phase-invereted signals are brought back into phase, which in turn removes any noise or hum that the cable may have induced.

In other words..... balanced cables help reduce noise.

Unbalanced cables simply use two wires.... signal and ground. They are prone to creating hum or noise in the signal path.

+4 is a balanced connection.... -10 is unbalanced.


Search Google and read read read..... also try wikipedia.com
 
JoeNovice said:
hmmm..... where to begin.

Balanced vs. Unbalanced has to do with how the cables function. Balanced uses a ground wire and two signal wires. The two signals (from the same source) are in phase-inversion. When the cable is connected to a balanced input these phase-invereted signals are brought back into phase, which in turn removes any noise or hum that the cable may have induced.

In other words..... balanced cables help reduce noise.

Unbalanced cables simply use two wires.... signal and ground. They are prone to creating hum or noise in the signal path.

+4 is a balanced connection.... -10 is unbalanced.


Search Google and read read read..... also try wikipedia.com
Click to expand...

close, but not quite...on both questions.
first, it's not the cable that is balanced or unbalanced, it's the actual hardware that you are using that decides whether the signal is balanced or not. You just need to use the appropriate cables for each device. Just using a balanced cable does not automatically mean that you have a balanced signal...your sound card, microphone, DI box, etc. has to convert the signal before it enters the cable. THEN the final destination gear (sound card, speaker, etc.) has to convert it back.
The cable itself is just the pathway the signal follows. If you want your audio to remain balanced, you need to use two conductor cable (ie. XLR or TRS). The receiving circuitry calculates the difference between the two signals and thus (hopefully) cancelling out any noise that was introduced in the cable.


The -10dBV and +4dBu on your gear have to do with their nominal inputs/outputs. Generally +4dBu is known as "professional" while -10dBV is known as consumer. Each has their own voltage reference level. There will be an 11.79dB difference between the two. In other words, if both are calibrated to 0dBVU and you plug a piece of consumer gear with -10dBV outputs into a piece of gear with + 4dBu inputs...the pro gear will read about -11.79dB on it's meters.
This has nothing to do with them being balanced or unbalanced.
 
The principle at work here is common mode rejection. A differential amplifier has two inputs, and will amplify (or pass at unity) any differences between the inputs, but will reject any signal that is common to both inputs. The spec CMMR (common mode rejection ratio) is the measure of how well it does this.
So if you take a signal, split it into two signals, then invert the phase of one of the signals, and send them over a two hot plus ground cable, you get the two signals plus any induced noise at the other end. The two signals will be 180 deg out of phase, but the noise will be in phase. The differential amplifier at the balanced input will then amplify the difference signal, and reject the common mode noise.
 
thanks..you guys should get together and write a book because you guys explain much more concise and too the point. so if i am running from my mixer XLR balanced outputs into 1/4 inputs..i would need xlr-1/4 cable? or do i need a specific type? (what is the technical term for a 1/4 cable like a guitar cable or patch cord? is that TSR? )

ALSO...i cannot seem to find out if my E-mu 0404 inputs are balanced or not....can anyone help me? i am looking..everyone that sells them online dont list that info and unless i missed it...neither does the manual.


thanks again for all of your help guys.
 
it says it in the specs on the EMU site

both inputs and outputs are unbalanced and operate at only -10dBV

So in other words you're running balanced outputs of your mixer (XLR) into unbalanced inputs (TS). There is nothing wrong with this, you just MIGHT get noise introduced to your signal. With a short cable run, this probably won't be a big deal. You'll also lose a little bit of volume level doing it this way.
Robert gave you a nice explanation of the science behind it.
Just go to Radio Shack and ask them for an XLR to TS cable...or get an XLR cable and just buy a small XLR-TS adapter to plug into your soundcard.
 
With short, 15-20 feet cable runs in a home studio, unbalanced cables are fine.

In fact Bob Katz himself would recommend unbalanced cables. His argument is if you already have an electrically quiet environment, that extra signal processing at either end of a balanced cable has the potential to introduce noise...and he hates noise
 
Just to hop in on this subject , in terms of cable run lengths , what is the maximum length you can use with a balanced system ? Meaning a balanced mixer output , thru balanced TRS cables to a balanced PC a/d/a interface like a Presonus FirePod or Tascam US 122 .
At what point does the signal degrade ?? I'm using 25 feet now but could really use 35 or 40 .
 
I don't know the max length either, but it's over 100ft I'm sure.
Mic cables are also balanced, they carry much, much weaker signals yet in stage work they're run all the way to the mixer at the back of the house with few problems.

A rule of thumb for comparing +4dBU with -10dBV is that +4 is 4x the level of -10.
In very rounded figures....
+4dBU = 1.2v RMS
-10dBV = 300mV RMS

I'll try and explain the significance of RMS...
RMS (Root/mean/square) is a formula for finding the "true" average level of a signal although the peaks go higher. The majority of audio measurements are done with RMS values.
For sine waves (pure tone with no harmonics), the RMS volts is roughly 0.7 x the peak volts. Roughly RMS x 1.4 = Peak.

It is the RMS level that we percieve as the volume of sound, however it's the peak level that causes distortion in circuits!
 
TRS vs TS

I originally posted this in Newbies, maybe someone has the answer...

I just picked up some KRK RP5s today, and the guys at the music shop sold me some instrument cables to go from my mixer to the monitors. The outputs on the mixer are TRS, as are the inputs on the monitors. According to the music store guys, this doesn't matter; they said guitar cables, even though they are TS, are fine. Is this true?

I haven't used the guitar cables just yet; I might return them. I used a stereo 1/4" TS-to-RCA cord from the TRS outputs on the mixer to the unbalanced RCA inputs on the monitors, and it sounded fine. Do TRS outputs work OK with TS cords, as long as the input on the monitors is unbalanced?

Any help is appreciated!
 
bennychico11 said:
close, but not quite...on both questions.
first, it's not the cable that is balanced or unbalanced, it's the actual hardware that you are using that decides whether the signal is balanced or not. You just need to use the appropriate cables for each device. Just using a balanced cable does not automatically mean that you have a balanced signal...your sound card, microphone, DI box, etc. has to convert the signal before it enters the cable. THEN the final destination gear (sound card, speaker, etc.) has to convert it back.
Click to expand...

Just to be a pedant, it's a property of both the cable and the electronics on both ends. Balanced circuitry can usually handle an unbalanced connection between them, just at a 6dB loss (IIRC) and with a slightly higher noise floor.

A true balanced cable will typically be a twisted pair to ensure that the signal introduced in the normal and inverted lines are as similar as possible. This makes an ideal balanced TRS cable somewhat different from, for example, a stereo audio cable.

I know, a little pedantic, but....


Sabu said:
I just picked up some KRK RP5s today, and the guys at the music shop sold me some instrument cables to go from my mixer to the monitors. The outputs on the mixer are TRS, as are the inputs on the monitors. According to the music store guys, this doesn't matter; they said guitar cables, even though they are TS, are fine. Is this true?
Click to expand...

Like I said.... 6dB loss and a slightly higher noise floor. Yes, it's true, though you might be slightly happier with a TRS cable if both ends are TRS, as you'd be able to turn down the monitors a bit and still get the same signal level with slightly less noise.
 
rudibass2 said:
Just to hop in on this subject , in terms of cable run lengths , what is the maximum length you can use with a balanced system ? Meaning a balanced mixer output , thru balanced TRS cables to a balanced PC a/d/a interface like a Presonus FirePod or Tascam US 122 .
At what point does the signal degrade ?? I'm using 25 feet now but could really use 35 or 40 .
Click to expand...

Thousands of feet? :D

Seriously. Line level balanced signals are often run hundreds of feet around stadiums, etc. At mic level, I personally wouldn't go much over 50-100, preferring instead to kick it up to line level and send it at a hotter level. That said, you could probably get away with quite a bit more than that as long as your cables are of good quality and are THOROUGHLY grounded.

WARNING: Most XLR cables don't have ground wires attached to the metal jacket of the connectors. Woe be unto anyone in an electrically noisy environment who hooks two of such cables together in a row, as those metal jackets basically become a giant antenna. For long cable runs, make sure every metal XLR plug/jack back is tied to the cable ground and don't lift it anywhere except at one end (and only then if it goes between two pieces of grounded equipment---never lift the ground on a mic cable).
 
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