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View Full Version : Unbalaced vs Balanced Cables



Valentin
02-28-2005, 03:35 PM
My question is about the lenged of the unbalaced cables (do i loss information in long distance 15ft)
my actual sistem:

cd to DACProceed DAP) toslink
DAC to pre(Mark Levinson ML10A) unbalaced rca 3ft
pre to sub jbl lsr12sp 15ft rca
sub to ampMark Levinson ML9) 15ft rca
amp to lsr6332

will a here a change if i use balaced cabling

stevem
02-28-2005, 07:32 PM
You shuoldn't have any problems with 15 feet of unbalanced interconnect, it's not that long a run. Depending upon where you live, however, you might encounter some Radio Frequency Interference (RFI) which could affect the sound. Balanced cables will eliminate this problem. I use balanced cables for multiple runs of 25 feet because with my system, they just sound a little better.

scott fitlin
03-01-2005, 10:19 AM
15ft of unbalnced cable is no problem, and as long as your using shielded interconnects, RF, and other assocociated noise shouldnt be a problem! In a 15ft run you wont experience any signal loss either!

As for what sounds better, balanced or unbalanced, I say it depends on your gear! Some units, especially preamps, have good sounding balanced outputs, while others are mediocre sounding! Listen to both balanced and unbalanced and your ears will have a definite preference for one way or the other!

Charlie4350
03-01-2005, 10:39 AM
I remember way back a little test out of curiosity. I placed an rca cable from cd to pre and then turned the volume way up (no cd playing of course). Quite a bit of noise. Then replaced with balanced and did the same thing. Absolute silence. This was done with only 1 meter cable. YMMV.

Zilch
03-01-2005, 10:47 AM
The single most significant advantage of balanced line interconnects is common-mode noise rejection. The single most common source of common-mode noise is AC line and device radiation inducing hum in the line.

Balanced line connections work optimally only when both the output and input devices use differential amplification and connections to drive and sense them. While there is some advantage to using a balanced interconnect to an unbalanced device, the practice should be minimized. There is little advantage to using balanced lines between unbalanced devices, and then only if the shield is not used as one of the conductors.

The practical limit for unbalanced line interconnects is about 25 feet length, though it depends upon what's running with them or nearby. It's also important that they not be coiled or looped near AC carrying lines or devices, as that will increase the probability of hum and noise pickup. Run them next to a current-carrying extension cord or AC wiring in the wall, and trouble is virtually guaranteed.

Even when interconnecting gear in a rack or stack, use unbalanced lines only where they are absolutely required, and keep their length to a minimum. Don't coil them to shorten them, as you're only making an air-core transformer out of them in the presence of AC electomagnetic fields. You can purchase stock unbalanced to balanced cables as short as one foot in length. If both options are available, pay the extra cost of making or buying cables and connectors and use balanced.

I commonly coil and strap line cords for many devices in a stack to get them organized and out of the way, a bad practice when it comes to induced noise. It's easily seen that I'm creating a bunch of transformer primaries there. Balanced signal-level interconnects are a necessity wherever possible for my setups....

Mike Caldwell
03-01-2005, 12:43 PM
Hello
As far as hearing a difference between a balanced and unbalanced connections not really......if the balanced inputs and outputs signals are of the same quality that the unbalanced signals are and vise versa. You will hear a difference if your unbalanced connections are picking up any interferance. As the other have said unbalanced cabling is only good for up to about 20 feet or so not only is noise pick up an issue but depending on the cable you can start to lose some high frequecny signal. The high impeadance of the outputs and inputs in conjunction with the capacitance of the cable acts as a filter for high frequencies. To realize the advantage of balanced cabling your equipment needs to provide balanced inputs and outputs.
Balanced inputs and outputs are the main type of connection in pro audio where cable runs can be in the hundreds of feet. Most connectors are the three pin XLR and the tip ring sleve 1/4 inch jack. For audio pin #1 is ground, pin 2 is signal + and pin 3 is signal -. When mixing and matching makes models and brands of balanced equipment you need to check what polarity it is. Most equipment uses pin 2 as + and pin 3 as - some older equipment used pin 3 as+ mixing the wrong things together could create phase cancellation. This is simple to take care of by making a cable the flips pin 2 for pin 3 at one end.
I'll try to explain what happens within a balanced audio circut, let me know if this make sense.....
The audio signal being carried on two separate lines out of phase with each other and then summed together at the input of the connected piece of equipment. What this does is cancel any noise that is picked up on the cable. Any noise pick up will be equal on both the + & - lines and at the same phase while the audio is of 180 dregees out of phase between the two lines.
At the input of say an amplifier the - line is inverted to be + and equally summs together with the + audio line, but the inversion of the - line while putting the audio signal in phase with it self will put any picked up noise out of phase and durning the summing process the audio signal remains and the noise is canceled out.

Mike Caldwell