Balance-in?

[PigGuy]

How about a FAQ answer for what a balance-in or balanced in is? I'm lost.

[DeepFreeze]

Balanced inputs and outputs in the audio world indicate a higher end signal chain.

balanced, in simple terms, includes signal, and grounding wires.

the two signal wires are measuring the signal when it leaves, and when it arrives.

the reason? to deflect noise, hum, problems.

example. take a optical reference audio signal from a DVD player. it has balanced outputs, A , which leaves the back of the deck. it travels down the car passenger side, and picks up 2db Z noise of noise. this sucks. the cables are nearly $5 per meter. at 7 meters, = $35... now, the 'A' output has a 'Az' noise signal thru it,

forward to the amp. the amp has a balanced input....so, the signal is received. the DVD player sent out signal A, the shielding and signal pin say, we sent A, and 'A' only. the amp says, cool, i only need to let in 'A'.

BUT, the amp sees 'Az' signal. but the signal pin says, you shouldnt be here from the original signal. so the amp says, "im rejecting Z"

hence, you dont get the 2db of noise. the principal, which works well, is that balanced inputs send a signal, + and - sorta speak, which dictates a specific message. if the receiving comp get extra, it rejects it because the signal becomes OUT of BALANCE.

simple as i can get, without sending you to google for technical reference.

ill try again.

Balanced audio cables use an extra line, and consist of a hot line (positive), cold line (negative) and earth. The audio signal is transmitted on both the hot and cold lines, but the voltage in the cold line is inverted so it is negative when the hot signal is positive. These two signals are often referred to as being 180 degrees out of phase with each other. This terminology can be confusing — it does not mean one signal is delayed until it is out of phase, it means one signal is effectively flipped upside down.

Along the length of the cable, noise can be introduced from external sources such as power cables, RF interference, etc. This noise will be identical on both hot and cold lines. This is known as a common mode signal - a signal which appears equally on both conductors of a two wire line.

So the hot and cold lines carry two signals: A desirable audio signal which has an opposite voltage on each line, and unwanted noise which is the same on both lines.

This is where the trick of balanced audio kicks in. At the input stage when the inverted audio signal is re-inverted to make both desirable audio signals the same, the unwanted noise is inverted (i.e. put out of phase). Viola - all the unwanted noise is cancelled out, leaving only the combined original signal.