Hey guy's I am wondering what the benefit of balance?
Because this all I understand about balance audio:
- [Headphone] Supply more power, because of the increase number of contacts to allow efficient power transfer
- Lower noise floor on mid tear to entry tear audio devices
- Balance connection can offer a hotter signal, compare to it unbalance counter part
- [Studio] Prevent any noise to be pickup by cables longer that 3 meters
My reason for asking this, is because I want to know if it worth investing into getting balance equipment for headphones. Also I am wondering why I can't find a studio grade equipment that offers a balance headphone out.
Some of your points are partially true. But as always the deeper you delve the more that comes out.
Firstly: balanced headphone (and speaker) drive. This, as has been said, is different to the line and mic connections in its benefits. It involves double the number of amplifiers, so adds cost. Speakers need to to go balanced (or bridged as it is usually called) at about 350W into 8 ohms and above in class B amps (class D amps higher), due to the safe operating area of the output transistors. Headphone amps there is no need, except that portable gear can be voltage limited, and balanced doubles the voltage. Where there is an advantage is where the ground connections no longer carry any signal, including inside the player. However, if the design is done well it doesn't really matter. The common return path in the headphone cable is a potential source of crosstalk, but it is benign in its nature.
Lower noise is not true, as two amplifiers are always noisier than one, if identical. The noise isn't double necessarily, but never lower. The signal to noise can be better, if the balanced signal is x2 or 6dB higher, and the noise is only 3dB higher, but this is a simplification of reality. The area where noise is lower, is in the line and mic connection, where extraneous noises picked up by the cable can be cancelled because the system rejects anything that isn't balanced, and the extraneous signals are not. It needs careful design to get best results, and is often misunderstood. A couple of fantastic papers by the great Bill Whitlock explain best practices, and his enlightened patent, are worth reading.
Balanced signals are often hotter, by design, but don't have to be. However the standards in pro audio generally allow much larger signals, so that unpredictable live signals don't get compressed until they hit the compressor. 16-20dB of headroom is often allowed.
Other benefits of balanced line connections can be the dumping of ground currents away from the audio. RCA single ended connections rely on the fact that there are no current flowing between units to mess up the audio. However in reality there always is. There is capacitance between the audio ground and the mains power. Good gear minimises this, but most is indifferent. Look at Apple laptops for bad example. In 230V countries you can feel the tingle on the metal chassis. Reverse the mains connector (if you can) and the tingling changes. These nasty signals will flow along the ground and mess up your sound. Balanced doesn't use the ground pin as a reference (or shouldn't. Some do and they are wrong) as it is a place to dump this into the chassis ground. Audio ground is separate. This is a significant benefit.
