balanced/unbalanced

[jrosenstein]

hi everyone,

been lurking for a bit ... but now i've got a general question:

people always emphasize the importance of a fully-balanced signal chain. i understand that long mic cables definitely need the shielding that balanced cables provide. yet speaker cables aren't balanced, and (please correct me if i'm wrong) it doesn't seem to me that channel Y-inserts can be balanced either (with a send, return, and ground on a TRS). can you run a compressor at +4 in an insert?

can someone spare a few words on this?

thanks,
- jacob

[Cave Dweller]

speaker cables dont need to be balanced because they are not as succeptable to noise as mic and line level signals are. speaker signals will not be amplified anymore, so noise is not really an issue. speaker cables can pick up RF interference, but that almost never happens.
it is not possible to run balanced on a TRS insert point. most inserts are either a 0db or (less frequently) a +4 db signal. some high end consoles offer 2 TRS jacks for inserts (1 send 1 return).

in a home studio it is almost impossible to run fully balanced. BUT it helps signal quality some if you can run balanced as much as possible. for example if your mic pre has a balanced out and your compressor has a balanced in, you could run balanced, even if your sound card is unbal. but on the other hand, you are probably only running less than 10 feet on any line, so if you run un-balanced it wont hurt. you can run around 20 feet with no noticible loss. (mics should always be balanced!)

the main reason you would run balanced is to drive long cable runs. like in a PA system where the main snake runs right past the lighting dimmers. in the home studio though, its not nearly as important

[M.Brane]

The only benefit to a balanced line over unbalanced is hum & RFI rejection. The signal level is dependant on the equipment, not the connection. You could have an unbalanced line at +4 or a balanced one at -10. Most pro gear runs at +4 and most consumer gear at -10 hence the assumption that balanced is always +4 and unbalanced -10.

[Light]

Balanced refers to a method of transmition noise rejection. Here is a post I made a while back on the subject, with pictures.

http://homerecording.com/bbs/showthr...threadid=59380

Light

"Cowards can never be moral."
M.K. Gandhi

[jrosenstein]

thanks guys!