E-MU 1212M PCIe - Manual (Page 115)

6 - Appendix
Useful Information
E-MU PCIe Digital Audio Systems 115
Useful Information
Cables - balanced or unbalanced?
All inputs and outputs on the E-MU Digital Audio System are designed to use either
balanced or unbalanced cables. Balanced signals provide an additional +6dB of gain
on the inputs and are recommended for best audio performance, although unbalanced
cables are fine for most applications. If you’re having problems with hum and noise or
just want the best possible performance, use balanced cables.
WARNING:
Do NOT use balanced
audio cables when
connecting balanced
outputs to unbalanced
inputs. Doing so can
actually increase noise
level and introduce hum.
Use balanced
(3-conductor) cables
ONLY if you are
connecting balanced
inputs to balanced
outputs.
Balanced Cables
Balanced cables are used in professional studios because they cancel out noise and
interference. Connector plugs used on balanced cables are XLR (3-prong mic
connector) or TRS (Tip, Ring, Sleeve) 1/4" phone plugs.
Balanced 1/4”
TRS Connectors
Balanced XLR
Connectors
Unbalanced 1/4”
Connectors
Balanced cables have one ground (shield) connection and two signal-carrying
conductors of equal potential but opposite polarity. There is one “hot” or positive lead,
and a “cold” or negative lead. At any point in time, both conductors are equal in
voltage but opposite in polarity. Both leads may pick up interference, but because it is
present both in and out of phase, this interference cancels out at the balanced input
connection.
Unbalanced Cables
Unbalanced cables have one conductor and one ground (shield) and usually connect
via unbalanced 1/4" phone plugs or RCA phono plugs. The shield stays at a constant
ground potential while the signal in the center conductor varies in positive and
negative voltage. The shield completely surrounds the center “hot” conductor and is
connected to ground in order to intercept most of the electrical interference encoun-
tered by the cable. Unbalanced cables are more prone to hum and interference than
balanced cables, but the shorter the cable, the less hum and noise is introduced into
the system.