DSC260 Preliminary Owners Manual
Revision 0.9
26
Appendix A : Connector Wiring Information
Balanced wiring: Whether as system is wired to a ‘pin 3 hot’ convention is not so important so long as the wiring to both the
input and output are the same. Input cable shield needs to be derived from the signal source end as pin 1 is ground lifted for
the inputs. It is recommended that high quality audio cable with two conductors and a shield for low noise be used.
Unbalanced wiring: If the equipment driving the DSC260 has only unbalanced outputs then the input plug to the DSC260
should be wired so that the shield connection on pin 1 is shorted to EITHER pin 2 OR pin 3, depending on the wiring
convention of the unbalanced equipment at the send end.
If the equipment connected to the DSC260 outputs has only unbalanced inputs, we recommend the use of balanced (i.e. 2-
connector shielded) cable. The interconnecting cable should have the shield grounded to pin 1 at the DSC260 output, the
output “cold” should be connected to the unbalanced input 0 V ground, and the output “hot” should be connected to the
unbalanced live input. There should be no connection between the cable screen and the 0 V/chassis ground connection of
the unbalanced equipment. Strict adherence to this will help to eliminate potential ground loop hums by removing signal
currents from the cable shield.
Following the wiring conventions noted above within a fully balanced signal system will yield the best possible results with
none of the problems often associated with interconnected audio equipment. Wherever possible, the cable shield should not
be connected to any signal pin, but rather left to perform a cable shielding function only.
Under no circumstances should safety ground wire be removed from the AC power connector as an interim measure to
achieve similar results.
Avoiding ground loops: A typical example of a ground loop situation is shown in the diagram below. Two interconnected
components of a system are grounded through their individual AC power ground connections to separate AC power outlets.
In this situation a path to ground exists both directly through the mains earth of each component and also via the shield in the
signal wire to the AC power ground connection of the other component. In effect the two paths to ground form a loop antenna
which picks up interference currents from surrounding equipment. Because of lead resistance these induced currents are
transformed into voltage fluctuations in the ground system and hence the reference ground is no longer at a stable potential.
Various connection configurations are possible to prevent ground loops occurring. The aim is always to ensure that a loop
path is never actually formed. It can be seen from the diagram above that this could, in theory, be achieved by disconnecting
the AC power ground connection, however this practice is totally unsafe and should never be implemented as it could produce
a potentially lethal voltage at the case or accessible parts of the unit.
The most flexible solution, and easiest to implement in touring system, is to use the practice of telescoping shields. This
method is highly effective in removing ground loops and prevents unwanted signals entering the signal chain as the shield is
always connected to ground at only one point. The DSC260 is designed with the input ground connections isolated so that a
ground loop will not occur between the DSC260 and the preceding source component as shown below.
