D Audio Interfacing - Solid State Logic C300 HD Installation Manual

Appendix D: Audio Interfacing
All analogue audio inputs and outputs are electronically balanced. The screen pins are all directly connected to the chassis
at the point of entry to comply with AES/EBU grounding and EMC recommendations.
Balanced Circuits
It is strongly recommended that balanced connections are used wherever possible using high quality screened cable. The
following diagram shows the recommended connection with both screens connected to the chassis:
chassis
On some older items of equipment the screen connection may still be referenced to the circuit 0V rather than the chassis.
In these cases it may be advantageous to disconnect the screen at this connection. Note however that this practice will
degrade the EMC performance.
chassis
Connecting to Unbalanced Equipment
Connecting to unbalanced equipment can be much more problematic. It is much more likely that earth and induced RF
currents will become referenced to the audio 0V which will give rise to audible hum and buzz.
The recommendation for connection of balanced to unbalanced equipment is to isolate unbalanced connections by using
a balancing transformer.
chassis
Appendix D – Audio Interfacing
Balanced – Balanced
both screens connected to chassis
chassis
Balanced – Balanced
one screen connected to chassis
0V
Balanced – Unbalanced
one screen connected to chassis
0V
(recommended)
(recommended)
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