Mains Installation
General Wiring Procedures
To take full advantage of the excellent signal to noise ratio and low distortion of Soundcraft consoles care must be taken to ensure that incorrect installation and wiring does not degrade the performance of the desk. Hum, buzz, instability and Radio Frequency interference can usually be traced to earth loops and inferior earth- ing systems. In some areas, especially heavily industrial areas, the incoming mains earth will not be adequate and a separate technical earth for all the audio equipment must be supplied. However, check with your local electricity supply company to ensure that safety regulations are not infringed or negated.
The successful, hum free, installation of a system requires forethought, and the estab- lishment of a set of ground rules, which must be consistently adhered to at all stages of installation.
Initial Wiring Considerations
For optimum performance, it is essential for the earthing system to be clean and noise free, as all signals are referenced to this earth. A central point should be decided on for the main earth point system, and all earths should be `star fed’ from this point. It is common electrical practice to ‘daisy chain’ the earths to all electrical outlets but this method is unsuitable for audio installations. The preferred method is to run an indi- vidual earth wire from each outlet, back to the system star point to provide a safety earth screen reference for each piece of equipment.
A separate earth wire should also be run from each equipment rack and area, to the star point. This may or may not be used depending on circumstances, but it is easier to install in the first place, than later when problems arise.
The location of the star point should be a convenient, easily accessible place, prefer- ably at the rear of the console or in the main equipment rack.
Install separate ‘clean’ and ’dirty’ mains outlets, wired individually back to the incom- ing mains distribution box. Use the ‘clean’ supply for all audio equipment and the ‘dirty’ supply for all lighting, etc. Never mix the two systems.
If necessary, to provide sufficient isolation from mains borne interference, install an isolating transformer. This should be provided with a Faraday Shield which must be connected with earth.
Never locate the incoming mains distribution box near audio equipment, especially tape recorders, which are very sensitive to
Ensure that all equipment racks are connected to earth, via a separate wire back to the star point.
Equipment which has unbalanced inputs and outputs may need to be isolated from the rack to prevent earth loops.
Audio Wiring
Having provided all equipment with power and earthing connections, consideration must be given to the method of providing audio interconnection and adequate screen- ing of those interconnections. This must be done in a logical sequence to avoid prob- lems and assist in the localisation of problem equipment.
lConnect the Monitor system to the console and check for any hum, buzz, or RFI. Only when you are satisfied with the quietness of the console and the monitor system should you proceed with the next step.
lConnect stereo tape recorders, echo and foldback sends one at a time, check- ing and isolating any connection which degrades performance.
lConnect all other peripheral devices.
2.4 | FIVE Monitor Installation |