SYSTEM PRE-TUNE CHECKS

Before attempting to tune any sound system it’s vital to very carefully check all the various sections of the system; ensure all the rigging, wiring, patching and powering up have been performed correctly. Then listen to each section of the system in isolation to verify the complete integrity of the entire system.

When setting up in a new venue you should never assume everything in a large-scale sound system will work perfectly when first turned on!

You must be extremely careful at this first system turn on/check out stage to ensure you’re not starting to tune a system that is not working correctly. There are so many small elements that can be overlooked. If the system is being run with digital AES wiring it’s essential to check that all processors are seeing and locked to a digital AES source. Do this every time the system is set up as having any portion of the system automatically swap over to its analogue input will create some very strange sounding artifacts indeed! A favourite board microphone plugged into the console with some, ‘Check one, twos’ while panning between the left and right stereo outputs will tell you very quickly if the system, in its raw state, is at least reasonably stereo matched on the Mains.

THE BASIC PRINCIPLES

Most concert sound systems used in large venues consist of a larger main system with multiple separate support systems that must be tuned and optimised to work together as a complete system. As an example, a typical arena system will comprise a large main left and right stereo front system (the Mains); a set of dedicated subs systems; in some cases an additional pair of side hangs to increase the horizontal coverage beyond the limits of the main system; a dedicated front fill system; and in some cases, a separate set of delay systems to reinforce the sound for audience members situated beyond the real limits of the main system’s coverage area.

FOH sound engineers primarily use the Mains of the system as the reference to create the show’s final mix — the same mix the audience across the coverage area of the full system will hear. It is therefore vital that all the other support systems absolutely relate in both level and tonality to what the sound engineer is hearing from the Mains.

THE ‘CREEP’ FACTOR

A frequently overlooked danger when tuning and optimising the same sound system in a touring situation is the ‘creep’ factor. This very subtle but serious problem occurs when typically, at the beginning of a tour, the system is first tuned in a venue for a particular setup of the system. This could be all of the available touring components or, for a smaller venue with rigging limitations, a cut down setup. Upon moving to the next venue and possibly changing the rigging/size/combination of the available touring equipment, all the tuning settings (levels and EQ) from the previous setup are not reset back to the factory defaults for the system as designed.

Without fully realising the dangers, the engineer starts tuning the system from the previous (sometimes forgotten or hidden!) delay, level or EQ settings that do not relate to either the new venue or the different setup configuration. This means the engineer is now adding more and more settings over the previous ones to attempt to tune the system, and basing decisions on a completely false premise of what the system is actually doing.

Over the course of many shows in many venues this situation ‘creeps’ up on the engineer, and the system — now with masses of overused EQ and level settings — doesn’t sound anything like it was originally designed to.

With so many differing combinations of programmable system drive setups available (especially with line array-style systems) — not to mention how venues around the world can sound vastly different —