• It is dangerous to lift the mains earth when trying to
eliminate hum. You can isolate hum by lifting the
appropriate audio signal shield.
•
When using wireless mics, set the receiver on stage and run
back to the console at balanced mic level. This will help
avoid interference from digital sources and lighting
controllers.
•
Keep unbalanced ‘insert’ leads away from mains and keep
them short - no longer than about 2 metres.
Connecting External Effects and Processors
We talked about Effects and Processors in Sections 2 and 3,
so you’re now aware of their functions and applications.
Effects units are best connected via the console’s Auxiliary
Send and Return Loop (sometimes known as the Effects
Send and Return Loop) or the Insert Point. When used in
the Aux Send system, the dry signal level should be turned
off on the effects unit, but when used via Insert Points (for
guidance on how to wire a jack for use with Insert Points,
see Section 6), the dry/effects balance must be set on the
effects unit itself. Processors treat the whole of the
incoming signal and therefore may only be used via console
Insert Points or directly ‘in-line’ with a signal: they cannot
be used in the Aux Send/Return loop system.
Setting Up
•
Position the mixing console so that you can hear the on-
stage performance as the audience will hear it. Ensure that
you have a clear view of the performers.
•
After setting up, switch the power amps on last to prevent
any thumps occurring when effects or instruments are
powered up. Ensure the console’s master gain is down
before you switch on the amplifiers.
•
Don’t set up the vocal mic directly in front of the drum kit
or a guitar stack.
•
Make sure the speakers aren’t obstructed by the audience
and that the majority of the sound is being directed
towards the audience, not towards the rear or side walls.
•
Set up the vocal levels first - it’s no use getting a great drum
sound if the vocals feed back before they can even be heard.
•
Keep the vocals panned towards the centre of the mix. Not
only will this sound more natural, but it will allow the
greatest vocal level before feedback or distortion occurs.
•
Be sparing on the use of artificial reverb. Most venues are
too reverberant anyway, and excessive reverb will ruin the
intelligibility of the vocal performance.
•
Do not use reverb on low frequency sound sources such as
bass, kick drums and tom toms.
•
Keep backline amp levels down: let the mic and mixer do
the work!
•
Always leave a little gain in hand so you can wind up the
level slightly as the show progresses.
•
Putting high levels of bass guitar or kick drum through a
small PA can overload the system and distort vocal quality.
Try rolling off some of the low bass, you’ll get a higher
subjective sound level without overload.
Ringing Out: Nulling Room Acoustics
As experienced engineers will tell you, there’s no such thing
as a perfect venue. To help tailor the sound to the room
acoustics, insert a Graphic Equalizer into the console’s mix
insert jacks which are effectively between the mixer and the
power amp.
‘Ringing Out’ the system prior to the sound check will help
reduce troublesome feedback. To Ring Out, follow this
procedure:
1 Set all graphic EQ controls to centre (0).
2 Turn up amp volume until feedback is just beginning to
‘ring’.
3 Turn back the amp volume slightly to prevent accidental
feedback.
4 Starting from the left, adjust the first graphic EQ frequency
gain control to ‘max’: if the system doesn’t feedback, then
this is not a problem frequency. Return this gain control to
centre position.
If the system feeds back, reduce the EQ gain by the same
amount you boosted to get feedback.
5 Repeat this procedure for all graphic EQ frequencies.
SECTION 4: P
A
Mixing
18
Caution: Ringing out can cause howl around which can
damage speakers, so use care when adjusting levels.
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Summary of Contents for Spirit SX
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