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Using large amplifiers and speakers at venue

A few days ago I got to play with a venue audio system containing 10x2400 watt of amplifier power. It was daunting at first but by following some basic know how it worked out just fine.

A lot of larger amplifiers don't have a volume control. They are designed to be put in a rack and audio levels are controlled by a audio mixer. This audio mixer might have multiple outputs that can be separately controlled. By not having a volume knob on each amplifier you have full control on the audio mixer and you reduce the possible points of fault when you stand there and there is no sound. But having the amplifiers always on "full" is also a challange.

You know the sound when someone shorts the jack plug when they connects and disconnects a phone from a small amplifier. Think about 100 times as bad as that.

Never turn on the amplifier before it is connected to both speakers and audio source A.K.A audio mixer.

Turn down all level knobs on the audio mixer before turning it on.

This is the second big thing. When you set up your audio mixer you most likely have turned some knobs or faders in the mixer. Turn everything downn only exseption is EQ knobs that you set to 0 (middle position).

When everything else is powered on then I start the amplifiers. If you have a broken cable you might hear it right away, then you can shut down the amplifier in question and start faultfinding.  If everything is okay the you can put a audio source into your mixer. A microphone or MP3 player and slowly crack up volume.

If you can't get sound out on the speakers I would recommend that you turn down mixer volume before starting a search for faults.  If you need to switch cables from mixser to amplifiers then iI would turn off the amplifiers before doing anything.

When iI got to play with the amplifier rack on the picture above it was already connected to speakers. The amplifiers was connected together by an elaborate system. This reduced my workload a lot. And I could connect to the system in minutes instead of hours or days if things had been non functioning.

If you are using the venus audio system. If possible get a walk-true or possibility to test the system before match day.

In the beginning I talked a bit about the amplifiers being set to "full" with no individual volume control. If you get any problems with your audio signal going to the mixer. perhaps that you have a bad cable or maybe that the cable absorbs noise from external sources. There is some things you can do to avoid this.

If you have anymore then a few meters from the mixer to your amplifier you should user a balanced cable. These will reduce the amount of noise a lot at the same time as they help you get a low signal loss on the cable. 

Avoid laying audio and power cables close to each other. Especially if you use dimmers for lights and these cables get anywhere near audio cables you will have a bad day. The important thing is not allowing the cables to lie side by side. 

If you need to cross power and audio cables. do so at a 90 degree angle. That way you get as little noise as possible. 

Test lighting with audiosystems on (also microphones). That way you can see if there is any noise going from the lighting to the audio system. Espesially old light dimmers will make a lot of noice.