Where do I set my amp levels?
By Chris Vice, Crown International
This is probably the most often asked question about power amplifiers. Misconceptions about the proper way to set system levels prevail in our industry. To help de-mystify the subject with respect to amplifier gain, lets explore the function and purpose of the amplifier level control.
First, its imperative to understand that amplifier level controls are not "gain" controls. They do not control the amount of gain the amplifier produces. You may have heard some say the controls must be turned all the way up for the amplifier to provide full power. This statement is not true, and while that approach could work in some cases, in the majority of instances it will yield more noise and less overall system gain than is otherwise possible.
All power amplifiers are designed to produce a set amount of gain. The function of the level control knob is to adjust the signal level coming into the amplifiers input stage. Where to set the level controls on the amp depends on the system and how much gain you have available prior to the amplifier. With the level controls turned down the amplifier can still reach full rated output power, it just takes more drive level from your mixer to achieve it.
When setting system gain, start at the front of the system and work your way toward the amplifier. A system with the lowest noise floor and maximum overall gain will have as much gain as possible early in the signal chain.
Start out by setting the mixers individual channels to 0 dB. The individual channels will vary somewhat from this in the course of setting the mix, but it is a good target position. After the mix is set, adjust the master levels on the mixer to 0 dB. Any signal processing equipment should generally be set to 0 dB as well, with some exceptions.
Once these levels are set, its time to set up the amplifier. If the amplifier has a sensitivity setting, set it to match as closely as possible the output of our mixer and other gear (usually around 1.4v). Now turn on the amplifier and adjust the level controls to the desired sound level. You may find that if you need high volume levels, the amplifier level controls may need to be turned up high. If your application calls for low system levels, like an acoustic set or speech indoors, you may need to turn down the amplifier levels. In the latter case, avoid the temptation to leave the amp levels up and turn down the mixer levels to compensate. Doing so induces more noise in the system than is necessary.
The subject of system gain is often misunderstood by the average audio system operator, yet is very important to achieve desired results when setting up and running a system. I recommend seeking out additional material on audio systems and studying system gain further. You wont regret it!
Technical Writer, Crown International, Inc.
firstname.lastname@example.org; 800-342-6939 or 219-294-8200