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I have concerns about overpowering/under-powering my passive speakers during live church recordings. I have two large speakers that are powered by an external amplifier (these are passive speakers). There are NO settings on the speakers themselves. All you can do is plugin the audio cable.

The amplifier, on the other hand, has an adjustable gain control for each channel. I'd like to know the implications of using this control.

Suppose I'm monitoring my audio mixer via headphones, and all sounds good. However, the loudspeakers are too quiet, but I don't want to boost either the channel faders nor the main faders too far about 0dB. My obvious option is to boost the gain on the amp. But how much is too much? Obviously if it starts to clip, it's too much. But in the middle of the service, I don't want to be fiddling with the amp gain. Isn't there some kind of power rating that I can use to match the output of the amp to the MAXIMUM allotted input on the speakers?

Also, in boosting the amp gain, am I also boosting the noise floor?

As you can see, I know how to connect the amp to the speakers, but I don't know how to operate the two in tandem.


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bouldersound Tue, 05/15/2012 - 16:24

Some idea of which amp and which speakers would help us help you.

Gain is a change in level, not an absolute level itself. You can decrease gain at the amp and increase it at the board (or the reverse) for a net zero change in gain to the speakers, so turning down the amp doesn't necessarily limit the power it can produce.

I would set your input gains on the board according to the manuals suggestion, set the board's main fader to 0 or U and use the amps gain to set the volume in the room. If the speakers are decent and the amp is big enough and you don't push the system beyond reason everything should be fine. If the amp clips or the limiter lights flash you have reached its limit. If the speaker distorts or clatters or stops getting louder when you apply more gain you have surpassed its limits. Overdriving the amp just sounds bad. Overdriving the speaker burns or breaks things inside.

There are other ways of doing it. If you are using any processing between the mixer and the amp you can control the gain there. In rock clubs where the amp gains are exposed to the public some guys like to run them wide open so they can't be turned up.