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Amplifiers > Amplifiers in your church sound system

Amplifiers in your church sound system

Amplifiers play an important role in your church sound system. After the sound has been mixed and equalized the signal is then passed on to the amplifier to power the main speakers. It is important to have a decent quality amplifier that matches the speakers in your system.

The power rating of your amplifier should be more than you will use, but not higher (or much higher) than the power handling capability of your speakers. With highly efficient speakers like the Electro-Voice EVF series which we often use in Churches, you really don't need a lot of power. For speech, you will probably use only about 10-20 watts. For live music in an average size church, you could get up to 50 - 100 watts. Peaks however could be higher than that, and you amplifier needs to handle these peaks without distorting the sound. We often use one of the amplifiers below as our main amplifier.

If your speakers have lower efficiency, you need a more powerful amplifier to get the same amount of volume as a high efficiency speaker with less power. For example 50 watts into a speaker system with a rating of 100 dB at 1 watt / 1 metre will give you the same volume of sound as 400 watts with a 91 dB at 1 watt / 1 metre.

Here are a few things to watch for when comparing power amplifiers:

1) When you look at power rating, make sure you are using the proper speaker impedance. Most speakers are 8 ohms, but some are 4 ohms.

2) If the amplifier is not located in a back room, fan noise can be an issue. An amplifier with a quiet multi-stage fan and high efficiency is important.

3) Just because the amplifier says it can deliver a certain wattage, it doesn't mean it will do it continuously. Unfortunately you won't find this in the specs. We have bench tested some well known amplifiers which can only deliver under half their rated power for less than 20 minutes before overheating and shutting down. If you need continuous power, you need a good amplifier which really delivers what it claims.

Below are some of our favorite choices for amplifiers that we use in our church sound installations.

Electro-Voice Q44-II and Q66-II Power Amplifiers Electro-Voice 7100 Amplifier

The Electro-Voice Q44-II is a clean, quiet two channel power amplifier. It delivers Continuous Power of 280 watts per channel into 8 ohms, 450 watts into 4 ohms and 650 watts into 2 ohms with wide power bandwidth, low distortion and full load and amplifier protection. This makes it an excellent choice for live sound reinforcement and monitors in mid sized applications. Each channel has an independent gain control and balanced and unbalanced inputs.

Other models include the Q66 which delivers 380/600/900 watts per channel, and the Q99 which delivers 550/900/1250 watts per channel. There is also an even higher powered Q1212 which provides 750/1200/1800 watts per channel

Cooling is provided by two 3-speed fans. This makes the amplifier very quiet and reliable. Many of the amplifier problems

Price and Data Sheet

QSC ISA Series Amplifiers

The ISA 280 is a professional quality, dual channel power amplifier. It provides 185 watts per channel at 8 ohms, 280 watts at 4 ohms and 430 watts at 2 ohms. The ISA series comes with XLR and Barrier strip inputs and barrier strip outputs. Protection includes short circuit, open circuit, thermal, ultrasonic and RF.

ISA models range from 185 watts per channel up to 800 watts per channel into 8 ohms.

Price and Data Sheet

QSC RMX Series Amplifiers

The RMX Series of amplifiers are new from QSC. They give you clean, dynamic power with low background (fan) noise.

These amplifiers are available in several power ratings from 200 to 850 watts into 8 ohms (2000 watts into 2 ohms).