Building a PA system. What sort of power amps do I need?

You definitely don't want to underpower your speakers - that is a common mistake. You want an amp that can supply at least the program rating - that would be 400 watts into 8 ohms each channel (assuming your speakers are 8 ohms).

Remember an underpowered amp is more likely to blow your speakers than one that is up to the rating of the speakers. A underpowered amp will more likely be driven into distortion and distortion is what damages speakers. Always check the "peak" lights on the amp - they should only light occasionally on peaks (if at all).

http://www.sweetwater.com/shop/live-sound/power-am...

By the way...the Behringer EP 2500 is a great amp for the money (I have two). If you have more money to spend..check out the QSC amps.

It IS difficult to provide a rule of thumb since there are so many parameters affecting your needs. How large an audience are you targetting? Are they sitting or standing/moving around? Densely packed, like in a bar, or sparsely, like at a store entrance? Lots of ambient noise like many people talking, or traffic noise? Or a quiet audience listening only to your PA?

See what I mean? If you're just trying to reach an audience within a 90° range of maybe 10 - 15 feet, then 200w (100w /ch) is more than enough.

But if you're going to DJ in a crowded bar with a range of 180°, then you're going to need more like 600w per channel, or 1200w total, at a minimum (and appropriately rated speakers).

By the way, 'peak' is meaningless. The numbers I mentioned are RMS.

Depending on how many speakers you have, its hard to say. If its just the 2 speakers with 400W rms, you would be plenty loud with a 200W amp. That means 100W x 2.

you are able to easily do what you recommend with that amplifier and on your applications you received't opt to get a preamp on condition that that amplifier has volume controls. you'll, in spite of the undeniable fact that, opt to get a speaker selector (see links below). you'll deliver the speaker element output from the amp to the enter on the speaker selector and also you may connect the cord from the audio device to the outputs on the speaker selector. this may insure that you do not latest the amplifier with too low of an impedance which may reason it to overwork. in case you decide on to have distinct volumes in distinct places you are able to deploy impedance matching volume controls close to each and every pair of audio device (see between the links below for assistance in this). this decision may eliminate the will for the speaker selector. Installers I used to artwork with also prevalent impedance matching blocks fairly than speaker selectors. They maintained that those had a lot less signal loss and they are an staggering selection in case you do not choose man or woman administration over the speaker pairs. i could not discover any on a short search for of the web yet you're able to look into this. do not hardship. What you're doing is amazingly trouble-free and may be done particularly easily with the elements you've. by utilising the way, do not bridge the amp. That makes it a mono amplifier and that i anticipate you decide on stereo. _____ replace: Your Bose device effectively purposes as a preamp. Any switching of elements could be done on it. because you've switching and volume administration you do not choose a separate preamp. The amp is definitely deceptively low in high quality yet you are able to attempt it and be conscious what consequences you get. You wont listen the fan when you're in a unmarried of the different zones. in case you don't love the amps performance you are able to attempt yet another yet because you've already got this one it received't damage to attempt it.