setting up an amp

[zac850]

So, my school is getting an amp that should be showing up tomorrow.
We are getting a BEHRINGER EP2500. I know Behringer isn't the best equptment, but it was cheep enough, so, oh well.

Anyway, this amp is 500 watts at 8 ohms and the speakers we're going to be using are 400 watts at 8 ohms. So, would I need to turn the gain down on the amp or will it only put out 400 watts for the speakers.

I assume that it is the second, but I'm not sure. I've never set-up an amp, so I am just unsure of what to do with the gain settings.

I hope this makes sense. I'm coming off 3 weeks of back to back shows, and its 11:30, so my brain isn't really working right now.

I just don't know what to do with the left and right gain settings on the amp, everything else I can do. I hope that makes sense.

Good night all, thanks very much.

[RelativeMischief]

Oi, thats a toughie. I would've recommended checking your speaker specs before buying an amp :P You could've gotten a better quality amp matched to your speakers for the same amount. However, for what you've got, the amp is gonna put out 500W at 8ohms no matter whats hooked up at the other end. Best thing to do would be turn your amps down by 6dB or so. That should give you some breathing room. You have to bear in mind however, that your amp is gonna be running a little cool now, so don't judge anything by the LED's on the amp. Don't attempt to get it running at nominal, you'll just fry your inputs.

Hope I helped!

[Mayhem]

For what it is worth Zac, I always run my amps at full gain and control my overall volume from the board.

The reason that I do this is because I find the lower frequencses sometimes get lost or are lacking if the amp is turned down.

Just keep an ear out for any distortion and keep your eye on the clip meter and you should be fine.

With your speakers being suited to your amp (ie the amp output is greater than your speakers) you will (should) hear any distortion, in which case you drop the gain a little. On the other hand, were your amp underpowered, you are more likely to damage the speakers by clipping the amp in order to drive them.

If you are unsure. Wind the amp back to begin with. I know some people who just cannot stand having the master out on their board sitting at 30%. Even though the sound is good and at the right level.

[zac850]

I k now that the speakers are 400 watts at 8ohms and for the price, that was the closest we could do. It is better then our old amp, that only put out 250 watts at 8 ohms.

So, if I keep the gain on the amp turned way down, that will help save the speakers? I assumed this, but I just want to make sure.

Thanks guys,
-Zac

[ccfan213]

my only problem with turning my master up to 30 is that if someone else uses my board they may do something dumb, or if someone sees that i have that much power @ a concert they may try to make me turn it up.

[ccfan213]

my only problem with turning my master up to 30 is that if someone else uses my board they may do something dumb, or if someone sees that i have that much power @ a concert they may try to make me turn it up.

[zac850]

OK, so...
1) I assume that the extra 100 watts is harmful for the speaker and will cut down on speaker life, correct? Also, I assume that the excess power will cause clipping and other nastyness in the speaker... Also, is this correct?

2) Now that we're going to have an amp, I was wondering about power in the booth. The amp will be sitting under the table in the booth, pluged into the same circuct as a projector, a computer, the sound board, a mini disk player, a CD changer, and 2 desk lights. I can (if needed) change most of this stuff over to the lighting side of the desk, with its own seperate circuct without overloading anything (we have 2 20 amp circuts to the booth, one for lights and one for sound).

How much of this stuff should I move to keep speaker hiss to a minimum. I assume that it would be OK to keep the sound board on the same circuct, but what about the mini disk player and the CD changer. Also, is it even worth it, will there be enough hiss heard at the speakers to warrent this extra work?

Thanks a lot guys!
--Zac

[disc2slick]

zac,

as far as I know, having the Amp on the same circuit won't create lots of hiss. so long as you don't have lots of power cables running along side your sound cables you should be fine

[Peter]

The only time I have have to worry about where things are pluged in at my auditorum is the fact that we have two different sets of plugs, (one white and one orange). The orange ones are dedicated computer plugs, and have a seperate (longer) ground rod then the other circut does. The only problem is, two ground rods usualy means that there is a small bit of current wanting to get from one rod to the other, and that can make a bit of hiss, so i just make sure all my sound equipment is pluged into one or the other. (there are horror stories floating arround the internet about guitar players who's amp is pluged into one circut and the mic system is on a differnt ground, and them getting zapped through the mouth singing into the mic. I kinda doubt that the difference in voltage/amperage is that much... but.... i dont really see how it can hurt to be safe.

PS for more info on this, look up "ground loop" or "ground loop hiss" or something similar on google

[zac850]

Well, we hooked up the amp and it is WONDERFUL!

We have the gain somewhat lower then normal, to compensate for overpowering the speakers. The nice thing is, the speakers don't hiss anymore! Before we were running the outputs of the main board as 2 mic inputs of a powered board, and from that to our speakers. Now, however, main out is going to the amp, and it is silent now.

We are using the old soundboard/amp as a monitor for the keyboard, and listening to the difference between the two is amazing.