amp matching for a small sound system

[tweetersaway]

I'm currently working on getting together a small portable sound system that's mostly for a small cafeteria space and other gigs. The amp I'm looking at gives 160w/ch @ 8 ohms, and the speakers we're looking at are rated for 150w/300w rms/peak. I've never done any amp matching before, So I have no idea. Is the fact that the amp is rated higher than the speakers' rms bad and should be avoided, or is it ok or normal? thanks.

[waynehoskins]

160 compared with 150 is not bad. Power ratings are meaningless anyway.*

What speakers and amp are you looking at, by the way?


* - well, not meaningless, but there's a big difference between 160 watts at 8 absolute guaranteed minimum under full load 100 percent duty, and 160 watts at 2 with the ambient temperature inside the amplifier below freezing, absolute peak, right before the power transistor banks blow up.

[avare]

What are the gigs? What is important is the efficiency of the speakers. If you do not get enough volume, the matching is meaningless. If this system will be run by amateurs, then yes, the amp/speaker system is well matched.

To paraphrase slightly, a well matched wrong system is still a wrong system.

Andre

[TimmyP1955]

The common wisdom (with which I agree) is that in order to get all the speakers will deliver, the continuous rating of the amp should be 1.5 to 2 times the continuous rating of the speaker. So if your speakers are 150 continuous/300 program, the optimal amp would be 225 continuous to 300 continuous. However, no matter how small the amp may be, if it gives you plenty of volume without clipping, it is big enough for the job at hand.

[SHARYNF]

on the lower end portable systems I would suggest that you look at a powered speaker, most have bi amp setups, which work well, give better performance and make setting up and moving the systems a breeze.

Just a suggestion
Sharyn

[museav]

Originally Posted by tweetersaway

The amp I'm looking at gives 160w/ch @ 8 ohms, and the speakers we're looking at are rated for 150w/300w rms/peak.

A couple of things stand out. Are the speakers 8 Ohm? If not then the 8Ohm amplifier rating is not relevant. Also, a speaker would usually be rated 150W continuous/300W Program or 150W Program/300W Peak, for the Peak rating to be only twice (3dB) the continuous/RMS rating would be very unusual. I agree that it might help greatly to know the actual products involved.

Is the fact that the amp is rated higher than the speakers' rms bad and should be avoided, or is it ok or normal?

It is quite normal. However, I am very glad to see the comments already posted saying that what is "enough" power is based on the application and not just the ratings. Along with the desired levels, other factors in determining the proper power can include the type of content and the skill of the operators. If the source is heavily compressed music you may have to be more concerned with long term thermal problems than with peak levels. Conversely, very dynamic music may require that the system be run at a lower average level but have more headroom for peaks. Adding to that, a skilled operator can probably run a system much closer to the edge without damaging it than might a less experienced operator. But typically a 160W rated amplifier running a 150W continuous/RMS rated speaker would not be a problem.

[avare]

Thanks Brad for your post right above this one. I was going to expand on why I wrote

Originally Posted by avare

If this system will be run by amateurs, then yes, the amp/speaker system is well matched.

after reading

Originally Posted by TimmyP1955

The common wisdom (with which I agree) is that in order to get all the speakers will deliver, the continuous rating of the amp should be 1.5 to 2 times the continuous rating of the speaker

What TimmyP1955 is based upon knowledgeable operators. An amateur, especially one that thinks a sound system is operating at its best when it is distorting, will blow the speakers very quickly. You gave an excellent summary with (the bolding is mine, not museav's).

Originally Posted by museav

Along with the desired levels, other factors in determining the proper power can include the type of content and the skill of the operators. If the source is heavily compressed music you may have to be more concerned with long term thermal problems than with peak levels. Conversely, very dynamic music may require that the system be run at a lower average level but have more headroom for peaks. Adding to that, a skilled operator can probably run a system much closer to the edge without damaging it than might a less experienced operator. But typically a 160W rated amplifier running a 150W continuous/RMS rated speaker would not be a problem.

To paraphrase slightly what has already been written, if the system will be operated by non skilled operators, then the amp is a good match.

Skillfully,
Andre

[tweetersaway]

Thanks everybody for the input. The more I read here and all over in the forums, the more I've been starting to look at active speakers as an alternative. The original system I was looking at was a 500 watt Behringer amp which pushed 160w per channel at 8 ohms with a pair of 2x10s made by (don't go off about this) Kustom. Frankly I am a little ashamed that I was seriously looking at Kustom speakers, but I've heard that they've done an alright job on these ones for low budget venues.

Anyway, as I said, I'm now looking at active solutions because it just seems logical. I took a look at the Behringer Eurolive B212A, and it looks like a very good solution. I've read numerous reviews and talked to a few people who have all said very good things about the sound quality and durability of them, and I don't think I could ask for a better price as they weigh in at about 460 us for a pair. Any thoughts on these?

For the most part, I will be the operator of this equipment. But those times when I'm not there, you never know who could be running the gear.

Could someone please expain what exactly 'biamp'ed means? Does it just mean that there are two seperate amps for the tweeter and the woofer so there isn't a post-amp crossover? thanks.

[waynehoskins]

You've got biamping right.

Behringer power and Kustom loudspeakers wouldn't be my first choice, nor would Behringer powered boxes. Actually, they'd be my last choice. But you're right, you can't do it for less money than that, 500 a pair. You'd spend that in conventional amplification, and you'd spend at least that per loudspeaker. Plus all the other goodies, and console and, and, and...

What's the application? Lecture? Rock? Musical theatre?

[tweetersaway]

I know a lot of people in the professional world don't like Behringer, but I've never had a problem with their equipment, and the price simply can't be matched.

They will be used as mains mostly for relatively small live music venues, whether it be rock or whatever. Probably will be used as stage monitors for similar shows as well. Of course, you never know what you'll end up using it for. Possibly DJ-esque gigs and reinforcement for plays in small venues.