Matching Speakers to Amp

jimmy29

jimmy29

jimmy29

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Apologies for the n00bish question.....

I've just bought an amp rated at 60W per channel into 8 ohms and I'm wondering what wattage the speakers should be rated at?
I've read reports that the amp should be twice as powerful as the maximum peak power of the speaker - but surely you risk blowing your speakers this way?

Any help much appreciated
 
Yep, most good speakers will be rated over 60W RMS anyhow, so you probably won't need to consider it. My speakers are rated at 150W each, and are driven by a 40WPC amp, it doesn't cause any problems and will go extremely loud.
 
jimmy29 said:
I've read reports that the amp should be twice as powerful as the maximum peak power of the speaker
Click to expand...

Can I ask where you read that? Seems quite a bizarre statement :D
 
As long as you match the impedance, there should be no issues. Although it's generally best to allow for some headroom with your amplifier, so that they can 'comfortably' drive the speakers for the transients in music.
 
fish99 said:
Can I ask where you read that? Seems quite a bizarre statement :D
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yeh it is very strange. like a valve amp that was rated at 20watts was matched with some 250watt studio speakers
 
I remember from quite a few years ago (more than I care to remember), being said that a set of speakers rated at say 50W could cope with X 5 that power, ie 50W rated speakers could cope with up to 250W from an amp.

If I'm misinformed, I'm sure somebody will set me right. :)
 
What I was thinking was - my speakers (MA B2) are 100W RMS power handling. The peak (PMPO) would probably be double that. Double the peak would mean they need a 400W RMS amp.

I know bugger all about hi-fi really, but wouldn't a 400W amp kill the speakers stone dead? :D

As it is they sound great with my 40W Rotel RA02.
 
jbloggs said:
I remember from quite a few years ago (more than I care to remember), being said that a set of speakers rated at say 50W could cope with X 5 that power, ie 50W rated speakers could cope with up to 250W from an amp.

If I'm misinformed, I'm sure somebody will set me right. :)
Click to expand...

maybe, but the cones would fly out after about 1/2 - 3/4 on the dial. (like my mates speakers did he brought around to test on an old amp i had)
didnt literally fly out but detatched and so knackered them up
 
You can blow drivers with any system, whether or not the amplifiers are above speakers maximum power handling of the speaker, or under.

Worst is the amplifier clipping, if it's incapable of driving the impedence of the speakers, and/or if they're so unefficient the amp has to run harder to be at the same volume.
 
/Reads the guide again

Ok my bad :o

What its saying is you need double the power of each speaker overall, hence you get the rated speaker power per channel.
Makes sense now :o :o
 
Not sure whether amps are rated for one or two channels, I suspect it's two, but someone else can confirm that.

Basically I would ignore that guide. He'd have you buying a 400W amp to drive 100W speakers, which is ridiculous and would cost a fortune. I've got two 80W Eltax Monitor 3's being driven by a 15W Sonic Impact t-amp, and it sounds every bit as good as my 40W Rotel amp or my 80W Marantz amp, just it can't achieve the same volume of course (not that 15W is at all quiet).

I'm sure your 60W amp will drive pretty much any sub £300 speakers.
 
Some amplifiers are tested by the manufactuer with only one channel driven to falsly inflate amplifier ratings. One good example is a AV amplifier, where the power supply is incapable of driving all channels at the same output of just one channel. ie 140W one channel driven, 70W all channels. Al amplifier should be all channels driven, RMS, into 8Ohm, with very low THD.

In most cases a 30W amplifier is more than enough, just make sure it's quality amplification. A 100W rating is not always 100W.
 
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