2. amps-preamps
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Whats with the Watts ??

Hi everyone. I'm starting an audio system for the first time and I've been doing my homework -- reading and listening as much as I can. Sorry if I ask some dumb questions along the way...

One aspect I'm very confused over is how much power I need in an amp. So many highly rated amps seem to be in the 50 watt range, yet there are also those in the 100's of watts. My room is about 25 x 15 with a ceiling that slopes from 8 feet at one end to about 18 feet at the other end. The room has 3 walls but opens up into a foyer on one side. I listen to all types of music, but mostly blues, jazz, and some rock. I like to listen at low to medium volumes. Its rare that I would play very loud. If it's important to my question, I seem to prefer the sound of solid state amps.

Being uneducated on the subject, my initial thought is, get more watts. Better to have too much than too little. So my questions are; how many watts should I be looking for and is there something to be gained or lost with too much or too few watts? Thanks.
silver911
rlwainwright
1,904 posts
 
What speakers are you driving? No matter what, 50 watts/ch. should deliver satisfying volume if you are not a headbanger...

-RW-
dcstep
1,518 posts
 
We need to know the efficiency of your speakers first. Do you know that? Or, tell us what brand and model speaker you plan to use.

That's a good sized room (about 5000 cubic feet), so I'm betting that you'll need 200 watts or more, UNLESS you select some very efficient speakers.

Dave
pubul57
3,712 posts
 
Your speaker specs are essential. I also think the wattage you need will differ between SS and tube; tubes tend to permit louder playing before clipping becomes a problem so you generally need fewer tube watts that SS watts, not because watts are not all watts, but because the clipping characteristics and distoritions are different between the two approaches. With 88db or higher speaker, 50 watts should be plenty of power, especially if you don't play at headbanging volume. Another issue is the impedance curves of the speakers and the amps ability to drive the load, which is not just a matter of watts. But let's start with the speaker you will be using.
undertow
1,033 posts
 
You can play headbanging volume with 10 watts on the right speakers, so don't get confused.
montytx
138 posts
 
The reason the speaker efficiency and sensitivity are paramount is because that determines how loudly they will play given 1 watt of power.

A simple example is that it takes an 87db sensitive speaker 1 watt of power to produce a sound pressure level of 87db at 1 meter. It takes a 90db sensitive speaker 1 watt of power to produce a 90db level at 1 meter and so on and so fourth.

In order to increase the sound pressure level 3db, it takes a doubling of wattage. 87db @ 1 watt needs 2 watts to produce 90db. It needs 4 watts to produce 93db, 8 watts to reach 96db, 16 watts to produce 99db....just keep going.

Keep in mind that this is measured at a distance of 1 meter for uniformity. The size of the room, the distance you listen from the speakers and the furnishings and layout will all impact the sound pressure levels reaching your ears.
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