How much power is to much power?


When is an amp overkill for a speaker? More specifically, I have 91db speakers and I'm considering two SS amps, one 140 watts and the other 200 watts. Are they both too much? Is it too much simply because you're paying for extra power but don't need it, or because it's a detriment to the overall system sound?

Thanks.
128x128jtnicolosi
What does "more control of bass" mean? If you meant sufficient current to drive the bass woofers without more distortion, then it is equivalent to a higher SPL. If you meant a higher damping factor, then it is independent to the wattage anyway.

I have learned the following things recently.

I bought my current speakers, JMlab Alto Utopia, with the impression that they are easy to drive: 91dB and 8ohm load. But my KT88 monoblocks, 50wpc, couldn't drive them well. Upon more investigation, I found the speaker impedance drops to 3.2ohms. This means that bass will need 2.5X more power than the mid-range.

Then I bought a Counterpoint SA100 and upgraded it to NP100. Note that NP100 has several upgrade levels and they all have the same rating, 100Wpc into 8ohm and 170Wpc into 4ohm, with a damping factor around 40. I have tried the following upgrade levels: Basic, Basic Gold, Premium Gold, and Platinum. They sound *very* different even though they all have the same outout ratings.

So what have I learned?

1. The matching between power amp and speakers is very important.
2. The amp rating can be misleading at times.
As to the magazine article referred to- I beg to differ that the phase angle is all that important - the proper term for what is imporant is the group delay.

I think it all depends on the speaker and amp combo. The Spectron Musician III SE in mono-block delivers 2400watts @ 4ohm. I do have to set the volume nob down than when I had only one M3 SE stereo amp, but the level of detail, effortless sound and fitness is world class.

Reports of blown tweeter fuses on the Maggies 3.6R are not that uncommon. I've read cases where the tweeter fuses blows up with an 800watt amp. I mostly listen to Jazz and Classical music, so it's unlikely that I'll go up to uncomfortable levels. But listening as loud as my room allows, I've never blown up a tweeter fuse with the 2400watt Spectron mono-blocks.

You can check the technical details of safety features for this amp, which may help to explain why I never feel anything forced upon the sound. All I perceive is the easiness of the music, just like a live musical event.
Vett93, You have learned something of great value, I think. Now to have an even more complete understanding of amp/speaker matching, consider that not only do speakers have an irregular impedence so do amplifiers have an output impedence that is irregular. Not so much SS which usually have a very low output impedence and its not a real issue, but tube amps can, and do, have output impedences that are fairly high and can make a substantial difference in what you hear from speakers. It's has been discussed here before so some night when you can't sleep, it will give you something to research. :-)
09-13-08: Vett93 said:
"What does "more control of bass" mean? If you meant sufficient current to drive the bass woofers without more distortion, then it is equivalent to a higher SPL. If you meant a higher damping factor, then it is independent to the wattage anyway."

I'm talking about effective damping, not damping factor. DF is part of the equation, but a 100 wpc with a damping factor of 1000 isn't going to control the woofers as well as my 1000 wpc amp with a DF of 1000. Someone up the thread said something along the lines that watts are like horse power. There's something too that.

Uncontrolled bass is too bloomy and resonant. An amp that grabs the woofers and prevents them from uncontrolled ringing is what's needed.

Dave