2. amps-preamps
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A little deeper on amp power please....

If somebody could elaborate on exactly how a higher watt amp will improve the sound of speakers (lower sensitivity speakers that “need” power).  More specifically, I get that when the nature of the recording and the volume setting demand an immediate spike in power, an amp that delivers the spike will perform better than one that does not.  But when I used to have an amp with output meters, it would be in single digits for most normal listening, and I don’t recall what a spike would have been - I want to say 15 or 20 watts.  What I am scratching at is whether there is something more to power, i.e. the notion that the effortless power of, say, a 300 watt amp would somehow be an improvement over an otherwise similar 75 watt amp…even if a spike is just 20 watts.  Hope the question make sense.

mathiasmingus
ozzy's avatar
ozzy
7,239 posts
 

Best analogy I can think of is:

Think of it as a high-power race car that can go 200 miles an hour. Even at the required speed limit, it will display an effortless response that you can feel.

ozzy

carlsbad2's avatar
carlsbad2
1,384 posts
 

I'm using a 2 wpc amp right now with great success.  I've been told that the "rule of thumb" is that you need 20dB headroom which means that if I'm listening at 70dB, I should have enough power available to go to 90 dB just for the extremely loud parts.  I think they are especially referring to classical music that has tremendous variations in volume.  That said, my 2 wpc amp will indeed play much louder than I need it to.

So I've been thinking about it quite a bit and critically listening to my system, trying to find a weakness at higher volume. And I can't.

I'll keep reading this thread but I think there are 2 reasons people say this:  1.  It is natural to feel more secure having more power than you need.  2.  Cheap amps that were overrated in the first place and probably has nothing to do with us here.

I'm sure my skepticism will inspire replies.  I'm open minded.

Jerry

zlone
446 posts
 

As a low volume listener with hard to drive speakers, I think total wattage is less important than how the amp handles changes in impedance. It is a good sign if the wattage doubles as the impedance halves. To use the race car analogy, I think of this as having lots of torque even at low RPM’s. 

carlsbad2's avatar
carlsbad2
1,384 posts
 

I forgot to mention, I agree current capability of the amp is more important. --Jerry

mlsstl
1,405 posts
 

Speakers are a much more complicated load than the fixed value resistor used on a test bench to determine the power spec rating for an amp.  First, speakers typically have a resistance curve that varies widely with frequency. An 8 ohm speaker may vary from below that number to way above it. Second, many speakers also present a capacitive load which can be difficult for some amps. And, the amp also has to deal with the signal it gets back from the speaker. Once a speaker starts moving, particularly at lower frequencies, it has inertia, so continues vibrating momentarily after the input signal stops. This turns the voice coil/magnet assembly into a power generator which can return power back to the amp. How the amp reacts to this signal can be an issue.

So, you can see this issue is more complex than just how many amplifier watts are generated. Some amps handle complex loads better than others. The specs alone rarely cover all the bases.

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