Is there such a thing as too much power?

@agwca If only a sine wave then your numbers are reasonable. But if reproducing a full spectrum audio signal its a bit different!

Atmasphere, Is there a way to determine an amplifier's lowest point of distortion apriori or is an empirical issue?

If the specs are published, its easy, if not, a distortion analyzer is handy.


But as I mentioned, with most amplifiers this is about 5-7% of full power. Having unlimited power is great, but the practical issues around that are profound. If you need that power because you have inefficient speakers, thermal compression will prevent you from ever playing the system all that loud and getting the dynamic contrasts right. One problem that is epidemic with higher powered amps is poor application of loop negative feedback, owing largely to inadequate Gain Bandwidth Product. This causes such amps to sound harsh due to higher ordered harmonic distortion.


This is why efficiency is important in loudspeakers, and there is no reason why a speaker has to trade off anything if resolution is a higher goal. The speakers I'm running at home are 97.5dB, the first breakup of the midrange driver is at 35KHz. So its very fast and smooth. On such speakers you can use lower powered amps and still achieve sound pressures well over 100dB.

So, at least for the 2 manufacturers above, higher power is possible & better :-) It is only the cost that will be the negative aspect.

From a designer/manufacturing/engineering point of view I can tell you that this is simply incorrect. Its much easier to build a low power amp than a large one, and even though in a larger amp you can have the advantage of paralleled devices to minimize individual device aberrations, the simple fact is that the added complexity is a **frequent** downfall!

I've also mentioned several times on this thread one of the peskier issues dealing with the myth of more power which is outlined in @pragmasi  and @shahram 's posts above. If the amp is always operating ***below*** its minimum distortion level, you won't be hearing the best out of the amp or the speaker. For this reason the amplifier power has to be matched properly to the speaker efficiency such that the amplifier is doing its best work at normal listening levels. This isn't ideal but we live in a real world that does not care what we humans regard as ideal. So you have to be pragmatic and recognize that amps aren't perfect!

Now anyone whose read this far may have picked up on something- that in addition to a distinct advantage in terms of sound quality to matching the amp and speaker (a powerful amp working with a lower efficiency speaker and a higher efficiency speaker is better off with a lower powered amp), that also unlimited sound pressures are often not possible in many listening environments. Since thermal compression in loudspeakers is a very real thing, there is an obvious advantage to working with easier to drive speakers since they will play the dynamics in the recording better. At the same time because the amp isn't working as hard, it won't have to make as much distortion either.

The reason the industry moved away from high efficiency has a lot to do with the large size of typical high efficiency speakers.

Not all higher efficiency speakers are all that large. Many 'full range' drivers can be quite efficient yet the cabinets are reasonable sizes.

ALL OTHER THINGS BEING EQUAL (That is the part people seem to be missing) a higher power amplifier will always be preferable. It will run less stressed and have much more headroom.

As for the higher distortion at lower levels of a power amp, even those higher levels of distortion is still well BELOW anyone's hearing so it is a moot point.

The first statement is correct. The only problem is things are never equal. The second statement is simply false- it subscribes to the idea that 0.005% THD is 'low'. Its not low if that distortion is all higher ordered harmonics, owing to the fact that the ear uses these harmonic to sense how loud a sound is. It is this simple fact that is why solid state has a reputation for brightness- that's not coming from a frequency response error, its caused by distortion. 

Why is everyone assuming that the make, quality and characteristics of an amplifier are changing when going to higher power ?

Because they often do.

Given everything else being equal, there is no argument except maybe just the cost and power consumption, that going to a higher power is always better.

The 'Given' isn't a given. One problem you can have is that higher powered amps usually also have more gain. If you put that amp on a higher efficiency loudspeaker, the noise floor can be annoying, the additional distortion (due to the amp operating below its point of lowest distortion) notwithstanding.

Do not equate going to a higher power, with also changing the quality. The two have nothing to do with each other.

In this regard your statement flies in the face of conventional wisdom which is based on experience of many many people over decades! As a manufacturer we deal with this all the time: "Don't your smaller amps sound better?" Ask any manufacturer- they will tell you they get this question often.

We are one of the very few manufacturers that make more powerful amps that actually **do** sound better than our smaller ones- this owing to how we scale up our power levels. But most solid state and nearly all tube amps sound better in their smaller embodiments, so long as the speaker allows for the lower power.

@alexberger +1

You can never have too much power. Full stop.

This statement is only true in theory.  In the real world where we all live, there are practical considerations that cause this statement to be false.

Apparently there is a need to explain why as I see a lot of myth in the posts above. If you look at the distortion curve of many amps, you will see the distortion starts at a certain level, **drops** as power is increased to about 5-7% of full power, then rises at power levels above that until it takes off at clipping.

Now the simple fact is that most of the time the music you hear is not requiring a lot of power- that power is needed mostly for transients.

If the speaker you have selected is very easy to drive, and the amplifier is very powerful, then you might say you have unlimited power since you can't clip the amp and stay in the room. But you won't be hearing what the speaker or amplifier can really do, since you'll be operating the amplifier 97% of the time **below** that minimum distortion point. Below that point, noise and distortion obscure detail due to the ear's masking principle. There will also be tonal aberrations as the ear converts distortion into tonality, and favors that over actual frequency response.


So there is a reason why matching an amplifier to a speaker on a simple power basis is good if **sound quality** is your goal!  A very powerful amplifier works best on a speaker that is less efficient, so that you can operate at power levels where the amp is making less distortion. Conversely this is why a lower power amp sounds best on a higher efficiency speaker.


Now *some* amplifiers have a distortion curve where the distortion drops linearly to unmeasurable as power is decreased. If you have one of those amps, then you can have a lot of power on an efficient speaker and get away with it- have your cake and eat it too.


But there aren't many amps that do that, and most of them don't make a lot of power- being SETs. Now we make an amp that gets around this problem, because of our topography (and the lack of feedback) we are able to get this type of distortion curve. We're not the only ones- Nelson Pass is successful with this approach in some of his designs. Its tricky- the amp has to be linear at low power levels. Amps with feedback often have the feedback poorly applied (and so is not always able to correct the way it should) and so you see the distortion rise at lower power levels. One of the few solid state amps I can think of that has a better feedback setup is the Benchmark, and there are a few class D amps as well.

The point here is saying that higher power is better without taking into consideration how the amp behaves is the same as suggesting that flushing $$$$$ down the loo is a good idea. Its isn't. You have to take into consideration how it is the amp makes all that power. Now I happen to agree that paralleled devices to get more power is a good thing- that's how we do it as well. I've already outlined where I think the problem lies, although I've only nutshelled it for the sake of brevity and this is already a too long post.

Ya, there's a reason Nelson calls his stuff "First Watt".


It applies to both tubes and transistors.

I can think of plenty of reasons why a 70 watt amp can sound better than a 300 watt amp. This should come as no surprise whatsoever!