Why power amps have more wattage than speakers can handle

[edwardrandolph]

This was the clearest, most concise, and informative explanation of this topic that I've heard. Well done, and thank you!

[gdownz]

I bought my 1st stereo in 1978 when I was 16 at Tech HiFi & the salesman sold me Ohm speakers & a 25 watt Pioneer receiver & I blew up both tweeters by the end of the week. They swapped the speakers & upgraded me to a 35 watt Technics receiver & within the next 2 weeks I blew a woofer & tweeter in one speaker & the midrange on the other. I went back & the manager took over & listened to everything I had done & what I was really looking for in a stereo system as a young man. Finally my message got through & he upgraded me the right way with a pair of JBL L40s & a 100 watt Nikko receiver that changed EVERYTHING. I was in teenage heaven. 1st thing he said to me before the upgrading was that you will never damage a speaker if it's over powered as long as you play it within it's limits but you will always cause damage when you underpower & push it past it's limits. I don't remember the term "headroom" then but that's the day I was taught about it. Thank You Ralph wherever you are.. much appreciated 👍

[meade]

also...amps are full of caps and if there is enough capacitance you can use a larger amp than the outlet is rated for, especially for actual music which is usually very dynamic. A 10 second sine wave would pop the breaker a lot quicker for sure. But music, even at full power, you can get a lot more out of the outlet than most people think.

[patrickgeorge]

I have used small and large amps and my preference for all of what Paul described is large monoblocks. Just effortless! Thanks Paul!

[arunsukumaran]

Excellent... Nicely explained sir....And that Car analogy... I often use in my teck talks with my clients..

[DalstonVinyl]

We can also add that certain brief bits of the audio signal, called transients, require much more power, but only for milliseconds, which shouldn't in any way harm a speaker, although they may technically require more than the speakers rated power, or close to it, but only for milliseconds.

[mr.george]

Some years ago I decided to try a tube amp for the first time. I did not want to spend a lot of money for one & I purchased the Reisong A10 a 6 watt per channel amp. I had a pair of vintage JBL 4312C monitors that are. very efficient & was shocked at how good they sounded. Went very Loud effortlessly w/ deep bass. Only 6 watts! I eventually purchased a Willsenton R8 w/ 40 watts per channel. I have more power than I'll ever need. Can't even turn up the volume half way it's so loud. More power than i'll ever need.

[Themotorcyclechannel]

thank you Paul great explanation. you hit the nail on the head, take care

[budgetaudiophilelife-long]

🤗😎 GREAT EXPLAINATION PAUL 🧐 looking forward to hearing your big blocks😁💚💚💚

[buckzxr]

I upgraded to PSA M1200, with a Gain Cell DAC, JBL L100 speakers, medium sized room.I play most LPs and CDs and Streaming Qobuz at like 35.Sometimes 40, but good quality recordings i can leave it in the 20s.But 35 seems to be a sweet spot where all of a sudden stuff plays way brighter and clearer.Also added REL T5, one for each channel, and this made another big difference.Thanks for all your advice!

[jeffreyscott]

Perfect explanation Paul.
All a person needs to do is listen to the sound produced by the amp at higher thresholds, (volume) and this immediately becomes very clear. As long as the speakers are rated for the wattage.
I'm about to invest in a new 2 channel kit and am targeting an amp with 200, maybe 250 watts for the very reason you explained.
I appreciate the information you share regarding HiFi.

Cheers

[av]

What a wonderful explanation! 😊
Simple.

[mikee]

I think a lot of people don’t understand the fact that an audio amplifier isn’t putting out a constant measurement of power or watts. It is constantly varying depending on the signal that is put into it which is also constantly varying. In addition to the fact that the impedance of the speaker is varying with the frequency of the signal. In a typical home stereo configuration in the average size room, 10 continuous watts in most cases would be deafening. But at that continuous power level, bass heavy signals may require 100 or more watts. Also if a speaker is rated at 100 watts, it won’t be destroyed if for a very brief period of time it sees 150 watts. To compare it to something most people understand, when a table saw or an air compressor first starts, it may draw something like 50 amps for a split second. It doesn’t trip the breaker or burn the motor up because it’s for a brief period of time. If the saw is on its own breaker, it won’t trip the breaker if it’s properly sized. But if it shares a circuit with a couple lights and a radio and battery charger, it is likely to trip when you first turn it on. As Paul says, if you have more power than you need, the amplifier will never strain, delivering the clean power required for transient peaks cleanly. While it would certainly be overkill to buy a 1200 watt monoblock amp for a speaker rated at 100 watts and would damage the speaker if played loud enough but pairing that 100 watt speaker with a 200 watt amp would be a good idea. You just have to have common sense to turn the volume down if something doesn’t sound right.

[小王-rb]

High damping factor is another reason. Easier to achieve with big amps.

[vjsr]

OUTSTANDING explanation! Very well done and easily understandable. Now, does that also apply to the speakers and/or how does speaker rating best be applied to amp wattage?

[tristanjones]

The answer is actually a bit more complicated. The idea that a higher wattage rating will have a wider linear region is almost complete nonsense. Here is the catch. Every transistor, tube, etc. has a set of operating curves. Your job as an amp designer is to find a point in these curves where the amp will have a wide linear voltage swing. The wider the linear region, the bigger the sweet spot. Say we have a mosfet that is biased at 24v. It's linear region is between 32 and 16 volts. You could design the amp with a 32v power supply and significantly cut down on the rated power for the amplifier. There is nothing stopping you from doing that. But generally people will design the power supply such that you can achieve full output which in this case is 48v. After all, why would we want 50 watts when we can have 200 watts? Of course the catch is that increasing the power did not increase the linear region of the amplifier.

Where it gets tricky is when you start to parallel devices. An old trick to improve performance in an amplifier is to use smaller - less powerful - amplifying devices in parallel. When you put matched devices in parallel you get an interesting effect. Noise and distortion go down and you generally get more power out. So the trick is to find a device with the widest possible linear voltage swing. If the device has a wide voltage swing, but can't source a lot of current, you can parallel a bunch of devices in order to improve power and distortion. The kicker is that you can parallel devices even when you have enough current because you will still lower distortion. This is why you might see 8 or 16 devices in parallel in some giant 1500 watt amp. You won't use the power, but you will get cleaner power when you use the amp in it's sweet spot. Nelson pass famously built an amp with a couple thousand Jfets in parallel and the performance is hard to beat.

So the idea that more power inherently means a wider linear region is not true. It all depends on how the amp was designed.

[rd-lj]

Back in the day ( late 1970s ) Infinity Systems packed with their loudspeakers an advisory concerning amplifier clipping and how it could damage drivers. It cautioned users not to turn the level (volume)control past the 1 o'clock position because musical transients could drive the amp into hard clipping.

[savvassidiropoulos]

The analogy to cars made me thing something that might be silly, or not. We have a power rating on amplifiers, Watts, and we also have a power rating on cars, HP or kW. We also have a torque rating on cars, that relates to the effortlessness. I don't see a similar rating on amplifiers, unless that would be slew rate.

[tomooo]

There is an additional issue of the point of "damage".
If a speaker reaches its power limit it will sound bad, and we will want to turn it down way before you damage anything.
If an amplifier reaches it limit it will suddenly clip - the signal voltage curve will suddenly dip in a sharp cliff edge. A clipping amplifier will tear a speaker cone apart in seconds as it is impossible for the speaker to follow the clip curve.
It is just good practice to have an amplifier with more reserve space than a speaker, if not you are unlikely to get much warning before needing to replace the speakers as they rip the cones apart.

[twelvebears]

You can (and I have) drive small speakers really hard without issues as long as the amps provide clean, unclipped power. Usually the first thing you hear is a clack as the woofer runs out of travel. But an over-driven amp which clips will fry tweeters before you get a chance to do anything about it.