It doesn’t cause moments with no sound. It causes distortion. It’s easier and safer to overload the input of a preamp to see what it sounds like. If you have a computer audio interface, connect a music player to an input and turn up the input gain 7ntil the level meters show clipping keep turning it up until you hear something. Usually the loudest things are bass notes and drum hits and these are hard to hear distortion on until it gets bad.
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Clipping & Underpowered Speakers
- Thread starter killdozzer
- Start date
? How is medium sensitivity speakers in a medium sized room, occasionally played loud, a special case. Seems like a pretty normal case to me.
So, you are telling me your normal? Do you have any data to back that up?
My normal is not your normal. So, we could both be abnormal. Or, we could be normal depending on what we are referring to. Normal is in the eye of the beholder. I will go out on a limb and say you are normal! Maybe I'm just pulling your leg. Bottom line is in your case your are correct. A win/win!
Prana Ferox
Addicted to Fun and Learning
1 watt into even pretty low efficiency speakers is pretty loud. It becomes a factor of how close you are to the speakers.
If you have moments with no sound at all you have another problem. That's possibly that the amplifier is going into some protection mode, possibly because impedance is dropping lower than it can handle, but it can be a bunch of things (your room could be too hot, your amp could just be broken etc) but it's beyond the scope of this thread.
If you have moments with no sound at all you have another problem. That's possibly that the amplifier is going into some protection mode, possibly because impedance is dropping lower than it can handle, but it can be a bunch of things (your room could be too hot, your amp could just be broken etc) but it's beyond the scope of this thread.
Clipping is not "no sound" it is distorted sound.
If you put a sine wave into the amp, then turn it up until the clipping starts, the peak of the sine wave is "clipped off" and instead of being a sine wave it gets a flat at the peak (positive and negative peaks.
Obviously music is not a sine wave, but the result is the same. Once the waveform reaches the clipping point (max voltage the amp can kick out) it goes flat - the top is clipped off.
See:
Clipping (audio) - Wikipedia
Basically it sounds like crap. And it is bad for your speakers also (it suddenly results in a lot of high frequency energy).
That makes sense to me. Thank you for the thoughtful explanation.
If my speaker’s sensitivity is 87db 1w/1m which is kind of average, when I am sitting 10 feet back the SPL is under 77db. Not very loud. If my speaker is a low sensitivity stand mount at 83 db/w/m it would be under 73 db. So no, people with average sensitivity speakers in medium sized rooms are no listening to their amps at 1 watt much of the time.
Prana Ferox
Addicted to Fun and Learning
I'm too lazy to check your math but assuming you have a stereo pair of speakers, that 77db increases to 80dB which is still 'can cause long term hearing damage' range. And again, we're talking average power and SPL, the peaks are obviously much louder.
Again, it's a function of distance. I'm sitting here listening to small, inefficient speakers nearfield and they're probably a half meter from my ears and (understanding volume knob position is not gain structure) the 40 watt amp I drive them with never gets cranked beyond 9:00. Find an old amp with power meters and (assume average speakers) you'll be surprised how loud things get before you get to 1w steady state.
Tom C
Major Contributor
I think I’m getting a feel for the original post. Sometimes it helps me to understand if I rephrase the question, so that’s what I’ll do here.
What happens electrically, and what does it sound like, when an amp is faced with an impedance dip lower than what it is able to compensate for (the case of the so called hard to drive speaker). Does the amp then clip, and is that the only possible response? Or does the amp simply “run out of steam” and not reproduce that section of music with the same volume as the rest? And if that’s the case, does what you hear coming out of the speaker differ from what you hear when you listen to a speaker with frequency response errors in the same region, or does it sound the same?
Have I got it, @killdozzer ?
What happens electrically, and what does it sound like, when an amp is faced with an impedance dip lower than what it is able to compensate for (the case of the so called hard to drive speaker). Does the amp then clip, and is that the only possible response? Or does the amp simply “run out of steam” and not reproduce that section of music with the same volume as the rest? And if that’s the case, does what you hear coming out of the speaker differ from what you hear when you listen to a speaker with frequency response errors in the same region, or does it sound the same?
Have I got it, @killdozzer ?
D
Deleted member 46664
Guest
Nit picking .... but ...
Speakers don't _need_ power ... they absorb it, transforming it into sound waves.
The amp doesn't have to clip ... you could simply turn down the volume.
Yes, of course there are. One of the best example is playing at a very low volume. Some speakers need to be played pretty loud to perform well (old dynaudio speakers are one of them). I believe many low sensitivity speakers need a fair amount of power to perform well, if you driving them as very low volume, its not going to perform well.
Clipping is not "no sound" it is distorted sound.
If you put a sine wave into the amp, then turn it up until the clipping starts, the peak of the sine wave is "clipped off" and instead of being a sine wave it gets a flat at the peak (positive and negative peaks.
Obviously music is not a sine wave, but the result is the same. Once the waveform reaches the clipping point (max voltage the amp can kick out) it goes flat - the top is clipped off.
See:
Clipping (audio) - Wikipedia
en.wikipedia.org
Basically it sounds like crap. And it is bad for your speakers also (it suddenly results in a lot of high frequency energy).
I would it depends on amp design.. some do simply cut the sound (like an on/off switch).
It does affect. Because when power gets too low, you will be affected by other factors like air resistance, voice coil inertia, spider damping issues etc. Even semiconductor performance too is affected if voltage goes too low.
So i would say sufficient power is needed, esp. for bigger cones.
If the sound guy at a concert delivers 80db average levels he probably never gets the gig again because almost everyone is going to complain that it isn’t loud enough.
I said I was talking about average speakers in an average listening room. Half meter from your ears is a special case. I used to have an old Yamaha amp with ”power meters” (most of them aren’t really) and they well above 1 watt level when I was really listening and not in background music mode. While agree that modest listening levels only average a few watts, every speaker I’ve owned save my Forte II’s sounded better to me when driven by a fairly powerful amp. Watts are fairly cheap.
So for me, I've got two different situations.
- My amp goes into protection mode: best example it the Ta Da from Netfilix
- My amp possibly is clipping: this is a guess Onkyo, is less than forthcoming in the specs with more than one channel driven.
OP
killdozzer
Major Contributor
- Thread Starter
- #36
Hey guys! You really made my day. I got up this morning, made my coffee, sat down to read your posts and it really put a smile on my face.
First, I know that a question from someone who is not a professional can sound weird or ill defined. I can only apologize. But you had patience and you really covered it well. My one and only reason to try and understand is is to stop obsessing about extra power. This is not without importance as watts still drive the price and the difference between 80w and 120w can be quiet substantial. OTOH it's not very smart to cap it exactly at your listening levels since you might want to crank it up.
@Tom C you could hardly get closer to what I meant. Great guess. So, any other symptom to not enough power other than clipping.
@rwortman a lot of good info and your rough assessment on 75-100w for low sensitivity speakers means more to me than you think
@Douglas Blake I understand it's just a figure of speech, but what I meant was that in order for your speaker to hit 96dB at freqs around the impedance dip, they need more power than at nominal impedance. Sure enough, they don't need anything, you don't have to use them at all. I just phrased it from the "speakers perspective". As if the speaker was saying, dude, if you want me to go that loud at that particular freq range, you gotta give me more juice.
@Spkrdctr thank you for kind words and explanations. You took obvious numbers to explain your idea more easily. But things get more interesting at border case. You could argue that simply swapping one CD for another, leaving everything else as it is, might mean the difference between clipping and not, simply for having one CD program material being filled with frequencies at the impedance dip region. If it's a guitar and a vocal, you may be fine. Put Metallica and you're in trouble.
Precisely because we're talking about variable load, you wanna cover for the peak. Or, make it, your peak - the SPL peak you listen to bearing in mind the impedance curve. If your amp's power doesn't cover for all the peaks at your listening levels for your specific speakers, does sound deteriorate in any other way then clipping. Is either/or situation. Is there such a thing as short of breath? Sure, it's very metaphorical, but I think we understand each other now.
First, I know that a question from someone who is not a professional can sound weird or ill defined. I can only apologize. But you had patience and you really covered it well. My one and only reason to try and understand is is to stop obsessing about extra power. This is not without importance as watts still drive the price and the difference between 80w and 120w can be quiet substantial. OTOH it's not very smart to cap it exactly at your listening levels since you might want to crank it up.
@Tom C you could hardly get closer to what I meant. Great guess. So, any other symptom to not enough power other than clipping.
@rwortman a lot of good info and your rough assessment on 75-100w for low sensitivity speakers means more to me than you think
@Douglas Blake I understand it's just a figure of speech, but what I meant was that in order for your speaker to hit 96dB at freqs around the impedance dip, they need more power than at nominal impedance. Sure enough, they don't need anything, you don't have to use them at all. I just phrased it from the "speakers perspective". As if the speaker was saying, dude, if you want me to go that loud at that particular freq range, you gotta give me more juice.
@Spkrdctr thank you for kind words and explanations. You took obvious numbers to explain your idea more easily. But things get more interesting at border case. You could argue that simply swapping one CD for another, leaving everything else as it is, might mean the difference between clipping and not, simply for having one CD program material being filled with frequencies at the impedance dip region. If it's a guitar and a vocal, you may be fine. Put Metallica and you're in trouble.
Precisely because we're talking about variable load, you wanna cover for the peak. Or, make it, your peak - the SPL peak you listen to bearing in mind the impedance curve. If your amp's power doesn't cover for all the peaks at your listening levels for your specific speakers, does sound deteriorate in any other way then clipping. Is either/or situation. Is there such a thing as short of breath? Sure, it's very metaphorical, but I think we understand each other now.
They'll only cut the sound if going into a thermal safety limit. That is not clipping. There is no amp that shuts off the output just when it reaches maximum voltage, it would be unusable for playing anywhere near loud, as the peaks would send it into shutdown. Imagine your amp cutting out with every drum strike.
Sorry my bad, I confused thermal cut-off with hard clipping. Thanks for correcting me.
OP
killdozzer
Major Contributor
- Thread Starter
- #39
This is also very helpful. So, there is such a thing as listening at safe levels and then a single instrument pushes it over the limit and causes short term clipping? And of course, this wouldn't happen if the amp had more power...
Then there's the case of the anniversary Denon amp that is rated 2x80 into 8, but has enough reserve which is, I guess, achieved by having large capacitors.
D
Deleted member 46664
Guest
It might help to inject some understanding of the dynamics of music at this point...
First of all, if your SPL tests are reading about 80db on a steady tone, on properly produced music (not this highly compressed 0 dynamic range garbage they crank out today) you are probably getting peaks that are 10 to 15 db higher than your steady tone average as well as quiet segments that could be 20 to 30 db lower. (Streaming services now normalize at -16dbfs for just this reason)
Music is not steady state... that's why you need "headroom" in an amplifier. So, for example... you have a pair of speakers rated at 85db @ 1 watt .... When you get that + 15 db peak of a snare drum or gunshot you are asking your amplifier for about 30 watts of power, with a 1 watt average! So, yes, an under powered amplifier is going to clip ... rather noticeably.
(Handy calculator ... HERE)
But it's a bit more complex than that... music has a natural decay in that as frequency increases, power tends to ramp down somewhat as higher pitched sounds are easier to hear. Something like 60% of musical power is under 250hz with the rest being in a tapered decline. Also, musical notes end at about 5khz with practically everything above that being harmonics for timbre (voicing). Most of musical sound is actually below 10khz so by the time you get above that, there really isn't a lot of content to be had... and the demands on your amplifiers will be much less. (This is also how they get away with putting a 20 watt tweeter in a 100 watt speaker)
The problem with clipping an amplifier is not just audible distortion... The clipping will almost always happen in the bass region of the music, producing an almost square wave output. Square waves are loaded with harmonics and some of them will reach well into the 30khz region, which is abnormal for a speaker to handle. Then just to make it worse, when you do clip an amplifier you are also feeding through the treble content of the music at much higher than normal levels. Put these two effects together and you end up with an overheated tweeter that just might give up on you. (Yes, I just told you that most "blown tweeters" are usually caused by not having enough amplifier power.)
So what's the takeaway from all this?
Well, most people listen at about 1 to 2 watts of average power --and yeah, that's pretty LOUD-- but with well produced music that can create demands for 30 to 50 watts of power on peaks. So trying to figure this out with test tones is something of a snipe hunt. You really do need calibrated power meters connected to your amplifier outputs and an SPL meter to get a good handle on it.
This is also why most speakers have 2 power ratings. We've all seen the "20 to 100 watts" thing before. The lower value is recommended amplifier power to get comfortable listening levels without clipping. The higher rating is the maximum safe amplifier power before you start melting down your woofers. Of course anyone listening at 100 watts of average power is going to be deaf in very short order... so my general advice is to buy an amp in the upper end of your speakers power ratings and call it a day.
Gosh that got long ... hope it helps.
First of all, if your SPL tests are reading about 80db on a steady tone, on properly produced music (not this highly compressed 0 dynamic range garbage they crank out today) you are probably getting peaks that are 10 to 15 db higher than your steady tone average as well as quiet segments that could be 20 to 30 db lower. (Streaming services now normalize at -16dbfs for just this reason)
Music is not steady state... that's why you need "headroom" in an amplifier. So, for example... you have a pair of speakers rated at 85db @ 1 watt .... When you get that + 15 db peak of a snare drum or gunshot you are asking your amplifier for about 30 watts of power, with a 1 watt average! So, yes, an under powered amplifier is going to clip ... rather noticeably.
(Handy calculator ... HERE)
But it's a bit more complex than that... music has a natural decay in that as frequency increases, power tends to ramp down somewhat as higher pitched sounds are easier to hear. Something like 60% of musical power is under 250hz with the rest being in a tapered decline. Also, musical notes end at about 5khz with practically everything above that being harmonics for timbre (voicing). Most of musical sound is actually below 10khz so by the time you get above that, there really isn't a lot of content to be had... and the demands on your amplifiers will be much less. (This is also how they get away with putting a 20 watt tweeter in a 100 watt speaker)
The problem with clipping an amplifier is not just audible distortion... The clipping will almost always happen in the bass region of the music, producing an almost square wave output. Square waves are loaded with harmonics and some of them will reach well into the 30khz region, which is abnormal for a speaker to handle. Then just to make it worse, when you do clip an amplifier you are also feeding through the treble content of the music at much higher than normal levels. Put these two effects together and you end up with an overheated tweeter that just might give up on you. (Yes, I just told you that most "blown tweeters" are usually caused by not having enough amplifier power.)
So what's the takeaway from all this?
Well, most people listen at about 1 to 2 watts of average power --and yeah, that's pretty LOUD-- but with well produced music that can create demands for 30 to 50 watts of power on peaks. So trying to figure this out with test tones is something of a snipe hunt. You really do need calibrated power meters connected to your amplifier outputs and an SPL meter to get a good handle on it.
This is also why most speakers have 2 power ratings. We've all seen the "20 to 100 watts" thing before. The lower value is recommended amplifier power to get comfortable listening levels without clipping. The higher rating is the maximum safe amplifier power before you start melting down your woofers. Of course anyone listening at 100 watts of average power is going to be deaf in very short order... so my general advice is to buy an amp in the upper end of your speakers power ratings and call it a day.
Gosh that got long ... hope it helps.
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