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Importance of impulse response

thanossapiens

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I have seen a lot of people here say that impulse response is not relevant, and that basically only frequency response matters.
This confused me because I happen to use Eclipse single driver speakers, which I like a lot and I indeed think they sound really transparent like they claim, and their whole philosophy is basically designing for good impulse response. Is it just BS?
Also I always thought that it makes sense that a smaller driver would be faster and thus sound faster, due to it being lighter.
Some people say that if it can reproduce 20Khz its fast enough which also makes sense. Is that actually true? and if it is, is fastness really FR related too, because it really feels like a different "sensation" if that makes any sense.


outou.png
 

NTK

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For linear time invariant (LTI) systems, frequency response and impulse response describe the same thing, one in the frequency domain and the other in the time domain. Note that the second highlighted statement goes both ways -- if you know the frequency response (both magnitude and phase), you can calculate the impulse response.

FR and IR.png
 

Soundstage

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For linear time invariant (LTI) systems, frequency response and impulse response describe the same thing, one in the frequency domain and the other in the time domain. Note that the second highlighted statement goes both ways -- if you know the frequency response (both magnitude and phase), you can calculate the impulse response.

View attachment 242014
Nice.

So if the impulse response is perfect, you get text book frequency response?

And what other benefits appart from receiving the sound from different frequencies at the same time in your hear?
 

antcollinet

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Nice.

So if the impulse response is perfect, you get text book frequency response?

And what other benefits appart from receiving the sound from different frequencies at the same time in your hear?
Except, of course, you don't. Since your room response messes up the impulse response anyway.
 

fpitas

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I have seen a lot of people here say that impulse response is not relevant, and that basically only frequency response matters.
This confused me because I happen to use Eclipse single driver speakers, which I like a lot and I indeed think they sound really transparent like they claim, and their whole philosophy is basically designing for good impulse response. Is it just BS?
Also I always thought that it makes sense that a smaller driver would be faster and thus sound faster, due to it being lighter.
Some people say that if it can reproduce 20Khz its fast enough which also makes sense. Is that actually true? and if it is, is fastness really FR related too, because it really feels like a different "sensation" if that makes any sense.


outou.png
Whatever "faster" means (and no one really explains it, it's a buzzword) it probably has to do with FR. Unfortunately the people who toss around audio buzzwords are allergic to measuring and demonstrating their pet concepts.
 
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thanossapiens

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For linear time invariant (LTI) systems, frequency response and impulse response describe the same thing, one in the frequency domain and the other in the time domain. Note that the second highlighted statement goes both ways -- if you know the frequency response (both magnitude and phase), you can calculate the impulse response.
I see. Honestly I am not very knowledgeable about this stuff, but from what I understand, if a speaker can reach 20Khz, then it will have perfect impulse response? Why is this company doing extra things to improve it then? I mean, I usually dont believe what, especially audio, companies say and their bogus terms, but this seems to be one of the few ones that says measurements can describe everything(mainly this measurement). They have also said that their biggest model has "worse impulse response" because the driver is bigger, but it can also reach 20Khz at the same db so what gives
 

fpitas

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I see. Honestly I am not very knowledgeable about this stuff, but from what I understand, if a speaker can reach 20Khz, then it will have perfect impulse response? Why is this company doing extra things to improve it then? I mean, I usually dont believe what, especially audio, companies say and their bogus terms, but this seems to be one of the few ones that says measurements can describe everything(mainly this measurement). They have also said that their biggest model has "worse impulse response" because the driver is bigger, but it can also reach 20Khz at the same db so what gives
Not perfect impulse response, that would require response to an infinite frequency. But most of us can't hear past 20kHz, and most fall far short.
 
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thanossapiens

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Whatever "faster" means (and no one really explains it, it's a buzzword) it probably has to do with FR. Unfortunately the people who toss around audio buzzwords are allergic to measuring and demonstrating their pet concepts.
Well, I don't really know how else to explain this aspect of the sound besides fast. I see it most obviously in the bass, some speakers sound more sluggish and inarticulate. I had tried to EQ less low bass in one that felt slow to me, in case the excessive sub-bass it had was causing it, but it still felt "slow".
So all speakers go from 0 db to lets say 90 db equally as fast?
 

fpitas

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Well, I don't really know how else to explain this aspect of the sound besides fast. I see it most obviously in the bass, some speakers sound more sluggish and inarticulate. I had tried to EQ less low bass in one that felt slow to me, in case the excessive sub-bass it had was causing it, but it still felt "slow".
So all speakers go from 0 db to lets say 90 db equally as fast?
That's just it, the term has no scientific definition. My system perhaps sounds fast (I guess?), but then it responds fairly flat from about 20Hz to 20kHz. When I've heard it be sluggish or whatever, there was too much midbass around 100 - 200Hz. But I have no idea if that's what is commonly referred to as fast, or not being fast etc.
 

617

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Generally 'faster' means less bass, or that the room isn't causing certain bass frequencies to be inordinately loud. The easiest way to remedy bass/room problems is to simply take the bass out.

Bass is intrinsically slow - its slowness is what defines it as bass. How long does it take for a sound to have a pattern that can be called a 5000hz frequency? 1/5000 of a second is one period, so give it a two periods to even out and we're talking 1/2500 of a second. At 50hz it takes 1/25 of a second, which is 100 times slower.

This is a very crude illustration but I hope you can see my point. In reality our physiology requires different amounts of time to 'hear' a periodic pressure variation as a pitch. If I remember correctly, it takes even longer for bass to be recognized as such.

The most important effect this has is that bass will travel all around your room and interact with itself in all kinds of chaotic ways before you can even recognize it as a bass pitch. This is why bass is not localizable. If you can hear where your subwoofer is, you're either fooling yourself or it is creating distortion products several octaves into the midrange and treble.
 
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thanossapiens

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Generally 'faster' means less bass, or that the room isn't causing certain bass frequencies to be inordinately loud. The easiest way to remedy bass/room problems is to simply take the bass out.

Bass is intrinsically slow - its slowness is what defines it as bass. How long does it take for a sound to have a pattern that can be called a 5000hz frequency? 1/5000 of a second is one period, so give it a two periods to even out and we're talking 1/2500 of a second. At 50hz it takes 1/25 of a second, which is 100 times slower.

This is a very crude illustration but I hope you can see my point. In reality our physiology requires different amounts of time to 'hear' a periodic pressure variation as a pitch. If I remember correctly, it takes even longer for bass to be recognized as such.

The most important effect this has is that bass will travel all around your room and interact with itself in all kinds of chaotic ways before you can even recognize it as a bass pitch. This is why bass is not localizable. If you can hear where your subwoofer is, you're either fooling yourself or it is creating distortion products several octaves into the midrange and treble.
I assume reflected sound and cabinet resonance reach the ear later than than the speaker's sound does? That could explain perceived slowness then.
 

gino1961

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Hi i have a question ... looking at the picture it looks like there is some ringing before the impulse ???
how can this be possible ?
the following one taken from the Stereophile magazine looks more correct (its measured very well i guess)

E14FIG08.jpg

i do not want to sound trivial but if you send a signal in you should get a very similar signal out The difference signal out - signal in is something added by the driver not present in the original signal Like a sort of distortion
 

gino1961

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I assume reflected sound and cabinet resonance reach the ear later than than the speaker's sound does? That could explain perceived slowness then.
just a word about cabinet resonance I think that they are so much lower in level than the direct signal that can be neglected ?
 

fpitas

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just a word about cabinet resonance I think that they are so much lower in level than the direct signal that can be neglected
The secret stays in the baffle design and construction The baffle should not move This is the reason why the best speakers i have listened to had a very thick and heavy baffle
Like the very nice Thiel for instance Just look at their baffle
1l11o3b2bmpx.jpg
I too subscribe to the thick and massively braced front baffle approach.
 

617

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Hi i have a question ... looking at the picture it looks like there is some ringing before the impulse ???
how can this be possible ?
the following one taken from the Stereophile magazine looks more correct (its measured very well i guess)

E14FIG08.jpg

i do not want to sound trivial but if you send a signal in you should get a very similar signal out The difference signal out - signal in is something added by the driver not present in the original signal Like a sort of distortion
The graphic you linked is flipped left and right.
No good loudspeaker (or microphone) has a 'good' impulse response. All loudspeakers are band limited - none of them produce 0hz (maybe one) and none of them have infinite bandwidth. Additionally, an impulse response is a 'raw' measurement which includes room effects that can be excluded when you generate frequency response. All of these things add crap to the impulse response, which would otherwise be an infinitely narrow blip.

We don't measure speakers using impulse signals anyway (such as a popping balloon) because the test signal is short, prone to noise and so on. We derive the impulse response from a swept sine or pink noise signal. Balloons are used in architectural acoustics but even then I believe MLS and swept sine are possible.

In other words, the impulse response is not a graph meant to show anything, it is simply a convenient way of encapsulating the data produced by various measurements before you turn it into something useful (such as a FR graph, or a CSD graph)

Do not use it to evaluate speaker quality. The spinorama is the correct tool for that job, along with a directivity sonogram if you're a huge nerd.
 

fpitas

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The graphic you linked is flipped left and right.
No good loudspeaker (or microphone) has a 'good' impulse response. All loudspeakers are band limited - none of them produce 0hz (maybe one) and none of them have infinite bandwidth. Additionally, an impulse response is a 'raw' measurement which includes room effects that can be excluded when you generate frequency response. All of these things add crap to the impulse response, which would otherwise be an infinitely narrow blip.

We don't measure speakers using impulse signals anyway (such as a popping balloon) because the test signal is short, prone to noise and so on. We derive the impulse response from a swept sine or pink noise signal. Balloons are used in architectural acoustics but even then I believe MLS and swept sine are possible.

In other words, the impulse response is not a graph meant to show anything, it is simply a convenient way of encapsulating the data produced by various measurements before you turn it into something useful (such as a FR graph, or a CSD graph)

Do not use it to evaluate speaker quality. The spinorama is the correct tool for that job, along with a directivity sonogram if you're a huge nerd.
Agreed. I glance at it when I measure, but the FR is far easier to interpret.
 
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thanossapiens

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For linear time invariant (LTI) systems, frequency response and impulse response describe the same thing, one in the frequency domain and the other in the time domain. Note that the second highlighted statement goes both ways -- if you know the frequency response (both magnitude and phase), you can calculate the impulse response.
Can the impulse response show the distortion of the speaker?
 

fpitas

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Can the impulse response show the distortion of the speaker?
Not very well. Distortion is a tiny percentage of the desired signal, hopefully.
 

TPF

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Generally 'faster' means less bass, or that the room isn't causing certain bass frequencies to be inordinately loud. The easiest way to remedy bass/room problems is to simply take the bass out.

Bass is intrinsically slow - its slowness is what defines it as bass. How long does it take for a sound to have a pattern that can be called a 5000hz frequency? 1/5000 of a second is one period, so give it a two periods to even out and we're talking 1/2500 of a second. At 50hz it takes 1/25 of a second, which is 100 times slower.

This is a very crude illustration but I hope you can see my point. In reality our physiology requires different amounts of time to 'hear' a periodic pressure variation as a pitch. If I remember correctly, it takes even longer for bass to be recognized as such.

The most important effect this has is that bass will travel all around your room and interact with itself in all kinds of chaotic ways before you can even recognize it as a bass pitch. This is why bass is not localizable. If you can hear where your subwoofer is, you're either fooling yourself or it is creating distortion products several octaves into the midrange and treble.
Are you saying that the speed of sound varies with frequency? The speed has to do with the medium, not how the wave looks like.
 

617

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Are you saying that the speed of sound varies with frequency? The speed has to do with the medium, not how the wave looks like.
The amount of time for a pressure variation to exhibit the perceptual quality we call 'pitch' varies by frequency. The amount of time for it to exhibit the quality we would call a 'frequency' also varies with frequency.

If you take a 1/5000 of a second long sound, it by definition cannot contain a 50hz tone.
 
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