How important is impulse response? - AVS Forum | Home Theater Discussions And Reviews
Baselworld is only a few weeks away. Getting the latest news is easy, Click Here for info on how to join the Watchuseek.com newsletter list. Follow our team for updates featuring event coverage, new product unveilings, watch industry news & more!



Forum Jump: 
 1Likes
  • 1 Post By bear123
 
Thread Tools
post #1 of 20 Old 06-23-2013, 11:52 AM - Thread Starter
AVS Special Member
 
Saturn94's Avatar
 
Join Date: May 2008
Posts: 4,405
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 138 Post(s)
Liked: 468
Looking at the impulse response measurements on data-bass, there's quite a variety of results among the different sub models.

How important is this and how does impulse response manifest itself in what we hear?

Saturn94 is offline  
Sponsored Links
Advertisement
 
post #2 of 20 Old 06-24-2013, 04:58 AM
 
arnyk's Avatar
 
Join Date: Oct 2002
Location: Grosse Pointe Woods, MI
Posts: 14,593
Mentioned: 2 Post(s)
Tagged: 0 Thread(s)
Quoted: 851 Post(s)
Liked: 1236
Quote:
Originally Posted by Saturn94 View Post

Looking at the impulse response measurements on data-bass, there's quite a variety of results among the different sub models.

How important is this and how does impulse response manifest itself in what we hear?

Impulse response in this context is just another way of saying frequency response.

Frequency response is one of the most important properties of reproduced sound.

Of course I am speaking of reproduced sound in the perceptible frequency range. Sound is perceptible (either heard or felt) down into almost impossibly low frequency ranges. It is not very perceptible at all above about 16 KHz.
arnyk is offline  
post #3 of 20 Old 06-25-2013, 06:43 AM - Thread Starter
AVS Special Member
 
Saturn94's Avatar
 
Join Date: May 2008
Posts: 4,405
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 138 Post(s)
Liked: 468
On the Data Bass site their measurements include a graph for "impulse response". For example, here's the graph for an SVS sub;



I thought maybe what it's showing is how quickly the driver settles down when the signal stops, but I don't know. It seems if they are taking these measurements and posting them they must be important to sub performance.

So I'm trying to get a handle on what this measurement is showing us and what it means in terms of what we hear.

Saturn94 is offline  
post #4 of 20 Old 06-25-2013, 07:30 AM
AVS Addicted Member
 
Bill Fitzmaurice's Avatar
 
Join Date: Nov 2009
Location: New Hampshire
Posts: 13,566
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 3 Post(s)
Liked: 3858
Quote:
Originally Posted by Saturn94 View Post

On the Data Bass site their measurements include a graph for "impulse response"...
I thought maybe what it's showing is how quickly the driver settles down when the signal stops.
Correct.
Quote:
It seems if they are taking these measurements and posting them they must be important to sub performance.
Not terribly so. What the impulse mainly shows is how quickly inertia is overcome and the cone returns to rest after a single cycle pulse is applied. We don't listen to single cycle impulses, we listen to a continuous stream of impulses, and the inertial force is totally dwarfed by the electro-magnetic force provided by the motor. If the impulse response was really bad you'd hear it, but the frequency response would also point out the speaker deficiencies, and it would do so far more obviously. The main use of impulse response is to help identify what might be causing a really poor frequency response.

Bill Fitzmaurice Loudspeaker Design

The Laws of Physics aren't swayed by opinion.
Bill Fitzmaurice is offline  
post #5 of 20 Old 06-25-2013, 07:37 AM
 
arnyk's Avatar
 
Join Date: Oct 2002
Location: Grosse Pointe Woods, MI
Posts: 14,593
Mentioned: 2 Post(s)
Tagged: 0 Thread(s)
Quoted: 851 Post(s)
Liked: 1236
Quote:
Originally Posted by Saturn94 View Post

On the Data Bass site their measurements include a graph for "impulse response". For example, here's the graph for an SVS sub;



I thought maybe what it's showing is how quickly the driver settles down when the signal stops, but I don't know. It seems if they are taking these measurements and posting them they must be important to sub performance.

So I'm trying to get a handle on what this measurement is showing us and what it means in terms of what we hear.

One rule of thumb is that an impulse response that settles down right quick represents more extended frequency response, so you're right.

Ideal impulse response is a nearly zero width impulse. Ideal band limited response is still very narrow, but looks more like a highly damped sine wave.

arnyk is offline  
post #6 of 20 Old 06-25-2013, 12:13 PM - Thread Starter
AVS Special Member
 
Saturn94's Avatar
 
Join Date: May 2008
Posts: 4,405
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 138 Post(s)
Liked: 468
Quote:
Originally Posted by Bill Fitzmaurice View Post

Correct.
Not terribly so. What the impulse mainly shows is how quickly inertia is overcome and the cone returns to rest after a single cycle pulse is applied. We don't listen to single cycle impulses, we listen to a continuous stream of impulses, and the inertial force is totally dwarfed by the electro-magnetic force provided by the motor. If the impulse response was really bad you'd hear it, but the frequency response would also point out the speaker deficiencies, and it would do so far more obviously. The main use of impulse response is to help identify what might be causing a really poor frequency response.

So impulse performance bad enough to be audible will show up as an issue in frequency response? What would I look for in the frequency response to determine if there is an issue? Is there a particular part of the fequency band that would be affected?

Saturn94 is offline  
post #7 of 20 Old 06-25-2013, 01:42 PM
AVS Addicted Member
 
cschang's Avatar
 
Join Date: Mar 2003
Location: Manhattan Beach, CA
Posts: 14,986
Mentioned: 2 Post(s)
Tagged: 0 Thread(s)
Quoted: 95 Post(s)
Liked: 156
Would the impulse response give any indication of transient response?

-curtis

Owner of Wave Crest Audio
Volunteer Mod at the Ascend Acoustics Forum
Like all things on the Internet, do your research, as forums have a good amount of misinformation.
Help beat breast cancer!

cschang is offline  
post #8 of 20 Old 01-03-2016, 03:50 PM
AVS Special Member
 
tvuong's Avatar
 
Join Date: Dec 2000
Posts: 3,643
Mentioned: 33 Post(s)
Tagged: 0 Thread(s)
Quoted: 1397 Post(s)
Liked: 761
Quote:
Originally Posted by Bill Fitzmaurice View Post
Quote:Originally Posted by Saturn94 

On the Data Bass site their measurements include a graph for "impulse response"...
I thought maybe what it's showing is how quickly the driver settles down when the signal stops.

Correct.Quote:It seems if they are taking these measurements and posting them they must be important to sub performance.

Not terribly so. What the impulse mainly shows is how quickly inertia is overcome and the cone returns to rest after a single cycle pulse is applied. We don't listen to single cycle impulses, we listen to a continuous stream of impulses, and the inertial force is totally dwarfed by the electro-magnetic force provided by the motor. If the impulse response was really bad you'd hear it, but the frequency response would also point out the speaker deficiencies, and it would do so far more obviously. The main use of impulse response is to help identify what might be causing a really poor frequency response.
So, which graph shows sound quality difference, Bill? Group delay graph?
tvuong is online now  
post #9 of 20 Old 01-04-2016, 05:09 AM
AVS Addicted Member
 
Bill Fitzmaurice's Avatar
 
Join Date: Nov 2009
Location: New Hampshire
Posts: 13,566
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 3 Post(s)
Liked: 3858
Quote:
Originally Posted by tvuong View Post
So, which graph shows sound quality difference, Bill? Group delay graph?
Waterfall probably gives the best indication of sound quality, as it shows both broadband response and decay. THD would be the next to consider. Group delay is almost meaningless, as it can only be heard in extreme cases, and in those cases it would indicate a design so poor that group delay would be the least of its issues.

Bill Fitzmaurice Loudspeaker Design

The Laws of Physics aren't swayed by opinion.
Bill Fitzmaurice is offline  
post #10 of 20 Old 01-04-2016, 06:11 AM
AVS Special Member
 
bear123's Avatar
 
Join Date: Dec 2013
Location: PA
Posts: 4,743
Mentioned: 24 Post(s)
Tagged: 0 Thread(s)
Quoted: 1550 Post(s)
Liked: 2241
I think for the most part, there are way too many people who think there is some kind of magical sound quality difference between various high quality, well designed subs. I'm not saying all subs sound exactly the same, but I am saying that if you took someones "preferred" audiophile sub using some sort of magic technology that improves its "accuracy, tightness, speed, articulation" etc etc, put it behind a curtain with any other well designed, quality ID sub(PSA S1500, SB13 Ultra, ULS15, Gamma15, etc), eq'd them the same in the same room, people would not be able to tell them apart.

Now if they are looking at it, and know which one is playing, then of course their preferred sub will undoubtedly sound crisper, tighter, and more "musical".
lovinthehd likes this.
bear123 is offline  
post #11 of 20 Old 01-04-2016, 07:36 AM
AVS Addicted Member
 
Bill Fitzmaurice's Avatar
 
Join Date: Nov 2009
Location: New Hampshire
Posts: 13,566
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 3 Post(s)
Liked: 3858
Quote:
Originally Posted by bear123 View Post
if you took someones "preferred" audiophile sub using some sort of magic technology that improves its "accuracy, tightness, speed, articulation" etc etc put it behind a curtain with any other well designed, quality ID sub(PSA S1500, SB13 Ultra, ULS15, Gamma15, etc), eq'd them the same in the same room, people would not be able to tell them apart
+1, especially as those aspects generally don't apply to subs anyway.

Bill Fitzmaurice Loudspeaker Design

The Laws of Physics aren't swayed by opinion.
Bill Fitzmaurice is offline  
post #12 of 20 Old 01-04-2016, 07:54 AM
AVS Special Member
 
JT78681's Avatar
 
Join Date: Apr 2012
Location: Austin, Texas
Posts: 3,126
Mentioned: 5 Post(s)
Tagged: 0 Thread(s)
Quoted: 1275 Post(s)
Liked: 796
Quote:
Originally Posted by bear123 View Post
I think for the most part, there are way too many people who think there is some kind of magical sound quality difference between various high quality, well designed subs. I'm not saying all subs sound exactly the same, but I am saying that if you took someones "preferred" audiophile sub using some sort of magic technology that improves its "accuracy, tightness, speed, articulation" etc etc, put it behind a curtain with any other well designed, quality ID sub(PSA S1500, SB13 Ultra, ULS15, Gamma15, etc), eq'd them the same in the same room, people would not be able to tell them apart.

Now if they are looking at it, and know which one is playing, then of course their preferred sub will undoubtedly sound crisper, tighter, and more "musical".
I can't help, but to think this is some sort of cheap shot at a certain company.

Display - LG 65EF9500
Receiver - Denon 4311CI
Speakers - Klipsch RF-82 II's, RC-62 II, RB-61 II's
Subs - Rythmik FV15HP's
JT78681 is offline  
post #13 of 20 Old 01-04-2016, 08:16 AM
AVS Special Member
 
bear123's Avatar
 
Join Date: Dec 2013
Location: PA
Posts: 4,743
Mentioned: 24 Post(s)
Tagged: 0 Thread(s)
Quoted: 1550 Post(s)
Liked: 2241
Quote:
Originally Posted by JT78681 View Post
I can't help, but to think this is some sort of cheap shot at a certain company.
I think it can be widely applied to many subs who market themselves as "musical" to appeal to audiophiles. Plenty of people who think their small sealed B&W sub, or REL, or JL etc is going to be more "musical" or "faster" or "accurate" etc etc than for example, an F15HP, or FV15HP, or V1500, VTF3.5 etc. Cuz you know, 10" drivers are so much faster and crispy.
bear123 is offline  
post #14 of 20 Old 01-04-2016, 08:21 AM
Member
 
highender1970's Avatar
 
Join Date: May 2009
Posts: 19
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 5 Post(s)
Liked: 5
This should be the impulse reponse from my system (according Dirac Live).



Light blue = before correction
Green = after correction

I do not know if it is caused by the impulse reponse correction alone but I do notice:
- more precise imaging
- better defined bass with more impact

Mini PC: Guleek i8 WIN10 + Wireless keyboard: Logitech K400 + HDD: Oyen Digital 1TB external HDD
Mediaplayer: Albumplayer
Room Correction Software: Dirac Live
Main Loudspeakers: KEF X300A with subwoofer output
Subwoofer: KEF Q400
highender1970 is offline  
post #15 of 20 Old 01-04-2016, 08:22 AM
AVS Special Member
 
JT78681's Avatar
 
Join Date: Apr 2012
Location: Austin, Texas
Posts: 3,126
Mentioned: 5 Post(s)
Tagged: 0 Thread(s)
Quoted: 1275 Post(s)
Liked: 796
Quote:
Originally Posted by bear123 View Post
I think it can be widely applied to many subs who market themselves as "musical" to appeal to audiophiles. Plenty of people who think their small sealed B&W sub, or REL, or JL etc is going to be more "musical" or "faster" or "accurate" etc etc than for example, an F15HP, or FV15HP, or V1500, VTF3.5 etc. Cuz you know, 10" drivers are so much faster and crispy.
Gotcha! As long as it wasn't only Rythmik that was directed at I'm okay with that.

Display - LG 65EF9500
Receiver - Denon 4311CI
Speakers - Klipsch RF-82 II's, RC-62 II, RB-61 II's
Subs - Rythmik FV15HP's
JT78681 is offline  
post #16 of 20 Old 01-04-2016, 10:46 AM
AVS Special Member
 
tvuong's Avatar
 
Join Date: Dec 2000
Posts: 3,643
Mentioned: 33 Post(s)
Tagged: 0 Thread(s)
Quoted: 1397 Post(s)
Liked: 761
Doesn't eq the subs equally flat affect output, waterfall, and other area that makes one sub sound different than the other? What are the points of Ricci posting different area/type of sub graphs then?
tvuong is online now  
post #17 of 20 Old 01-04-2016, 10:59 AM
AVS Special Member
 
braveheart123's Avatar
 
Join Date: Jul 2011
Location: Lone Wolf McQuade from Islamabad Pakistan
Posts: 2,438
Mentioned: 1 Post(s)
Tagged: 0 Thread(s)
Quoted: 303 Post(s)
Liked: 271
Quote:
Originally Posted by highender1970 View Post
This should be the impulse reponse from my system (according Dirac Live).



Light blue = before correction
Green = after correction

I do not know if it is caused by the impulse reponse correction alone but I do notice:
- more precise imaging
- better defined bass with more impact
Sub pass band does not focus on imaging.

History is written by those who have hanged heroes ...

Main System: PSB X2T, PSB XC, PSB XB, Cambridge Audio Azur 751R, Rythmik FV15HP, PSB S500
braveheart123 is offline  
post #18 of 20 Old 01-04-2016, 12:09 PM
AVS Addicted Member
 
Bill Fitzmaurice's Avatar
 
Join Date: Nov 2009
Location: New Hampshire
Posts: 13,566
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 3 Post(s)
Liked: 3858
Quote:
Originally Posted by tvuong View Post
Doesn't eq the subs equally flat affect output, waterfall, and other area that makes one sub sound different than the other?
EQ only affects frequency response. You can have a dozen subs with the same frequency response but they won't necessarily sound the same. The factor that would make them sound the most different is THD, although that's by no means the only factor. The reason why THD is so important is that it manifests not only within the subwoofer pass band but also above the sub pass band.

Bill Fitzmaurice Loudspeaker Design

The Laws of Physics aren't swayed by opinion.
Bill Fitzmaurice is offline  
post #19 of 20 Old 01-04-2016, 12:33 PM
Advanced Member
 
Steve1981's Avatar
 
Join Date: Jul 2011
Location: Maryland
Posts: 783
Mentioned: 2 Post(s)
Tagged: 0 Thread(s)
Quoted: 153 Post(s)
Liked: 152
Quote:
Originally Posted by Bill Fitzmaurice View Post
EQ only affects frequency response. You can have a dozen subs with the same frequency response but they won't necessarily sound the same. The factor that would make them sound the most different is THD, although that's by no means the only factor. The reason why THD is so important is that it manifests not only within the subwoofer pass band but also above the sub pass band.
There's also the small matter of how well the sub can hold its EQed response. For example, I can take this sub and EQ it so that it looks nice and flat on a 75dB sweep in my room. Even barring differences in THD, is it going to sound the same as a top end sub from (insert your favorite brand here) when I play a bass movie at spirited levels? Of course not. The room only adds further complexity to this. Imagine having the aforementioned sub in a room that exhibited a peak centered at 50Hz and a dip between 60-80Hz.
Steve1981 is offline  
post #20 of 20 Old 01-04-2016, 01:54 PM
AVS Addicted Member
 
Bill Fitzmaurice's Avatar
 
Join Date: Nov 2009
Location: New Hampshire
Posts: 13,566
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 3 Post(s)
Liked: 3858
Quote:
Originally Posted by Steve1981 View Post
There's also the small matter of how well the sub can hold its EQed response. For example, I can take this sub and EQ it so that it looks nice and flat on a 75dB sweep in my room. Even barring differences in THD, is it going to sound the same as a top end sub from (insert your favorite brand here) when I play a bass movie at spirited levels?
In that it wouldn't sound the same that's very much a product of THD. Once the driver reaches xmax at low frequencies additional power applied causes increased THD, which manifests as response no longer being linear.
What you end up with is similar to clipping of the signal.
One of the issues with an SPL and THD charts is that they're typically measured at small signal levels. To be definitive you need a series of charts, measured at every increasing power levels.
Even very high xmax doesn't insure linear response and low THD to high power levels, as high cone excursion results in increased THD even when xmax hasn't been reached.

Bill Fitzmaurice Loudspeaker Design

The Laws of Physics aren't swayed by opinion.

Last edited by Bill Fitzmaurice; 01-04-2016 at 01:57 PM.
Bill Fitzmaurice is offline  
Sponsored Links
Advertisement
 
Reply Subwoofers, Bass, and Transducers

Thread Tools
Show Printable Version Show Printable Version
Email this Page Email this Page


Forum Jump: 

Posting Rules  
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off