• WANTED: Happy members who like to discuss audio and other topics related to our interest. Desire to learn and share knowledge of science required as is 20 years of participation in forums (not all true). Come here to have fun, be ready to be teased and not take online life too seriously. We now measure and review equipment for free! Click here for details.

How important is good speaker design if you have Digital Room Correction

o2so

Active Member
Forum Donor
Joined
Sep 9, 2019
Messages
186
Likes
104
Location
Sydney, Australia
#1
I could not quite encapsulate the topic I wanted to discuss here in the title, because it is a bit more complex than that.

ASR provides incredibly helpful information on - among other things - speaker performance. One of the key elements considered to determine such performance is Frequency Response, with a particular emphasis given - rightfully - to the Predicetd In Room (PIR) response.

This depends on the FR on-axis, off-axis and first reflections. The latter two items, correct me if I am wrong, depend on the capability of the speaker to project a relatively flat FR off-axis, so that when this bounces off the wall or the ceiling and gets to us it does not mess up the balance of the on-axis FR.
Speakers such as Revels or Genelec are particularly good at this (and also at most other things, minus the awful design IMHO). In some cases we have seen some of these speakers having a non-perfect on-axis FR, but an almost perfect PIR because the first reflections would end up FIXING the issues seen in the on-axis response.

At the same time Digital Rom Correction systems have become increasingly popular, very effective and really not more expensive than most traditional preamplifiers (I am thinking MiniDSP SHD). These systems simply measure the frequency response at the listening position and apply equalisation and time delays to ensure that what gets to your ears is a flat response, or whichever response you ask the software to generate. Not only this, but software like DIRAC fix time alignment of multiple drivers and phase.

Now, in a system that has this type of DSP, how important is the speaker natural PIR and step response, really?
I think these speaker attributes become important only if:
  • one listens to music in different parts of the room, not always in the same spot. In this case, DRC can not do much as FR and step response can really only be properly fixed at one listening spot. BUT seriously, who on earth would spend thousands on a hi-fi system and then not sit right in the sweet spot to enjoy it? Yes ok we all like background music when we do other stuff around the house, but being background music its fidelity is also relatively unimportant.
  • one believes that DSP is evil and will pollute your analog music with evil digital artifacts.
In addition to the above, if most of our listening is in the sweet spot and our speakers are good on-axis but not so good off-axis, we can simply treat the sidewalls, use a nice thick rug and absorb first reflections so that the DRC does not have to work too hard (not that I have ever heard my MiniDSP complaining though).

Finally, even if we have speakers with near-perfect PIR that do not require DRC (this is really a non-possible case, because even these speakers will massively benefit from DRC for the lower frequencies), is there not a time-smear issue due to the high frequencies being "sprayed" (like Mr Sanders would say) all over the room and bouncing back at us at different times? Is it not better to absorb first reflections ANYWAY?

So, if one:
  • uses DRC on the full frequency range
  • only or mostly sits in the sweet spot
  • has some floor and side-walls absorption
How important is to have speakers with great diffusion and PIR?
 

Sancus

Major Contributor
Forum Donor
Joined
Nov 30, 2018
Messages
1,060
Likes
2,356
Location
Canada
#4
In addition to the above, if most of our listening is in the sweet spot and our speakers are good on-axis but not so good off-axis, we can simply treat the sidewalls, use a nice thick rug and absorb first reflections so that the DRC does not have to work too hard (not that I have ever heard my MiniDSP complaining though).
This is just putting lipstick on a pig, though. Full range treatment effectively does not exist, so you are just arbitrarily altering tonality when you absorb reflections. While you can use a variety of (expensive, time consuming, and/or ugly) treatments to heavily reduce reflections, if you (somehow) fully eliminated them, most people would not like the resulting sound. It is far cheaper, more effective, and simpler to just buy speakers with good off-axis response than hope to fix a bad speaker with room treatment.

On axis response matters far less than off axis. If you have good off axis response, then any EQ you perform on the speaker will equally affect the on and off axis sound, allowing you to correct any on axis issues fairly easily. And indeed change the response to your preferences.

Considering that good FR both on and off-axis is not really hard to find, though, the real question is: Why bother buying anything that doesn't have those attributes to begin with?
 

Absolute

Addicted to Fun and Learning
Forum Donor
Joined
Feb 5, 2017
Messages
633
Likes
1,123
#5
Paramount importance. Room correction will never make a bad speaker sound good, assuming you're not in an anechoic chamber. I don't know how many hundreds of hours I've measured and re-calibrated both Dirac and Audiolense with various speakers, but to me it never sounds better with full-range correction with any speaker than it does limited to the bass range.
 
OP
o2so

o2so

Active Member
Forum Donor
Joined
Sep 9, 2019
Messages
186
Likes
104
Location
Sydney, Australia
Thread Starter #6
This is just putting lipstick on a pig, though. Full range treatment effectively does not exist, so you are just arbitrarily altering tonality when you absorb reflections. While you can use a variety of (expensive, time consuming, and/or ugly) treatments to heavily reduce reflections, if you (somehow) fully eliminated them, most people would not like the resulting sound. It is far cheaper, more effective, and simpler to just buy speakers with good off-axis response than hope to fix a bad speaker with room treatment.

On axis response matters far less than off axis. If you have good off axis response, then any EQ you perform on the speaker will equally affect the on and off axis sound, allowing you to correct any on axis issues fairly easily. And indeed change the response to your preferences.

Considering that good FR both on and off-axis is not really hard to find, though, the real question is: Why bother buying anything that doesn't have those attributes to begin with?
Lipstick on a pig = using DRC? I think it is more like magically turning a pig into a playmate! (provided that other speaker parameters that DRC cannot fix are good, especially distortion).

There arent really THAT MANY options of speakers with great PIR, except Revels, Genelecs and few others. I could be incorrect though. So the reasons could be just as simple as all the available options look ugly, or I cannot find these at a good price or anything else that comes into play when you buy something, really.
 

FrantzM

Major Contributor
Forum Donor
Joined
Mar 12, 2016
Messages
1,976
Likes
2,598
#7
What "garbage in" are you talking about? There is no "garbage in" assumption whatsoever in what I wrote.
Sorry... If the speaker is not properly designed what comes out is likely garbage.. That would be the DSP input (the GI),,, The likelihood of low performance remains high(GO). You can make it better which is not the same as good , but not optimal...
You don't have to believe,
You could try and report to us. We will learn from it.
 
OP
o2so

o2so

Active Member
Forum Donor
Joined
Sep 9, 2019
Messages
186
Likes
104
Location
Sydney, Australia
Thread Starter #8
Paramount importance. Room correction will never make a bad speaker sound good, assuming you're not in an anechoic chamber. I don't know how many hundreds of hours I've measured and re-calibrated both Dirac and Audiolense with various speakers, but to me it never sounds better with full-range correction with any speaker than it does limited to the bass range.
I accept that this is your experience. However when I measure my speakers with DIRAC on, the FR is pretty darn perfect
 
Joined
Oct 27, 2020
Messages
17
Likes
11
#9
I could not quite encapsulate the topic I wanted to discuss here in the title, because it is a bit more complex than that.

ASR provides incredibly helpful information on - among other things - speaker performance. One of the key elements considered to determine such performance is Frequency Response, with a particular emphasis given - rightfully - to the Predicetd In Room (PIR) response.

This depends on the FR on-axis, off-axis and first reflections. The latter two items, correct me if I am wrong, depend on the capability of the speaker to project a relatively flat FR off-axis, so that when this bounces off the wall or the ceiling and gets to us it does not mess up the balance of the on-axis FR.
Speakers such as Revels or Genelec are particularly good at this (and also at most other things, minus the awful design IMHO). In some cases we have seen some of these speakers having a non-perfect on-axis FR, but an almost perfect PIR because the first reflections would end up FIXING the issues seen in the on-axis response.

At the same time Digital Rom Correction systems have become increasingly popular, very effective and really not more expensive than most traditional preamplifiers (I am thinking MiniDSP SHD). These systems simply measure the frequency response at the listening position and apply equalisation and time delays to ensure that what gets to your ears is a flat response, or whichever response you ask the software to generate. Not only this, but software like DIRAC fix time alignment of multiple drivers and phase.

Now, in a system that has this type of DSP, how important is the speaker natural PIR and step response, really?
I think these speaker attributes become important only if:
  • one listens to music in different parts of the room, not always in the same spot. In this case, DRC can not do much as FR and step response can really only be properly fixed at one listening spot. BUT seriously, who on earth would spend thousands on a hi-fi system and then not sit right in the sweet spot to enjoy it? Yes ok we all like background music when we do other stuff around the house, but being background music its fidelity is also relatively unimportant.
  • one believes that DSP is evil and will pollute your analog music with evil digital artifacts.
In addition to the above, if most of our listening is in the sweet spot and our speakers are good on-axis but not so good off-axis, we can simply treat the sidewalls, use a nice thick rug and absorb first reflections so that the DRC does not have to work too hard (not that I have ever heard my MiniDSP complaining though).

Finally, even if we have speakers with near-perfect PIR that do not require DRC (this is really a non-possible case, because even these speakers will massively benefit from DRC for the lower frequencies), is there not a time-smear issue due to the high frequencies being "sprayed" (like Mr Sanders would say) all over the room and bouncing back at us at different times? Is it not better to absorb first reflections ANYWAY?

So, if one:
  • uses DRC on the full frequency range
  • only or mostly sits in the sweet spot
  • has some floor and side-walls absorption
How important is to have speakers with great diffusion and PIR?
It's a good question. We see this as well in headphones, e.g. Bose vs. Sennheiser. And not just for sound, but for optics/photography as well. You don't have to design a perfect lens, when you can correct a lot of the distortion in postprocessing. From the experience I can tell the same happens in fibre optics communication, where a lot of the recent gains in bandwidth are due to heavy DSP.
Personally I think the DSP is here to stay, and I don't see anything wrong with it. Essentially it allows you to tweak the overall frequency response of the system. What's the difference (to a degree!) where it is done.
 
OP
o2so

o2so

Active Member
Forum Donor
Joined
Sep 9, 2019
Messages
186
Likes
104
Location
Sydney, Australia
Thread Starter #11
Sorry... If the speaker is not properly designed what comes out is likely garbage.. That would be the DSP input (the GI),,, The likelihood of low performance remains high(GO). You can make it better which is not the same as good , but not optimal...
You don't have to believe,
You could try and report to us. We will learn from it.
dont follow, sorry.
We are talking about two speakers that are identical in everything but off-axis response. One has great off-axis response, the other one has pretty bad off-axis response. Dirac will fix this mismatch so that what gets to your ears is the same thing, or really, really close to it.

Of course, if your speakers have loads of distortion you will still get that, but this is not the example I am discussing here.
 

Sancus

Major Contributor
Forum Donor
Joined
Nov 30, 2018
Messages
1,060
Likes
2,356
Location
Canada
#12
Lipstick on a pig = using DRC?
Your response indicates to me that you don't understand my post. If your speaker has poor off-axis response, then EQ will change your reflections unpredictably relative to your on-axis response. In addition, room treatments can help, but you still won't be able to fix all the issues because treatments can only affect certain frequencies, not all of them.

Lipstick on a pig = DRC or room treatments for a bad speaker.

On the other hand, if a speaker has smooth off-axis response, any change you make with EQ(DRC or manual, doesn't matter) will equally affect the on and off-axis. That's what you want, because you cannot separately EQ the on and off-axis, so you want them to change together linearly and predictably.

There arent really THAT MANY options of speakers with great PIR, except Revels, Genelecs and few others. I could be incorrect though.
You are incorrect. There are many. Amir has only reviewed 100 or so speakers(which is a LOT for a year's work, but few compared to all the speakers out there). There are long, long threads listing many manufacturers that pursue evidence-based design and sell speakers that likely measure reasonably well.

Here's a cheap, passive speaker that has great on and off-axis response. If what you're looking for is aesthetics and a traditional hi-fi speaker design, there are companies like Selah and Salk producing the BMR out there. I'm not gonna try to list all of them but seriously, there are SO many options it'll make your head spin.
 

Absolute

Addicted to Fun and Learning
Forum Donor
Joined
Feb 5, 2017
Messages
633
Likes
1,123
#13
dont follow, sorry.
We are talking about two speakers that are identical in everything but off-axis response. One has great off-axis response, the other one has pretty bad off-axis response. Dirac will fix this mismatch so that what gets to your ears is the same thing, or really, really close to it.
No, it won't. The mismatch between direct and indirect sound will always be the same in a reflective environment.
 
OP
o2so

o2so

Active Member
Forum Donor
Joined
Sep 9, 2019
Messages
186
Likes
104
Location
Sydney, Australia
Thread Starter #14
ok
Your response indicates to me that you don't understand my post. If your speaker has poor off-axis response, then EQ will change your reflections unpredictably relative to your on-axis response. In addition, room treatments can help, but you still won't be able to fix all the issues because treatments can only affect certain frequencies, not all of them.

Lipstick on a pig = DRC or room treatments for a bad speaker.

On the other hand, if a speaker has smooth off-axis response, any change you make with EQ(DRC or manual, doesn't matter) will equally affect the on and off-axis. That's what you want, because you cannot separately EQ the on and off-axis, so you want them to change together linearly and predictably.



You are incorrect. There are many. Amir has only reviewed 100 or so speakers(which is a LOT for a year's work, but few compared to all the speakers out there). There are long, long threads listing many manufacturers that pursue evidence-based design and sell speakers that likely measure reasonably well.

Here's a cheap, passive speaker that has great on and off-axis response. If what you're looking for is aesthetics and a traditional hi-fi speaker design, there are companies like Selah and Salk producing the BMR out there. I'm not gonna try to list all of them but seriously, there are SO many options it'll make your head spin.
Ok thanks. So you are saying that DIRAC only makes fixes based on on axis response? Is that right?
 

Absolute

Addicted to Fun and Learning
Forum Donor
Joined
Feb 5, 2017
Messages
633
Likes
1,123
#15
ok


Ok thanks. So you are saying that DIRAC only makes fixes based on on axis response? Is that right?
No, he's saying that if you add 4 dB at 1000 hz you will make a 4 dB peak in the direct sound to fix that 4 dB sound power problem the DRC found. No way around that.
 
OP
o2so

o2so

Active Member
Forum Donor
Joined
Sep 9, 2019
Messages
186
Likes
104
Location
Sydney, Australia
Thread Starter #16
Not following. If I measure a 4db dip at 1000 Hz and this is the result of on-axis and off-axis response, why would not a +4db eq at 1000 Hz fix that? Is that because that could turn into an unpredictable increase off axis?
 

Sancus

Major Contributor
Forum Donor
Joined
Nov 30, 2018
Messages
1,060
Likes
2,356
Location
Canada
#17
Ok thanks. So you are saying that DIRAC only makes fixes based on on axis response? Is that right?
Dirac does fixes based on all the sound arriving at the measurement point(s). It has no way of distinguishing between reflections and direct sound, as microphones cannot measure those separately. Our ears, on the other hand, distinguish direct sound and reflections very easily.

It is possible to measure reflections and direct sound separately by using time-based gating, however, this has many limitations, and in any event it doesn't help your DRC very much because Dirac has no magical way to change the EQ for on and off-axis sound separately. Dirac can do exactly two things: EQ all the sound your speaker is outputting at a given frequency, and change the timing for all the sound at a given frequency.

It cannot do things like "change the sound at 30 degrees off axis by +2dB and the sound at 0 degrees by -2dB". Which is the minimum that would be required to fix off-axis problems.
 

thewas

Major Contributor
Forum Donor
Joined
Jan 15, 2020
Messages
2,113
Likes
4,535
#18
Dirac does fixes based on all the sound arriving at the measurement point(s). It has no way of distinguishing between reflections and direct sound, as microphones cannot measure those separately. Our ears, on the other hand, distinguish direct sound and reflections very easily.

It is possible to measure reflections and direct sound separately by using time-based gating, however, this has many limitations, and in any event it doesn't help your DRC very much because Dirac has no magical way to change the EQ for on and off-axis sound separately. Dirac can do exactly two things: EQ all the sound your speaker is outputting at a given frequency, and change the timing for all the sound at a given frequency.

It cannot do things like "change the sound at 30 degrees off axis by +2dB and the sound at 0 degrees by -2dB". Which is the minimum that would be required to fix off-axis problems.
Exactly, like Floyd Toole had written:

Equalization can address frequency response issues, but cannot fix directivity issues. Consider getting better loudspeakers. Equalizing flawed loudspeakers to match this room curve does not guarantee anything in terms of sound quality.

More interesting reading about room correction from him in below thread:
https://www.audiosciencereview.com/...ut-room-curve-targets-room-eq-and-more.10950/
 
OP
o2so

o2so

Active Member
Forum Donor
Joined
Sep 9, 2019
Messages
186
Likes
104
Location
Sydney, Australia
Thread Starter #19
Dirac does fixes based on all the sound arriving at the measurement point(s). It has no way of distinguishing between reflections and direct sound, as microphones cannot measure those separately. Our ears, on the other hand, distinguish direct sound and reflections very easily.

It is possible to measure reflections and direct sound separately by using time-based gating, however, this has many limitations, and in any event it doesn't help your DRC very much because Dirac has no magical way to change the EQ for on and off-axis sound separately. Dirac can do exactly two things: EQ all the sound your speaker is outputting at a given frequency, and change the timing for all the sound at a given frequency.

It cannot do things like "change the sound at 30 degrees off axis by +2dB and the sound at 0 degrees by -2dB". Which is the minimum that would be required to fix off-axis problems.
This sounds important but I cannot quite grasp it.
In order for me to understand, can you confirm if on axis and off axis response simply sum up at the listening spot to get the measured response?
So if I measure a -4db dip at a given frequency, that would be the result of the sum of on-axis and off-axis at that frequency. For instance, I could have a -4db coming from off axis and a flat on-axis. Or -2dbs both on and off axis. or any other combination whose sum is -4. Is that correct?
 

Chrispy

Major Contributor
Forum Donor
Joined
Feb 7, 2020
Messages
1,015
Likes
729
Location
PNW
#20
I'd always prefer to start with better speakers than rely on REQ to fix things up....
 
Top Bottom