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

[richard12511]

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.

The issue is that Dirac has no way to correct the off axis response without also changing the on axis response. Any filter you apply to try and fix an off axis response error will also alter the on axis response, which is why you need the two to be of similar shape.

 

[NTK]

Steady state measurement (using pink noise, for example) can give you none of the above, as it doesn't record time-domain information.

It will however give you the same frequency response as the one of the green curve.

I realize I should have used the vector sum to calculate the "measured" magnitude. Just feel a bit lazy to correct it now . I will probably update the graph in my earlier post tomorrow. But not considering the phase will introduce errors.

[Edit] Updated the graph in my earlier post (#28).

 

[dfuller]

sorry for bothering you with my ignorance. And by the way, any consideration on decay was out of scope. I know it cannot be fixed. Never suggested you could play music in a cathedral as long as you have DIRAC

I'm sorry, I didn't mean it to come off that way. I more meant that room correction EQ is not a magic bullet like gets thrown around in this forum a lot. Apologies again, I came off as kind of a dick.

Anyway, longer version: EQ can correct for on-axis or off-axis response, but not both at the same time, which is why generally wider dispersion is preferred if you're not sitting extremely nearfield (like within 1m). With that said, it cannot correct for resonances (modes), slaps, or flutter echo. It can kinda mitigate modes a bit (though the ability to do so is limited), but a good in-room response requires some amount of absorption.

 

[o2so]

The issue is that Dirac has no way to correct the off axis response without also changing the on axis response. Any filter you apply to try and fix an off axis response error will also alter the on axis response, which is why you need the two to be of similar shape.

This explains it very well, thank you. I think however that DIRAC records time-domain info and will probably guess how much is direct and how much is reflected based on that. Then it would have to make some sort of compromise correction I guess. Hence it is definitely better to have speakers with similar on/off axis, so the compromise is smaller. Which answers my original question. Thanks all.

 

[Ellebob]

There is no doubt a measurement system like Dirac or other auto EQ has the capability to determine direct sound and reflected sound. I'm not sure if they do as it would add some time but in theory they should be capable. While it can measure it, it can't change the speaker's dispersion properties or the room properties. They can't fix many acoustic problems like SBIR (speaker boundary interference response).

The software we use at work (TEF based) it will show us where reflections are happening in a room. Trinnov with its 4 microphones can do something similar for its remapping. We can decide whether to treat that reflection and what type of treatment would work best. These auto EQ systems simply do not take enough measurements with just a few locations that a mic is placed. It basically does averaging with multiple locations with a weighting towards the primary listening location. But, they can determine the direct vs reflected sound if they choose.

In a nutshell they take a few measurements and try to take their best educated guess on what to EQ and what to leave alone. Sometimes it is a positive result other times it is not. Also, in a given room one EQ algorithm might do a better job than another. So while Dirac might technically be better it might not have better result in every room. In some rooms YPAO, Audyssey, ARC, Room Perfect, etc. might work better. We can measure 100 rooms and see which one gets improvement in most rooms but in a given room does mean it will be the best. Auto EQ is somewhat of a crapshoot.

People should not rely on EQ to get good sound. with acoustics we say good sound comes from location, location, location just like real estate. But with acoustics it is... location of seating, location of speakers/subs, location of acoustic treatments. Of course this assumes quality equipment including speakers and subs. If you have decent speakers and equipment, place everything well and do a proper set up, EQ will be the icing on the cake but it can't replace the cake.

 

[sfdoddsy]

#Ellebob. How do you decide which one is doing the best job?

Ears can’t be trusted, and most measurement systems have the same issues as the RoomEQ they are measuring.

 

[phoenixdogfan]

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?

Don't you have LS 50 Metas? Those speakers have very good, smooth directivity. That is, the off axis frequency response curves closely match the on axis curve for the most part. Such a design will lend itself quite well for use with Dirac Live. So, while the theoretical issue is correct--namely, that you can't make a sow's ear into a silk purse--you are already starting with some raw material that came from a worm rather than a porker. Same would probably be true if you pulled the trigger on your contemplated purchase of the Revel 228be's.

 

[ppataki]

Just sharing here my personal and subjective experience:

I have full-range Audio Nirvana speakers with extreme beaming (if I sit 10cm away from the sweet spot I lose half the sound....)
But I consider that as a feature and not a bug since I barely have any reflections this way. I can clearly see that from my impulse response curves compared to my previous multiway speakers

I have been using Dirac Live for many years and in my case it indeed does the magic
It fixes the frequency range deficiencies of my speakers and the sound is just awesome. It also corrects the <1ms part of the impulse response curve and the step response curve also looks better

I have recently tested multiple full range drivers (multiple ANs, Monacor, Mark Audio, Morel) and this was the case with all of them - extremely good results with Dirac Live
(I am not affiliated with them of course, just sharing my experience in case anybody was thinking about using full range speakers with DSP/DRC)

 

[vavan]

that comment from @mitchco might be of some interest: "I have yet to come across anyone who prefers the partial over the full range correction"

 

[Pio2001]

that comment from @mitchco might be of some interest: "I have yet to come across anyone who prefers the partial over the full range correction"

Wasn't Mitchco talking about excess phase correction ?

 

[FrantzM]

Just sharing here my personal and subjective experience:

I have full-range Audio Nirvana speakers with extreme beaming (if I sit 10cm away from the sweet spot I lose half the sound....)
But I consider that as a feature and not a bug since I barely have any reflections this way. I can clearly see that from my impulse response curves compared to my previous multiway speakers

I have been using Dirac Live for many years and in my case it indeed does the magic
It fixes the frequency range deficiencies of my speakers and the sound is just awesome. It also corrects the <1ms part of the impulse response curve and the step response curve also looks better

I have recently tested multiple full range drivers (multiple ANs, Monacor, Mark Audio, Morel) and this was the case with all of them - extremely good results with Dirac Live
(I am not affiliated with them of course, just sharing my experience in case anybody was thinking about using full range speakers with DSP/DRC)

10 cm is tight ...
Head in a vise comes to mind. No head bobbing without "losing half the sound"
To each his own, I guess

 

[Ellebob]

#Ellebob. How do you decide which one is doing the best job?

Ears can’t be trusted, and most measurement systems have the same issues as the RoomEQ they are measuring.

For most it would be which one is most pleasing to them. Most people use their auto set up and if they like the sound they keep it, otherwise they turn it off.

If you have the ability to take measurements then you can see what the EQ did and with knowing the speaker and room measurements you can get and idea what it tried to correct. I don't believe there is a best EQ system that works best for all rooms. The best is hire someone or do it manually which is not always an option.

My favorite for the enthusiast that isn't too geeky is Anthem's ARC. Why? Because with its quick measure feature you can measure your speakers on/off axis with it and use it to find the best placement for your subs and seating. It is easier to do this for many than learn something like REW. ARC also has good adjustability in the how high you want to EQ and some other settings for some personalization. But it will still require some learning curve over just using the auto feature. For someone more geeky and willing to spend more time learning than get REW. The enthusiast might prefer Dirac, Audyssey or using a manual parametric EQ which Yamaha has a useful but limited one built in many of their receivers or possibly a mini DSP. If you have REW you have the ability to do a lot more but the learning curve is steeper not only for REW but for what you are trying to achieve.

 

[firedog]

Better speaker performance=better source. Always a good thing. DRC can be great, but the less it "needs" to do the better it works.
And in any case if you have what most rooms have - one or more significant room nodes - no speaker can make up for that. DRC takes care of it as no speaker can.
There are some DRC programs that have an option for output to one listening point or a wider "sofa" presentation. One for solo listening, the other for social listening.

 

[o2so]

The issue is that Dirac has no way to correct the off axis response without also changing the on axis response. Any filter you apply to try and fix an off axis response error will also alter the on axis response, which is why you need the two to be of similar shape.

does this mean that If I have a decent off axis response I should NOT absorb first reflections, especially not with home decor such as pillows or thick blankets because these would mess up what otherwise would be a decent off axis response?

 

[Sancus]

does this mean that If I have a decent off axis response I should NOT absorb first reflections, especially not with home decor such as pillows or thick blankets because these would mess up what otherwise would be a decent off axis response?

This is broadly correct. Room treatment and amount of preferred reflections are very complex topics. There's well over 100 pages about it in Toole's book. Amount of reflections preferred varies although most prefer "some". Not too few and not too many.

Reflections improve envelopment and also fix the timbre of stereo: "Early reflections from different directions tend to fill in the interference dip, making the spectrum more neutral. This is a spectral reason to prefer wide dispersion loudspeakers and to encourage reflections." Toole, p. 183

That doesn't mean absorption is a bad idea. It's encouraged for multi-channel, for example, and if your room is in any way asymmetric, it's also useful. You also may need some simply to reach the optimal level of reflections. However, as you say, you need to make sure your absorption is actually absorbing frequencies reasonably evenly, otherwise you can make things worse.

There have been many previous discussions on this topic although some of them are a bit of a mess...

 

[Tangband]

The issue is that Dirac has no way to correct the off axis response without also changing the on axis response. Any filter you apply to try and fix an off axis response error will also alter the on axis response, which is why you need the two to be of similar shape.

Yes - and the direct sound is always the dominant when youre perceiving sound - the direct sound from the loudspeaker to your ears is the most important, depending on the HAAS effect and the precedence-effect. So what looks good with a microphone at listeningposition is not the same what the ear hears.

With that said, you also can not correct a loudspeaker with bad directivity .

Best result will always be without room correction,- in a very good room with optimal placement of the loudspeaker no correction at all is needed. This will sound the best, but might require a professional installation service to make it good.

If one needs to have the loudspeaker in a less than optimal place , in a bad room , the sound can be less bad with room correction.

 

[DanielT]

Try doing Digital Room Correction with your mobile phone's speaker and you'll see how good it will be.
There is a limit to what you can cream out of a pair of speakers.

 

[dasdoing]

personaly, the only reason for me to upgrade is less distorsion. my reflection points are heavily treated though

 

[sfdoddsy]

does this mean that If I have a decent off axis response I should NOT absorb first reflections, especially not with home decor such as pillows or thick blankets because these would mess up what otherwise would be a decent off axis response?

It doesn't mean you should NOT. It means you don't necessarily have to.

I've been using room EQ in one form or another for almost 20 years.

I started out with a heavy hand. Because I could. And because I could measure it.

But all my recent speakers have very good response and very good directivity.

That's why I picked them.

So, unless the room is truly awful, I only EQ below 200Hz or so.

There is certainly a difference if I do full range EQ. But that's not the same as a benefit.

 

[MusicNBeer]

In addition to on/off axis directivity issue, room correction will never fix a poorly designed enclosure or high distortion due to poor driver design. Poor crossover design generally exacerbates the on/off directivity issues.

Fancy DSP can help but it's no magical cure. I've generally found that a well engineered speaker will sound good with almost all music and it will sound good in most rooms without any EQ. With that said, I do like the idea of EQing the deep bass response.