Target Room Response and Cinema X-curve

[mctron]

Were the systems that produced the responses in Figure 4. calibrated to the same level? Another interpretation of the graphed results would be that listeners prefer louder systems regardless of spectral content assuming they are not offset in magnitude for dsplay clarity.

I think we can safely assume they aren't doing a blind test with 30db SPL variation

 

[Sebastiaan de Vries]

A fascinating and informative discussion.

Is it then necessary to assume that all or most releases have a perfectly flat response? If they do not and they already have an incorporated curve, then are we in fact doubling up by adding the curve to our systems?

A flat response could mean we are hearing the recording as it was intended. Perhaps it all depends on the response of studio monitors?

Agree. I listen to a flat curve (Trinnov). I have tried various downward slopes from very mild to moderate. The HARMAN curve as well. I always end up getting annoyed by the obvious bass boosts which to me sounds as the same sauce over all content I feed the system. Ruler flat to me sounds transparant and allows me to hear various intent and tricks in the production.

 

[OCA]

Agree. I listen to a flat curve (Trinnov). I have tried various downward slopes from very mild to moderate. The HARMAN curve as well. I always end up getting annoyed by the obvious bass boosts which to me sounds as the same sauce over all content I feed the system. Ruler flat to me sounds transparant and allows me to hear various intent and tricks in the production.

Are your speakers toed-in towards the LP?

 

[Sebastiaan de Vries]

Are your speakers toed-in towards the LP?

Yes they are toed in 28° azimuth toward the LP. I am considered in the upper limit of near field.

 

[OCA]

I see, I thought maybe your speakers treble level could be low due to lack of toe-in or something because I don't like too much bass either but still prefer a 0.7 fixed slope as my target curve.

 

[Newman]

Agree. I listen to a flat curve (Trinnov). I have tried various downward slopes from very mild to moderate. The HARMAN curve as well. I always end up getting annoyed by the obvious bass boosts which to me sounds as the same sauce over all content I feed the system. Ruler flat to me sounds transparant and allows me to hear various intent and tricks in the production.

The only way I can think of to make such a preference (ungated FR at the listening position completely ruler flat) understandable, is if the Trinnov has a method for isolating direct from reflected sound, and is in fact applying the correction to the direct sound only. Does it???

Other than that, if your room is not completely anechoic, or your speakers are not completely omnidirectional, then your chosen settings are horribly mashing the frequency response of the direct sound reaching your ears from your speakers.

And, psychoacoustically, that direct sound is the most important one to have a flat FR in order to avoid perceptions of colouration.

cheers

 

[Sebastiaan de Vries]

The only way I can think of to make such a preference (ungated FR at the listening position completely ruler flat) understandable, is if the Trinnov has a method for isolating direct from reflected sound, and is in fact applying the correction to the direct sound only. Does it???

Other than that, if your room is not completely anechoic, or your speakers are not completely omnidirectional, then your chosen settings are horribly mashing the frequency response of the direct sound reaching your ears from your speakers.

And, psychoacoustically, that direct sound is the most important one to have a flat FR in order to avoid perceptions of colouration.

cheers

No one knows exactly “what” the Trinnov does, but I suspect with their beam-forming 3D measuring methods, they can subtract direct sound from indirect sound.

This reflects in the graphs it generates, where there is a tab displaying the direct sound plot only. Also, you can set in the setting how many cycles of indirect sound it must take into its measurements.

That being said. All recording engineers who own a Trinnov and control rooms have been corrected to a flat curve.

Genelecs GLM, by default, also corrects to a flat curve.

It doesn’t sound harsh or sterile but provides a precise sound reproduction compatible with the Sennheiser HD800 headphones.

Another possibility is my brain is wired to this sound and adapted to it. Any bass boost or tilt doesn’t sound natural to me.

That being said, in the latest software update Trinnov provide some suggested target curves, and the lightest slope (3.5dB total) does sound smooth and pleasant. But in an absolute sense to my ears, not natural, and I am still undecided between flat and that curve,

 

[sigbergaudio]

No one knows exactly “what” the Trinnov does, but I suspect with their beam-forming 3D measuring methods, they can subtract direct sound from indirect sound.

This reflects in the graphs it generates, where there is a tab displaying the direct sound plot only. Also, you can set in the setting how many cycles of indirect sound it must take into its measurements.

That being said. All recording engineers who own a Trinnov and control rooms have been corrected to a flat curve.

Genelecs GLM, by default, also corrects to a flat curve.

It doesn’t sound harsh or sterile but provides a precise sound reproduction compatible with the Sennheiser HD800 headphones.

Another possibility is my brain is wired to this sound and adapted to it. Any bass boost or tilt doesn’t sound natural to me.

That being said, in the latest software update Trinnov provide some suggested target curves, and the lightest slope (3.5dB total) does sound smooth and pleasant. But in an absolute sense to my ears, not natural, and I am still undecided between flat and that curve,

"All recording engineers who own a Trinnov and control rooms have been corrected to a flat curve" - how can you possibly know this?

A flat in-room response sounds harsh/sterile/too lean to most people. It's the wrong curve at home, and it's the wrong curve in a recording/mixing/mastering studio. A typical curve will slope gently towards the high frequencies.

The "correct" curve will vary based on the speakers dispersion characteristics, the size and characteristics of the room, etc. Also, a well engineered speaker will naturally give you the correct in-room slope, you don't have to force a target with room correction systems (such systems can however be used to reduce room interaction especially in the bass/midbass area).

 

[Sebastiaan de Vries]

"All recording engineers who own a Trinnov and control rooms have been corrected to a flat curve" - how can you possibly know this?

Because I work in the industry for most of my life and have installed many in the past.

You don’t need to take my word for it. YouTube tutorials about trinnov in the studio or calibrate to a flat response.

Most sound engineers don’t want a sloped target curve, it doesn’t translate well.

 

[sigbergaudio]

Most sound engineers don’t want a sloped target curve, it doesn’t translate well.

This is incorrect.

 

[Sebastiaan de Vries]

This is incorrect.

I beg to disagree. Look what they do with sonar works, GLM, Trinnov and other app’s.

 

[OCA]

Left speaker FR at the LP with all reflections vs direct sound, both physcoacoustic smoothed. Direct sound is obtained by applying 6ms gating to the original response. Given the distance from the speaker to LP in my room, 8.7ms would suffice to remove all reflections from the direct sound but I wanted to keep it at Linkwitz suggested 6ms after when reflections will be ignored by the brain.

Target curves are flat vs tilted by a 0.7 slope, both auto-leveled. No SPL alignment, gated response is as is with reflection volume boosts removed by windowing. I am open to debates about whether this is a good idea.

Obviously, most of the bass and low-mid information is lost or compromised but I guess it's fair to say that with no gating/FDW applied (response including all room reflections), a flat target will be a lot "less wrong" than a sloped one to correct for the HF. With proper windowing though, sloped target seems to make more sense.

 

[sigbergaudio]

I beg to disagree. Look what they do with sonar works, GLM, Trinnov and other app’s.

Here is Trinnov arguing that they DO NOT recommend a flat response "except for near field studio situations" <- which would be interesting to define, I would argue I only partly agree, and only if nearfield is like 1m or less. If the speaker is good it will give the correct response nearfield as well without forcing them to a flat curve. The reason flat is default isn't because you're supposed to use it, but because Trinnov can't ship a curve that fits all rooms. Ideally they should probably have the "According to L+R" as default.

Trinnov | Does Room Correction Remove A Loudspeaker’s Sound Character

www.trinnov.com

If you have Trinnov I would recommend using the "According to LR" feature, as does Trinnov.

 

[dasdoing]

A flat in-room response sounds harsh/sterile/too lean to most people.

well, it depends on the windowing and/or smoothing

 

[sigbergaudio]

well, it depends on the windowing and/or smoothing

Does it?

 

[sigbergaudio]

Here is Sonarworks, also not recommending flat in-room response as a blanket solution:

Successful Mixing with the Proper Frequency Response and a House Curve - Sonarworks Blog

Flat frequency response or your own house curve - what’s best for you? We analized thousand of creator preferences and here's what we found.

www.sonarworks.com

However, in general most producers of room calibration systems are guilty of focusing too much on a flat response, and also forcing target curves rather than preserving the natural tonality of the speakers. But even Genelec admits this isn't always ideal: "Once GLM has served you a flat in-room frequency response on a silver plate, the result might be brighter than you like. While a flat frequency response is necessary as a reference, it may not be perceived as the best option with all types of content and environments, particularly when working long hours and monitoring above 80 dB SPL."

Side note: If we argue that a flat in-room response is correct, we also argue that a speaker should not be anechoically flat, but have a negative tilt anechoically. Which would be an "interesting" suggestion.

I'm not sure exactly how this myth of flat in-room sound for studios took hold, but it's just wrong. Sometimes I feel like that kid in the "Emperor's new clothes" story, who is the only one who can see that the Emperor is actually naked.

 

[Newman]

Exactly.

 

[Newman]

No one knows exactly “what” the Trinnov does, but I suspect with their beam-forming 3D measuring methods, they can subtract direct sound from indirect sound.

Only the top mic in the pod is used for room correction; the other mics are inactive. So it’s not doing anything other RC mics can’t do for room correction measurement, and their ‘direct’ curve is probably not anything other than some ‘indicative’ calculation.

This reflects in the graphs it generates, where there is a tab displaying the direct sound plot only.

I would think it is more useful for diagnosing setup errors than getting reliable information about the actual direct sound FR.

Look, the main thing I am trying to emphasise is that you need to compare the RC filter generated with the anechoic response of your speakers, and imagine it added to your speakers’ direct sound. If it makes the direct sound less flat than it originally was, that’s a red flag.

cheers

 

[Thomas_A]

The Harman average sloping room curve applies to far-field in a quite large room. When DR ratio increases in near field the curve approaches the on-axis response. There is this unsolved question is whether a near-field monitor should have higher dispersion to compensate, but I guess this is dependent on its use. Any source change character in near vs. far-field due to room reflections. Real sources are always neutral, per definition, but their character may be modified by room reflections. Thus a speaker should act the same. Always neutral.

 

[thewas]

Does it?

Yes it does. Above room transition frequency we mainly perceive tonality from the direct sound which thus should be flat, so if the window would be so short that it would only catch the direct sound and not its reflections the measurement would be flat without sounding harsh. Thus in typical rooms for correction in that region some anechoic loudspeaker measurements are more helpful than a measurements at the listening position where the gap after the reflections is too short for a large enough window.

Some good reading material on the topic:

https://www.aes.org/e-lib/browse.cfm?elib=17839 (free download)

Some comments from Floyd Toole about room curve targets, room EQ and more

Room curve targets Every so often it is good to review what we know about room curves, targets, etc. Almost 50 years of double-blind listening tests have shown persuasively that listeners like loudspeakers with flat, smooth, anechoic on-axis and listening-window frequency responses. Those with...

www.audiosciencereview.com