OCA's target curves

[gorman]

I've had a look at the target curves provided by @Keith_W , along with his free ebook downloads (thanks again!), here: https://www.audiosciencereview.com/...eting-measurements-with-rew-free-ebook.66771/.

What drew my attention are OCA's two curves: OCA and Neuron. I don't know if @OCA could chime in but I'd be interested to understand the reasoning behind the large highs downward curve when, if I'm not mistaken, he advises against EQing mid-high frequencies? What's its purpose? Is that how he would like speakers to sound?

 

[Sokel]

I don't know about OCA's targets (although mid-high's response cannot be a target, only a result) but here's the gospel:

What is your favorite house curve

OK. Next question for you folks. As far as I can tell there is no spinorama for the Focal Aria 926's, which happen to be my main speakers. However, Amir did do a spinorama for the Aria 906 standmount speakers. They use the same tweeter and mid driver as the 926, but lack the two woofers as they...

www.audiosciencereview.com

 

[OCA]

If you're talking about the dip around 2700Hz, it helps leveling speaker volume correctly since these are for multichannel systems equal volume across channels is important. Most high end speakers have a design dip around that area which also happens to be the region human ear is most sensitive to volume differences.

 

[gorman]

If you're talking about the dip around 2700Hz, it helps leveling speaker volume correctly since these are for multichannel systems equal volume across channels is important. Most high end speakers have a design dip around that area which also happens to be the region human ear is most sensitive to volume differences.

Thanks for chiming in. I am talking about the curves Keith is sharing here: https://drive.google.com/file/d/1ziiH7NaGYxyIA1LFzUNiUWY6OOV-3phZ/view?usp=drive_link

 

[Curvature]

If you're talking about the dip around 2700Hz, it helps leveling speaker volume correctly since these are for multichannel systems equal volume across channels is important. Most high end speakers have a design dip around that area which also happens to be the region human ear is most sensitive to volume differences.

Whatever speakers, high end or not, have a dip in that region it's because because of cancellations from the tweeter crossover. If intentional, it's caused by many mistaken assumptions piled on each other.

The ear is most sensitive to small SPL differences in the low bass. Look at the convergence of equal loudness curves. And in 2-6kHz the ear requires the least SPL, but changes in loudness are consistent with lower and high frequencies in a wide range.

Sorry for the off-topic comment, OP. On topic, there's a difference between correction of room-related issues and EQ for taste. Room targets are the latter, and many people like different tilts within a fairly tight range overall. The general advice is not to correct small peaks and dips beyond 500Hz or so. Using EQ for broad trends, sure.

 

[OCA]

I don’t think that’s quite right. The dip around 2.7kHz in speakers like the $150k Grande Utopia's isn’t a crossover design flaw, but an intentional voicing choice. The ear is most sensitive around 2–5 kHz, not in the bass, which is why designers often smooth or slightly dip that region for a more natural tonal balance. Not all speakers are designed for studio use as monitors.

Equal-loudness contours actually show we need less SPL there, while the bass requires more to sound equally loud. The “convergence” of the curves at low frequencies doesn’t mean we’re more sensitive in the bass, it just reflects how those contours flatten at higher listening levels.

 

[OCA]

Thanks for chiming in. I am talking about the curves Keith is sharing here: https://drive.google.com/file/d/1ziiH7NaGYxyIA1LFzUNiUWY6OOV-3phZ/view?usp=drive_link

These are quite old curves. My most recent favorite is Dolby Atmos Music curve

 

[gorman]

These are quite old curves. My most recent favorite is Dolby Atmos Music curve

Ok, thanks for clarifying.

 

[Curvature]

The dip around 2.7kHz in speakers like the $150k Grande Utopia's isn’t a crossover design flaw, but an intentional voicing choice.

It's a flaw in old designs which became elevated as a voicing choice in newer ones.

The ear is most sensitive around 2–5 kHz, not in the bass

Sensitive in terms of absolute SPL (highs) is different from sensitivity to SPL changes (bass).

 

[Geert]

The ear is most sensitive around 2–5 kHz, not in the bass, which is why designers often smooth or slightly dip that region for a more natural tonal balan

There’s nothing more natural about a dip in the midrange. If these frequencies are to hot after recording, the mix or mastering engineer will correct them. There's no need to attenuate them even furher during reproduction. When I hear a piano recording on speakers like that I immediately recognize something’s off.

The dip around 2.7kHz in speakers like the $150k Grande Utopia's isn’t a crossover design flaw, but an intentional voicing choice

Focal should make up their mind, because on the Focal Maestro Utopia III the magic dip is at 1.2 kHz:



(Source https://www.stereophile.com/content/focal-maestro-utopia-iii-loudspeaker-measurements).

 

[sigbergaudio]

Been discussed to death here already I guess, but it's misleading to call these targets, at least the Harman one, because that's not what it is.

One should be a bit careful to EQ speakers to these "targets" too, at least above 200-300hz or so. If you can get there with moderate shelf filters you might be okay.

 

[Elkerton]

Dr. Toole mentions in the 4th edition of his book (it may also be in earlier ones though I don't remember) that he was told that, because microphones placed above string sections tend to accentuate that range, a dip is introduced in speakers to compensate rather than at the source, the microphone or its eq where it should be.

 

[RexrothPigeon]

Dr. Toole mentions in the 4th edition of his book (it may also be in earlier ones though I don't remember) that he was told that, because microphones placed above string sections tend to accentuate that range, a dip is introduced in speakers to compensate rather than at the source, the microphone or its eq where it should be.

This makes no sense. If mic techniques are incompetent enough to result in inaccurate or unwanted sound characteristics, engineers at the mixing and mastering levels should fix them. It's insane to shunt off that responsibility to speaker designers, and anyone doing so should be laughed out of the industry. Speakers are reproduction devices, not creative ones, and anyway, the overwhelming majority of music played on speakers involves zero mic'd string sections lmfao

 

[Sokel]

, the overwhelming majority of music played on speakers involves zero mic'd string sections lmfao

(Mother ((classical)) nods with understanding)

 

[Elkerton]

This makes no sense. If mic techniques are incompetent enough to result in inaccurate or unwanted sound characteristics, engineers at the mixing and mastering levels should fix them. It's insane to shunt off that responsibility to speaker designers, and anyone doing so should be laughed out of the industry. Speakers are reproduction devices, not creative ones, and anyway, the overwhelming majority of music played on speakers involves zero mic'd string sections lmfao

That’s Toole’s position too.

 

[Jumu]

It's a flaw in old designs which became elevated as a voicing choice in newer ones.

Sensitive in terms of absolute SPL (highs) is different from sensitivity to SPL changes (bass).

It is absolutely a design flaw or if it is intentional, it is worse

And you are absolutely right about F&M graphic.

But there is some thruth to sensitivity to frequencies. Ear is not just sensitive to 2700hz or whatsoever, it’s sensitive around 4khz and 9khz.

But…it doesn’t mean that we should design a speaker with these in mind. If we cut these frequencies off, then we perceive an unnatural sound.

 

[Jumu]

These are quite old curves. My most recent favorite is Dolby Atmos Music curve

Merhaba Oca. My friends in Türkiye, love your calibration so much. I have tried it and I loved especially center channel voicing. And I am proud of you my Turkish brother for doing such great work
My question is, I don’t wanna touch frequencies above transition frequencies in my room. Does your calibration let me adjust the frequencies which will not be touched? I mean can I chose transition frequency? I am not sure, but someone told that it is not touched above 500hz. But if it is so, why there are target curves showing different curves on high frequencies?

 

[Curvature]

But there is some thruth to sensitivity to frequencies. Ear is not just sensitive to 2700hz or whatsoever, it’s sensitive around 4khz and 9khz.

Individual sensitivity to absolute SPLs per frequency varies a decent amount. Below is a chart of 12 HRTFs.

https://www.researchgate.net/publication/12527417_Multichannel_speech_intelligibility_and_talker_recognition_using_monaural_binaural_and_three-dimensional_auditory_presentation

 

[OCA]

Focal should make up their mind, because on the Focal Maestro Utopia III the magic dip is at 1.2 kHz:

They actually used different jumper settings in that rather random test, measured from about 50 inches on the tweeter axis — and they even noted that in their comments:

I get the skepticism; I’m not exactly a believer in corporate innocence either. But I do think Focal knows a thing or two about how we perceive sound in real-world listening spaces, and that 2.7kHz dip is almost certainly intentional.

Personally, I always do a final “ear check” with tracks I know inside out, and these speakers consistently give me that emotional connection — the goosebumps factor — that I’ve never quite gotten from studio monitors. That said, my monitor experience is limited, and I am aware John of REW (my go-to reference) uses Dutch & Dutch in his own setup. But I happen to get daily direct (and regularly quite harsh) feedback from about 10k audio enthusiasts on my DSP methods.

And sure, ASR leans heavily on measurements and tends to dismiss listening impressions as bias — but to me, that’s missing half the story of what good sound really is.

It’s also worth noting that Focal isn’t alone in this; you’ll see a similar mid-range dip in high-end designs from B&W and Sonus Faber and Audyssey implemented this for 2 decades claiming it's "the" BBC dip and nobody disagreed.

 

[OCA]

Merhaba Oca. My friends in Türkiye, love your calibration so much. I have tried it and I loved especially center channel voicing. And I am proud of you my Turkish brother for doing such great work
My question is, I don’t wanna touch frequencies above transition frequencies in my room. Does your calibration let me adjust the frequencies which will not be touched? I mean can I chose transition frequency? I am not sure, but someone told that it is not touched above 500hz. But if it is so, why there are target curves showing different curves on high frequencies?

Express filters only about up to 200Hz for front mains, and to about 250Hz for the rest of the speakers. My experience of touching beyond that has been consistently quite negative. You can only invert min phase part of the room boundary effects and excess phase part of the speaker cabin. With min phase EQ, that limits you to room transient frequency which is about 200Hz. With linear phase filters, you can additionally throw in a crossover/box phase correction targeting LP.