What is your favorite house curve

[Floyd Toole]

@ Floyd Toole, Your view of room correction notwithstanding, I would think you are still using the Room Optimizer in your JBL/Trinnov AV processor? Are you restricting it to correction below the Schroeder frequency? Are you using just IIR filters or FIR as well? I have a quite similar system based on an SDP75, Salon2/Voice2, but with JBL 705i surround speakers ...

I have sold the California house with the 17 channel theater intact. Now getting installed in a new luxury condo in my old home town of Ottawa Canada. Glad to be rid of the SDP75, which when used in its normal mode to "calibrate" the system simply ruined my fundamentally neutral Revel loudspeakers. I hired an expert to disable the worst offending attempts at non-minimum-phase "corrections" and add in some correcting EQ, finally getting close to what should have simply been left alone above the transition frequency. Not impressed. I was told that Trinnov was listening to my complaints and were making changes - I would hope so. I don't know where they stand at the moment but back then in 2020ish it was a triumph of numbers, graphs and exotic microphones over sound quality. Marketing.

My new system will be much less complex, but I fully anticipate no less rewarding. Above the transition frequency your loudspeakers (the same that I had) should need negligible attention, beyond broadband tweaks related to program material if you are fussy. And, of course, multiple subs. I had four used in a Sound Field Management scheme - no room resonances measurable or audible. Nice.

 

[Sal1950]

I have sold the California house with the 17 channel theater intact.

Well thanks a lot Floyd, I thought you promised to offer me first right of refusal if you ever sold that crib.

 

[amirm]

You are all wrong. Audyssey (a textbook value deliverer to consumers) has solved the target curve problem decades ago. No matter what speakers you have, it can correct it perfectly including filling room mode wave cancellations along with an embedded midrange compensation sorting out all phase anomalies in the crossover region (no matter what frequency):

View attachment 368267

Those are simulations. You have to measure yourself to see the "after" results. See my review of here: https://www.audiosciencereview.com/forum/index.php?threads/audyssey-room-eq-review.12746/

See what I labeled on the right. This is actual results:

With higher level of filtering to see what is done:

 

[Scott Borduin]

I have sold the California house with the 17 channel theater intact. Now getting installed in a new luxury condo in my old home town of Ottawa Canada. Glad to be rid of the SDP75, which when used in its normal mode to "calibrate" the system simply ruined my fundamentally neutral Revel loudspeakers. I hired an expert to disable the worst offending attempts at non-minimum-phase "corrections" and add in some correcting EQ, finally getting close to what should have simply been left alone above the transition frequency. Not impressed. I was told that Trinnov was listening to my complaints and were making changes - I would hope so. I don't know where they stand at the moment but back then in 2020ish it was a triumph of numbers, graphs and exotic microphones over sound quality. Marketing.

My new system will be much less complex, but I fully anticipate no less rewarding. Above the transition frequency your loudspeakers (the same that I had) should need negligible attention, beyond broadband tweaks related to program material if you are fussy. And, of course, multiple subs. I had four used in a Sound Field Management scheme - no room resonances measurable or audible. Nice.

Thanks much for the response. In my case I ended up using only IIR (min phase) filters and limiting auto correction to around 300 hz, then used user EQ to touch up a couple of boundary-related mid-range issues on the surrounds. It seems like we finished in a somewhat similar place.

After considerable iteration I wound up using 3 subs in a different configuration than any of those in the Welti paper. In my room this worked better for eliminating troublesome 1st and 2nd order width modes.

I thought that California system you put together was a model for integrating a high-performance audio and video system into an attractive and functional living space. I will be interested to see what you do in the new space if you choose to share it with us. Enjoy your new home!

 

[StigErik]

Thank you @amirm for your test of Audyssey. I played around with it when I had Marantz AVRs. I found it will correct the bass very well if the starting point is not too bad. Above Schroder.. it’s a mess. Using multipoint measurements actually made it worse in all positions.

I’ve gotten better results ( objective as well as subjective ) by using better speakers, multiple subs, improving the rooms acoustics, and then carefully EQ the room response manually from Schroder and down.

 

[Basic Channel]

Most of the room gain creating the curve is in the bass. To change that require more and thicker treatment than most have. But yes, gain will be different from room to room, but mostly due to room size. As you likely already know, what treatment often helps with is to even out the frequency response (especially in the mid and higher frequencies) and reduce decay. It won't usually change the tonality or shape of the curve.

Excuse my misunderstanding. As I started out by saying its a bit confusing. I am wrong what I said before anyway, I think the only EQ required to achieve a sloping general response in my room is fixing slight peaks in the speaker. I am a wee bit confused by the idea of not EQing the room above 400hz or so, as I can barely see the room (I think) above that. If I ask REW to make EQ it only fixes a few peaks above 400hz that would seem to agree with the closest I can find to anechoic measurements for my speaker.

 

[StigErik]

There are some speakers that don't get that downward slope in a room. In order to get that downward slope, the speaker needs to have directivity that is increasing towards high frequencies. There are speakers that don't behave like that; horns and line sources to name a few. Such speakers can measure flat both anechoic and in the listening position, and in my opinion they will sound too bright. Using EQ to slope down the response will work, and to my ears it sounds better.

 

[goat76]

Excuse my misunderstanding. As I started out by saying its a bit confusing. I am wrong what I said before anyway, I think the only EQ required to achieve a sloping general response in my room is fixing slight peaks in the speaker. I am a wee bit confused by the idea of not EQing the room above 400hz or so, as I can barely see the room (I think) above that. If I ask REW to make EQ it only fixes a few peaks above 400hz that would seem to agree with the closest I can find to anechoic measurements for my speaker.

As you have REW and a measuring microphone, you can fairly easily make a measurement suited for a gated analysis. Just place both your speaker and the microphone as far away as possible from boundaries, with the microphone at the height of your speaker's acoustic axis and about 2 meters away to make sure the sound from all the drivers unified. In REE you can then gate the measurement to exclude the first reflections, and you will see how the actual response looks like from your speakers without interference from your listening environment. The result will be of fairly low resolution, but it will be good enough to base your EQ adjustments on the actual response of your speakers which according to Toole’s work is the dominant thing we hear in a room (and not the flawed response the microscope picks up at the listening position).

The regular in-room response measurements can be used for adjusting the bass frequency area of the response, as that will be similar to the sound we hear with our ears, again according to the science.

 

[Andysu]

ideally speakers should be half way of the height of the room and certain distance away from the sidewalls as the sine wave tones will magnify increase when some or others are nearer to boundary surfaces (than they would be when outdoors as its more open to less boundary reflections )

but i am not down-scaling my JBL 4673 no way , not on your nelly

so i am to listen to the possible highest frequencies , special highs above 8KHz , i can give simple list of those to listen out for , that's of course anyone here is real dedicated THX listener of course , nothing personal , purely scientific

--- often there be some high like sine wave sound effects above 8KHz ---
star trek 6 the undiscovered country , the excelsior after the shockwave passes by on the bridge i won;t point actual scene out , listen if you can hear it ?
the truman show
apollo 13
alien 3
die another day

 

[Thomas_A]

I was notified that my name had come up in this conversation, and I have not been following this forum for some time. It is remarkable that this debate is still going on. People don't read, or don't learn, and are inclined to put more faith in profit making products than in the real science underlying the process. I am flattered that my name and "god" are in the same sentence, but I am just a retired research scientist, reporting facts as they are observed in accurate measurements and controlled listening tests. I think I need to repeat something I have said before in this and other forums:
Let me state now: there isn’t, nor can there be, an ideal steady-state “target” room curve. The room curve is a “result” of a loudspeaker delivering sound to a complex semi-reflective listening environment, it is not a “target”. If that loudspeaker is a typical forward-firing design, with desirably flat and smooth on-axis frequency response, and desirably smooth, gradually changing, off-axis frequency response, the room curve in typical rooms will have a gradual, quite linear, downward tilt above about 500 Hz. This result is strongly correlated with double-blind listening tests – if you see such a curve there is a good chance you have well-designed loudspeakers. That is all the so-called Harman curve is about. But misinterpretations and folklore have taken over.

In the end it is comprehensive anechoic measurements that are definitive of sound quality, not the steady state room curve. If the loudspeaker is not “well designed”, and many are not, especially in off-axis behavior, the steady-state room curve will not be a smooth decline. The shape of a steady-state room curve at middle and high frequencies is dominated by off-axis radiated “early reflections” and that is a property of loudspeakers that cannot be equalized. Equalizing an irregular room curve to have a more visually appealing shape – even the Harman curve - guarantees nothing. The loudspeaker is at fault, and the solution is most likely a better loudspeaker. That is why, these days, it is such a powerful advantage to have anechoic measurements presented in “spinorama” format available on so many products. It takes much of the guesswork out of getting genuinely neutral sound reproduction.

Those are the hard facts in a nutshell. Those having a long attention span might find value in the attached long document I wrote a while back and probably posted somewhere in ASR, or wait for the 4th edition of my book which is currently being written.

I guess curves get misunderstood and mixed up once they are published and spread around on the internet. There are Harman target curves for headphones, and there are curves for a typical room response with good speakers etc. The expressions "target curve" and "Harman" get mixed up and the story grows. The title of this thread "What is your favourite house curve" gives further confusion to the matter.

 

[sigbergaudio]

I am a wee bit confused by the idea of not EQing the room above 400hz or so, as I can barely see the room (I think) above that. If I ask REW to make EQ it only fixes a few peaks above 400hz that would seem to agree with the closest I can find to anechoic measurements for my speaker.

Not sure I understand what you mean by "can barely see the room above 400hz" ?

 

[Andysu]

i guess use movie like , the fugitive some high levels on it , guess if one has complex proper home cinema to check actual RTA of direct signal vs in-room RTA levels ( both at same time ) but only true dedicated THX listeners would do this
i find some scenes thou have more control now than several years ago , dynamics can reach too much for smaller rooms , don't need the film mix tampered with near field , leave levels as they are , its down to home cinema owners , if they want THX proper b-chains or they can chase their tail around in circles

 

[Basic Channel]

Not sure I understand what you mean by "can barely see the room above 400hz" ?

I think that’s another misunderstanding on my part. I think I’m misinterpreting the stability of my room response above that with lack of room response.

I’m kinda also thinking that my measurements are more “true” above 400hz, I.e closer to what amir would measure.

 

[sigbergaudio]

I think that’s another misunderstanding on my part. I think I’m misinterpreting the stability of my room response above that with lack of room response.

I’m kinda also thinking that my measurements are more “true” above 400hz, I.e closer to what amir would measure.

The measurements in higher frequencies are often closer to the anechoic response, but can still be affected by speaker placement, distance and room acoustics. It's pretty normal to see deviations up in the khz area when measuring speakers in a room at the listening position, that are not present anechoically.

 

[007Shorty]

I'm afraid that Floyd Toole is long gone, after all he has to adjust his hi-fi system which is a top priority for all of us, but what is the target volume for blind tests at Harman?
I know it's in a book or article somewhere, but I don't have it. I'm asking of course because of the loudness curves and the reference tracks.

So if anyone can help me a thousand thanks!

 

[Tell]

Personally I don't get the appeal of that downward slope in the treble, it sounds flat, dull, boring, lifeless etc etc to me. Instead I've tuned my system to this curve:

Note that this is with a pair of ported bookshelves with a 4" woofer each (Ino Audio piP), I've had these for some years now but I still get impressed with their bass performance!

 

[007Shorty]

Personally I don't get the appeal of that downward slope in the treble, it sounds flat, dull, boring, lifeless etc etc to me. Instead I've tuned my system to this curve:
Note that this is with a pair of ported bookshelves with a 4" woofer each (Ino Audio piP), I've had these for some years now but I still get impressed with their bass performance!

This looks like a loudness correction curve. Do you listen at a lower volume or have you had loud hobbies in the past?

 

[Keith_W]

I think that’s another misunderstanding on my part. I think I’m misinterpreting the stability of my room response above that with lack of room response.

I’m kinda also thinking that my measurements are more “true” above 400hz, I.e closer to what amir would measure.

All in-room measurements are affected by reflections, but there is a difference between short and long wavelengths.

For short wavelengths, e.g. a 20kHz sound has a 17.15mm wavelength (about 2/3"), several full cycles will be produced by the speaker before it reflects and arrives at the measurement mic. Thus it can be easily windowed out.

As wavelengths get longer, we reach a point where a single wavelength reflects before it reaches the mic. Measurement of any frequencies below this do not give the speaker response, but the room + speaker response. We can calculate this lower frequency limit with this equation:

F = c / (2* (x^2 + d^2)^0.5)

Where c = speed of sound (343m/s or 1125ft/s), x = 1/2 the distance between microphone and speaker, and d = distance to the nearest reflecting surface, usually the floor. Source.

Thus for a mic placed 1m from the speaker and 1m from the floor, we have 343 / (2*0.5^2 + 1^2)^0.5) = 153Hz. If you have a sofa which is 30cm from the microphone, it is 294Hz, meaning any frequency measured <294Hz is nonsense.

Bear in mind that microphone stands can be reflecting surfaces and contribute to little wiggles in the FR. Read more about it here.

Note this is not the Schroder frequency, that is something else entirely. Of course, the measurement is valid if our intention is room correction. But it is not a valid measurement of loudspeaker performance below a certain frequency.

 

[Tell]

This looks like a loudness correction curve. Do you listen at a lower volume or have you had loud hobbies in the past?

Both. Got a two month old daughter and I've lived in an apartment for some years now so I can't listen as loud as I would like to, but in the past I've had a pair of 12" bandpassed subs together with these to play as loud as possible in the small cabin I used to live in. I also grew up having the loudness button always in when listening to my ginormous teenage stereos, so I guess I've gotten used to the loudness curve sound

 

[dasdoing]

saying a perfect speaker in a room makes the perfect playback makes no sense at all, since the response is all over the place depending on where we are in the room.
This is a rather purist approach and saying people are wrong in searching for the best room EQ is a little arrogant.