What is your favorite house curve

[Floyd Toole]

With respect Mr Toole, why is it remarkable that a "debate is still going on"? Without debate, nothing changes or advances- surely you know that.

People do read, and they do learn. Why should they not question, debate and discuss? And what does that have to do with "profit making products"?

I love a good debate, and have benefitted from many. But not all topics are good for debate, especially when it come down to opinion, not facts. Profit making products that I referred to are those that generate revenue for the sellers, without delivering value to customers. Room EQ is in that category - prove me wrong, and I will not argue. Properly designed loudspeakers deliver value.

 

[sigbergaudio]

I thought a lot, and came to the conclusion that Bruel Kjaer 1974 Target Curve is ingenious and simple.

This curve is specifically calculated (averaged, if you will) for an average, unprepared or poorly prepared home environment.

A rise of about 3 decibels, starting from 2 kHz and below, gives expressiveness to the most important range for us - the mid frequencies,

and adds solidity to the bass, which is missing if you simply make the frequency response linear.

A smooth roll-off from about 3 kHz onwards provides us with restrained high frequencies, devoid of loudness and harshness.


This target curve is a great invention, created by a man who understands great sound quality. It's a pity that Floyd is not able to appreciate it.
PS. BK 1974 is NOT the Harman curve, please do not confuse it

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But it's not a target curve, in the same way as the Harman curve isn't a target curve. They are both measured (and averaged) results of well behaved speakers that have not been EQed. So what you can learn from these curves, is that if you measure your speakers in-room without EQ, and they resemble these curves, your speakers are probably reasonably decent.

You can also EQ to force your system to resemble the curves if it doesn't measure like the curves to begin with. This is a hit and miss process, the result may be good, and it may not. And it was never the original intent of either curves.

 

[landco]

The problem with room curves is that they cannot reveal resonances in loudspeakers that listeners can hear.

Do I understand correctly that when you talk about the speaker's own resonances, you mean a problem (peak) in a narrow frequency band? That is, for the listener it will not be a general deterioration in sound quality, but a specific artifact that “hurts the ear”?

 

[Ron Texas]

I'm a bit overwhelmed by some of this techno speak. Perhaps what Dr. Toole means by profit making products are things like Dirac. What I do is a rough cut and it appears to work. I EQ to a curve which is +2 Db @ 20Hz and -8 Db @ 20 kHz. Then I read things he is saying here and I have no idea as to how the reconcile his comments with a straight line.

I find all room stuff up to about 400 Hz which is where most people say to stop. My LS50's have a few defects which show up as peaks at 700 and 2200 Hz so I take those out. Klippel measurements say the peak is at 830 Hz, not 700 and I can't explain the difference. The highs drop off markedly after 15 KHz which I ignore . Over time I have found taking out the peak at 700 Hz makes a big difference by preventing female vocals from becoming harsh. I'm not as convinced about the audibility of bringing down the peak @ 2200 Hz. One may observe that in Kef's redesign of the LS50 they took at 2 db peak at 2500 Hz and turned it into a 2 dB dip instead of flat. Maybe someone can explain that one.

"Properly designed loudspeakers deliver value" says Dr Toole and I agree strongly. Yet, there is a thread where several ASR members are vigorously defending expensive poorly designed loudspeakers with hocus hocus design features like silver wire and exotic capacitors.

 

[napfkuchen]

You can also EQ to force your system to resemble the curves if it doesn't measure like the curves to begin with. This is a hit and miss process, the result may be good, and it may not.

The problem is that Dirac kind of "tricks you" into thinking it will magically improve the loudspeakers performance ... For my surround system the frequency-response-graph after calibration looked almost the same before and after replacing (some) speakers. The actual perceived sound quality is another level though. While the new speakers sound pleasing without any eq and besides subwoofer integration Dirac doesn't do much, the old speakers never sounded "right".

 

[AdamG]

It's a pity that Floyd is not able to appreciate it.

Open and lively debate is how science advances and is the foundation of well engineered products. We encourage debate. But you can make your point without the backhanded insults. Personal insults have no place in debate and no place here at ASR.

 

[Sal1950]

"Properly designed loudspeakers deliver value" says Dr Toole and I agree strongly. Yet, there is a thread where several ASR members are vigorously defending expensive poorly designed loudspeakers with hocus hocus design features like silver wire and exotic capacitors.

What can ya do Ron, every website has it's trolls.
But whether speakers, innerconnects, or power cables, excellent engineering or snake-oil marketing will always shine through

 

[Basic Channel]

But it's not a target curve, in the same way as the Harman curve isn't a target curve. They are both measured (and averaged) results of well behaved speakers that have not been EQed. So what you can learn from these curves, is that if you measure your speakers in-room without EQ, and they resemble these curves, your speakers are probably reasonably decent.

You can also EQ to force your system to resemble the curves if it doesn't measure like the curves to begin with. This is a hit and miss process, the result may be good, and it may not. And it was never the original intent of either curves.

I think it's confusing because there are so many variables, and seemingly lots of conflicting opinions on top of that. You'd need an acoustically perfect room in order to see your speakers being decent based on their in-room measurement without EQ, and it'd need to be acoustically outstanding without any treatment.

As I understand it, you will start to approach a flat line response the more you actually treat the room (assuming a perfectly flat speaker). Is rolling off treble at that point really considered room EQ though? I mean if you EQd listening in an anechoic chamber you'd be EQing the speaker.

If room EQ refers to sitting speakers in an untreated room and EQing them to some target, then it is obviously not comparable to treatment.

 

[OMas]

What is the real world parallel of a user-preferred house EQ setting? I don't think it makes any sense.

In the real world you can't ask the orchestra to boost the mids and cut the treble. All you can do is ask them to play louder on the violins and play the trumpets more quietly. And then they sound as though they are playing louder on the violins and playing the trumpets more quietly. Once you get into the subjective EQ game you have already lost the hi-fi battle; your EQ variations bleed all over the individual instruments and blur them all together; you are regarding sound as textureless audio paste.

All there is is 'high fidelity' (as close as you can get) and 'audio paste'. If you find that 'high fidelity' doesn't sound any good, your system isn't high fidelity!

If tone controls don’t make any sense, then simply opt out. While there is something to be said about a purely acoustic “unplugged” experience, in the real world monitor mixer and individual musicians apply all kinds on equalization in addition to a dozen other processing options. Even classical music is not exempt though, in that case, it’s usually the venue’s reinforcement that's tweaking what you hear…active acoustics anyone?†

Back to using EQ in your playback chain for voicing, not correction. I mention correction as most compensation mechanisms on the market, from Sonarworks to ARC to Dirac (my fave), use some combination of filtering plus trade secrets. So, let’s assume that is pre–processing, not post–EQ for voicing or something else…stereo recordings and their playback are, for most of us, first and foremost an entertainment. As such, whatever makes one happy is what one should use. Don’t even start to consider the massive amount of manipulation that goes into creating recorded music. You said: “Once you get into the subjective EQ game you have already lost the hi-fi battle…” I respectfully disagree. As with all things in audio; everything matters. In a highly resolving system, you should be able to hear any change to the signal chain. Crap in equals crap out, and that includes EQ. I, for one, routinely keep a fancy linear or minimum phase parametric “in circuit” to correct for inadequacies in the current playback chain, in the room I’m in at that moment, and to subjectively improve individual recordings or to suit the mood. Old skool analog tone controls and graphic EQs have rightfully acquired a bad rap as their center frequencies, headroom and topologies are fixed at the design stage. In the digital domain, most equalizers are saddled with a lower rez processing environment; I/O sample rate; I/O word length; internal precision; or all of the above. As with all things digital, the algorithms themselves also heavily influence the resulting sound quality.

Throwing a wet blanket over all EQ–to –taste is simply reductionist and not fair to today’s designers. Cheap EQ sounds as poor as cheap anything else. A Realistic analog graphic EQ from back in the days sounds very different from the EQ in a state of the art analog tone control found in audiophile preamplifiers today. Pick your fave; NBS’s Universal II, Luxman’s C–10X, or Accuphase’s C-2300, etc etc. They all sound “good” when compared to some 5534–based (or worse) simple EQ circuit. Why? Because their design does not start with selling price and work backwards from there. Heck, I’m reviewing a DAC+HPA stack from Geshelli right now, and Geno has included quite nice, hard bypassable tone controls in the $450 Archel 3 Pro.

† — As an example, see <https://meyersound.com/product/constellation/> Constellation is one example of several on the market that, when set up and operated skillfully, are “invisible” to both audience and performer.

 

[Floyd Toole]

Do I understand correctly that when you talk about the speaker's own resonances, you mean a problem (peak) in a narrow frequency band? That is, for the listener it will not be a general deterioration in sound quality, but a specific artifact that “hurts the ear”?

I think you need to do some homework. All voices and musical instrument sounds are combinations of resonances that define their characteristic sounds. Resonances in loudspeakers change how they sound, which is not what we want. Loudspeaker resonances add the same timbral modification to every sound that is reproduced. Loudspeakers with the least evidence of resonances receive the highest ratings in double-blind listening tests, as was first recognized in my original 1985, 1986 JAES papers. Nothing has changed - neutral loudspeakers win properly conducted listening tests. So, the resonances I am talking about don't "hurt the ear", but they can be annoying.

 

[sigbergaudio]

I think it's confusing because there are so many variables, and seemingly lots of conflicting opinions on top of that. You'd need an acoustically perfect room in order to see your speakers being decent based on their in-room measurement without EQ, and it'd need to be acoustically outstanding without any treatment.

Not really, but properly treating the room certainly helps, not only with measurement but also with the subjectively experienced sound quality. In a decently treated room and good speakers, you should see generally ok overall tonality (shape of the curve) at least above 100hz. You may need 1-3 individual EQ points to dampen peaks in the bass.

As I understand it, you will start to approach a flat line response the more you actually treat the room (assuming a perfectly flat speaker). Is rolling off treble at that point really considered room EQ though? I mean if you EQd listening in an anechoic chamber you'd be EQing the speaker.

I think you will find almost zero rooms that are so treated that you approach a flat line. Treating the room will generally reduce the need for EQing to a target, not increase it.

 

[Thomas_A]

Do I understand correctly that when you talk about the speaker's own resonances, you mean a problem (peak) in a narrow frequency band? That is, for the listener it will not be a general deterioration in sound quality, but a specific artifact that “hurts the ear”?

If you have a natural sound source in your room in front of you like your own voice, would you like to alter it according to a room curve to sound "not like you" in that room?

 

[Scott Borduin]

I love a good debate, and have benefitted from many. But not all topics are good for debate, especially when it come down to opinion, not facts. Profit making products that I referred to are those that generate revenue for the sellers, without delivering value to customers. Room EQ is in that category - prove me wrong, and I will not argue. Properly designed loudspeakers deliver value.

@ 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 ...

 

[Tim Link]

Do I understand correctly that when you talk about the speaker's own resonances, you mean a problem (peak) in a narrow frequency band? That is, for the listener it will not be a general deterioration in sound quality, but a specific artifact that “hurts the ear”?

I don't think there necessarily has to be a peak in response at a resonance. I've got a problem with my bass horns that causes a sharp null at around 80 Hz, but there's also a long reverb tail associated with that frequency, so the energy is getting stored and released at a resonance, and sometimes canceled. I can brute force EQ it and end up with a tremendous amount of reverberation at that frequency. If you're stuck with a resonance it might be best to always EQ it down. A gap in response is probably less bothersome than a peak that rings.

 

[Tim Link]

If you have a natural sound source in your room in front of you like your own voice, would you like to alter it according to a room curve to sound "not like you" in that room?

I'll have to do a sweep with my voice and have REW analyze it.

 

[OCA]

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):

 

[Basic Channel]

I think you will find almost zero rooms that are so treated that you approach a flat line. Treating the room will generally reduce the need for EQing to a target, not increase it.

Yes I was using the extreme to make my admittedly (probably) bad point. A speaker that measures flat in an anechoic chamber has an in room response, but in real rooms there will be different levels of absorption/etc. My room has 12/14 ceiling corners, 6/8 floor corners, a bed, a couch, and a ridiculous amount of clothes. Some fibreglass panels. It’s a very abnormal room

Plus distance. I sit about 1.5m away. Personally there isn’t any real roll off until 10k.

 

[Thomas_A]

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

You can EQ a suboptimal speaker based on its anechoic response. If your speaker is good from start there is no point in using correction above Shroeder f.

 

[sigbergaudio]

Yes I was using the extreme to make my admittedly (probably) bad point. A speaker that measures flat in an anechoic chamber has an in room response, but in real rooms there will be different levels of absorption/etc. My room has 12/14 ceiling corners, 6/8 floor corners, a bed, a couch, and a ridiculous amount of clothes. Some fibreglass panels. It’s a very abnormal room

Plus distance. I sit about 1.5m away. Personally there isn’t any real roll off until 10k.

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.

 

[OCA]

Are you restricting it to correction below the Schroeder frequency? Are you using just IIR filters or FIR as well?

How is he supposed to know when he's blindfolded