Should Speakers be Designed to Have a Flat SPL?

zhimbo

zhimbo

Audioholic General
"Well he corrects it with an EQ." He doesn't correct the loudness contour, he corrects a limited difference between directional and diffuse fields - a difference that applies only to concert halls and not, for example, small rooms or open areas, (and, of course, electronic music).
 
Swerd

Swerd

Audioholic Warlord
But you just made the assumption that a flat loudspeaker and an orchestra are one and the same entity and they project the sound in the exact same way. That's a very huge assumption and a rather flawed one. That's what I'm trying to explain. Mics are more directional, speakers are more directional, they record nothing like what you would have heard at the live event.
Your quote from Linkwitz spoke about the differences between close placed microphones and more distant microphones when recording music in large concert halls.

Playing back with a speaker that has the so-called BBC dip in its mid range frequency response can produce an overall warmer sound perception, but cannot truly affect the relative amount of concert hall ambiance present or absent in the recording.

The quote from Harbeth (supplied by Chu Gai) tells us more:
"According to Harbeth's founder, who worked at the BBC during the time that this psychoacoustic effect was being explored, the primary benefit this little dip gave was in masking of defects in the early plastic cone drive units available in the 1960's."

A woofer used at the time, with a cone made from bextrene plastic, had a prominent sounding resonance at about 1800 Hz. This ugly sounding noise had to be filtered out, supressed, by adding a midrange dip to the crossover network.

Those bextrene cone woofers are history, but we are plagued by the dip even today.
 
T

TheStalker

Banned
"Well he corrects it with an EQ." He doesn't correct the loudness contour, he corrects a limited difference between directional and diffuse fields - a difference that applies only to concert halls and not, for example, small rooms or open areas, (and, of course, electronic music).
These directional and diffuse fields are what make up the equal loudness chart and define how a human ear hears. Linkwitz chooses to correct the biggest offender, the 3-4kHz region. Because we are extremely sensitive there and the mic/speaker system is very directional in the same region, unlike how a live orchestra would be. Again, I'm not suggesting to EQ all speaker systems to follow the equal loudness chart exactly. But to slightly correct such an offending region like the 3-4kHz range should be IMO part of a proper loudspeaker design. Or an EQ should be somewhere in the sound system.
 
ski2xblack

ski2xblack

Audioholic Field Marshall
But you just made the assumption that a flat loudspeaker and an orchestra are one and the same entity and they project the sound in the exact same way. That's a very huge assumption and a rather flawed one. That's what I'm trying to explain. Mics are more directional, speakers are more directional, they record nothing like what you would have heard at the live event.
That seems more your own projection than anything implicitly or explicitly stated by Swerd (or anyone).

The best hope of listening to reproduced music is some sort of convincing illusion of the real event, not an exact duplication, which is simply impossible for the reasons you have given. But it's no coincidence that pursuit of accuracy results in more compelling illusions to most listeners, at least per the studies that have taken place. If you take your rather philosophical argument to the extreme, nothing short of live music is adequate, as the whole recording process is flawed from mics at one end to speakers on the other.
 
T

TheStalker

Banned
I personally think that Harbeth is full of it. No offense to anyone. As been pointed out, BBC did not even use the BBC dip for the LS3/5 which used the baxtrene woofers. The woofer itself has a fairly damped cone and would not have a bad break-up regardless, as can be seen in many measurements online. BBC at that point was also able to measure and make a proper crossover which would suppress any break-up.

Linkwitz's conclusions are completely unrelated. He uses a lot of Seas driver, etc.

Nothing what Harbeth says adds up in any meaningful way IMO.
 
T

TheStalker

Banned
That seems more your own projection than anything implicitly or explicitly stated by Swerd (or anyone).

The best hope of listening to reproduced music is some sort of convincing illusion of the real event, not an exact duplication, which is simply impossible for the reasons you have given. But it's no coincidence that pursuit of accuracy results in more compelling illusions to most listeners, at least per the studies that have taken place. If you take your rather philosophical argument to the extreme, nothing short of live music is adequate, as the whole recording process is flawed from mics at one end to speakers on the other.
But we're all trying to get closer to the truth. So if a dip gets us closer, then why such negativity towards it?
 
j_garcia

j_garcia

Audioholic Jedi
But we're all trying to get closer to the truth. So if a dip gets us closer, then why such negativity towards it?
Speakers should be deigned to sound pleasing to the user and there are a lot of options out there because each person's hearing AND personal preferences are not the same. A perfectly accurate, flat speaker will NOT sound perfect to every person, nor does a speaker need to be ruler flat to sound good. I've been to concerts that sounded bad at the venue as well as ones that sounded amazing. If you want "reality" go see it live. At home you can achieve something that makes you happy, which means selecting gear based on YOUR preferences. Making assumptions about what others will like will not guarantee a good product and even if it IS a good product, that does not guarantee it will sell.
 
zhimbo

zhimbo

Audioholic General
From what you posted in the opening post: "This applies primarily to recordings of large orchestral pieces in concert halls where the microphones are much closer to the instruments than any listener. At most listening positions in the hall the sound field has strong diffuse components." Linkwitz's point is NOT a universal solution to the "correct" speaker frequency response. Rather, for *certain* kinds of recordings, mic'd in certain ways in a certain environments, a bit of EQ will result in a more natural sound.
 
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Swerd

Swerd

Audioholic Warlord
But we're all trying to get closer to the truth. So if a dip gets us closer, then why such negativity towards it?
I really think you're making conclusions that are much too black and white.

The whole question of human perception of loudness across the sound spectrum is more complex. Read this on wikipedia Equal-loudness contour - Wikipedia, the free encyclopedia.

The orginal Fletcher-Munson paper was published in 1933, and was determined using earphones. I wonder if they were primarily concerned with human voice reproduction by telephones? Later work was done with loudspeakers.

What struck me as I read the sections titled Side versus Frontal Presentation and Headphones versus Loudspeaker Testing, is that it becomes clear just how weak our understanding is of psychoacoustics, especially in trying to describe the significant differences of sound in concert halls versus sound in typical rooms in our homes.

After reading this, I think any decision that a midrange dip or a flat midrange is simply good or bad is actually a broad oversimplification.
 
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ski2xblack

ski2xblack

Audioholic Field Marshall
But we're all trying to get closer to the truth. So if a dip gets us closer, then why such negativity towards it?
Then I would like the option to apply that dip at home, in my system, not have it cooked into the speaker recipe or mixed into the recording, that's all.

No negativity here. If one needs a 3khz dip to achieve a convincing illusion of a live event, then apply it and enjoy. I'm all about the post-processing at home, as my "truth" invariably ends up being a system eq'd for it's particular environment, and not true to the input per se.
 
D

Dennis Murphy

Audioholic General
I certainly agree with some of what you're saying. But what many here have been trying to point out is that your original argument was based on a logical error. Just because we don't hear "flat" doesn't mean the speakers shouldn't be flat. That flat sound won't be flat when processed by the ear. You've resorted to other arguments dealing with directionality and vague arguments about differences between live orchestras and loudspeakers that don't necessarily point in any particular direction. And in any event variations in recordings in terms of mic placement and equalization are just too wide to take aim at with basic loudspeaker response.
 
AcuDefTechGuy

AcuDefTechGuy

Audioholic Jedi
We've been having a slight discussion regarding this topic in the subwoofer thread and it might be a little more fun and on topic to discuss it further here. I believe that speakers should not have a flat SPL, but follow more closely to how an average human ear hears. Flat speakers to me sound hard, bright, and unnatural. I find B&W speakers to sound very pleasing tonally and if any measurements are to be looked at, they follow the equal loudness scale very accurately. B&W being a multi-million dollar company who owns two anechoic chambers and uses computer software to model crossovers could build a flat SPL speaker in a matter of minutes.

If a recording was made with a flat calibrated microphone, then it should be played back on a non flat speaker system in order to sound flat to an average ear. Playing the recording back on a flat system will actually make it sound incorrect, because at that point one hears what the microphone did and not what a person would have during the event

This is what Linkwitz had to say...
Are you saying the Linkwitz Orion measures like a B&W speaker? :mad: :D The Audio Critic measured the Orion and it measured flat on-axis and smooth off-axis, like all great speakers should. ;) So in your opinion, B&W speakers sound the best and Revel, KEF, TAD, RBH, Salk/Phil speakers that measure flat/smooth do not sound very good to you?
 
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T

TheStalker

Banned
Are you saying the Linkwitz Orion measures like a B&W speaker? :mad: :D The Audio Critic measured the Orion and it measured flat on-axis and smooth off-axis, like all great speakers should. ;) So in your opinion, B&W speakers sound the best and Revel, KEF, TAD, RBH, Salk/Phil speakers that measure flat/smooth do not sound very good to you?
As been discussed, Linkwitz uses an EQ to dip the upper midrange.
 
JerryLove

JerryLove

Audioholic Samurai
Yes. A speaker should be completely flat on all axis if at all possible (and should roll smoothly if flat is not possible).

If you find the reality such a speaker would produce sub-optimal, you can adjust that with a DSP.
If room interactions cause issues (they will on any arbitrary speaker curve) you can adjust that on a DSP.
If recording X was too close to the orchestra, and recording B inserted a baffle between the L and R mics to make a binaural recording, you can adjust that on a DSP.
If artist A masters too loud, and B likes to pump up the bass too far, you can correct that with an EQ or DSP.

A flat speaker gives you the most even and simple tool to then adjust to taste.

The whole "what the mic heard" thing is insane and I cannot believe it made it 4 pages. Your ear will still hear selectively regardless.
 
U

UnxpectedError

Enthusiast
Interesting Read. Some may laugh but heres my EQ settings that i've been using for the past 20 years(Even with my 803D's).

Switching eq on and off the other night with about 8 people there and all except one liked my sound versus no eq.

Seems I deaded the very frequencies discussed here.

 
fuzz092888

fuzz092888

Audioholic Warlord
Interesting Read. Some may laugh but heres my EQ settings that i've been using for the past 20 years(Even with my 803D's).

Switching eq on and off the other night with about 8 people there and all except one liked my sound versus no eq.

Seems I deaded the very frequencies discussed here.

But without knowing what the FR of the speakers are in room, you could unknowingly be EQing your speakers flat.
 
U

UnxpectedError

Enthusiast
I've been in lots of different rooms with many different speakers over the years. I tweak the eq a lot, and it always ends up looking a lot like my pic above.

Comes back to personal preference i'm sure. But maybe my preference was influenced by the topics discussed here? I dunno
 
T

TheStalker

Banned
I certainly agree with some of what you're saying. But what many here have been trying to point out is that your original argument was based on a logical error. Just because we don't hear "flat" doesn't mean the speakers shouldn't be flat. That flat sound won't be flat when processed by the ear. You've resorted to other arguments dealing with directionality and vague arguments about differences between live orchestras and loudspeakers that don't necessarily point in any particular direction. And in any event variations in recordings in terms of mic placement and equalization are just too wide to take aim at with basic loudspeaker response.
Dennis, how about a 2-3dB BBC dip in your next design? :)
 
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