Jump to content


Photo

Time to kill the myth that "flat" bass is "correct" bass.


  • Please log in to reply
64 replies to this topic

#41 lowerFE

lowerFE

    Power Member

  • Members
  • PipPipPipPip
  • 109 posts

Posted 08 March 2017 - 02:36 AM

I want to just give my 2 cents on this topic, almost purely subjective without much scientific backing.

 

I work in different cities a lot. This is why I spent significant effort building a fantastic sounding small speaker that I can bring with me. Because of that, I've heard my speaker in 20+ different rooms. Here are my thoughts

 

Rooms suck ass.

 

But we all know that. The problem is, each room can sound very different even with similar frequency response at the LP. I've been in rooms that sounded absolutely terrible, and some rooms that were great! But since we are talking about the bass, I've found that some rooms are impossible to work with. I'll give a very extreme example. 

 

I once bought my speakers to a large auditorium that seated 450 people in order to get a room with a high ceiling to get high quality quasi anechoic measurements. I also brought along a small sealed 15" Martin Logan subwoofer to see how my speakers perform in a very large room if it does not have to produce bass, and to have some silly fun blasting bass :P. The bass sounded terrible. It was peaky, it had no depth, no impact, no matter where I am in the auditorium. It basically sounded like the fundamental is gone and all I'm hearing are the 2nd and 3rd harmonics.

 

So I turned on miniDSP and put a huge shelf boost to crank up the deep bass. But no matter what I did, no matter how much boost I give, play with phase, or how much louder I turn up the subwoofer, there was no sense of bass below <50Hz. I measured the FR at a listening position where it sounded bad (pretty much everywhere outside of the 1 meter radius around the sub), and the subwoofer response is fairly flat, no nulls or even dips. I ran the subwoofer up to 30dB hot with the mic registering 110dB of bass, and even though the walls were very audibly rattling, it STILL sounded like there was no bass. 

 

While I haven't experienced anything to that extreme in a normal home environment, there were definitely rooms where the bass FR looks fine, but the bass sounded very different. This tells me a frequency response measurement is woefully incomplete, and there must be something else that completes the picture. 


  • lukeamdman likes this

#42 lukeamdman

lukeamdman

    Bass Overlord

  • Members
  • PipPipPipPipPipPipPip
  • 829 posts
  • LocationBurnsville, MN

Posted 08 March 2017 - 02:46 AM

I don't know what you mean by input headroom.

 

dBFS = decibels relative to full scale, so when you say -20dBFS I'm wondering what you're using for scale.  Depending on which mic and preamp I'm using, -20dBFS could easily be over 140db at the seats!

 

I was curious if you were using 105db as your scale since 85dBC is about 20db below that.  



#43 SME

SME

    Super Bass Overlord

  • Members
  • PipPipPipPipPipPipPipPip
  • 962 posts

Posted 08 March 2017 - 04:17 AM

dBFS = decibels relative to full scale, so when you say -20dBFS I'm wondering what you're using for scale.  Depending on which mic and preamp I'm using, -20dBFS could easily be over 140db at the seats!

 

I was curious if you were using 105db as your scale since 85dBC is about 20db below that.  

 

Oh!  I see what you're saying.  The -20 dBFS refers to the RMS level, relative to a full scale sine wave, of the test signal going from my PC over HMDI to the AVR.  It is definitely not the same digital scale that is captured by my measurement mic!  That would be in the neighborhood of 100 dB on my UMIK-1, I think.  It is also not the same digital scale that my Motu 16A uses.  On my 16A, I actually use different digital scales for each output channel because they go to different kinds of amps with different sensitivities.

 

Getting back to your question.  The digital scale doesn't really work like that.  If you my AVR to master volume "0" and feed it a 0 dBFS sine wave, what you measure will depend entirely on the frequency and will almost certainly not be 105 dB or even necessarily close.  There is a common misconception that if the system is calibrated right then a signal that reaches digital full-scale in the soundtrack will reach 108 dB (peak) at the seat.  Just as with sine waves, it depends entirely on the signal AND the room.  For a very transient signal, most likely you will measure quite a bit less than 108 dB at the seats because you won't have all the extra room energy that would be present with a continuous signal.  This is especially true for a bigger room with a lot of reverb.  This is a very important point, which explains a lot about why reference level typically sounds too loud in small rooms.  It's not just a psychoacoustic perception thing.  It's because the transients actually *are* higher SPL in the small room than the big room.  It's a side-effect of the calibration method.



#44 Bossobass Dave

Bossobass Dave

    Bass Overlord

  • Members
  • PipPipPipPipPipPipPip
  • 914 posts

Posted 08 March 2017 - 08:33 PM

To be clear, my concern and comments are confined to the subwoofer (RB+LFE+10dB summed signal) and the crossover region of the subwoofer and the satellites.

 

 

How would one know if the content sounds bloated?  By using one's ears.  I realize that evaluation using one's ears is kind of heretical on a forum like this.  I can't blame anyone for being skeptical of claims that listening can be used to evaluate sound quality in any objective sense, given that so much of the audio industry is completely fraudulent and successful in so far as placebo effect influences subjective judgments.  However, until we have a complete experimentally validated model of human hearing, our ears remain the best judge of what things sound like.

 

I was afraid you'd resort to hearing as the arbiter of success after calibration... I have 60-odd discs you're invited to "listen" to and grade the muddiness or the thinness thereof. I've conducted these sorts of casual listening tests myself as well as exploring the directional cognizance claims by many that supposedly correlate to crossover point. I've asked elderly, young, clueless, musicians, producers, male, female, friend and foe. Listeners are generally clueless and so extremely biased (or in serious stages of hearing loss) as to border on the comical (not that there's anything wrong with that <disclaimer for the feelings of the less well-adjusted readers>).

 

Hacksaw Ridge is a good example. If your system is sharply rolled off <20 Hz (as yours is), the presentation will be noticeably lacking, and the calibration will be a fruitless exercise. Even if your system is full bandwidth to 1 Hz and flawlessly calibrated, there is no, zero, minus infinity chance you can judge the systems accuracy with your ears without a reference. As I've said far too many times in various forums, applying a steep HPF at 20 Hz is not a trivial tweak to content bandwidth and certainl;y affects playback accuracy and perceptions.

 

The trouble with the whole audiophile industry is people's obsessive focus on the subtle.  "Did those new speaker cables make a difference?"  "Yes, of course.  It was subtle, but it definitely made a difference."  Uh huh.  I'm far more interested in aspects of audio that are *not subtle*.  If dialog sounds too muddy, that is not a subtle problem, especially it prevents you from understanding what is being said.  If the individual notes in a bass-line can't be discerned because of too much deep bass from the subwoofer, then that is *not subtle*.  I can demo this on my system for any interested listener who can come here to Denver.  I can shelve the bass from 50 Hz and below by +2 dB, and switch the filter in with only a fraction of a second of gap while a song is playing.  A bass line that was once snappy and a kick drum that once punched the chest turn into mush and rumble.  That's *not subtle*.  I'm convinced that everyone who heard the difference would agree that the latter sound was muddy and inferior.

 

You want some pictures?  Check out the first two frequency response plots I posted under the "Speaker / Room Calibration" section in the first post of my system/room thread.  One is processed with 1/3rd octave smoothing and the other with 1/3rd octave FDW.  The latter is a much more accurate approximation of the first arrival sound coming from my speakers and is also much closer to what I think my speakers sound like.  I don't have any good time-frequency plots to show, for a variety of reasons, chief among them is the difficulty of visualizing everything that's relevant to hearing in a single plot.  I believe this to be a problem with Spec Lab spectrograms as well.  The choice of window size always involves a compromise between time and frequency resolution.  To really understand what's going on, you need to view the data with a variety of window sizes.

 

This is what I suspected is the final answer... frequency response. It is indeed what we hear, irrespective of the particular curve you or anyone else might prefer and regardless of the method used to arrive at it. It remains one of the best tools for calibration.

 

 

A few of us have discussed and explored windowing in years past. I was once told that I need to use 'X' window for better accuracy of measurement, for whatever 'scientific' reason, which I forget now. Smoothing can take you all the way to anechoic response, as in a close mic with 1/2 octave smoothing (which is always what I've used). Shown below id the no-smoothing vs 1/2 octave smoothing close mic of my subwoofer system:

 

iI3MJ4h.jpg

 

This (comparing the close mic with the seats mic versions) is basically what you're doing with smoothing, but with your own choice of compromise:

 

oquLJdj.jpg

 

My response graph was a result of the suggestion by AVS member <forgot his SN> that I have bad response measurements because i use the wrong window. I used my usual window and then used the one he suggested. That result also has the smoothed close mic version laid over it.

 

Then there are your graphs, smoothed and windowed, with scale normalized.

 

Of course, I do not "hear" the 6 Hz resonance exhibited by my floor system, but I think it a bit absurd to suggest its influence should be noted by the close mic response or any in-between resulting FR due to smoothing and/or window views.

 

Curious; are you suggesting that the peak your 1st FR shows at 110 Hz isn't what I would hear at the mic position?


  • Electrodynamic likes this

#45 SME

SME

    Super Bass Overlord

  • Members
  • PipPipPipPipPipPipPipPip
  • 962 posts

Posted 09 March 2017 - 12:29 AM

To be clear, my concern and comments are confined to the subwoofer (RB+LFE+10dB summed signal) and the crossover region of the subwoofer and the satellites.

 

Why?  I would regard the bass range to formally start at around 200-250 Hz.  Actual bass instruments and sound effects tend to have harmonics well above there that affect the perception of the overall sound.  Even tactile sensation is affected by higher frequencies, up to 500 Hz in my experience.  If you don't care about the rest of the spectrum, why not just low pass everything at 120 Hz?

 

I was afraid you'd resort to hearing as the arbiter of success after calibration... I have 60-odd discs you're invited to "listen" to and grade the muddiness or the thinness thereof. I've conducted these sorts of casual listening tests myself as well as exploring the directional cognizance claims by many that supposedly correlate to crossover point. I've asked elderly, young, clueless, musicians, producers, male, female, friend and foe. Listeners are generally clueless and so extremely biased (or in serious stages of hearing loss) as to border on the comical (not that there's anything wrong with that <disclaimer for the feelings of the less well-adjusted readers>).

 

Grading the quality of bass on discs is not my focus.  My focus is to optimize the tonal balance of my playback system to maximize enjoyment of those discs.  This requires matching the tonal characteristics of my system to those used in the mastering studio or the mix room, if no mastering was done.

 

Even though I talk of a "bass" boost, the transition point of this shelf falls in the range of 100-500 Hz.  For what it's worth, the effect of changing this transition point on the response in the sub range is actually very minor.  Changes below 100 Hz are actually very minor.  My choice for bass boost transition point and gain for any particular content is guided more by the subjective balance of lower mids with higher harmonics.

 

The transition frequency and gain I use most often with music, kind of my default, is about +3.5 dB @ 120 Hz.  This works with a large variety of music I listen to, particularly a lot of electronic music, much of which was probably mixed on near-field monitors and never even mastered.  Content that is released by major labels is more likely to have been mastered, probably with floor standing speakers that exhibit a somewhat greater boost with a higher transition frequency.

 

If there are vocals in the track, a clear give-away is that the female voices sound thin even though the male voices sound full.  Likewise, the piano may sound tinny with higher notes but not lower notes.  Or maybe the cello sounds good but violin that sounds harsh as it ascends to higher notes.  On the flip side, if I set the transition frequency for the bass boost too high, then I might notice clear and detailed female vocals but muddiness in the male vocals.

 

Hacksaw Ridge is a good example. If your system is sharply rolled off <20 Hz (as yours is), the presentation will be noticeably lacking, and the calibration will be a fruitless exercise. Even if your system is full bandwidth to 1 Hz and flawlessly calibrated, there is no, zero, minus infinity chance you can judge the systems accuracy with your ears without a reference. As I've said far too many times in various forums, applying a steep HPF at 20 Hz is not a trivial tweak to content bandwidth and certainl;y affects playback accuracy and perceptions.

 

Umm, I thought we were talking about listening tests with music?  And anyway, if your goal is to hear what the director or artist intended, you'd best throw away that stuff under 20 Hz.  We both know probably 99% of pro system used for mastering and re-recording mixing roll-off at 20 Hz and above.  Probably 99.9% roll-off at or above 15 Hz, which is where my system actually rolls off, by the way.

 

This is what I suspected is the final answer... frequency response. It is indeed what we hear, irrespective of the particular curve you or anyone else might prefer and regardless of the method used to arrive at it. It remains one of the best tools for calibration.

 

Of the two plots of mine that I had you look at, neither is my frequency response.  One is frequency response magnitude smoothed with 1/3rd octave resolution.  The other is frequency response with 1/3rd octave FDW.  For various reasons, neither of them reveals my extension below 20 Hz.  If you insist on calling one of these "frequency response", then which one?  Which one should be used for calibration?

 

A few of us have discussed and explored windowing in years past. I was once told that I need to use 'X' window for better accuracy of measurement, for whatever 'scientific' reason, which I forget now. Smoothing can take you all the way to anechoic response, as in a close mic with 1/2 octave smoothing (which is always what I've used). Shown below id the no-smoothing vs 1/2 octave smoothing close mic of my subwoofer system:

 

Windowing is a complex subject.  There are many different kinds and sizes of windows that may be used, and of course, frequency-dependent windowing opens up an entire new range of possibilities.  Each of them may be used to explore the data in different ways, to create a multitude of different SPL vs. frequency curves, whose meaning must be interpreted in the context of the windowing and smoothing that is used.

 

You cannot smooth "all the way to anechoic response".  You can use windowing to recover the anechoic response for mid and high frequencies where the direct sound is readily distinguished from the reflected sound.  For bass, you can't recover the anechoic sound at all.  Nor will close mic measurements give you the anechoic sound in the bass.  Such measurements will be affected both by near-field effects and by room effects, where they are strong enough to overwhelm the direct sound even at the close distance.  There is a reason Josh Ricci does his measurements outdoors.

 

At the same time, my interest is to recover the anechoic sound only for those frequencies in which it can be distinguished from room reflections.  For bass frequencies, I care about the first arrival sound that is perceived by the listener.  And I believe that first arrival sound exhibits a bass boost when an anechoic flat speaker is used in a typical mixing or mastering environment.

 

Of course, I do not "hear" the 6 Hz resonance exhibited by my floor system, but I think it a bit absurd to suggest its influence should be noted by the close mic response or any in-between resulting FR due to smoothing and/or window views.

 

Curious; are you suggesting that the peak your 1st FR shows at 110 Hz isn't what I would hear at the mic position?

 

I'm not sure what you're saying here, but resonances are a different story.  They are typically audible well beyond their influence on first arrival sound.  But I consider fixing resonances in the response to be a separate activity, one that improves sound quality, but is not directly relevant to tonal balance calibration.

 

My center channel response has inconsistent coverage in the bass range because of its placement up against the wall.  I am planning to address that problem using either thick absorption or an extended baffle wall, but until then, the response shown reflects a compromise to minimize deviation across multiple seats.  At the MLP, center channel output is weak in the broad region around ~180 Hz and strong in the broad region around ~90 Hz.  These features are visible in the second plot, and while they constitute deviations of only +/- 2 dB, they are in fact quite audible.

 

In contrast, the peak at 110 Hz in the second plot results from a combination of the strong direct sound output around 90 Hz and constructive interference from a series of reflections that arrive in the range of 10-20 ms after the initial impulse.  These reflections blend together in the bass frequencies, but the entire group can be readily distinguished from the direct sound.  By my hypothesis, the series of peaks and dips that arise from the interference of the reflections with the direct sound are not likely to be heard as such.  Instead, the brain is likely to hear the direct sound and reflections as separate events, each with their own tonal composition.  The brain may use information from the later arriving reflected sound to revise its assessment of the tonal qualities of the direct sound, but the overall effect of that later arriving sound on perception will likely be greatly diminished compared to the direct sound.



#46 Bossobass Dave

Bossobass Dave

    Bass Overlord

  • Members
  • PipPipPipPipPipPipPip
  • 914 posts

Posted 09 March 2017 - 06:21 PM

Okey Dokey, we're in unrecoverable mode now...

 

I've played electric bass for some 50 years now. Not sure if you're that confused or yanking my chain? I'm keenly aware of its range and possible harmonics that may or may not survive production methods. You can't write music without knowing the ranges of the instruments involved.

 

TvCl522.gif

 

Actual bass instruments have fundamentals in the bass range. Their harmonics are played back by satellites and are far easier to manipulate to taste. My basses are all 4 string and cover low E (41.2 Hz) to 2 octaves higher E on the G string (123.5). A 100 Hz crossover point takes the subwoofer to 200 Hz, where it is down -30dB with LR4 LPF. Keyboard and 5-7 string basses go lower. Synth can generate fundamental to single digits.

 

Transients (an impulse is one) have content to DC, regardless of the fundamental, unless they are purposely filtered. I'm not aware of anyone who has successfully generated, played back and measured transients cleanly and accurately.

 

If you intend to only discuss your front 3 satellites, that would be a useful disclaimer. Of course, this isn't the case according to what you've posted thus far, so not sure what the LPF @ 120 Hz comment is supposed to mean..

 

My close mic measurements have turned out to be more accurate that Ilkka's ground plane measurements of the same Tumult driver in slightly different Vb Josh chooses to measure ground plane because the battery of tests he uses that were devised by others requires it. My close mic showed a perfect 12 dB/octave roll off whereas Ilk's showed a 10dB/octave roll off (which appeared in nearly all of his GP measurements of an unfiltered sealed subwoofer as unexplained phenomena in our private conversations about the subject).

 

art-598742.jpg

 

The bottom line is that the close mic method can be extremely accurate and has been used my many noted engineers over the decades.

 

I realize that both of your frequency response magnitude graphs are smoothed. The question remains.. do you think I would not hear that peak because it isn't comprised of only the anechoic response of the loudspeaker or that it's possible to distinguish that distortion by your brain separating the anechoic (direct radiated) sound from the latent release of the stored energy sound? If not, how does smoothing help with the dominant distortion in your system at the mic?

 

And, let's just say that I don't believe a human can even acknowledge 10-20 ms of delay much less distinguish the first and second sounds. Curious to know if you've ever employed a processor with delay and increased the delay until it is audible to you? And, that sort of experiment is with only a single sound and repeat, but it might help prioritize.

 

You can use any means of manipulating the FR at the primary listening position that you feel distinguishes itself from the multiple theories on the subject best to your logical thinking. The best smoothing method is that of treating the room to the degree of dead you prefer. I remember the avalanche of posts when Audyssey first hit the streets that exclaimed and extolled the religious experience of a difference once Audyssey was run. Thank goodness, like most theroies, the crowds have calmed down and the manufacturers have made improvements. None of that will help you with the subwoofer which dominates the distortion of the input signal at the PLP. That's why my focus is there and not with the short wave frequencies of the audible bandwidth.


  • Electrodynamic likes this

#47 SME

SME

    Super Bass Overlord

  • Members
  • PipPipPipPipPipPipPipPip
  • 962 posts

Posted 10 March 2017 - 10:41 AM

Okey Dokey, we're in unrecoverable mode now...

 

I've played electric bass for some 50 years now. Not sure if you're that confused or yanking my chain? I'm keenly aware of its range and possible harmonics that may or may not survive production methods. You can't write music without knowing the ranges of the instruments involved.

 

[---cut---]

 

Actual bass instruments have fundamentals in the bass range. Their harmonics are played back by satellites and are far easier to manipulate to taste. My basses are all 4 string and cover low E (41.2 Hz) to 2 octaves higher E on the G string (123.5). A 100 Hz crossover point takes the subwoofer to 200 Hz, where it is down -30dB with LR4 LPF. Keyboard and 5-7 string basses go lower. Synth can generate fundamental to single digits.

 

You totally missed the point.  The point is that the bass instrument *usually* has strong harmonic content, which has a big impact on the sound.  Do you ever just plug your electric bass directly into a subwoofer when you play?

 

Transients (an impulse is one) have content to DC, regardless of the fundamental, unless they are purposely filtered. I'm not aware of anyone who has successfully generated, played back and measured transients cleanly and accurately.

 

All realistic transients are rolled off somewhere at the bottom or they wouldn't be transient.  An impulse is a theoretical construct that does not exist in real life in an unfiltered form.  An unfiltered impulse also has content to an infinitely high frequency, which is impossible in reality.

 

Anyway, I don't know why you are bringing this up other than to try to turn this conversation into *yet another debate about ULF*.  No thanks.

 

If you intend to only discuss your front 3 satellites, that would be a useful disclaimer. Of course, this isn't the case according to what you've posted thus far, so not sure what the LPF @ 120 Hz comment is supposed to mean..

 

You told me: "My concern and comments are confined to the subwoofer (RB+LFE+10dB summed signal) and the crossover region of the subwoofer and the satellites."  I pointed out that any discussion about calibration and bass balance has to include the mains well above the crossover frequency.  If you don't believe me, then try running an LPF at 120 Hz, or just don't bother to turn on the amps for your mains.  Great bass, huh?  Yeah.  I thought so.

 

My close mic measurements have turned out to be more accurate that Ilkka's ground plane measurements of the same Tumult driver in slightly different Vb Josh chooses to measure ground plane because the battery of tests he uses that were devised by others requires it. My close mic showed a perfect 12 dB/octave roll off whereas Ilk's showed a 10dB/octave roll off (which appeared in nearly all of his GP measurements of an unfiltered sealed subwoofer as unexplained phenomena in our private conversations about the subject).

 

[---cut---]

 

The bottom line is that the close mic method can be extremely accurate and has been used my many noted engineers over the decades.

 

Haven't we discussed this before?  Close mic measurements have uses, and can approximate the shape of the ground plane curve, but they don't replace ground plane measurements.  Even if you avoid the caveats of near-field effects (you certainly won't with your Raptor's) and interference from strong room modes, they don't give you absolute sensitivity needed to compare performance.

 

I realize that both of your frequency response magnitude graphs are smoothed. The question remains.. do you think I would not hear that peak because it isn't comprised of only the anechoic response of the loudspeaker or that it's possible to distinguish that distortion by your brain separating the anechoic (direct radiated) sound from the latent release of the stored energy sound? If not, how does smoothing help with the dominant distortion in your system at the mic?

 

No, I don't think you are really going to hear a peak at 120 Hz.  You are more likely to hear the presence of the reflections that contribute to the peak there as well as the peaks and dips across the 100-400 Hz bandwidth of the reflections.

 
The part of the spectrum that sounds less than great to my ears is at 190 Hz where the direct sound is weak and the reflected sound is stronger than the direct sound.  This can make voices sound a bit weird.  Solving this problem requires me to improve the acoustic integration ff the speaker with the wall, something I plan to do fairly soon.  Other than that, the group of reflections is unusually strong because of symmetry.  Both the center channel and MLP are centered in the room, so the reflections from each sidewall arrive at the same time within that range.  This is probably a common problem in home theaters.

 

 And, let's just say that I don't believe a human can even acknowledge 10-20 ms of delay much less distinguish the first and second sounds. Curious to know if you've ever employed a processor with delay and increased the delay until it is audible to you? And, that sort of experiment is with only a single sound and repeat, but it might help prioritize.

 

The ear and brain are absolutely able to discern audible events separated by 10-20 ms, but they won't necessarily be perceived as discrete echos.  The separate arrivals of the direct sound and the group of reflections are likely to be fused into a single perception of the sound of the speaker being heard in a room like the one you are sitting in.



#48 Bossobass Dave

Bossobass Dave

    Bass Overlord

  • Members
  • PipPipPipPipPipPipPip
  • 914 posts

Posted 10 March 2017 - 05:29 PM

You totally missed the point.  The point is that the bass instrument *usually* has strong harmonic content, which has a big impact on the sound.  Do you ever just plug your electric bass directly into a subwoofer when you play?

 

This is waaaaay off topic from the OP. I'm not interested in the rabbit hole of educating a non-musician as to what my bass sounds like or can sound like when played through my HT subwoofer system. The reasons should go without saying but if they don't in this case c'est la vie.

 

All realistic transients are rolled off somewhere at the bottom or they wouldn't be transient.  An impulse is a theoretical construct that does not exist in real life in an unfiltered form.  An unfiltered impulse also has content to an infinitely high frequency, which is impossible in reality.

 

Anyway, I don't know why you are bringing this up other than to try to turn this conversation into *yet another debate about ULF*.  No thanks.

 

Yet another debate about ULF? Wow. How about yet another SME lecture point about what calibration philosophy is bullshit?

 

You told me: "My concern and comments are confined to the subwoofer (RB+LFE+10dB summed signal) and the crossover region of the subwoofer and the satellites."  I pointed out that any discussion about calibration and bass balance has to include the mains well above the crossover frequency.  If you don't believe me, then try running an LPF at 120 Hz, or just don't bother to turn on the amps for your mains.  Great bass, huh?  Yeah.  I thought so.

 

Yes, I've analyzed my many systems over the decades with and without the satellites dating back to the 70s. Analysis of subs only is useful to hear the effect of crossover point and slope selection and extraneous vibration noise. Oh, and yes, of course the subs only listening test is crucial, but I'm not the one here who claims his pschoacoustic abilities are a primary tool in calibration... you are.

 

Haven't we discussed this before?  Close mic measurements have uses, and can approximate the shape of the ground plane curve, but they don't replace ground plane measurements.  Even if you avoid the caveats of near-field effects (you certainly won't with your Raptor's) and interference from strong room modes, they don't give you absolute sensitivity needed to compare performance.

 

Ground plane measurements can approximate close mic... yes. Sometimes ground plane measurements contain non-trivial errors, as shown in my previous post. How many times that fact is discussed isn't relevant. Comparing performance is also not relevant to the discussion.

 

No, I don't think you are really going to hear a peak at 120 Hz.  You are more likely to hear the presence of the reflections that contribute to the peak there as well as the peaks and dips across the 100-400 Hz bandwidth of the reflections.

 

Reflections are responsible for the peak at 110 Hz? You mean reflections that create a standing wave or RT60 reflections? And, you don't hear the +7dB peak, but you hear the individual reflections that produce it? I'm not misreading, I just don't get what you're trying to say. Please provide some... any... evidence/data when you make proclamations. It makes for a much less frustrating discussion.

 
The part of the spectrum that sounds less than great to my ears is at 190 Hz where the direct sound is weak and the reflected sound is stronger than the direct sound.  This can make voices sound a bit weird.  Solving this problem requires me to improve the acoustic integration ff the speaker with the wall, something I plan to do fairly soon.  Other than that, the group of reflections is unusually strong because of symmetry.  Both the center channel and MLP are centered in the room, so the reflections from each sidewall arrive at the same time within that range.  This is probably a common problem in home theaters.
 
Agreed that room treatment is the fix for how it sounds and has something to do with calibration but this is straying from your OP and falling into the nuance category you've mentioned to be unimportant.

 

The ear and brain are absolutely able to discern audible events separated by 10-20 ms, but they won't necessarily be perceived as discrete echos.  The separate arrivals of the direct sound and the group of reflections are likely to be fused into a single perception of the sound of the speaker being heard in a room like the one you are sitting in.

 

You're obviously confusing echolocation with detection of latency. Test yourself and get back to me.

 

I responded to your thread based on your OP in which you declared that it's sad that any authority would suggest the best calibration from a recorded source playback system is a flat response. You declared it, right here and now, to be bullshit with no disclaimer. You support that absurd declaration by mentioning "numerous blind listening studies conducted by Harman" though you don't define numerous nor do you cite any of them.

 

I've said about a thousand or more times; the equal loudness curves are built into all commercially available recorded material. I have been a participant in enough of those sessions and processes over the past half century, beginning at age 13YO, to assure you that no producer has ever mixed the content flat assuming that SME or anyone else will re-mix the product, post production, using a one size fits all calibration adjustment. For various reasons, that material may end up anywhere on the quality scale which exposes the flaw in such an approach.

 

Think about it. A producer is deduced to have radically different hearing than some random collection of listeners to the point of requiring post production production to get the mix right. And, THAT conclusion isn't bullshit?

 

For the record, I don't have any music program that requires a +5dB boost in the bass region to correct for a thin sound. That doesn't mean there is no such program, it just means that i don't keep poorly produced source in my collection.

 

If one falls prey to Harman (or any other of the thousands of 'listening studies') conclusions and calibrates to some distorted bias, then every recording played back on that system will show that bias. This is proven on the production side. Mix on a system other than flat and get a result that has too much bass or too little bass, which is what happens in reality. The proper method is indeed to calibrate flat and "season to taste' after that on a disc-to-disc basis. What others preferred during a listening test positively changes in those test subjects over time with the evolution of hardware and software, room construction differences, age and preference adjustment. Why you or anyone would think that he/she should conform to such a metric is beyond me, but calling a flat calibration bullshit is just not the way to be taken seriously.



#49 andyc56

andyc56

    Newbie

  • Members
  • Pip
  • 9 posts

Posted 11 March 2017 - 04:45 AM

Here is a link to a Harman study about target curves.Hopefully it will work.



#50 Bossobass Dave

Bossobass Dave

    Bass Overlord

  • Members
  • PipPipPipPipPipPipPip
  • 914 posts

Posted 12 March 2017 - 07:04 PM

Here is a link to a Harman study about target curves.Hopefully it will work.

Thanks for the link.

 

I've read this and the auto EQ vs the "target FR" articles in the past. I compared (one of many that have changed with remodels and changes in hardware over the past 15 years of measuring in-room) my response at the LP to the results of the auto EQ article.

 

jrASsYb.jpg

 

1) One guy preferred the low end bumped +15dB (IIRC).

2) IMO, 1dB/octave, which amounts to (+/-5dB) is tantamount to a flat response without EQ post smoothing, which I don't use.

3) My high end is bumped because I've lost a chunk of hearing capability up there, but I don't find a more rolled off high end objectionable.

4) I listen at significantly higher playback levels, which alters perception. Any test should use only program where the mix level is known and matched.

5) A noted caveat in the auto EQ article is: "Program material is a nuisance variable".

6) The results of all of Harman's studies leave out the fact that they reveal a simple conclusion; a) either the producers of the selected program source had seriously flawed  monitoring hardware or b ) they really sucked at mix production.

7) Playback systems that roll off sharply below 50 Hz shouldn't even be a part of a listening session of any kind, IMO.

8) All of the hardware used is a Harman product.

9) Sine sweep FRM graphs are always the metric used.

 

Reminds one of "listening tests" over the past century:

 

N77xIJA.jpg

 

Was Edison serious, or was he selling his invention? Note that some of the "listeners" have the blindfolds covering their ears!! Also note that they are all old guys whose hearing might be dubious.

 

Acoustic Research conducted many "listening tests" comparing "Live vs Playback": WUT??

 

PF18eIy.jpg

 

If I post the Ground Plane measurements results of the Raptor, someone please predict what will happen before the virtual ink is dried?

 

This "test" cracks me up. It seems the principals got the wrong memo on which of the human senses were being tested?

 

anxyeCK.png

 

Preferences don't mean much and the industry should get that and move on. Nothing against any preferred curve, just that proclaiming one a "target" over others is just silly. Members are appreciated for their posting efforts, especially guys like SME who have interesting stuff to post. But, edicts such as "your method is BS because Harman said so" should expect some blowback.



#51 Ricci

Ricci

    Super Bass Overlord

  • Moderators
  • 1,067 posts
  • LocationLouisville, KY

Posted 13 March 2017 - 01:41 PM

I'd like to throw in one more observation I have about the final mix of any track. We already talked about varying rooms, playback systems and playback level, unknown response in them, etc and how these can affect the final mix. Another thing to consider is the upper ceiling of digital formats. In my opinion this makes a large impact on modern mixing and the overall balance of music. In theory you would simply lower the overall level of the various tracks to maintain the headroom needed for the loudest signals in the hottest track in the mix, all you need do is turn the playback system up a bit more, but in practice this is very rarely done anymore. If your "dynamic" or alternatively mixed track comes on the radio in between 2 other tracks that are heavily compressed and densely mixed right up against a limiter, like modern tracks are, yours will be less loud and will seem weak in comparison. We all know louder is preferred by most. The artist will not be happy that their tracks are quieter and ultimately this will affect your reputation as a mix engineer and ability to earn a living. Also the majority of people are listening to content on tiny phone speakers, Bluetooth docks, tv speakers, PC sub sat system, or perhaps a soundbar. The best playback system many people might have access to is their factory car stereo and we all know that would leave a lot to be desired in most cases. Mixes have to be made to sound clear and loud on these types of miniature, response limited devices.

 

Most of the above is in reference to recorded music but much of it also applies to motion picture soundtracks as well.


  • deepthoughts and lukeamdman like this

#52 SME

SME

    Super Bass Overlord

  • Members
  • PipPipPipPipPipPipPipPip
  • 962 posts

Posted 20 March 2017 - 10:24 AM

 

You totally missed the point.  The point is that the bass instrument *usually* has strong harmonic content, which has a big impact on the sound.  Do you ever just plug your electric bass directly into a subwoofer when you play?

 

This is waaaaay off topic from the OP. I'm not interested in the rabbit hole of educating a non-musician as to what my bass sounds like or can sound like when played through my HT subwoofer system. The reasons should go without saying but if they don't in this case c'est la vie.

 

You already educated us about the electric bass (at least with regard to its range of fundamental frequencies) without even asking for permission.  And what I said is absolutely on topic.  Here I've re-quoted what you responded to.

 

When I speak of calibrating tonal balance, I'm talking about the full range of frequencies, including those typically reproduced by a subwoofer.  I don't see any need to make a distinction between the frequencies reproduced by speakers vs. subs.  For all I care, you could be running huge full-range speakers without subs.  That's not to minimize or ignore the problems that arise with blending subs with the mains channels, but I ignore that here because I'm more interested in discussing the goal than the method of achieving it.  There are other more subtle issues that can lead to inconsistencies in reproduction of soundtracks where bass management, but I'm also ignoring these for now.

 

Dave, If you want to discuss calibrating subs but ignore everything above the sub/main crossover region of 100 Hz (as seems to be your preference), then I suggest you pursue that interest in another thread.

 

Ground plane measurements can approximate close mic... yes. Sometimes ground plane measurements contain non-trivial errors, as shown in my previous post. How many times that fact is discussed isn't relevant. Comparing performance is also not relevant to the discussion.

 

All measurement methods are prone to errors if done improperly or care taken to achieve consistency.  Without knowing the reason that those errors crept into Ilkka's measurements, I would guess they are due to a mic calibration problem, which of course has *nothing* to do with ground plane measurements vs. using other methods.

 

Reflections are responsible for the peak at 110 Hz? You mean reflections that create a standing wave or RT60 reflections? And, you don't hear the +7dB peak, but you hear the individual reflections that produce it? I'm not misreading, I just don't get what you're trying to say. Please provide some... any... evidence/data when you make proclamations. It makes for a much less frustrating discussion.

 

To your first two questions, the answer is neither.  My room response is not dominated by standing waves around the frequency nor does it develop a diffuse field, which would be necessary to speaker with regard to RT60.

 

I'm suggesting that the ear "hears" the first arrival and reflections as separate acoustic events.  Higher level processing in the brain correlates these events and fuses them into a single event, which is what is actually perceived.  What is perceived is the sound from the speaker occurring within an acoustic space.  The perception of the temporal and tonal characteristics of the sound is dominated by the first arrival.  The early reflections make only minor contribution to the temporal and tonal characteristics, but they can impact perception of spatial characteristics of the sound and listening room.

 

I responded to your thread based on your OP in which you declared that it's sad that any authority would suggest the best calibration from a recorded source playback system is a flat response. You declared it, right here and now, to be bullshit with no disclaimer. You support that absurd declaration by mentioning "numerous blind listening studies conducted by Harman" though you don't define numerous nor do you cite any of them.

 

It *is* sad.  I'm sure most who recommend as much mean well, but flat in-room response just doesn't sound good most of the time.  Worst still, when production/mastering systems are calibrated this way, the tonal balance of the mix becomes skewed.  The calibration method skews the tonal balance of the system to try to correct for mostly inaudible room characteristics, and then the mix reflects the inverse of these characteristics.  This is confirmed to be the case with cinema dub stages where everyone calibrates in-room 1/3rd octave binned power response (at the MLP only) to the same in-room X curve target.

 

Apparently I didn't need to cite any studies because you are already familiar with much of Toole / Harman's work.  Though you also dedicated most of the space of an additional post to deriding Harman's use of listening tests to try to figure out what sounds good.

 

I've said about a thousand or more times; the equal loudness curves are built into all commercially available recorded material. I have been a participant in enough of those sessions and processes over the past half century, beginning at age 13YO, to assure you that no producer has ever mixed the content flat assuming that SME or anyone else will re-mix the product, post production, using a one size fits all calibration adjustment. For various reasons, that material may end up anywhere on the quality scale which exposes the flaw in such an approach.

 

I'm not talking about equal loudness curves, except in so far as almost all ULF content is inaudible without boost or excessive playback levels.  (That's another point that's already been beat to death on these forums.)

 

Otherwise, I don't even know what you are trying to say here.  I can't remix anything post-production without having access to the original tracks.  I *can* and *do* effectively re-master content these days.  I've learned to identify tonal balance issues by ear and make improvements with EQ.  This process is absolutely *not* "one-size fits all".  However, the vast majority of music sounds better with some bass boost somewhere in the measured smoothed in-room frequency response.  With cinema, things are all over the map, and cinema content is more likely to need aggressive EQ to clean up.

 


Think about it. A producer is deduced to have radically different hearing than some random collection of listeners to the point of requiring post production production to get the mix right. And, THAT conclusion isn't bullshit?
Nope.  The problem isn't with the hearing of the engineer.  The problem is that the references are insufficiently defined.  Even if every mastering engineer had a ruler flat 1/6th octave smoothed in-room response, the subjective tonal balance of each of their systems could vary dramatically.  This is not far off from what is done in cinema (albeit using 1/3rd octave RTA and the X curve target), and this leads to major inconsistency between mixes.  In the music world where EQ to flat in-room response is much less likely to be done, inconsistencies are still present but are more minor.

 

For the record, I don't have any music program that requires a +5dB boost in the bass region to correct for a thin sound. That doesn't mean there is no such program, it just means that i don't keep poorly produced source in my collection.

 

For what it's worth, I rarely stray beyond +4 dB.  When I do so, the center frequency of the shelf is almost always up pretty high, at like 250 Hz or above.  As  a point of interest, for music that needs the shelf moved up higher like that, I usually hear the thinness a lot more on sounds / instruments whose fundamental frequencies are above the center frequency.  Harshness on women's voices can be a good clue, but any kind of ascending sequence of notes in which the timbre obviously shifts from a full to a thin sound over the sequence.  This might involve piano, keyboard, violin, saxophone, or any number of others.

 

I have a lot of recordings that are of very high quality and sound great, provided that I get the bass shelf center frequency and gain set optimally.  If I did not have the capability to adjust these things, as is the case for the vast majority of listeners even on "top of the line" systems, I would regard a much narrower subset of those mixes as being high quality.

 

But anyway, to your point about not needing a bass boost with most content.  It's not clear to me how you calibrate your system and whether you use EQ with your speakers.  How do you level match your subs to your mains?  I also don't know what kind of speakers you use, how far away from boundaries they are, and how far away from them you sit.  These details matter a lot.  Depending on your setup, you may even benefit from some attenuation in the bass for music playback.  This can happen if the speakers are designed for placement away far away from walls, but yours are placed too close to them.  Your Raptor subs will also likely interact with the room differently from your speakers most likely.  They are likely to offer a lot more directivity and may actually sound better if run with a little bit less gain than a typical level match would suggest.  But this is all speculation without more info.

 

If one falls prey to Harman (or any other of the thousands of 'listening studies') conclusions and calibrates to some distorted bias, then every recording played back on that system will show that bias. This is proven on the production side. Mix on a system other than flat and get a result that has too much bass or too little bass, which is what happens in reality. The proper method is indeed to calibrate flat and "season to taste' after that on a disc-to-disc basis. What others preferred during a listening test positively changes in those test subjects over time with the evolution of hardware and software, room construction differences, age and preference adjustment. Why you or anyone would think that he/she should conform to such a metric is beyond me, but calling a flat calibration bullshit is just not the way to be taken seriously.

 

I'm citing Harman to give credit where it is due, but in fact, I reached my conclusions mostly on my own.  My overall approach is also quite different from Harman's.  Harman aims to create the best sounding speakers and headphones.  I aim to achieve the best sound I can using EQ.  Because my speakers use an active crossover, the EQ is required to provide the voicing that would be done with passive components instead.  Where our approaches overlap is with regard to the importance of flat anechoic response and smooth off-axis response.  They use anechoic chamber measurements to optimize their speakers, and "flat" is the design target.  My approach relies entirely on in-room measurements, and regards "flat anechoic response" as merely the imperfect reference for music mastering.  Neither of our approaches lead to a smoothed, in-room frequency response that's flat at all in most cases.

 

I'm getting tired of repeating this, but you have to get through your head.  Calibration to flat in-room response does not lead to consistent sound between mix environments.  It's not even close.  SMPTE pretty much trashed this notion in their recent studies of dubbing stages and theaters.  Flat anechoic response of the speakers gets you a lot closer but it still allows inconsistency in the low mids and bass.  To the best of my knowledge, there is no validated solution to this problem other than to try to kill 100% of the low mid and bass reflections and calibrate to flat in-room response.  This solution is not realistic.  Even the best rooms likely see at least a few dB of gain from reflections.  I might have a solution to that problem, but it needs time to develop and will eventually need listener studies to validate.

 

The thing is, you can't claim that any calibration method will lead to consistent results *without* listening tests to validate that the method works.  The best listening studies are the ones done by Harman that indicate flat anechoic response is best and not flat power response or flat in-room response.

 

I think you are very confused about what listener preference really means here.  If one is doing a mix, one often has a a lot of latitude as to how loud the bass instruments sound compared to the rest of the mix.  The easiest thing to do is just make the bass instruments louder than everything else.  There may be a point at which masking of higher frequency content becomes a problem, but there are a lot of tricks to compensate for this that can be applied during the mix stage.  However, once the mix is done, most of the preferences for the sound itself are locked in.  If you want kick drum to hit harder but it shares bandwidth with the bass, then you can't do what you want to the kick drum without messing up the sound of the bass.  Indeed, about the best thing you can do with EQ in the mastering and playback stages is to *improve the audibility of the content that's in the mix*.

 

In most cases, any content that is in a mix is meant to be heard.  There are certainly exceptions like unintended noise (including ULF) or clipping that the mixer does not hear, but if we are talking about particular musical passages or voices, the goal is definitely to be able to hear everything in the mix.  Most of this work happens in the mix stage, but there is the translation problem in which the tonal balance of the mix monitoring system doesn't match the tonal balance of the playback system.  The mastering engineer attempts to bridge this gap by making adjustments to the overall sound while monitoring on a (usually) higher quality "reference" system.  The window of what actually allows for all the content to be heard is quite narrow.  Once you deviate from the ideal by more than say +/-2 dB, you're likely to encounter significantly more masking, which means that musically relevant content becomes difficult or impossible to hear.  That narrow window doesn't offer much flexibility at all for either a mastering engineer or a home listener to "season the sound to taste" without damaging the integrity of the mix.  As such, a good mastering engineer can do most or all of his/her work without even consulting the artist or mixer.  He or she can spend some time listening to the music and tweaking the tonal balance until he or she is confident that he or she knows what is in the mix and has reset the tonal balance to maximize audibility of that content on the reference system.

 

Therein holds a key to better reproduction on playback system as well and listener preference of playback systems comes into play.  The preferred sound is the one that allows the listener to hear the most details.  Transients sound better and have more impact with better balance as well.  The more evenly a transient activates the various critical bands of the ear at the same time, the stronger it will seem to be.   A good sounding (and feeling) kick drum doesn't just hit at 30 Hz or 60 Hz.  It hits across a relatively wide bandwidth even as it may also ring around a few frequencies of resonance.


  • lukeamdman likes this

#53 SME

SME

    Super Bass Overlord

  • Members
  • PipPipPipPipPipPipPipPip
  • 962 posts

Posted 20 March 2017 - 09:46 PM

Here is a link to a Harman study about target curves.Hopefully it will work.

 

I'm not a big fan of this study for a couple reasons.

 

First of all, I'm skeptical that you can give untrained listeners access to crude tone controls and expect them to set them optimally, even if "optimal" is judged by their preferences.  As an analogy, imagine letting people without culinary training prepare "the best cake", giving them say over how much sugar and salt to use in the recipe but not the other ingredients.  Without training and experience, they won't have a good grasp of how these two flavors interact with one another and with the rest of the recipe.  For example, more salt can paradoxically increase sweetness.  And what if the other ingredients are not in ideal balance?  What if there isn't enough butter in the recipe?  How should this problem be compensated for?  The same issue arises in this study where the baseline is "flat in-room response", which is almost certain to create imbalances in the mid-range.  So how is an untrained listener supposed to strike a proper balance between treble and bass when the mid-range is out of whack?  Indeed, there's a saying among mixers: "get the mid-range right and everything else will fall into place".

 

The other issue I have is with the whole idea of trying to find a one-size fits all smoothed, in-room response target curve for speaker responses.  Such a curve undoubtedly varies with the room and speaker characteristics.  IMO, these differences will have more impact on the measured in-room response than on the subjective sound of anechoic flat speakers.  I'm OK with them looking for an ideal target curve for headphones because at least there are no room effects to alter the measured responses of the headphones in ways that are only marginally inaudible to the listener.

 

Indeed, I believe as long as Harman and others continue to pursue an optimal in-room response target, they will not succeed in solving the translation problem.



#54 BeastAudio

BeastAudio

    Ultra Member

  • Members
  • PipPipPipPipPipPip
  • 318 posts

Posted 21 March 2017 - 08:21 PM

I think we should have a data-bass bake-off for the best cake. Please send all entries to me and I will make a definitive and concrete supposition of who will win this bake-off and therefore have the theoretical absolute best cake on the internets.


  • lilmike, deepthoughts and SME like this

#55 Ricci

Ricci

    Super Bass Overlord

  • Moderators
  • 1,067 posts
  • LocationLouisville, KY

Posted 22 March 2017 - 01:27 PM

I think we should have a data-bass bake-off for the best cake. Please send all entries to me and I will make a definitive and concrete supposition of who will win this bake-off and therefore have the theoretical absolute best cake on the internets.

 

Yes. Of course we will need a full chemical analysis of each cake and readings of the brains electrical activity while eating them so we can log the peak enjoyment experienced.


  • lilmike and shadyJ like this

#56 BeastAudio

BeastAudio

    Ultra Member

  • Members
  • PipPipPipPipPipPip
  • 318 posts

Posted 22 March 2017 - 03:52 PM

MMMM my endorphines are already dancing.



#57 lilmike

lilmike

    Super Power Member

  • Members
  • PipPipPipPipPip
  • 154 posts
  • LocationPNW USA

Posted 22 March 2017 - 04:15 PM

mmmmm, cake.....



#58 maxmercy

maxmercy

    Super Bass Overlord

  • Moderators
  • 1,832 posts
  • LocationNW FL

Posted 23 March 2017 - 12:20 AM

But then won't someone be tempted to have a 'Lone Survivor' helping of cake and throw up......twice?

 

JSS


  • Infrasonic, lilmike and lukeamdman like this

#59 lilmike

lilmike

    Super Power Member

  • Members
  • PipPipPipPipPip
  • 154 posts
  • LocationPNW USA

Posted 23 March 2017 - 04:39 AM

Thanks. I just spat my drink onto my screen and keyboard...



#60 Infrasonic

Infrasonic

    Bass Overlord

  • Members
  • PipPipPipPipPipPipPip
  • 778 posts

Posted 23 March 2017 - 06:50 PM

Seriously trying to figure out how to combine Lone Survivor with a Devil's Food chocolate cake.

 

Hmm...






0 user(s) are reading this topic

0 members, 0 guests, 0 anonymous users