Why hardly any of us have truly clean deep bass.. - AVS Forum
Forum Jump: 
Reply
 
Thread Tools
post #1 of 33 Old 09-20-2013, 06:36 AM - Thread Starter
AVS Special Member
 
shadyJ's Avatar
 
Join Date: May 2009
Posts: 6,894
Mentioned: 3 Post(s)
Tagged: 0 Thread(s)
Quoted: 343 Post(s)
Liked: 592
I was struck by a comment made in this post in another message board regarding the equal loudness contour:
Quote:
What this chart also tells us is that low distortion is more important than absolute output. At 32Hz, which is plainly audible, our hearing is what, ~40db less sensitive than at 64Hz, the 2nd harmonic.

That means, if I'm reading the chart correctly, that with 1% 2nd harmonic distortion at 32Hz, the 2nd harmonic is audible at about the same level as the fundamental.

To expound on that observation just a bit, let us first define deep bass as anything under 40 Hz. Yes, its arbitrary, but to me 40 and below sounds pretty deep, and it doesn't really change the overall point. It also makes the math a bit easier when compared to the lowest sound there, 20 Hz. Now then let us compare the perceptual difference between 20 Hz at 100 dB and an octave above, 40 Hz, its second harmonic. These are familiar frequencies and loudness levels for most of us here, and it also makes for clean math and is easy to track on that chart. According to the chart, at 20 dB at just below 100 dB is perceptually equal to about maybe 77 dB at 40 Hz. Let round this off to a simple 20 dB difference, or a power ratio of 100. What that means is you need 100 times the loudness of 20 hz to perceptually equal a 40 Hz sound. So, like Irv Robinson said, to even have 1% second harmonic order distortion at 20 Hz at 100 dB would be as loud to human hearing as the fundamental. Of course, that becomes all the more worse when you get 3rd, 4rth, and higher order harmonic distortions. The cleanest subs that I know of out there can not output 100 dB at 20 Hz with less than 1% harmonic distortion. The situation also gets worse below 20 Hz as the curve gradient becomes steeper in those ultra deep frequencies. I pity the guys chasing after a clean 10 Hz.

Now I'm not one of those smarty pants acoustic scientist people what with their eye glasses and pocket calculators and book readin', but I have to wonder what it would take to get truly clean deep bass, perceptually speaking. I also have to question how the CEA2010 distortion limits are established, and I am guessing there is a practical consideration there as no subwoofer would pass a 20 Hz tone at any audible frequency without an audible component of distortion as well. So, to those better versed in acoustic science, I am asking if I am not somehow overstating the audibility of distortion here? Because if this is correct, none of us have true clean deep bass except perhaps a few of the most extreme bass systems in the world.
shadyJ is online now  
Sponsored Links
Advertisement
 
post #2 of 33 Old 09-20-2013, 10:11 AM
AVS Addicted Member
 
Bill Fitzmaurice's Avatar
 
Join Date: Nov 2009
Location: New Hampshire
Posts: 10,003
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 1 Post(s)
Liked: 1569
Quote:
Originally Posted by shadyJ View Post

So, to those better versed in acoustic science, I am asking if I am not somehow overstating the audibility of distortion here?
What you're not taking into account is that when media is mixed it's done so that at normal listening levels it sounds balanced across the spectrum.
As far as the capabilities of speakers are concerned, equal loudness isn't so much about how much more output capability one needs in the lows and highs as how much less is required in the mids, and that difference is why midrange drivers/speakers are so much smaller than subwoofer drivers and speakers if the system is properly set up.
Where users get into trouble is when they use subs that are simply too small to keep up with the mains, and/or they do not have enough of them. That pretty much applies to anyone using eight or ten inch loaded subs, unless their mains are loaded with tiny drivers, in which case the system is going to be balanced, but anemic.

Bill Fitzmaurice Loudspeaker Design

The Laws of Physics aren't swayed by opinion.
Bill Fitzmaurice is offline  
post #3 of 33 Old 09-22-2013, 12:51 AM
AVS Special Member
 
JHAz's Avatar
 
Join Date: Mar 2009
Posts: 4,009
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 112 Post(s)
Liked: 158
Moreover, since few of us sit around listening to sine wave test tones, the question of whether the distortion would actually be audible with real content is important. Of course most special effects noises have a broad frequency range, and my sorta rough sense from following the movies with bass thread is that there will normally be at least as much energy in the 40 to 80 Hz octave, say, as in the 20 to 40 Hz octave. So the original sound would have, theoretically, a 100 dB 20 Hz component and a 100 dB 40 and 80 Hz components, and the distortion, at 60 dB, will be fully masked.

BTW, every ten dB is ty0ically considered subjectively twice as loud, not ten times as loud . . .

OTOH, most electric basses, it appears, will have the second harmonic of lower notes fully 10 dB LOUDER than the fundamental. So if you're listening to a 30ish Hz tone from a 5 string, if the fundamental is at 80 dB, the second harmonic at 60 Hz is at 90 dB, and one percent distortion, at 40 dB, will be fully masked . . . .

I think based on less data that acoustic basses, and electric upright basses, will have a more nearly even level of fundamental to second harmonic. But that still means that there is already present in the music the frequency of the second harmonic fully 40 dB louder than the distortion because real instruments don't make single frequency sine waves. You could create such sounds with a synth, of course, but I kind of suspect it doesn't happen often because our ears tend to like the texture of harmonics, since they exist for real sounds in real life.
JHAz is offline  
post #4 of 33 Old 09-22-2013, 01:13 AM
AVS Special Member
 
braveheart123's Avatar
 
Join Date: Jul 2011
Location: Lone Wolf McQuade from Islamabad Pakistan
Posts: 1,828
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 11 Post(s)
Liked: 116
Quote:
BTW, every ten dB is ty0ically considered subjectively twice as loud, not ten times as loud . . .

More correctly, it takes 10 times more power for subjectively double the loudness.

History is written by those who have hanged heroes ...

The best EQ is no EQ ...

Alpine SWR-1223D Slot Ported HT Sub

Dual Dayton RSS390HO-4 Reference 15 Build For HT

Main System: Klipsch RF-82 II, Klipsch RC-62 II, RS-52 II, Onkyo 5010, Rythmik FV15HP, PSB S300
braveheart123 is offline  
post #5 of 33 Old 09-22-2013, 02:00 AM
AVS Special Member
 
audiofan1's Avatar
 
Join Date: Feb 2009
Posts: 3,163
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 114 Post(s)
Liked: 484
Nice Thread and one of the reasons I choose clean bass over max spl with the KK DXD12012 and to the numbers in the measurements add 6db for corner loading!

http://www.hometheaterhifi.com/subwoofers/subwoofers-reviews/ken-kreisel-dxd-12012-dual-12-push-pull-subwoofer/page-4-on-the-bench.html
audiofan1 is offline  
post #6 of 33 Old 09-22-2013, 02:55 AM - Thread Starter
AVS Special Member
 
shadyJ's Avatar
 
Join Date: May 2009
Posts: 6,894
Mentioned: 3 Post(s)
Tagged: 0 Thread(s)
Quoted: 343 Post(s)
Liked: 592
10 dB being a perceptual doubling of loudness is a subjective evaluation, of course, and it turns not to be completely true anyway:
Quote:
Widely accepted is still the theory of psycho-acoustic pioneer Stanley Smith Stevens, indicating that the doubling or halving of the sensation of loudness corresponds to a level difference of 10 dB. Recent research by Richard M. Warren, on the other hand leads to a level difference of only 6 dB.
As for other harmonics masking deep bass distortion, music typically does not have deep bass at all, with a few exceptions. Yes, film effects will have a lot of stuff that can mask harmonic distortion, but still, can the bass truly be said to be clean? To determine this we would need to run an A/B test and see if anyone could tell the difference. If they can, then what we have is not truly clean bass, but that isn't to say it would be bad bass, it could still be relatively clean bass.
shadyJ is online now  
post #7 of 33 Old 09-22-2013, 03:21 AM
AVS Special Member
 
braveheart123's Avatar
 
Join Date: Jul 2011
Location: Lone Wolf McQuade from Islamabad Pakistan
Posts: 1,828
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 11 Post(s)
Liked: 116
Quote:
Yes, film effects will have a lot of stuff that can mask harmonic distortion, but still, can the bass truly be said to be clean?

IMO it is more to do with the construction quality of the box. Inert box construction coupled with quality driver and clean power minimize distortion to a great level. I know just the words "great level" are not enough and must be backed by measurements. But that lies within the domain of manufacturers and DIYers.

Yes there is a day/night difference in a distortion free response and full of distortion high spl response. Distortion free response is not as loud. I think if one feels he has less SPL but clean bass, he'd be better off adding more similar subs to make up for less SPL than not spending money and pushing it beyond its limits and introducing distortion, which actually makes it sound louder. A lot of people do the later to save cost and they don't even know if they are listening to distortion.

History is written by those who have hanged heroes ...

The best EQ is no EQ ...

Alpine SWR-1223D Slot Ported HT Sub

Dual Dayton RSS390HO-4 Reference 15 Build For HT

Main System: Klipsch RF-82 II, Klipsch RC-62 II, RS-52 II, Onkyo 5010, Rythmik FV15HP, PSB S300
braveheart123 is offline  
post #8 of 33 Old 09-22-2013, 06:07 AM
 
BeeMan458's Avatar
 
Join Date: Jun 2012
Location: Magalia, CA
Posts: 8,374
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Liked: 801
From the linked information:

A volume increase of 6 to 10 dB in gain level should give a
sense of doubling in loudness, the psychoacousticians tell us.
The loudness of N = 1 sone is equivalent to 40 phons, which is the loudness level
of LN = 40 dB of a sine wave (sinusoid) with a frequency of f = 1000 Hz.


1000Hz vs subwoofer output of 20Hz. Staying out of the conversation, just saying, regarding our sensitivity to lower frequencies, these are two entirely different sonic animals which we perceive totally different from each other which is graphically noted by the Phon graph.

It has been brought to my attention, at the sound engineer's level, sound engineers master the sound track to take the Phon graph's curve into consideration. Hence the "NEED" for recreating a flat room response. In my opinion, after not properly integrating a subwoofer system into a room's acoustics, the worst enemy of a subwoofer sound reproduction system (clean, deep bass), is to intentionally over-drive a subwoofer.
BeeMan458 is offline  
post #9 of 33 Old 09-22-2013, 12:48 PM
AVS Special Member
 
Mark Seaton's Avatar
 
Join Date: Jul 2000
Location: Chicago, IL, USA
Posts: 6,073
Mentioned: 3 Post(s)
Tagged: 0 Thread(s)
Quoted: 88 Post(s)
Liked: 301
Quote:
Originally Posted by shadyJ View Post

10 dB being a perceptual doubling of loudness is a subjective evaluation, of course, and it turns not to be completely true anyway:
Quote:
Widely accepted is still the theory of psycho-acoustic pioneer Stanley Smith Stevens, indicating that the doubling or halving of the sensation of loudness corresponds to a level difference of 10 dB. Recent research by Richard M. Warren, on the other hand leads to a level difference of only 6 dB.
Quote:
Originally Posted by BeeMan458 View Post

From the linked information:

A volume increase of 6 to 10 dB in gain level should give a
sense of doubling in loudness, the psychoacousticians tell us.
The loudness of N = 1 sone is equivalent to 40 phons, which is the loudness level
of LN = 40 dB of a sine wave (sinusoid) with a frequency of f = 1000 Hz.


1000Hz vs subwoofer output of 20Hz. Staying out of the conversation, just saying, regarding our sensitivity to lower frequencies, these are two entirely different sonic animals which we perceive totally different from each other which is graphically noted by the Phon graph.

There's no shortage of misinterpretation of the graph of equal loudness curves...

  1. We do NOT want our frequency response to look at all like these curves.
  2. The CHANGE in shape of the curve from one phon level to another is what is of actual interest for sound reproduction, along with the minimum thresholds.
  3. Examining the curves you see that the generalization of ~10dB = doubling of perceived loudness is referenced to 1kHz and changes at the frequency extremes.
  4. Since one curve to the next = ~doubling of loudness, once above the hearing threshold below ~250Hz, it takes much less than 10dB for a perceived doubling of loudness (=dB jump curve to curve).

Mark Seaton
Seaton Sound, Inc.
"Make no little plans; they have no magic to stir men's blood..." Daniel H. Burnham
Mark Seaton is offline  
post #10 of 33 Old 09-22-2013, 04:37 PM
AVS Addicted Member
 
LTD02's Avatar
 
Join Date: Oct 2003
Posts: 16,788
Mentioned: 21 Post(s)
Tagged: 0 Thread(s)
Quoted: 529 Post(s)
Liked: 1148
"1.We do NOT want our frequency response to look at all like these curves."

agree, but you may want the *change* between equal loudness curves if playing back movies at less than reference and want to perceive a balanced playback. otherwise the bass gets too weak.

and same thing for music but in the other direction. might want to take out a little midrange or it might be overpowering when the volume is turned up over reference.

Listen. It's All Good.
LTD02 is offline  
post #11 of 33 Old 09-22-2013, 05:19 PM
AVS Special Member
 
JHAz's Avatar
 
Join Date: Mar 2009
Posts: 4,009
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 112 Post(s)
Liked: 158
Quote:
Originally Posted by Mark Seaton View Post


There's no shortage of misinterpretation of the graph of equal loudness curves...

  1. We do NOT want our frequency response to look at all like these curves.
  2. The CHANGE in shape of the curve from one phon level to another is what is of actual interest for sound reproduction, along with the minimum thresholds.
  3. Examining the curves you see that the generalization of ~10dB = doubling of perceived loudness is referenced to 1kHz and changes at the frequency extremes.
  4. Since one curve to the next = ~doubling of loudness, once above the hearing threshold below ~250Hz, it takes much less than 10dB for a perceived doubling of loudness (=dB jump curve to curve).

plus`. I was too lazy to point out thatthe curves bunch up at the bass end, but it seems to me that this one simple fact particularly complicates especially music playback, where for whatever reason I personally am, IMO, unduly sensitive to minor "misalignments" on the positive end. That is, on balance if I have a choice between a little too much bass and a little too little bass (but can't find goldilocks to get "just right" I wans the slightly leaner presentation because the fatter one sounds unnatural to my ears. I wonder whether individual differences are greater, on average, at the low frequency end of the equal loudness curve scale. Or maybe I'm just weird (in one more way . . .) BTW, give me all the extension I can get, and as clean as you can get it.

But to answer, from my perspective, an earlier question, no speaker, no amplifier is utterly without noise and harmonic distortion at anypower level. There is always distortion present in the playback. So, to me, until the distortion becomes audible, it's meaningless. I'd like to stay well below audible, but in truth if it can't be heard it doesn't matter, to me, if the distortion would become audible if it were 10 dB higher or if it were 20 or even 100 dB higher. Inaudible is, uh, inaudible . . . And perfect doesn't exist.

And I jones for a submersive. But first . . . just today I played on a perfectly right on 1964 Strat at a jam (courtesy of a very kind collector who has decided that I'm not gonna kill his guitars and he likes hearing me play them). The subM cash gets in the way of the $15K or so I'd need to wrestle that, or a similar, strat out of somebody's hands. My loves/hobbies are entirely too expensive, if I let them be. OTOH, both I and folks who hear me play also love what comes out of my Epiphone ES175 (Gibson pickups and for all you hollowbody folks out there, the wonderful Doug's plugs to keep feedback down) . . . But that '64 was OMG inspiring . . .
JHAz is offline  
post #12 of 33 Old 09-22-2013, 05:48 PM
 
BeeMan458's Avatar
 
Join Date: Jun 2012
Location: Magalia, CA
Posts: 8,374
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Liked: 801
Quote:
Originally Posted by Mark Seaton View Post


[*] We do NOT want our frequency response to look at all like these curves.

A point I noted in the part of my unquoted post you referenced. confused.gif

"It has been brought to my attention, at the sound engineer's level, sound engineers master the sound track to take the Phon graph's curve into consideration. Hence the "NEED" for recreating a flat room response."

What am I missing or misunderstanding with my above?

-
BeeMan458 is offline  
post #13 of 33 Old 09-22-2013, 08:37 PM
Member
 
tenderchkn's Avatar
 
Join Date: Jun 2013
Posts: 128
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Liked: 28
Where does the chart show a 40dB difference between 30hz and 60hz? The difference at minimum audible levels is 20dB, which is four times as loud or would require a 25% 2nd harmonic distortion for it to sound as loud as the fundamental. At 100dB, the difference is 6dB, which is less than twice as loud. 1% 2nd harmonic distortion at 30hz will not be audible at any volume.

Even if our hearing was 40dB less sensitive at 30hz compared to 60hz, it would take 6.25% distortion for the 2nd harmonic to sound as loud as the fundamental. Where did this 1% number come from?
tenderchkn is offline  
post #14 of 33 Old 09-23-2013, 03:13 AM - Thread Starter
AVS Special Member
 
shadyJ's Avatar
 
Join Date: May 2009
Posts: 6,894
Mentioned: 3 Post(s)
Tagged: 0 Thread(s)
Quoted: 343 Post(s)
Liked: 592
That 40 dB difference is overstated, it looks to be closer to 20 dB. As for 20 dB difference being four times as loud, that is from psychoacoustic perception tests which are still a matter of debate at this time. One thing is I may have mixed up the power ratio with the amplitude ratio, if so I may be off by a factor of 10.
shadyJ is online now  
post #15 of 33 Old 09-23-2013, 05:00 AM
AVS Addicted Member
 
Chu Gai's Avatar
 
Join Date: Sep 2002
Location: NYC area
Posts: 14,888
Mentioned: 1 Post(s)
Tagged: 0 Thread(s)
Quoted: 250 Post(s)
Liked: 554
You'll need to be off by more than a factor of ten if you expect to work in a gov't budget office.

"I've found that when you want to know the truth about someone that someone is probably the last person you should ask." - Gregory House
Chu Gai is online now  
post #16 of 33 Old 09-23-2013, 05:10 AM
AVS Addicted Member
 
LTD02's Avatar
 
Join Date: Oct 2003
Posts: 16,788
Mentioned: 21 Post(s)
Tagged: 0 Thread(s)
Quoted: 529 Post(s)
Liked: 1148
shady. there are two key points that haven't been factored in to your original post.

first is pressure vessel gain from the room, which tends to kick in around 30hz for a typical room and by 20hz is +6-8db.

second is you cannot hear 1% distortion at 20hz. most folks can't hear 10% distortion in the bass and the average distortion in the bass before perceptibility kicks in is surprisingly large on the order of 50% or so.

there are several studies that can be found with a search. i believe geddess has a paper on it as well.

Listen. It's All Good.
LTD02 is offline  
post #17 of 33 Old 09-23-2013, 06:01 AM
AVS Addicted Member
 
Bill Fitzmaurice's Avatar
 
Join Date: Nov 2009
Location: New Hampshire
Posts: 10,003
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 1 Post(s)
Liked: 1569
Quote:
Originally Posted by LTD02 View Post

second is you cannot hear 1% distortion at 20hz. most folks can't hear 10% distortion in the bass and the average distortion in the bass before perceptibility kicks in is surprisingly large on the order of 50% or so.
+1. It's unfortunate that a term other than 'distortion' wasn't adopted to describe the presence of harmonics in the playback not present in the original media, because 'distortion' is assumed to mean 'sounds bad', rather than what it really means, which is 'sounds different'. High THD can sound bad, especially when the added harmonics are odd-order and/or when they appear in the frequencies handled by tweeters, but it can also sound very good when the harmonics are even order and/or they appear in the midbass and mids. When they do the latter the resulting sound is often characterized as being 'sweet' or 'warm', and many's the audiophile, or for that matter recording studio, who's shelled out major bucks for tube gear to get that warm sweetness.

Bill Fitzmaurice Loudspeaker Design

The Laws of Physics aren't swayed by opinion.
Bill Fitzmaurice is offline  
post #18 of 33 Old 09-23-2013, 06:12 AM
AVS Addicted Member
 
arnyk's Avatar
 
Join Date: Oct 2002
Location: Grosse Pointe Woods, MI
Posts: 14,383
Mentioned: 2 Post(s)
Tagged: 0 Thread(s)
Quoted: 758 Post(s)
Liked: 1170
Quote:
Originally Posted by shadyJ View Post

I was struck by a comment made in this post in another message board regarding the equal loudness contour:
Quote:
What this chart also tells us is that low distortion is more important than absolute output. At 32Hz, which is plainly audible, our hearing is what, ~40db less sensitive than at 64Hz, the 2nd harmonic.

That means, if I'm reading the chart correctly, that with 1% 2nd harmonic distortion at 32Hz, the 2nd harmonic is audible at about the same level as the fundamental.

To expound on that observation just a bit, let us first define deep bass as anything under 40 Hz. Yes, its arbitrary, but to me 40 and below sounds pretty deep, and it doesn't really change the overall point. It also makes the math a bit easier when compared to the lowest sound there, 20 Hz. Now then let us compare the perceptual difference between 20 Hz at 100 dB and an octave above, 40 Hz, its second harmonic. These are familiar frequencies and loudness levels for most of us here, and it also makes for clean math and is easy to track on that chart. According to the chart, at 20 dB at just below 100 dB is perceptually equal to about maybe 77 dB at 40 Hz. Let round this off to a simple 20 dB difference, or a power ratio of 100. What that means is you need 100 times the loudness of 20 hz to perceptually equal a 40 Hz sound. So, like Irv Robinson said, to even have 1% second harmonic order distortion at 20 Hz at 100 dB would be as loud to human hearing as the fundamental. Of course, that becomes all the more worse when you get 3rd, 4rth, and higher order harmonic distortions. The cleanest subs that I know of out there can not output 100 dB at 20 Hz with less than 1% harmonic distortion. The situation also gets worse below 20 Hz as the curve gradient becomes steeper in those ultra deep frequencies. I pity the guys chasing after a clean 10 Hz.

Now I'm not one of those smarty pants acoustic scientist people what with their eye glasses and pocket calculators and book readin', but I have to wonder what it would take to get truly clean deep bass, perceptually speaking. I also have to question how the CEA2010 distortion limits are established, and I am guessing there is a practical consideration there as no subwoofer would pass a 20 Hz tone at any audible frequency without an audible component of distortion as well. So, to those better versed in acoustic science, I am asking if I am not somehow overstating the audibility of distortion here? Because if this is correct, none of us have true clean deep bass except perhaps a few of the most extreme bass systems in the world.

+1 to the comments above about room gain and the audibility of nonlinear distortion.

Another factoid that needs to be considered is the fact that natural music with fundamentals below 40 Hz generally has higher amplitude harmonics than the fundamental, and not by a little bit. IOW if a large pipe organ is pedaling out a note near 32 Hz, the wave produced has a lot more 64 Hz and 96 Hz than it has 32 Hz. It is not necessarily a recording problem because I've personally verified this with measurement mics known to be flat down to as low as 5 Hz. Drums, strings, you name it, are no different.

It is probable that a lot of musical instruments try to take advantage of the fact that when presented with the second harmonic, the ear often perceives substantial amounts of the fundamental.

http://en.wikipedia.org/wiki/Missing_fundamental

Since the musical source contains so much energy in the form of harmonics, a loudspeaker that produces harmonics has quite a bit of wiggle room. The harmonics that the speaker produces may be masked by the harmonics that are already in the music. If musical sounds were pure fundamentals, any harmonic that was created by the speaker would be easier to hear. But, the music itself has harmonics that may mix with like frequency harmonics that are produced by the speaker. Common forms of bass distortion are doubling and tripling which is the result of the speaker producing second and third harmonics. But the music already has considerable doubling and tripling built into it at the source.
LTD02 likes this.
arnyk is offline  
post #19 of 33 Old 09-23-2013, 06:19 AM
AVS Addicted Member
 
LTD02's Avatar
 
Join Date: Oct 2003
Posts: 16,788
Mentioned: 21 Post(s)
Tagged: 0 Thread(s)
Quoted: 529 Post(s)
Liked: 1148
+1 back at arny. i almost mentioned that fact...but got lazy typing. :-)

Listen. It's All Good.
LTD02 is offline  
post #20 of 33 Old 09-23-2013, 06:19 AM
AVS Addicted Member
 
arnyk's Avatar
 
Join Date: Oct 2002
Location: Grosse Pointe Woods, MI
Posts: 14,383
Mentioned: 2 Post(s)
Tagged: 0 Thread(s)
Quoted: 758 Post(s)
Liked: 1170
Quote:
Originally Posted by Mark Seaton View Post


There's no shortage of misinterpretation of the graph of equal loudness curves...

[*] We do NOT want our frequency response to look at all like these curves.

Only true when playback loudness = live performance loudness which is almost never actually true.

Then we do want playback loudness to be adjusted by the relevant curves.
Quote:
[*] The CHANGE in shape of the curve from one phon level to another is what is of actual interest for sound reproduction, along with the minimum thresholds.


Good points. One rather scary thing is the fact that the threshold of hearing @ 20 Hz is close to 80 Hz, which is higher than average reference level for broadband audio.
Quote:
[*] Examining the curves you see that the generalization of ~10dB = doubling of perceived loudness is referenced to 1kHz and changes at the frequency extremes.
[*] Since one curve to the next = ~doubling of loudness, once above the hearing threshold below ~250Hz, it takes much less than 10dB for a perceived doubling of loudness (=dB jump curve to curve).

This says that the benefit of improving dynamic range at low frequencies is greater than it is midband. Seems like a good thing given the higher cost of actually accomplishing it.
arnyk is offline  
post #21 of 33 Old 09-23-2013, 06:25 AM
AVS Special Member
 
KidHorn's Avatar
 
Join Date: Nov 2003
Location: Derwood, Maryland
Posts: 2,937
Mentioned: 1 Post(s)
Tagged: 0 Thread(s)
Quoted: 213 Post(s)
Liked: 227
I agree that it's basically impossible to get good clean bass in a home theater. The problem is you're watching a movie and a car explodes on a freeway and your system is trying to reproduce what it would sound like. The car is exploding outside, so second, third, etc harmonics won't factor in as much as an indoor explosion since the sound waves won't reflect as much. They'll always be there, but won't be as noticeable as they are indoors. Indoors, since the sound waves bounce back and forth inside a room, distortions will be much more of an issue. I don't think this problem is solvable. For music, I don't think this is as big an issue since music is almost always played indoors so live music has the same issues and hence sounds normal with these distortions.
KidHorn is offline  
post #22 of 33 Old 09-23-2013, 06:39 AM - Thread Starter
AVS Special Member
 
shadyJ's Avatar
 
Join Date: May 2009
Posts: 6,894
Mentioned: 3 Post(s)
Tagged: 0 Thread(s)
Quoted: 343 Post(s)
Liked: 592
Very interesting discussion. I did some searches, and the major paper dealing with the subject seems to be "Subwoofer Performance for Accurate reproduction of Music". Damn paper is buried behind a paywall, anyone a member of the AES E-library want to give us the scoop on that paper? Someone did scan some results from that paper:

Is there any smarty pants here who can tell me what that table means? I know it's somehow relevant to this discussion, but I am having trouble deciphering it.
shadyJ is online now  
post #23 of 33 Old 09-23-2013, 07:13 AM
AVS Addicted Member
 
arnyk's Avatar
 
Join Date: Oct 2002
Location: Grosse Pointe Woods, MI
Posts: 14,383
Mentioned: 2 Post(s)
Tagged: 0 Thread(s)
Quoted: 758 Post(s)
Liked: 1170
Quote:
Originally Posted by shadyJ View Post

Very interesting discussion. I did some searches, and the major paper dealing with the subject seems to be "Subwoofer Performance for Accurate reproduction of Music". Damn paper is buried behind a paywall, anyone a member of the AES E-library want to give us the scoop on that paper?

I have the paper here, but I'm a big believer in not breaking other people's IP on a public forum. ;-)
Quote:
Someone did scan some results from that paper:

Is there any smarty pants here who can tell me what that table means? I know it's somehow relevant to this discussion, but I am having trouble deciphering it.

There are three sets of data corresponding to the fundamental being played at 80 dB SPL, 100 dB SPL and 110 dB SPL.

For each set of data audibility was tested for fundamental frequencies of 100, 50, 20, and 10 Hz.

For each fundamental frequency the relative amplitude for Just Noticable Detection (JND) (as compared to the fundamental) was determined.

My reality check on my interpretation of the data is the fact that aside from audibility issues (the ear's sensitivity goes to #&!! in a hand basket as frequencies go below 100 Hz) the ear is more sensitive to distortion at 80 Hz than 110 Hz.

Also, higher harmonics are easier to hear than lower harmonics.. So the dB levels given for JND are more negative for the higher harmonics as a rule for two different reasons. First, they are higher frequencies so the ear hears them better. Secondly, the frequencies of the higher harmonics are further from the fundamental, so the fundamental masks them less.

http://en.wikipedia.org/wiki/Auditory_masking - partciularly the subtopic under simultaneous (or spectral) masking. Figure E is particularly relevant.
shadyJ likes this.
arnyk is offline  
post #24 of 33 Old 09-23-2013, 07:31 AM - Thread Starter
AVS Special Member
 
shadyJ's Avatar
 
Join Date: May 2009
Posts: 6,894
Mentioned: 3 Post(s)
Tagged: 0 Thread(s)
Quoted: 343 Post(s)
Liked: 592
So, if I am reading that table correctly, 4% second harmonic distortion of a 20 Hz fundamental at 100 dB would be audible, but just barely?
shadyJ is online now  
post #25 of 33 Old 09-23-2013, 07:48 AM
AVS Addicted Member
 
Bill Fitzmaurice's Avatar
 
Join Date: Nov 2009
Location: New Hampshire
Posts: 10,003
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 1 Post(s)
Liked: 1569
Quote:
Originally Posted by shadyJ View Post

So, if I am reading that table correctly, 4% second harmonic distortion of a 20 Hz fundamental at 100 dB would be audible, but just barely?
The second harmonic of 20Hz is 40Hz, so that's what you'd hear, and as 4% is about -28dB down from the 20Hz level you probably wouldn't notice it, being totally masked by what's already present at 40Hz.

Bill Fitzmaurice Loudspeaker Design

The Laws of Physics aren't swayed by opinion.
Bill Fitzmaurice is offline  
post #26 of 33 Old 09-23-2013, 08:03 AM - Thread Starter
AVS Special Member
 
shadyJ's Avatar
 
Join Date: May 2009
Posts: 6,894
Mentioned: 3 Post(s)
Tagged: 0 Thread(s)
Quoted: 343 Post(s)
Liked: 592
You mean that in normal material I wouldn't notice it, but if I was just listening to sine waves, I could conceivably notice it, correct?
shadyJ is online now  
post #27 of 33 Old 09-23-2013, 08:23 AM
AVS Addicted Member
 
MKtheater's Avatar
 
Join Date: Jul 2006
Location: New Hartford, NY
Posts: 14,674
Mentioned: 5 Post(s)
Tagged: 0 Thread(s)
Quoted: 319 Post(s)
Liked: 476
Define clean? 1%, 10%, 50%, whatever you can't hear? Already stated many people like harmonics and that is because real instruments which produce these sounds have harmonics. If you don't reproduce those then it won't be and sound accurate.

LCR-Dual stacked BFM DR-250's
Surrounds- Dual stacked BFM W10's
subs-12 SI 18's ported 6hz.
MKtheater is offline  
post #28 of 33 Old 09-23-2013, 08:34 AM - Thread Starter
AVS Special Member
 
shadyJ's Avatar
 
Join Date: May 2009
Posts: 6,894
Mentioned: 3 Post(s)
Tagged: 0 Thread(s)
Quoted: 343 Post(s)
Liked: 592
I would say cleanly reproduced bass is that which has no audible distortion, that is, no audible sound which is not in the recording.
shadyJ is online now  
post #29 of 33 Old 09-23-2013, 08:56 AM
AVS Addicted Member
 
MKtheater's Avatar
 
Join Date: Jul 2006
Location: New Hartford, NY
Posts: 14,674
Mentioned: 5 Post(s)
Tagged: 0 Thread(s)
Quoted: 319 Post(s)
Liked: 476
Quote:
Originally Posted by shadyJ View Post

I would say cleanly reproduced bass is that which has no audible distortion, that is, no audible sound which is not in the recording.

Then it has already been stated. Of course we can have clean bass. Do you hear distortions in your room?, I don't unless it was on the recordings. Especially during program material, I can hear them with sine waves but not until over 12% THD with 10hz sine waves. If there was 20hz material I doubt I would hear it over that.

LCR-Dual stacked BFM DR-250's
Surrounds- Dual stacked BFM W10's
subs-12 SI 18's ported 6hz.
MKtheater is offline  
post #30 of 33 Old 09-23-2013, 09:42 AM
AVS Addicted Member
 
Bill Fitzmaurice's Avatar
 
Join Date: Nov 2009
Location: New Hampshire
Posts: 10,003
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 1 Post(s)
Liked: 1569
Quote:
Originally Posted by shadyJ View Post

You mean that in normal material I wouldn't notice it, but if I was just listening to sine waves, I could conceivably notice it, correct?
And why would you do that?

Bill Fitzmaurice Loudspeaker Design

The Laws of Physics aren't swayed by opinion.
Bill Fitzmaurice is offline  
Reply Subwoofers, Bass, and Transducers

User Tag List

Thread Tools
Show Printable Version Show Printable Version
Email this Page Email this Page


Forum Jump: 

Posting Rules  
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off