My definition of Ambience

[Jud]

Question, is there low frequency ambience when the musical instruments don't go so low?

I think this has two possible answers;

First, caugh in a church. Doesn't that hall back to us in a lower frequency than what sprung from our caughing mouth ? I think it does. I don't think the brick walls will vibrate much of our caughing. So something else plays a role. And this is in the second answer :

Specifically referring to my (empirically !) found LF happening only when more than one (drumming) tom was used at the same time, this is about two frequencies which superimpose on eachother and the result is ... a lower frequency. Similar can happen with bouncing waves of the same frequency, but this is more difficult to explain, especially because it needs good graphical simulation of it. But that aside, look here (the best I could find in 15 minutes of time) :

http://www.acs.psu.edu/drussell/demos/superposition/superposition.html

Scroll to the bottom where you see "beats" explained;
Look at the top grey sine as one of the toms, and the line under that as the other, and both do not produce the same frequency. The resulting sound wave is the bottom blue wave.
Now, just look how fast the frequency of the two top waves change and compare that with the max amplitudes of the bottom wave passing by. Easy to count, and the resulting wave is 10 times slower than the original either two. So, my toms which play at 60Hz or so (try to look back in my mind what I saw yestyerday), now play at 6Hz. Rumble ! But especially rumble because of how this "beat" evolves. So, the blue line actually has a resulting frequency that is similar (in between) the two toms, but the level (max amplitude) changes at this much lower frequency.

Saw you mention 38Hz twice, and mention a couple of tracks sounding the same - I wonder if one possibility is your room and how what you describe above would work within it.  Same room dimensions, same frequency evolving from the superpositions?

[PeterSt]

Haha Jud, I thought about that too of course. But no.
My room length of 12M implies 28.67 Hz which is what I cam exactly measure. And if that bothers me I open a door.

and mention a couple of tracks sounding the same

I don't think I said that. What I did say is that when two very different albums put up a nice sine of the same low frequency, they both sound exactly the same, which is of course which should happen.
And next : when that sine would be subject to distortion and harmonics spring of it because of that, nothing sounds the same because the harmonics play in the same space as many other instruments. With any form of not-sine with a LF fundamental, same thing.

Actually this is very easy to understand but it is NOT easy at all to comprehend. So, elsewhere I said that I spent a fairly enormous amount of time in "discovering" that these were just the nice sine frequencies I perceived because it really looked like a speaker property. So, most obvious would be "sounds the same thus speaker colors". But the way much simpler answer is "is the same thus sounds the same".
We are just not used to this at all. And to keep in mind (I said this a couple of times too) : Those low frequencies always play alone. Not necessarily of course, but when I was to make a nice base line playing well under 40Hz I sure would not do that with two different (synth) "voices" and I also wouldn't use chords. I mean, it is difficult enough as it is to produce something audible in that region, so it has to be simple.
Anyway, of what I perceive this just is always so.
And thus again : when a simple sine is put up, it's on its own there, and should sound the same in any track putting up that sine of the same frequency.

Additionally, let's not forget that hardly anything can produce real sines but if so we would recognize it as an instrument instantly (certain organ pipes, flutes). So see ? we do recognize it after all. So why not LF synth produces sines.
I say it again (and again) : I never heard that LF (way interesting) stuff in there. It's two new dimensions at the same time (one for it being so audible and one for it is meant to be the melody most often).

Peter

[PeterSt]

Sorry about the caughing which must be coughing of course. Dunno why my perception of this was different in the morning than now in the afternoon ...

[CoenP]

Insights from the (former) "golden age" of audio.

Regards,  Coen

[PeterSt]

Yea, a bit old that is. Looks like pre-synth area.
Also, lowest organ is 16cps. But only 3 or so exist on the globe.

Anyway, still a nice reference.
Peter

[PeterSt]

And in aftermath, he really could have heard that 24Hz (?? - must check it !) organ.

So I checked it yesterday. 32Hz it is.
Funny though, the main two lower keyed organ pipes heard are this 32Hz and 66Hz (this should be the audible one which regularly is in the track). Not 64Hz.

But at watching the FFT I noticed something very interesting;
At 4:19 up to 4:29 there is a most clear 22Hz (inaudible for me);
When I was watching this yesterday I couldn't find much of an explanation. Later however, it sprung to my mind that this must have been such "beating" I have been talking about.
Too difficult for me to really see (and calculate) which of the other organ tones (chords are played there) would incur for this, but it sure must be that.

In the past I have been reading (or examining) about "sub harmonics". At least back then it was recognized as non-existent. But possibly it depends on how this is looked at, because a normal fundamental is not able to. However, and in my view, as soon as an instruments exhibits more than one frequency and those harmonics as such are not a 2nd, 3rd, etc. related harmonic, such an instrument will do it by itself. Just a thought : like a violin plays a normal frequency, but the fast "stuttering" of the resin over the string would be a very different frequency.

Peter

[PeterSt]

Ambience, rumble or just music ?

With my own example of the "Beating" in my mind, I have been watching the FFTs during music playback the past two days - now with the emphasis on this happening;

I can tell you now, it is actually very hard to find music where the sub-low (say under 30Hz where clearly no instruments are playing at all) is not present. So it is there always and with some music you can clearly see from what it (instruments etc.) originates. Also, experience from both listening and looking helps being able to hear it clearly.

I must tell you that I maybe even more explicitly started to watch for it, where in my observation it could not be "ambience" as how I described it. I mean, no recording room phenomena. Still gives an "ambience" presence, for its sheer more air-filled (or air based) playback. For example, once you feel air pressure on the stomache on some music beat, I may take I for granted that somehow this instrument creates this air pressure by means of its audible tone of the moment. You would too (assumed the fair amount of good sub low). However, once you watch the FFT at the same time, you can clearly see that it's the "umpf" at the real low frequencies which really perform that stomache punch. Not visible ? then no punch either.

Something else I saw now, is that this sub-low waves - and which don't need to be punches only - can go straight to 10Hz just as well (10Hz is the measurement limit for the FFT I use here). With "straight" I mean "all the way", because straight in level is not so (the Orelino is set to roll off under 18Hz). So, it is worse than I originally thought. Or more important - also good.

Generally - and when not about explicit low frequency sounds (like mentioned ambient music does it) - as soon as a more mass starts to play together, the sub low "rumble" emerges. So if only this "Beating" is allowed to be a directive for how two frequencies create the lower ones, it can't even happen otherwise. To what degree (for low frequency) this happens, should totally depend on the "offset" of the two (or many more) other frequencies playing. So, the less offset (the more close to eachother) the lower the resulting frequency of the beat will be. Thus, thinking about my given simulation example, when a 1000Hz and a 1001Hz would be playing, once in the 1000 (999 ?) wave cycles the beat would be at its maximum, and the frequency - remember, "modulated" on the 1000 and 1001, would be 1Hz. That this in this case would be a very slow moving up/down for level is something else and for that reason it will not be a clear peak (level drops from max to zero and back in one second (= 1000Hz per second base).

A next thing to notice (or maybe I have said that already) is that the max level of such a beat is the accumulated level of the both frequencies when they both meet at their tops. So when the level of the both frequencies would be at 60dB, the both together would form that low frequency at 66dB or two times as loud. This, while no musician created it like that. Now, this happens all over when coincidentally two instruments play the same frequency in the same phase so we are used to that. But with those ultra low frequencies we are not and/but it is thus easy to create the "effect" in pronounced form. In the mean time though, our subwoofers must be able to cope with this additional excursion (no designer weighed in), which they most probably will be able to, BUT will create distortion;

And now it becomes complicated because the distortion coming from that (just 2nd and 3rd and so on) are the most audible. So for example, when a 25Hz "rumble" is in order - and this is just audible as a frequency (for me it is), the 50Hz harmonic springing from it because the 25Hz being on a fairly high level, is always way way (way !) more audible. So, the whole lot can easily produce 50Hz which is nowhere in the original.

More about this later (if someone is interested anyway).

[pedal]

Peter,

Last time, did you get this title: Jøkleba LIVE. Its free jazz With awesome SQ. Note some old fashion synth generated looow frequency notes.

[PeterSt]

Ambience, rumble, music or just distortion ?

A couple of days ago I received an email from someone who I consider quite knowledgable in the field, and he pointed out to me that my perceived most strong bass most probably is harmonic distortion after all. Of course I refuse(d) to believe that, but it brought me the idea of "just measuring would be way more convincing than listening only". So I sat down to do just that.

Meanwhile the person told me that woofers in general easily allow for 7% of harmonic distortion.
I was shocked, but recognized that I saw some 0.1% figure somewhere when the microphone was up to some other task and that "I better not officially measure THD to begin with". Not being in denial, but merely thinking that measuring a loudspeaker this way makes no sense or is of no use. Otherwise, what to do about it when not-so-good after the the drivers have been selected (on whatever spec beyond me). It is just a given fact.

Not so (at all actually) when someone like me is tuning a speaker into its sub-low limits and that for an open baffle which would be more difficult to begin with.

So I started out with Google in order to find out specs for woofers or what they would be allowed for THD;
What did I find ? NOTHING. Ah, that was odd, but maybe just a good thing. Ok, I could find specs for woofers which tell about nice low figures, but they talk about some agreed low Wattage fed to them. Or Voltage, whatever. Useless (to me).
I found this though : http://www.audioholics.com/loudspeaker-design/2010-subwoofer-shootout/2010-subwoofer-shootout and the main picture in there is this one :

The red line indicates an official "spec" to what subwoofers are allowed to exhibit for harmonic distortion.

Although this is about subwoofers and not really woofers as such, for me it is the thing to deal with, because aren't we talking about subwoofers ?
So, if you look at the test signal there and see it is 20Hz, the red line tells that the first harmonic (40Hz) is allowed to be at not more than -10dB. If more, then the subwoofer is no good.
N.b.: I ran into ABX tests where similarly was examined in a group of people, and the results were that nobody could hear a difference in those lower registers anyway.
In advance of how this post will end : go figure.
Anyway, a subwoofer manufacturer should produce his product in compliance to this graph, and when it does it can "officially" go out. Of course, many do better, but this is about my quest to how actually others are performing, while I scream about a couple of things and whether that is justified (audible I say Yes, but what about some figures and what will they mean to you, you too not really knowing what would be normal and what would be in excess (either direction)).

So what a speaker driver is about (amonst other things) is that it should not produce too much HD (harmonic distortion) and we know that when excursion gets higher HD will increase. Also : when the SPL to be produced gets higher, excursion will be more. And : When the frequency to produce gets lower for the same to be produced SPL, excursion gets higher. So all is related especially when we try to achieve the lowest frequencies at workable SPLs for our music.

Now first the for me foremost important thing, and I see no writing about it anywhere :
When we talk subwoofers, we talk by sort of principle of frequencies we can not hear. Of course, a subwoofer can go higher (at will of the manufacture and which for sure is the case with our Orelino here), but a subwoofer is no subwoofer when it can't produce, say, 22Hz at reasonable SPL and which 22Hz is inaudible to most (to me it is inaudible). But, way beyond that just the same, like my former SVS Subwoofers who do 12Hz (I forgot at how many "dB down" but alas).
So, when producing inaudible frequencies this emerges as air pressure changes we will perceive and it gives additional layers of whatever we are listening to.

How shocking it was for me when I found that in general (frequency point) no less than 22dB down the 2nd harmonic has to be in order to let the fundamental do its inaudible job ... So, no single way that picture above resembles anything that can be good for music. Effects maybe, but no wind effects. So what happens ?
(it is too easy to even think about once you know how it works)

Suppose we have 30Hz. Sounds nice. Then at the same SPL we create a 25Hz. Hey, it sounds higher in frequency ? Hmm ...
To understand better we go more down : We have 20Hz and it should be silent. Why ? well, we can't hear it as such. Not silent ? ah, then you hear the 2nd harmonic which is 40Hz. Easliy audible ! And so with that 25Hz sounding higher than 30Hz, what we'll perceive is HD and it plays at 50Hz.

Now let me tell you, when I'd sustain that red line in the picture and wich actually tells that any 2nd harmonic is allowed to be 10dB down before we'd perceive it as distortion ... NO WAY. When I would allow for 10% HD on that 20Hz tone, a most blasting 40Hz would be audible.
And again, it is so easy : When some frequency (like 20Hz) is not to produce any sound, how high in level would we think it's 2nd harmonic (like at the very audible 40Hz) is allowed to be ? Hey, that's actually nothing man !


With a fairly still good audible 25Hz things become different, because now it is about how the 2nd harmonic will be perceived louder by us than the 25Hz. Well, that is not so much. 30Hz is the most well audible by all of us, so here we indeed have more headroom. Now it really becomes a matter of how we can a. hear the 30Hz be distorted (this is way difficult I think) but b. how the 60Hz 2nd will start to be profound over the 30Hz. So here YMMV (since I did not sort out the exact figures for this, but which also is not necessary, which you will hopefully grasp by the below text.


What I did in the end was not so much testing the HD levels but merely tuning all so that no audible HD tones could be heard. This is subjective, but measurements support it to some degree, so I used that foremost.
What I did, I did because of the process of "functionality" and this was as follows :

Find an acceptable SPL for my personal listening levels. This was 86dB. So, just measured from normal music playing. 86dBSPL would be sufficient (but carefully read the below topics as well).

Look per frequency what the THD is; Important notice : the general level of THD while spades of headroom on the SPL was still available, is 0.3% (this is invisible at the in-room ambient noise levels of -90dB through microphone).

At some point at going downwards in the frequency spectrum the THD starts to grow. I forgot where, but this is not important. Important is where it grows so much that the SPL for that frequency apparently is too high. What came from this is that from under 30HZ downwards the SPL had to be squeezed. The limit for this I took was a general 3% because more than that is audible, but it includes some headroom so I actually followed 2%. So, at no frequency under 30Hz I allowed more than 2% THD. This is all the way down to 10Hz.
So for example, all the way down to 10Hz I did not allow myself to hear a single thing coming from the speakers, were it for the frequencies under 23Hz which I can not hear anyway, and thus *should not hear*.

The result of this is that a linear decreasing slope of 9dB is needed from 29Hz to 18Hz, which latter 18Hz was rated as " the -3dB level". Officially this now should read as "18Hz at -12dB".

This all explicitly assumes that while music in normal frequencies play at 86dB, the lowest frequencies would play at the same level. It is my idea that this is not much the case (I just see that when music is playing). However, when indeed that does not happen but say at -10dB instead, my "set" 86dB would be 96dB and all would still be OK.
Small notice : this was before I realized that "Beating" should theoretically imply higher levels from the normally playing frequencies, ad explained per previous post. Still I just see that it is the most rare that the lowest frequencies go all the way up in level. So I think I'm good with this strategy.

Speaking about a commercial speaker, the net result would be :
- That when you play at 86dBSPL - which for me would be suffecient in my 12x8x3m room - there's the guarantee that no audible distortions come form whatever crazy bass up to even 10Hz and lower.
- That most will have a smaller room, and that the smaller the room, the more perceived SPL in the listening seat will be there at the 86dBSPL at 1 meter (read : for most the perceived output can be significant higher than what I think is enough).
- That I perceived the total image of the music to be more clean; couldn't hear any distortion previously explicitly, but it should have been there.
- That by empirical finding whatever distortion has been there before does not imply these crazy basses; they are still there as they were.
- That ... it net does not work for the better.

Oh.
So, the perceived cleanness - which might be a placebo in the first place - at least causes the "air pressure" output to be less, and I sure perceive that. Maybe that is too much anyway, but I got used to it and now I am not sure this is net for the better.

All could be much moot because at e.g. 30Hz it is way tough to play too loud so 2nd (and beyond) harmonics are audible. Same counts for the THD % which is only 1.1% at louder than the calibration level already and with the knowledge that  it was 0.8% at 6dB less output. So a very slow increase there, while in this area possibly the -10dB is allowed from the red line in the graph (I did not test that because way too loud). This 1.1% probably was at -20dB or so. Thus spades of headroom here.
And to keep in mind : the lot gets only really critical when actually almost no sound is to be heard and this non audibility fastly increases when going down from 29Hz.

The above said, not much plays explcitly in that area anyway. The reason is obvious : we can't hear it. That other thing, the "ambience" or what name we really should give it, is a far greater problem, once we allow our speakers to play in that area anyway. So, don't allow that (say cut at 27Hz) and there can't be a problem. In the mean time though, this "ambience" won't be there and this is what I can notice right away.

Of course, there's all kind of playground between my -9dB drop and 0dB drop which is related to the necessary SPL as explained. The smaller the room, the better it goes without distortion. At the far end this extends to : the more small the room, the lower we can go undistorted. Like 17Hz or 16Hz.
Whether this brings more ? My findings so far say Yes. The lower the better, because it is all in there.

Btw and FYI, with only one paramater in the DSP settings this slope can be set with full justification/consistency of further everything (example : the crossover should not change).

Hope this is helpful or even interesting ...
Peter

[PeterSt]

An additional remark about my drumming track :

Forget it;
I have to assume that at this moment nobody is able to perceive that "ambience" or low, say, rumble that I perceive myself. And the point is : with only that -9dB slope from my previous post it already does not work anymore, at all.

Actually it is totally stupid if you recall me telling about my perfect timing and "go with the flow" in warm water baths and what not; Without being in that warm water bath, my timing is nowhere. It is just not true. But being in the midst of that "rumble", yes, then I can do it. Not that I can do it, but then it is perceived like that.

So I don't know whether "timing" as such is now a new subject in the realm of "how can ... ?" but to me it definitely looks like wrong timing can be masked with a sufficient amount of air under all. Things just sound so nicely soft, while the first thing I noticed yesterday at retrying the track with the -9dB slope in, is that all is precise and hard. Precise eh ? yea, that maybe, but it also tells when things are precisely off beat and all.

Cymbals are still of extreme quality, but the drumming is too poor to put up, really.

[PeterSt]

PS on the larger previous topic : Apologies for all the typos which were in there at first; I tried to remove them now.

Peter

[PeterSt]

Jøkleba LIVE. Its free jazz With awesome SQ. Note some old fashion synth generated looow frequency notes.

Oh yes ! So first there's the more heavy drum with its so nice spread from its peak at 48Hz to the to the left and right (same slope) which creates that ambient sound full with air and next there's indeed what must be a synth with its lowest notes at 18Hz. Notice though that from the latter you'll only perceive its sqaure based higher harmonics but in my view the perceived deep warmth again is this 18Hz.

Maybe I should tell that you can be considered to have a real subwoofer ? I mean, a sufficient amount of drivers in there, but I forgot the size and amount (per side).

Btw a message from Ciska here :
Gry won't be happy with this album. Nor does Ciska. But didn't we know that ...

Best regards to you guys,
Peter

[PeterSt]

I just tried to find an example with at least "ambience" from the by now far past. After two Pink Floyd attempts which failed and which I actually just tried (Meddle and Obscured by Clouds) I dug in my mind and envisioned Emerson Lake and Palmer. Pictures at an Exhibition ? nah, ever described by me on this forum as "the guys never heard it themselves this way", I merely thought of Tarkus of having some "fat" sound. LP era.

Ha, spot on ! But but but, strange thing ...
I have the MFSL and noticed that it normalized from -29.5dBFS to -28dBFS. Can't be good. So, tried the the "normal" version I also have, and that normalized to -21dBFS. Hey, that looks way better (IOW less compressed). So, MFSL ? hmm ...

Anyway, that normal one indeed has that super fat flavour I recall, and it's only that it rolls off beyond 30Hz quite fast. For vinyl perhaps ? So rolled off so not too much "DC" (square) is not to be on there ? Perhaps.
Btw, all the LF I see is "ambience". So no clear very low frequencies (32Hz is the lowest I see from some (simulated ?) church organ).

Do notice : The "normal" version has a first 20 minute track named "Tarkus", while the MSFL has 7 or so indivudual tracks for that. Is it really the same ? not even sure. I played half of both versions.

On to the MFSL ... hey ! Straight to 20Hz ?!? (and gone right after that). Ok, now what does MSFL actually stand for ? hmm ...
(notice that the album is from 1971 in the first place).

Immediately I notice that the MFSL is full of air. Ok, clear.
Or ?
Or maybe not, because it sounds sibilant to me. More refined but sibilant. Nasty actually.
Anyway, these both versions sure contain the "ambience" as such and all my selection criterium was : fat sound of the past.

Next up will be Triumvirat. Same idea. I guess I can't be correct on this again (heck, this is long ago !).

[CoenP]

Just to support the long post about audibility of the extreme LF (sub) I post the famous Fletcher Munson "equal loudness" curves. The slope to the start of the curves (starting at 20 Hz) is very steep down , that means you can have only very little distortion before it appears above the audibility threshold. So a 89dB sound pressure 20 Hz tone will produce a second harmonic of 40 Hz that will be audible at a level of about 50 dB pressure. That is about 1% (-39dB) max for the second, but the third and fouth are even more important (38 or 30db threshold or less than 0.1%). The audibility of these is speculative though since they could well be masked by noise or music.

The classic way to reduce distortion is to reduce the motion of the bassdrivers (or linearise them by motion feedback). Usually this means more woofer surface and/or horn loading which has a practical limit of 35 hz is a domestic environment.

Anyway it is great to learn about the Bass of the Orelinos which does something special to the listening experience even with the distortions in place.
Please keep posting your progress!

Regards, Coen

[PeterSt]

Well Coen, I really start to wonder whether there is anything you don't know (about) - all seen through my own glasses of course, which can be mistified at times. Just saying.

Btw, I think that picture is not the official Fletcher Munson curves but rather the AES 2003 whatever representative. See here for the original F-M curves.

Still you don't know everything and amongst that is that the Orelino plays through curves which represent the F-M curves. well, almost, see text more below.
What you and everybody especially don't know is that my whole raving about this speaker's bass is all about the contradiction when these curves are taken as a lead. So, all you see me writing has as underlaying subject these curves, which are not correct for the bass at all. In other words, I feel supported by this "strange" contradiction because I am achieving things which are not recognized in the world so to speak and therefore "I am into something for sure". Again, through my own glasses. Ok, ears.

First this one :

So a 89dB sound pressure 20 Hz tone will produce a second harmonic of 40 Hz that will be audible at a level of about 50 dB pressure.

Nah, not quite. This one is simpler and I told about it in that larger post : 20Hz is just not audible. This is not related to any F-M curves etc., it just is not audible because our auditory system will not produce interpretable sound as such. It's wind. Also notice above F-M curves, which do not show 20Hz at all (starts at ~25Hz). In your picture it starts at 20Hz, but that doesn't make sense to begin with.
(Side note : who am I to say this ? well, read on.)
Anyway, when a frequency is not audible officially (23Hz and under for me), *any* harmonic distortion popping up at *any* level which makes it audible is too much. So, say that you can perceive a 40Hz at 70dB under your normal listening levels, then the 2nd harmonic of 20Hz will be audible when at 70dB down. So, not 20dB, not 40, not 50, just anything which makes it audible. For the inaudible fundamentals this is the most easy to check, and for the audible ones this is more difficult. But in general : when you go down step by step and suddenly the next step sounds as high or higher, you will notice the distortion by that means. This is also profound over the distortion in the fundamental. So, easy.
This is very different from putting up even 25Hz where you are to judge whether this distorts. So with a good absolute hearing you might be able to, but with less good you may not recognize that the net pitch got somewhat higher because it is mixed with 50Hz. And then to think that 25Hz is a most easy example actually, because already so less audible. But with 70Hz ? Good luck. Still though, when going from 72 to 71, to 70 it is the most easy to hear when 70 sounds suddenly higher than 71. Thus, do it like that - easy.

Although there is some sense in relating the F-M curves to harmonic distortion (HD) I don't think it is a real lead for this. But *if* there's a lead or base for how we can perceive HD it is about this (look at my picture now and just take the bottom curve for example) :
When we are to perceive 110Hz at a certain level, we will perceive 1000Hz an 11dB louder. Or, when we want to perceive 90Hz at a certain level, 1000Hz will sound 20dB louder to us.
(look for the more realistic comparison at e.g. the 80dB curve)
So all this says really is that once we want to perceive that 90Hz in well fashion, we must be careful about its 10th harmonic because at whatever level that comes forward, we perceive it 20dB louder than any FFT shows us.

But really, I only tried to reason out something which is no subject at all. It is maybe, but it is completely overwhelmed by other findings.
So, what actually happened here while "tuning" this speaker ?

Look at the 70dB curve;
Just by listening and after being satisfied, to my surprise I found that I am following this curve exactly. Mind the 70dB which is listening levels though on the low side. But anyway this is the best representative for the curves I created - so just to give the idea.
Especially because I wasn't aware of these F-M curves (although I had seen them ever back), I was shocked to find this prefect match. In other words, this could not be a coincidence.

Because this can not be a coincidence, everything *not* matching those curves should be explainable, right ?
And this is how I actually started the whole "bass" subject, because the low end of the curves do not match AT ALL. In other words, when you see me writing about super bass, up into the near inaudible levels (because of frequency we can't interpret anymore, for me 23Hz !), there is no single way these F-M curves represent what I perceive from this speaker.

When I was to tune the lot under 1000Hz like you see in the curves (those 2003 curves even far worse) then windows would go out because of bass alone. So, looking at that 70dB curve and assumed I would be playing at 70dPSPL, then 30Hz would come out something like 17-18dB more. So, music above 1000Hz plays at 70dB and when there's 30Hz it plays at a sheer 88dB. True, this is what our SPL meters would say  but this is also totally audible and I would die of too much bass.

It may be complicated to follow, but with measurement it would come down literally to tuning all for SPL levels, and that 30Hz should output 18dB more than 1000Hz and when so we would perceive the both equally. That's what the F-M curves say, and that is what they are for (but also investigate the Phon unit (mentioned in Coen's picture) which does about the same).

So completely contrary to the F-M curves (let alone the 2003 version) my curves are just completely straight; they are straight from 600 Hz downwards. And then STILL I report "concert level bass". And, of course, any measurement shows equally loud levels from horn (up from 280Hz) and woofers. But also, my former speaker did that too. And no concert level bass at all.

So you see ? this is how I end up raving with a "what is actually going on ?!" and this is how I try to explain that through the various posts. But this is also how I try to squeeze out similar from you all, where a perceived equally good 15"er (could be my previous, could be Juan's) - rated to 27Hz flat at least for my own former and measured by myself - does not make a 32Hz organ pipe come through. Even not at all when supported by "official" subwoofers.
So I could go through all that reasoning again, but I already did that (tried at least), because indeed *something* has to be going on really.

These F-M curves, but maybe more that 2003 version which is worse, should depict official science. Well, am I not always going against that, and would it not be the first time that empirical finding learns a few things (after being ignorant about any so-called science in the first place) to next meeting the necessity to come up with some explanations. Say that is me myself and I.

So I tried to find out under what conditions both the F-M curves and the 2003 version where derived, and all I can say is that the F-M curves emerged through headphones which seems to be for the better (as claimed) while the 2003 ... I am not sure. The only difference I really see is that this is all through a mere special open baffle setup which can better be named "horn" and that both designs will at least contribute to less harmonic distortion at a. the higher SPL and b. for the lower frequencies (see yesterday's post).

In the mean time I (thus) have been working on proving whether it all could be about distortion after all, and this is not the case.
All I can say at this moment, is that when we would try to derive those curves from my former speaker system, I probably would come to similar curves in the bass area. So, I guess I would sure be able to perceive those 32Hz pipes easily, if only first the bass would be pumped up by 10dB or whatever, but, which can not work because no speaker would allow for that without first heavily distort (even more). Otherwise I think no speaker designer will deliver his speakers with the bass pumped up by 10dB anyway (and I mean seen through SPL measurement) and thus we all *think* that the F-M curves apply.

But all what happened (in my view) is that they were obtained through means which are not today's best (loudspeaker) means. At least I see that this is so through the Orelino speaker and all I continuously try is to debunk my own findings. But so far I can not succeed.

Usually this means more woofer surface and/or horn loading which has a practical limit of 35 hz is a domestic environment.

Coen, what is this 35Hz based upon ?

Regards,
Peter