LOL, in humoresk memory to great fakes and great jokes in recent history :
Neil Armstrong performing Gary Peach:
„One small step for man, one giant leap for mankind“
One small mistake... The proof that Neil Armstrong got his famous 'One small step for man' Moon-landing line WRONG | Mail Online
British scientist claims he coined Neil Armstrong's moon landing quote - Times Online
************ **************** ************* ************* ***************
This isn't exactly about what audio guys are concerned with in usual speaker design process – but may be worth to put together nevertheless, as there seems to be a loooot of confusion among audio guys on this topic.
Beyond that, it may shade a light to strong (but wrong) believes among audio folks that – IMO - currently (and for quite some time now) act as massive mind blockers.
Though it may not sound like from the beginning - it will culminate in the question if we „hear in math terms“ or if we have the ability to recognize and distinguish specific sonic patterns in the time domain.
What will be addressed along the course:
the myth around „ill diffraction“ - most prominently popularized by Earl Geddes
the myth around „ill stored energy“ - most prominently popularized by Siegfried Linkwitz
- above two points of view finaly being highly interwoven with the (pretty limited) current paradigm of „frequency domain thinking“ - most prominently popularized by Floyd Toole.
To make my point I'd like to introduce a „new“ analysis method that I'd like to call PBW analysis = Packed Burst Wavelet analysis.
Being looking for quite some time for a visualization tool that most pin point displays time domain behaviour to easily distinguish the specific properties of CMP systems, I finally arrived at PBW analysis method that provides exceptional high resolution in time *and* frequency domain.
Its a form of visual representation to what most basically could be addressed as „Acoustic Source & Acoustic Room“ (ASAR) pattern.
As we will see, this pattern differs significantly from „simple filter“ patterns.
Anybody knows, I'm neither a math magician nor any well skilled in Matlab / Octave coding, so I'd like give credit to Elias Pekonen who has pioneered wavelet analysis for the DIY community and also to Jean-Michel LeCleach, both of which have been providing a looot of good work regarding spectral analysis, so that I finally was able to adapt wavelet analysis to my needs.
🙂
Michael
Neil Armstrong performing Gary Peach:
„One small step for man, one giant leap for mankind“
One small mistake... The proof that Neil Armstrong got his famous 'One small step for man' Moon-landing line WRONG | Mail Online
British scientist claims he coined Neil Armstrong's moon landing quote - Times Online
************ **************** ************* ************* ***************
This isn't exactly about what audio guys are concerned with in usual speaker design process – but may be worth to put together nevertheless, as there seems to be a loooot of confusion among audio guys on this topic.
Beyond that, it may shade a light to strong (but wrong) believes among audio folks that – IMO - currently (and for quite some time now) act as massive mind blockers.
Though it may not sound like from the beginning - it will culminate in the question if we „hear in math terms“ or if we have the ability to recognize and distinguish specific sonic patterns in the time domain.
What will be addressed along the course:
the myth around „ill diffraction“ - most prominently popularized by Earl Geddes
the myth around „ill stored energy“ - most prominently popularized by Siegfried Linkwitz
- above two points of view finaly being highly interwoven with the (pretty limited) current paradigm of „frequency domain thinking“ - most prominently popularized by Floyd Toole.
To make my point I'd like to introduce a „new“ analysis method that I'd like to call PBW analysis = Packed Burst Wavelet analysis.
Being looking for quite some time for a visualization tool that most pin point displays time domain behaviour to easily distinguish the specific properties of CMP systems, I finally arrived at PBW analysis method that provides exceptional high resolution in time *and* frequency domain.
Its a form of visual representation to what most basically could be addressed as „Acoustic Source & Acoustic Room“ (ASAR) pattern.
As we will see, this pattern differs significantly from „simple filter“ patterns.
Anybody knows, I'm neither a math magician nor any well skilled in Matlab / Octave coding, so I'd like give credit to Elias Pekonen who has pioneered wavelet analysis for the DIY community and also to Jean-Michel LeCleach, both of which have been providing a looot of good work regarding spectral analysis, so that I finally was able to adapt wavelet analysis to my needs.
🙂
Michael
PBW (Packed Burst Wavelet) analysis is just another tool in the box capable to provide – what some might call – another *bunch of pretty pictures*.
The kind of visualization I was aiming for, is to most clearly show the specific pattern of CMP behaviour / ASAR patterns.
In the „Horn Honk Wanted“ thread there already were analysis methods introduced to bring out patterns related to delay effects (= echo and looped echo) .
3-D PBW (Packed Burst Wavelet) analysis is just another – slightly refined - method to display time domain impacts.
In analogy to what I've shown with „Thermal Distortion“ we possibly should look at CMP and ASAR in categories.
Technically seen, its all based on one and the same mechanism but of course is *perceived* differently :
1.) very short time delay = chassis related (cone / dome / foil brake up)
2.) short time delay = related to speaker construction or due to multi-source overlap (second sources created by diffraction, honk of horns, TL behaviour, OB, back loaded horns, etc. or difference in time of flight from multiway speakers for example)
3.) long time delays = rooms (boundary reflections in rooms and room modes for example).
So ASAR patterns basically embraced each and every effect *not* related to „simple filters“ but to *time delay effects* .
More philosophically speaking – those time delay effects actually are an interwoven property to acoustic rooms (hence ASAR pattern) making room perception indistinguishable from CPM perception.
Of course all three above mentioned „delay time categories“ have equivalents in any original sound event (not any related to sound reproduction !), we are trained and already „familiar“ with recognizing such patterns for as long as mankind exists.
As ASAR patterns most basically could be characterized as „repetitive“, there is no loss of information happening (in theory) with adding a few more such patterns during reproduction.
Even so, we do not aim after that - from a „fidelity“ perspective – most people do not have any problems to „see through“ ASAR patterns that do not stem from the original sound event.
Thats even true for actually pretty annoying ASAR patterns like horn honk for example.
It means, that our ear brain system can detect, value and suppress or highlight (to some degree) specific ASAR patterns according to „getting used to a listening environment“.
Otherwise it would not have been possible to enjoy music in such a wide variety of listening rooms and with that many different speaker (and headphone) constructions as we do for centuries now.
Actually, technically seen, this isn't any different from sitting first row or balcony when enjoying the same concert – the impression / presentation may be different and picking up details will take more or less effort – but its actually „all there“.
At a „second thought“ it becomes obvious that the stability of ASAR patterns in time domain is more so a quality criterion.
This immediately explains the impact of jitter – both „true“ electronic generated one and from second order thermal and acoustic effects that act „as if“ – and whose absence / diminishing always is recognized as a clear gain in reproduction performance.
🙂
Michael
The kind of visualization I was aiming for, is to most clearly show the specific pattern of CMP behaviour / ASAR patterns.
In the „Horn Honk Wanted“ thread there already were analysis methods introduced to bring out patterns related to delay effects (= echo and looped echo) .
3-D PBW (Packed Burst Wavelet) analysis is just another – slightly refined - method to display time domain impacts.
In analogy to what I've shown with „Thermal Distortion“ we possibly should look at CMP and ASAR in categories.
Technically seen, its all based on one and the same mechanism but of course is *perceived* differently :
1.) very short time delay = chassis related (cone / dome / foil brake up)
2.) short time delay = related to speaker construction or due to multi-source overlap (second sources created by diffraction, honk of horns, TL behaviour, OB, back loaded horns, etc. or difference in time of flight from multiway speakers for example)
3.) long time delays = rooms (boundary reflections in rooms and room modes for example).
So ASAR patterns basically embraced each and every effect *not* related to „simple filters“ but to *time delay effects* .
More philosophically speaking – those time delay effects actually are an interwoven property to acoustic rooms (hence ASAR pattern) making room perception indistinguishable from CPM perception.
Of course all three above mentioned „delay time categories“ have equivalents in any original sound event (not any related to sound reproduction !), we are trained and already „familiar“ with recognizing such patterns for as long as mankind exists.
As ASAR patterns most basically could be characterized as „repetitive“, there is no loss of information happening (in theory) with adding a few more such patterns during reproduction.
Even so, we do not aim after that - from a „fidelity“ perspective – most people do not have any problems to „see through“ ASAR patterns that do not stem from the original sound event.
Thats even true for actually pretty annoying ASAR patterns like horn honk for example.
It means, that our ear brain system can detect, value and suppress or highlight (to some degree) specific ASAR patterns according to „getting used to a listening environment“.
Otherwise it would not have been possible to enjoy music in such a wide variety of listening rooms and with that many different speaker (and headphone) constructions as we do for centuries now.
Actually, technically seen, this isn't any different from sitting first row or balcony when enjoying the same concert – the impression / presentation may be different and picking up details will take more or less effort – but its actually „all there“.
At a „second thought“ it becomes obvious that the stability of ASAR patterns in time domain is more so a quality criterion.
This immediately explains the impact of jitter – both „true“ electronic generated one and from second order thermal and acoustic effects that act „as if“ – and whose absence / diminishing always is recognized as a clear gain in reproduction performance.
🙂
Michael
Lets start out with a variant of what also has been shown back in the „Stored Energy Bogus“ thread :
http://www.diyaudio.com/forums/everything-else/185011-debunking-sls-stored-energy.html
A simple sine burst – overlayed by a specific impulse response
First off - here the impulse response of a „simple filter“ 1kHz / Q10 / +6dB EQing :
Below is whats seen if we look at a bunch of sine bursts (look out for the second from left):
below is whats seen if we look at a single sine burst (rectified):
and finally here is whats seen if we take a bunch of wavlet analysed sine bursts – between 500Hz and 5kHZ - and display it in a 3D plot :
and the same plot animated :
http://www.kinotechnik.edis.at/pages/diyaudio/CMPB/ASAR/anim_1kHz_Q10_6dB_boost.gif (6MB)
🙂
Michael
http://www.diyaudio.com/forums/everything-else/185011-debunking-sls-stored-energy.html
A simple sine burst – overlayed by a specific impulse response
First off - here the impulse response of a „simple filter“ 1kHz / Q10 / +6dB EQing :
Below is whats seen if we look at a bunch of sine bursts (look out for the second from left):
below is whats seen if we look at a single sine burst (rectified):
and finally here is whats seen if we take a bunch of wavlet analysed sine bursts – between 500Hz and 5kHZ - and display it in a 3D plot :
and the same plot animated :
http://www.kinotechnik.edis.at/pages/diyaudio/CMPB/ASAR/anim_1kHz_Q10_6dB_boost.gif (6MB)
🙂
Michael
Last edited by a moderator:
To further warm up - same below for a „simple filter“ 1kHz / Q10 / -6dB EQing :
the impulse response:
a single sine burst (rectified):
and 3D plot plus animation :
http://www.kinotechnik.edis.at/pages/diyaudio/CMPB/ASAR/anim_1kHz_Q10_6dB_cut.gif (7MB)
OK – so far we *should* be familiar with – no ?
🙂
Michael
the impulse response:
a single sine burst (rectified):
and 3D plot plus animation :
http://www.kinotechnik.edis.at/pages/diyaudio/CMPB/ASAR/anim_1kHz_Q10_6dB_cut.gif (7MB)
OK – so far we *should* be familiar with – no ?
🙂
Michael
Now proceeding towards more interesting ASAR patterns / CMP behaviour :
the impulse response of a single 100% echo happening after 3ms :
a single sine burst (rectified):
and 3D plot plus animation :
http://www.kinotechnik.edis.at/pages/diyaudio/CMPB/ASAR/anim_ir_echo_3ms.gif (7MB)
🙂
Michael
the impulse response of a single 100% echo happening after 3ms :
a single sine burst (rectified):
and 3D plot plus animation :
http://www.kinotechnik.edis.at/pages/diyaudio/CMPB/ASAR/anim_ir_echo_3ms.gif (7MB)
🙂
Michael
And another ASAR patterns / CMP behaviour created by looped echos (three times looped by 6dB attenuation) to complete the story :
the impulse response :
a single sine burst (rectified):
and 3D plot plus animation :
http://www.kinotechnik.edis.at/pages/diyaudio/CMPB/ASAR/anim_ir_echo3_1ms.gif (7MB)
🙂
Michael
the impulse response :
a single sine burst (rectified):
and 3D plot plus animation :
http://www.kinotechnik.edis.at/pages/diyaudio/CMPB/ASAR/anim_ir_echo3_1ms.gif (7MB)
🙂
Michael
Last edited by a moderator:
So what we see in that plots – though they have not come out as visually perfect as I would have liked and may be replaced by better ones eventually :
1.) In the presence of CMP behaviour / ASAR patterns - any sound event gets „framed“
This means that at the beginning and the end there is always a „plateau“ for as long as the delay time lasts
For the time slot of delay time (the „opening frame part“) there is no spectral disturbance – same is true for the „CMP tail“ (the „closing frame part“) after source shut down.
2.) This „CMP framing“ is basically independent of frequency and as such can not be treated by „simple filter“ measures (just the whole signal can be attenuated / „knocked down“).
3.) The „combing“ of comb filter effects is not happen immediately – its happening delayed.
4.) There is no e-function rise nor tail with CMP behaviour / ASAR patterns – but - this can be sort of mimicked to some extent by looped echoes.
5.) As the „framing“ happening with CMP behaviour / ASAR patterns is „sharp edged“ at the points of spectral „discontinuity“ along the time line, we basically face the sonic specialty of „signal start“ / „signal end“ more than once.
This means that the spectral distribution of „signal start“ is overlaid to the original signal at delay time, adding high frequency content where its not expected to happen – if we can say so for such short events.
Same – to some degree – for „signal end“.
Also - for frequency bands of destructive interference – „signal start“ happens at time slot „signal end“ too.
This is one further specific property with any CMP behaviour / ASAR pattern in addition to the framing „plateaus“ and the combing time slot – though, quite often overlooked.
Taking above conclusions one step further, we easily see that CMP behaviour / ASAR patterns are creating kind of time / frequency grid upon any sound event.
As our ear is sensing sounds basically just in this manner (clues at specific frequency bands at specific time slots) we are of course relaying on the exact relationship of that „time / frequency grid“ in ASAR pattern recognition.
If those „matrix“ get degraded – by jitterering the time axis for example – our perception of ASAR patterns is compromised too.
So it may well be that – while enjoying Bethoven – we may not be busy with solving filter equations but rather comparing the beauty of matixes to each other.
From this point of view, valuing the *quality* of presentation / reproduction may rather be judging integrity and precision of those time / frequency matrices than anything else - but thats a different story.
🙂
Michael
1.) In the presence of CMP behaviour / ASAR patterns - any sound event gets „framed“
This means that at the beginning and the end there is always a „plateau“ for as long as the delay time lasts
For the time slot of delay time (the „opening frame part“) there is no spectral disturbance – same is true for the „CMP tail“ (the „closing frame part“) after source shut down.
2.) This „CMP framing“ is basically independent of frequency and as such can not be treated by „simple filter“ measures (just the whole signal can be attenuated / „knocked down“).
3.) The „combing“ of comb filter effects is not happen immediately – its happening delayed.
4.) There is no e-function rise nor tail with CMP behaviour / ASAR patterns – but - this can be sort of mimicked to some extent by looped echoes.
5.) As the „framing“ happening with CMP behaviour / ASAR patterns is „sharp edged“ at the points of spectral „discontinuity“ along the time line, we basically face the sonic specialty of „signal start“ / „signal end“ more than once.
This means that the spectral distribution of „signal start“ is overlaid to the original signal at delay time, adding high frequency content where its not expected to happen – if we can say so for such short events.
Same – to some degree – for „signal end“.
Also - for frequency bands of destructive interference – „signal start“ happens at time slot „signal end“ too.
This is one further specific property with any CMP behaviour / ASAR pattern in addition to the framing „plateaus“ and the combing time slot – though, quite often overlooked.
Taking above conclusions one step further, we easily see that CMP behaviour / ASAR patterns are creating kind of time / frequency grid upon any sound event.
As our ear is sensing sounds basically just in this manner (clues at specific frequency bands at specific time slots) we are of course relaying on the exact relationship of that „time / frequency grid“ in ASAR pattern recognition.
If those „matrix“ get degraded – by jitterering the time axis for example – our perception of ASAR patterns is compromised too.
So it may well be that – while enjoying Bethoven – we may not be busy with solving filter equations but rather comparing the beauty of matixes to each other.
From this point of view, valuing the *quality* of presentation / reproduction may rather be judging integrity and precision of those time / frequency matrices than anything else - but thats a different story.
🙂
Michael
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Anything presented above isn't exactly „new“ of course (- what actually is ?)
BUT
above visualisation of CMP framing / ASAR pattern hopefully may trigger re-thinking of time domain impacts.
This specific sonic pattern is most basically *related to room effects in audio perception* at many, many scales.
Following a lot of IMO fruitless discussions about binaural perception with respect to room effects – audio guys seem to have forgotten that most basic encoding of room effects into an audio stream is based on CMP behaviour – which by itself – isn't related to binaural reproduction nor to stereo mic'ing at all.
To get those room related effects „right“ – meaning - to have a system where things „fall into place“ is a quality of its own, that is (and was ever since) way higher in my list than to get tonal balance right – though – until now, I would not have been in a position to pinpoint what „quality“ I exactly was after.
Besides better understanding of perception of 3-D effects , this specific „time domain quality“ of CMP framing / ASAR patterns may also shade some light as to why some systems may sound gritty – especially when a notch in FR is EQ to flat that actually isnt a notch from „simple filter behaviour“, but is part of a CMP pattern.
Simply put, its applying the wrong tools if one tries to fill up – so called - „deep nulls“ (actually originating from CMP behavour) with a graphic or parametric equalizer.
Also – its a mis-belief that such „deep nulls“ cant be corrected at all – they actually can be corrected 100% to flat by „appropriate measures“ (as shown way earlier) - BUT – in reality, one will run out of steam pretty fast. Here also, CMP behaviour shows that its quite a different animal compared to „normal“ filter behavour.
Also – applying low pass filters do not provide *any* cure to (unwanted) CMP behaviour - as is the mis-belief of someone I usually highly respect – or possibly to be more precise - this kind of cure is the kind of „cure“ only people with „peacemaker personality“ usually find appropriate to „solve their problems“.
Also - it can be seen quite clearly:
If a frequency response plot is showing „deep nulls“ one would assume intuitively that this frequencies are „dead“.
Actually that's not the case at all !
At certain time slots those frequency bands are as alive and intact as any others - its just that at *some time slots* those frequency bands are mute.
Hence – when it comes to CMP behaviour / ASAR patterns, the concept of FR is simply void and misleading.
🙂
Michael
BUT
above visualisation of CMP framing / ASAR pattern hopefully may trigger re-thinking of time domain impacts.
This specific sonic pattern is most basically *related to room effects in audio perception* at many, many scales.
Following a lot of IMO fruitless discussions about binaural perception with respect to room effects – audio guys seem to have forgotten that most basic encoding of room effects into an audio stream is based on CMP behaviour – which by itself – isn't related to binaural reproduction nor to stereo mic'ing at all.
To get those room related effects „right“ – meaning - to have a system where things „fall into place“ is a quality of its own, that is (and was ever since) way higher in my list than to get tonal balance right – though – until now, I would not have been in a position to pinpoint what „quality“ I exactly was after.
Besides better understanding of perception of 3-D effects , this specific „time domain quality“ of CMP framing / ASAR patterns may also shade some light as to why some systems may sound gritty – especially when a notch in FR is EQ to flat that actually isnt a notch from „simple filter behaviour“, but is part of a CMP pattern.
Simply put, its applying the wrong tools if one tries to fill up – so called - „deep nulls“ (actually originating from CMP behavour) with a graphic or parametric equalizer.
Also – its a mis-belief that such „deep nulls“ cant be corrected at all – they actually can be corrected 100% to flat by „appropriate measures“ (as shown way earlier) - BUT – in reality, one will run out of steam pretty fast. Here also, CMP behaviour shows that its quite a different animal compared to „normal“ filter behavour.
Also – applying low pass filters do not provide *any* cure to (unwanted) CMP behaviour - as is the mis-belief of someone I usually highly respect – or possibly to be more precise - this kind of cure is the kind of „cure“ only people with „peacemaker personality“ usually find appropriate to „solve their problems“.
Also - it can be seen quite clearly:
If a frequency response plot is showing „deep nulls“ one would assume intuitively that this frequencies are „dead“.
Actually that's not the case at all !
At certain time slots those frequency bands are as alive and intact as any others - its just that at *some time slots* those frequency bands are mute.
Hence – when it comes to CMP behaviour / ASAR patterns, the concept of FR is simply void and misleading.
🙂
Michael
Having presented „another bunch of pretty pictures“ - what actually to learn from that ?
Basically - as said in the beginning – all above culminates in the question: „how do we hear ?“
If „we hear“ in math terms – well – then CMP behaviour and its basic component „delay“ is just the same filter behaviour than any other filter behaviour in the world – there would be no need to make any fuss around CMP.
BUT
if „we hear“ in terms of pattern recognition – well – then CMP behaviour can tell us:
1. about reflections caused by room boundary
2. about reflections and looped reflections of specific speaker makes
3. about source origin related to single versus multi placed sources
Point one
tells us in most basic terms about „room perception“ and possible identification thereof
(the one that was coded into the music we listen to, as well as the one we listen in)
Point two
tells us in most basic terms about „speaker perception“ and possible identification thereof
(horn honk, pronounced diffraction effects, cone brake up etc)
Point three
tells us in most basic terms about „perception of source origin“ and possible identification thereof
(with respect to what was coded into the music – with possibly some „special effects“ from mixdown – as well as with respect to the specific speaker make we may listen to – like multiway, line source, single or coax source)
All in all we may have learned that we actually „hear“ a pretty specific systemic pattern that has one and the same root cause turning out in different „perceptional scales“.
But of course – as an audio guy with pretty limited and biased perception of audio history once pointed out – „CMP does not cure common cold“
😉
And I may add: neither does ASAR pattern recognition...
🙂
Keep swingin'
Michael
Basically - as said in the beginning – all above culminates in the question: „how do we hear ?“
If „we hear“ in math terms – well – then CMP behaviour and its basic component „delay“ is just the same filter behaviour than any other filter behaviour in the world – there would be no need to make any fuss around CMP.
BUT
if „we hear“ in terms of pattern recognition – well – then CMP behaviour can tell us:
1. about reflections caused by room boundary
2. about reflections and looped reflections of specific speaker makes
3. about source origin related to single versus multi placed sources
Point one
tells us in most basic terms about „room perception“ and possible identification thereof
(the one that was coded into the music we listen to, as well as the one we listen in)
Point two
tells us in most basic terms about „speaker perception“ and possible identification thereof
(horn honk, pronounced diffraction effects, cone brake up etc)
Point three
tells us in most basic terms about „perception of source origin“ and possible identification thereof
(with respect to what was coded into the music – with possibly some „special effects“ from mixdown – as well as with respect to the specific speaker make we may listen to – like multiway, line source, single or coax source)
All in all we may have learned that we actually „hear“ a pretty specific systemic pattern that has one and the same root cause turning out in different „perceptional scales“.
But of course – as an audio guy with pretty limited and biased perception of audio history once pointed out – „CMP does not cure common cold“
😉
And I may add: neither does ASAR pattern recognition...
🙂
Keep swingin'
Michael
Do not load up the page with heavy animation files. Provide links instead.I have removed the embedded images and provided links.
You know what that is ?
I'm pretty sure anybody knows !
But then - lets step back and have a look again:
compared to whats been shown earlier we immediately see that its basically a time / frequency "plot" too - not *that* different to PBW analysis ( if we would add some colors 🙂 ).
Michael
I'm pretty sure anybody knows !
But then - lets step back and have a look again:
compared to whats been shown earlier we immediately see that its basically a time / frequency "plot" too - not *that* different to PBW analysis ( if we would add some colors 🙂 ).
Michael
Ever been scratching your head as to why the bass performance improved significantly when having pimped your tweeter only?
Here we see the mechanism how the (top end) low pass behaviour of our reproduction chain is „folding down“ into the sonic specialty of „signal start“ „signal stop“ in the lower department – eroding/ altering the framing of the „grid matrix“ we rely on in identifying ASAR patterns - thus making it more or less easy to perceive whats going on in the bass.
We have to keep clear about the fact that this „fold down“ mechanism is not a technical one like seen in mirroring effects related to Nyquist frequency – here its meant as a mere perceptional mechanism !
Above observation may also tells us that we are rather *not* listening in (isolated) frequency bands but valuing time / frequency matrix clues.
It also may shades some light as to why its so difficult to judge the quality of a tweeter without having it integrated.
Simply put – we (mostly) do not „hear“ the tweeter performance in the according frequency band but rather the „signal start“ / „signal stop“ performance in the lower department.
What at a first glance seems so contradictionally from a physically point of view is very easy to understand if we assume that our listening ability is mainly based upon pattern recognition.
🙂
Michael
Here we see the mechanism how the (top end) low pass behaviour of our reproduction chain is „folding down“ into the sonic specialty of „signal start“ „signal stop“ in the lower department – eroding/ altering the framing of the „grid matrix“ we rely on in identifying ASAR patterns - thus making it more or less easy to perceive whats going on in the bass.
We have to keep clear about the fact that this „fold down“ mechanism is not a technical one like seen in mirroring effects related to Nyquist frequency – here its meant as a mere perceptional mechanism !
Above observation may also tells us that we are rather *not* listening in (isolated) frequency bands but valuing time / frequency matrix clues.
It also may shades some light as to why its so difficult to judge the quality of a tweeter without having it integrated.
Simply put – we (mostly) do not „hear“ the tweeter performance in the according frequency band but rather the „signal start“ / „signal stop“ performance in the lower department.
What at a first glance seems so contradictionally from a physically point of view is very easy to understand if we assume that our listening ability is mainly based upon pattern recognition.
🙂
Michael
Before continuing with analysing more complex patterns – here is how a „simple“ 1kHz high pass filter looks like in PBW analysis:
Impulse response :
one „slice“ (rectified and in log scale):
finally PBW analysis:
and here the animated PBW:
http://www.kinotechnik.edis.at/pages/diyaudio/CMPB/ASAR/aanim_1kHz_HP_LR24.gif
Well nothing thrilling – I know...
🙂
Michael
Impulse response :
one „slice“ (rectified and in log scale):
finally PBW analysis:
and here the animated PBW:
http://www.kinotechnik.edis.at/pages/diyaudio/CMPB/ASAR/aanim_1kHz_HP_LR24.gif
Well nothing thrilling – I know...
🙂
Michael
And here is how a „simple“ 5kHz low pass filter looks like in PBW analysis:
Impulse response :
one „slice“ (rectified and in log scale):
finally PBW analysis:
and here the animated PBW:
http://www.kinotechnik.edis.at/pages/diyaudio/CMPB/ASAR/anim_5kHz_LP_LR24.gif
Well not that thrilling either ...
🙂
Michael
Impulse response :
one „slice“ (rectified and in log scale):
finally PBW analysis:
and here the animated PBW:
http://www.kinotechnik.edis.at/pages/diyaudio/CMPB/ASAR/anim_5kHz_LP_LR24.gif
Well not that thrilling either ...
🙂
Michael
The characterization / visualisaton of „simple filter“ behaviour versus "ASAR pattern" behaviour is now complete:
With respect to „simple filter“ there is basically:
- low pass (post # 15)
- high pass (post # 14)
- boost (post # 3)
- and cut (post # 4)
With respect to ASAR patterns there is basically:
- single delay (post # 5)
- looped delay (post # 6)
thats it.
Really not that much to get any confused about – no ?
🙂
Michael
With respect to „simple filter“ there is basically:
- low pass (post # 15)
- high pass (post # 14)
- boost (post # 3)
- and cut (post # 4)
With respect to ASAR patterns there is basically:
- single delay (post # 5)
- looped delay (post # 6)
thats it.
Really not that much to get any confused about – no ?
🙂
Michael
Last edited:
After all that „theory“ now lets look at a juicy „real world“ example.
Below (again) the NEO3 in round OB :
impulse response :
frequency response:
and PBW analaysis :
and the animation of ASAR pattern:
http://www.kinotechnik.edis.at/pages/diyaudio/CMPB/ASAR/aanim_NEO3_in_round_OB_43cm.gif
well – above is probably a little bit too much of ASAR patterns involved for now 😉
So – lets cut away room interaction / floor bounce happening after roughly 3ms :
and the animation of ASAR pattern:
http://www.kinotechnik.edis.at/pages/diyaudio/CMPB/ASAR/aanim_NEO3_in_round_OB_43cm_3ms_wind2.gif
Still pretty impressive ASAR patterns involved – no ?
🙂
Michael
Below (again) the NEO3 in round OB :
impulse response :
frequency response:
and PBW analaysis :
and the animation of ASAR pattern:
http://www.kinotechnik.edis.at/pages/diyaudio/CMPB/ASAR/aanim_NEO3_in_round_OB_43cm.gif
well – above is probably a little bit too much of ASAR patterns involved for now 😉
So – lets cut away room interaction / floor bounce happening after roughly 3ms :
and the animation of ASAR pattern:
http://www.kinotechnik.edis.at/pages/diyaudio/CMPB/ASAR/aanim_NEO3_in_round_OB_43cm_3ms_wind2.gif
Still pretty impressive ASAR patterns involved – no ?
🙂
Michael
If we want to analyse more complex patterns we may wish to explore how pattern types basically combine:
3ms ASAR Pattern combined with 1kHz HP
and animation:
http://www.kinotechnik.edis.at/pages/diyaudio/CMPB/ASAR/anim_1_ir_echo_3ms_HP_1kHz_LR24.gif
3ms ASAR Pattern combined with 5kHz LP
and animation:
http://www.kinotechnik.edis.at/pages/diyaudio/CMPB/ASAR/anim_1ir_echo_3ms_LP_LR24_5kHz.gif
3ms ASAR Pattern combined with 1kHz boost:
and animation:
http://www.kinotechnik.edis.at/pages/diyaudio/CMPB/ASAR/anim_1_ir_echo_3ms_1kHz_q10_6dB_boost.gif
3ms ASAR Pattern combined with 1kHz cut
and animation:
http://www.kinotechnik.edis.at/pages/diyaudio/CMPB/ASAR/anim_1ir_echo_3ms_1kHz_Q10_6dB_cut.gif
Here we see (again) that those ASAR effects and "simple" filter effects combine in the fashion of mere overlay without any further interaction.
This is not to say that there may not be any interaction at all. Depending upon the amount of energy re-directed back to the speaker there might be interaction with the source behaviour as easily can be measured and be seen at impedance plots of tapped horns, horns, transmission line speakers and the like.
ASAR patterns created from diffraction differ here (slightly) from those created from reflections.
Because, with "diffraction created" ASAR patterns there is - by definition - *always* reflection back to the source involved. Hence, depending upon the amount of energy re-directed to the source there may be more or less interaction so that it even easily can be visually identified in linear scale impedance plots.
With ASAR patterns created from mere boundary reflection at the other hand, there is *not necessarily* any energy reflected back to the source. Think of floor bounce at outdoor measurement as a simple example where practically no energy is redirected to the source.
Though other boundary reflections can cause quite some interaction if we look at closed or open TM, tapped horn and the like (plus some other effects) as mentioned above.
There is also the case of reflections (and diffraction) that happens behind the diaphragm and get re-radiated through the diaphragm - as is always the case with any sort of boxes.
A very specific form of this mechanism I outlined in the BDMD (Back Diaphragm Mirror Distortion) paper.
So it depends – as there is basically no interaction of patterns in general – just overlay - but there *can* be considerable interaction with the source.
Lets keep clear about those two *very* different mechanisms involved.
At this point its possibly a good idea to slow down, take a breath and give it a second thought:
If we talk about “resonance”, the technical definition is based upon energy transfer involved *and* that its a pole caused by “simple” filters.
In audio speak the term “resonance” is used way too sloppy IMO – thus causing and having caused a looooot of misunderstanding and misinterpretation - “cavity resonance” being an example for possibly the most prominent misnomer in this respect.
People are talking about “resonance” also when there is looped reflections involved like is the case in TM, tapped / unity horns and the like.
This kind of looped echoes (plus some energy interaction) isn't exactly a resonance – not at all !
Also – looking at tapped horns / tapped TM we easily realize that time of flight for energy transfer versus echo looping isn't necessarily identically
Whenever being in doubt about that – I suggest to scroll back to post #3 to have a look how a *real* resonance should look like.
To repeat:
there is no such thing like “cavity resonance” in the words meaning – what is meant is a plain simple ASAR pattern caused by consecutively min phase behaviour.
🙂
Michael
3ms ASAR Pattern combined with 1kHz HP
and animation:
http://www.kinotechnik.edis.at/pages/diyaudio/CMPB/ASAR/anim_1_ir_echo_3ms_HP_1kHz_LR24.gif
3ms ASAR Pattern combined with 5kHz LP
and animation:
http://www.kinotechnik.edis.at/pages/diyaudio/CMPB/ASAR/anim_1ir_echo_3ms_LP_LR24_5kHz.gif
3ms ASAR Pattern combined with 1kHz boost:
and animation:
http://www.kinotechnik.edis.at/pages/diyaudio/CMPB/ASAR/anim_1_ir_echo_3ms_1kHz_q10_6dB_boost.gif
3ms ASAR Pattern combined with 1kHz cut
and animation:
http://www.kinotechnik.edis.at/pages/diyaudio/CMPB/ASAR/anim_1ir_echo_3ms_1kHz_Q10_6dB_cut.gif
Here we see (again) that those ASAR effects and "simple" filter effects combine in the fashion of mere overlay without any further interaction.
This is not to say that there may not be any interaction at all. Depending upon the amount of energy re-directed back to the speaker there might be interaction with the source behaviour as easily can be measured and be seen at impedance plots of tapped horns, horns, transmission line speakers and the like.
ASAR patterns created from diffraction differ here (slightly) from those created from reflections.
Because, with "diffraction created" ASAR patterns there is - by definition - *always* reflection back to the source involved. Hence, depending upon the amount of energy re-directed to the source there may be more or less interaction so that it even easily can be visually identified in linear scale impedance plots.
With ASAR patterns created from mere boundary reflection at the other hand, there is *not necessarily* any energy reflected back to the source. Think of floor bounce at outdoor measurement as a simple example where practically no energy is redirected to the source.
Though other boundary reflections can cause quite some interaction if we look at closed or open TM, tapped horn and the like (plus some other effects) as mentioned above.
There is also the case of reflections (and diffraction) that happens behind the diaphragm and get re-radiated through the diaphragm - as is always the case with any sort of boxes.
A very specific form of this mechanism I outlined in the BDMD (Back Diaphragm Mirror Distortion) paper.
So it depends – as there is basically no interaction of patterns in general – just overlay - but there *can* be considerable interaction with the source.
Lets keep clear about those two *very* different mechanisms involved.
At this point its possibly a good idea to slow down, take a breath and give it a second thought:
If we talk about “resonance”, the technical definition is based upon energy transfer involved *and* that its a pole caused by “simple” filters.
In audio speak the term “resonance” is used way too sloppy IMO – thus causing and having caused a looooot of misunderstanding and misinterpretation - “cavity resonance” being an example for possibly the most prominent misnomer in this respect.
People are talking about “resonance” also when there is looped reflections involved like is the case in TM, tapped / unity horns and the like.
This kind of looped echoes (plus some energy interaction) isn't exactly a resonance – not at all !
Also – looking at tapped horns / tapped TM we easily realize that time of flight for energy transfer versus echo looping isn't necessarily identically
Whenever being in doubt about that – I suggest to scroll back to post #3 to have a look how a *real* resonance should look like.
To repeat:
there is no such thing like “cavity resonance” in the words meaning – what is meant is a plain simple ASAR pattern caused by consecutively min phase behaviour.
🙂
Michael
Last edited:
When preparing measurements for my next point I stumbled over this:
even better seen in the animation:
http://www.kinotechnik.edis.at/pages/diyaudio/CMPB/ASAR/anim_1_spitz_pipe.gif
From all we have learned this is an “impossible behaviour” !
there simply is no way to create an attack slope of linear shape in dB scale (neither from "simple" filters nor from ASAR pattern)
So lets zoom into the 1kHz – 2kHz band to have a closer look
and the animation
http://www.kinotechnik.edis.at/pages/diyaudio/CMPB/ASAR/anim_1spitz-pipe.gif
Well - *now* we see better whats going on:
its not the attack slope of a single sine burst that has that shape, The ridge as a whole does have *kind of* such slope – BUT – the ridge got frequency shifted with time.
So one global property we took as a given until now, we can no longer relay on as a constant:
"time in-varance" of the system under examination.
It will be another fun time to trace down whether the centre frequency of a resonance or an ASAR pattern got frequency shifted (or both) and what conclusions possibly to draw from that.
One thing is for certain though – if *that* sonic pattern does not represent something that we have learned for ages to be “a real thing” then it will have to be learned as part of the “new listening environment”.
Its a pretty save bet then, that such patterns do *not* aid in helping to pin point the original sound event but rather will detract us from identifying of “what's been happening”.
In other words: such "abnormalities" may become a pretty precise measure for the quality of reproduction and may be correlated by our ear brain system to the perception of a specific form of coloration / error / distortion.
The main question if our "alert system" may be triggered or not may not be related to the mere presence of a weird sonic pattern but more so if it sticks out like "an Englishman in New York" - or - if it goes as unnoticed as "just another tree in the woods"
But before going into too much of speculation about the interesting ideas I have with respect to the root cause of such “ridge shifting” there is needed some further investigation.
🙂
Michael
even better seen in the animation:
http://www.kinotechnik.edis.at/pages/diyaudio/CMPB/ASAR/anim_1_spitz_pipe.gif
From all we have learned this is an “impossible behaviour” !
there simply is no way to create an attack slope of linear shape in dB scale (neither from "simple" filters nor from ASAR pattern)
So lets zoom into the 1kHz – 2kHz band to have a closer look
and the animation
http://www.kinotechnik.edis.at/pages/diyaudio/CMPB/ASAR/anim_1spitz-pipe.gif
Well - *now* we see better whats going on:
its not the attack slope of a single sine burst that has that shape, The ridge as a whole does have *kind of* such slope – BUT – the ridge got frequency shifted with time.
So one global property we took as a given until now, we can no longer relay on as a constant:
"time in-varance" of the system under examination.
It will be another fun time to trace down whether the centre frequency of a resonance or an ASAR pattern got frequency shifted (or both) and what conclusions possibly to draw from that.
One thing is for certain though – if *that* sonic pattern does not represent something that we have learned for ages to be “a real thing” then it will have to be learned as part of the “new listening environment”.
Its a pretty save bet then, that such patterns do *not* aid in helping to pin point the original sound event but rather will detract us from identifying of “what's been happening”.
In other words: such "abnormalities" may become a pretty precise measure for the quality of reproduction and may be correlated by our ear brain system to the perception of a specific form of coloration / error / distortion.
The main question if our "alert system" may be triggered or not may not be related to the mere presence of a weird sonic pattern but more so if it sticks out like "an Englishman in New York" - or - if it goes as unnoticed as "just another tree in the woods"
But before going into too much of speculation about the interesting ideas I have with respect to the root cause of such “ridge shifting” there is needed some further investigation.
🙂
Michael
Last edited:
Back to track.
“A long time ago” I wondered if different shapes of closed boxes could do anything for me in my search to get rid of dampening materials and the specific coloration thereof.
I remembered the B&W design that claimed to having found “Kolumbus' Egg” with respect to ill re-radiation of the back wave in closed boxes .
The idea was presented that by making a long pipe that continuously gets smaller and smaller in cross area, there will be no (considerable less) reflection happening. Like a soft beach, where the waves can roll out without being reflected.
There are several speakers of that design, the “Nautilus” with its “ammonite styling” being definitely the prettiest (and most expensive) one.
Allow me to cite from their page (as to 2011):
**********************
„Briefed to stop at nothing in the quest for a perfect loudspeaker, our engineers arrived at a set of drive units whose tapering, tubular enclosures spirited away every trace of internal resonance.
It (meant: the tapering tubes) acts like a horn in reverse - reducing the sound level instead of increasing it.“
**********************
Here is a measurement of such a tapered pipe I built:
(cut at 60ms to get clear view at the deep nulls)
and the animation
http://www.kinotechnik.edis.at/pages/diyaudio/CMPB/ASAR/anim_1spitz_pipe_downsample_8000.gif
Above tapered (closed) pipe is roughly 2m long, resulting in looped echoes of 12ms delay....
Funny !
- no big change to see from tapering a pipe with respect to providing almost text book ASAR pattern - so what to think of above B&W statements?
Take your own pick !
One thing is for sure: the basic ASAR pattern of tubes / pipes / closed transmission lines is not altered by any tapering – as we clearly see.
No big deal, you know – but from time to time the most obvious has to be stated.
🙂
Michael
“A long time ago” I wondered if different shapes of closed boxes could do anything for me in my search to get rid of dampening materials and the specific coloration thereof.
I remembered the B&W design that claimed to having found “Kolumbus' Egg” with respect to ill re-radiation of the back wave in closed boxes .
The idea was presented that by making a long pipe that continuously gets smaller and smaller in cross area, there will be no (considerable less) reflection happening. Like a soft beach, where the waves can roll out without being reflected.
There are several speakers of that design, the “Nautilus” with its “ammonite styling” being definitely the prettiest (and most expensive) one.
Allow me to cite from their page (as to 2011):
**********************
„Briefed to stop at nothing in the quest for a perfect loudspeaker, our engineers arrived at a set of drive units whose tapering, tubular enclosures spirited away every trace of internal resonance.
It (meant: the tapering tubes) acts like a horn in reverse - reducing the sound level instead of increasing it.“
**********************
Here is a measurement of such a tapered pipe I built:
(cut at 60ms to get clear view at the deep nulls)
and the animation
http://www.kinotechnik.edis.at/pages/diyaudio/CMPB/ASAR/anim_1spitz_pipe_downsample_8000.gif
Above tapered (closed) pipe is roughly 2m long, resulting in looped echoes of 12ms delay....
Funny !
- no big change to see from tapering a pipe with respect to providing almost text book ASAR pattern - so what to think of above B&W statements?
Take your own pick !
One thing is for sure: the basic ASAR pattern of tubes / pipes / closed transmission lines is not altered by any tapering – as we clearly see.
No big deal, you know – but from time to time the most obvious has to be stated.
🙂
Michael
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