Acoustic treatment and acoustic mechanical control over gear upgrade for improvement


«NO speaker can beat the room»... I dont remember where i read these words coming from the mouth of an acoustician....😁😊

No speakers at any cost will beat, by their upgrading power ALONE, over another good speakers we owned before it, the power of acoustic control over them two...

 

 

 

 

Here are these 6 aspects of acoustic control parameters in a room i experimented with :

1 -Balance between absorbing surfaces,

2 -Reflecting one,

3 -Diffusive one....

This was "classical" passive material treatment of a room...

Now these 3 new other factors are related to my concept of the mechanical active control of a room ( what i called a mechanical equalizer):

4-control over reverberation time and timing of the wavefronts by using reflecting devices at the right spot...( the great advantage of a small room is the possibility to control reverberation time and timing in a positive way, in a way that amphiteater or great hall could not so easily, making speakers/room synergy better)

5- control over the distribution of the pressure zones with a grid of H.R from one speaker to the other around the room...And with some other devices...

6- fine layering and tuning of the flow of the sound waves by working with tubes of different zize and straws for example in the right location on the shear velocity of the waves and their sound pressure...

 

 

 

In a small room remember that at the speed of sound 1100 feet by second, the sound weaves cross your small room of 13 feet, like mine for example, cross it 84 times per second...Your room atmosphere is tense like a violin cord for the ears/brain. who take decision and make his computing between your 2 ears in couple of ten milliseconds... Do you begin to understand why even a straw or tube diameter/lenght/volume, can change the sound of a room /speakers relation ?

 

These 3 last aspects described above could be controlled with Helmhotz mechanical method NOT by electronical equalization...

( Imaging, soundstage, dynamic, timbre percption, listener envelopment, sound source dimension, colors,etc any acoustic qualities are all related with one another and changing one is changing the others a bit also, the key is changing all of them together with mechanical control in a fine tuning incremental optimizing process of listenings experiments)

Electronic E.Q. can be a useful tool but cannot tune a room nor be a PART of the room like a mechanical equalizer...And E.Q.uing with a frequency test ask for a location which could be accurate only in a millimeter range, anywhere else causing havoc...

Then the piano will not sound the same from the same pair of speakers in a non controlled room and in a controlled one...Not even close...

 

 

Dont upgrade good speakers with costly one BEFORE studying and experimenting with acoustic...

My acoustic devices and experiments were all homemade and cost me nothing...

I can then claim that great hi-Fi experience is possible at low cost contrary to what is claimed or supposed almost everywhere by almost everyone...

People dont know acoustic and never seriously try experimenting with it in a dedicated SMALL room...

Anyway if electronic engineering design is a mature technology for 70 yeears now with major improvement behind, acoustic of SMALL room is a new venture for few decades only because customers demands was not there enough till very recently....

A living room is not an audio dedicated room... I am happy to be retired and i could experiment for the last few years in acoustic and made the above discoveries for myself...

A dedicated audio room is the ONLY one luxury in audio not the price tag of the gear at all...

Basic relatively good gear is enough to give a very good audiophile experience FOR MOST PEOPLE... Claiming the opposite is most of the times ignorance of acoustic....Reviewers sells gear not acoustic information...Then the customer is conditioned to upgrade the gear not to understand acoustic...

By the way i am only a not skilled, non crafty, ordinary dude, but dedicated in my passion : listening music with a good sound but at NO COST or very low one...

Is it possible? Yes i proved it to myself and my goal here is to point to the right direction for improvement and spare people their money...

I learned a bit of acoustic by listening experiments not by resolving equations...Anyway acoustic phenomenon are too complex in a small room with his multidimensional numerous parameters to be reducible to simple linear equations...It is mostly non linear phenomena...

Anyway the ears could beat computer on the qualities recognition... It is the reason why blind people develop bat skill and learn to see sound...

Human ears evolve million of years to recognize "timbre voices" not tested frequency and qualities in the sound source not reflective abstract waves for themselves...A map is not reality....

Acoustic has a taste, a color, a touch, and a life of his own so to speak in a poetical way... 😁😊😊😊

 

P.S. My system basic value is around 500 bucks but every part is well chosen and after 7 years i dont think to upgrade any part at all thanks to acoustic...

The photo in my virtual page by the way are too old and are in no way able to describe my actual room....

It is way nuttier and more silly now than some here said it was, trying to discredit my claims and discoveries...But my room is more a LABORATORY, not a living room and not the usual audio room, and "at no cost", none of my devices homemade and with improvised design are esthetical and suited to a normal living room... More skilled people than me must make their own device more beautiful and more efficient...

I say that my room is a laboratory because nobody teach me acoustic here and how to control a room...

-Passive treatment is NOT active mechanical control for example, they are COMPLEMENTARY but one cannot replace the other at all,

-square small room are not "bad" if we know how to adress them , ( there is no bad room only improved one, my room : 13 feet by 13 feet and 8 feet 1/2))

-and near listening will be affected by the room acoustic like regular listening position in a small room...( then thinking that near listening will make acoustic treatment and control unnecessary is wrong)

These 3 facts for example were personal discoveries contradicting popular claims in audio thread.......

And to give you an idea about my speakers/room relation NONE of my 7 headphones, hybrid, electrostatic or magneplanar or dynamic are interesting to listen to now , they are in my closet retired....

I begin my audiophile journey by buying headphones and modifying them with success hoping to reach the better...But Headphones are not for most of them satisfying on all acoustical count even when modified positively... I decided to try my luck with speakers...

After i have sold my stupendous Tannoy dual gold 12 inches speaker...I was lucky enough to buy the best speaker Mission ever designed for 50 bucks : Mission cyrus speakers 780 for sure they dont have the Tannoy potential but they are smaller and very good with acoustic control... Ratio quality/price more than good...But this is only relatively good basic gear, nothing to brag about...Acoustic is more important than the gear piece...

I learned for 2 years of acoustic homemade treatment and many months of experiments in acoustic control non stop... I am retired and time was no problem only money was... 😁😊

😁😀😊😁😊

I sell creativity not gear .....I sell a method not "tweaks"...

128x128mahgister

Helpful and comprehensive post. Thank you.

This is not my situation, but I wonder how you might answer this question.

"I have done a lot of analysis of my room using your parameters. However, I do not have a speaker, yet.

Since every speaker will interact differently with my room, how do I choose which speaker to get?

After all, knowing my room’s character can help narrow down which speakers might work, but it cannot tell me what they will sound like or if they will work, well.

This is due to the very complex nature of speaker-room interaction which you describe so well.

Once I have a speaker, then measuring and adjusting all the parameters you mention will be crucial for optimizing things. Yes! I agree with you.

But until I have chosen the speaker, I cannot do the optimization. Please help with that phase of the process."

Any thoughts?

P.S. This kind of question would also apply to an upgrade. If one does not yet know how the upgrade speaker will interact with the room, the same difficult problem presents itself. 

 

Thanks very good question hilde45...

How to choose speakers?

I owned 2 pair of speakers in my life that pleased me...( i dont count very small computer speakers i tried for my desk)

The Tannoy dual gold 12 inches which i owned for 40 years ( 2 sets paid 400 bucks in 1975 each set) and i sold them because they were too big for my desk,
which i regret to have sold 1000 bucks because they needed refurbishing at the times and they were too big for my desk..

7 years ago i have decided, owning no more a really working audio system, to concentrate on desk small speakers and headphones...

I bought 8 headphones of 4 different types and modified them mechanically and acoustically and electrically...With success...But compared to speakers i stay unsatisfied...

My audio journey begin like that...

I stay unsatisfied a long time and one day i decided after having sold my marvellous Tannoy dual gold, to go back to speakers again...I decided to go British for the speakers because of my past Tannoy good experience...

I read non stop all REVIEWS about all speakers type but mostly vintage affordable one...I bought a small Mission speakers for my computer desk which was so good i decided to read all there is about the best and top Mission model...

I stumble on the Mission cyrus 781, i read all reviews on them... I bought them 50 bucks... :)

These were the best model Mission ever designed and they were sold around 1000 bucks in 1989... Dont confuse them with the newer Mission 781 (same number) the Cyrus model with the same number is superior...

I was lucky to buy them at this price and they were able to work again after some long warming for months... :)

Now this was luck!

And the result of studying all positive and i discovered no negative reviews... It was like my Sansui AU 7700 there is not a single negative reviews of this amplifier on the net and i look for them for months...

This is my story...

Now to answer your question ...

How do i choose a pair of speakers?

I dont know and even Floyd Toole the great acoustician explain in this video WHY it is so difficult...

Listen to this video for some answer....

Now i will say something to you which is the fruit of my own experience and experiments in acoustic...

i am not an acoustician at all only a regular passionnate dude who wanted to create sonic heaven on earth at no cost...

My experience is that NO SPEAKERS will sound the same in a non treated and non controlled room, compared to a treated and well controlled room... NONE... There will be no comparison at all....Save for a better "timbre" experience potential... eWhen i listen my Mission the first time after owning a very good hibrid magneplanar system the Monsoon desk computer, i was not so sure that it was better on all counts with the Mission... But my room at this time was nude not treated and uncontrolled...

Then choose the speakers with your studying of reviews and ratio price /quality, and "touch some wood" for luck if you are not able to listen to them before buying like me...

I dont know any other means... The specifications marked by the company are not all the story there is to know.... Listen to Floyd Toole video....

And knowing what i know by EXPERIMENTS about SMALL room acoustic i know and it is the good news, how to adapt the room response to a particular speakers... I know it by a long trial and errors process not by equations solving or by a simple recipe....

Acoustic of small room CANNOT be adressed and taking care of ONLY by simple recipe and few panels like said some acoustic panels sellers for the sake of their business...For sure it is better than nothing...

But adapting the room to some specific demand of our own ears and for specific speakers is a long TRIAL incremental tuning process.... The bad news is this is a different process mechanically for each different room and different speakers... There is no simple recipe , we must make a long tuning process with hundred of listenings sessions in a DEDICATED room...But the result is so ASTOUNDING that almost no upgrade of gear will compare... It is huge to the point there is no relation between the sound of speakers BEFORE and AFTER room treatment and especially room control... Someone who did not live the process himself cannot know it and believe it...

Acoustic is the key to audio... Nothing else... For sure the two other embeddings dimensions controls must be adress, the noise floor level of the house, and the mechanical vibrations of the system also.... What i called the three working dimensions of control for any audio system... But the acoustic is by far the most important one...

Then how do i choose speakers?

I dont know save for reading reviews and listening to them to eliminate the worst speakers and with luck stumble on a good one... This is the bad news.... The good news is that we can manage acoustically any relatively good speakers and put them on another level completely, on their own unknown peak working potential level of S.Q. with acoustic treatment and mechanical acoustic control...

My method is new and because i am not an acoustician i devised it by a trial and errors process on few years... I can describe the general recipe but i cannot replace the necessary long listening tuning process which is necessary to adapt to specific ears specific room to specific speakers by a magic formula...

Another aspect was that i modefied my Mission Speakers for the best with succees mechanically, with my own method of vibrations control with two set of 4 strings boxes at low cost dissymetrically compressed under and above the speakers under a heavy load of concrete...

I even use my "golden plate" device to modify the speakers, decreasing some noise of the electronics or coming from the cables ( shungite plate +copper tape on the external face)

And i used Helmholtz resonators near the drivers and the tweeters of each speakers but with diffferent H.R. for each speakers to make a better response for each one of my ears and brain when it compute the room distance...

I used 23 tubes of different size and lenght for each speakers and in the porthole and above the speakers to modify the velocity shear flow around the speakers and completely improve the imaging and timbre...

All my room is already under control with more than 50 tubes of different size, absorbing and diffusing resonators, which i adjusted by listening mechanically for their aperture and lenght and volume...

I know it is not easy and simple process but it is not so difficult that it seems if someone dare to try trusting his own skill for learning and training our ears which is the most fun experience i ever lived through.... Cost : almost nothing....

Then i apologize for not answering simply to the question : how do i choose my speakers?

But if even Floyd Toole cannot answered it simply i could not too....
I have said the essential i know of...

 

 

 

The one line answer is:

There is no relation between the S.Q. of a relatively good speakers BEFORE and AFTER acoustic treatment and control...We must read about and listen if possible to some speakers, buy them and AFTER THAT adapt the room to them... There is no other way for me...

No speakers will work the same in some nude room, their response will depend of the room response linked to them also, will depend of the high level or not of the passive treatment and and especially of the mechanical control settings of the room adapted for them and your own specfic ears structure and skills...

Small room acoustic is a very new field and no so much well understood practically because each speakers, each acoustic content, geometry, and topology for each room is very different... Then putting some acoustic panels at the right spot like most did and bass traps will help but it is a long shot from what i called mechanical control equalization of the room with Helmholtz method...

I apologize for not giving a simple recipe and simple answer ...I can only point to the right direction... And it is more easy that it seems it ask for a dedicated room yes and for plenty of time...But nothing is more fun to do...

A dedicated room is really the only luxury in audio, those who boast about costly gear are ignorant of acoustic for me like reviewers selling gear and not acoustic information with it...

But no one can make big money with acoustic... Only with upgrading the gear...

All audio is consumerism conditioning more than science...

 

 

This video is informative and moving at some time...And you will understand why it is not simple to buy a good set of speakers...

 

@mahgister Thank you for the reply. It will take me some time to read it. I will also watch the video.

There is a chicken and egg problem in all of this, but it is likely solved by iterative and experimental testing. 

You are better than me to say things simply and economically...English is by far not my language, i never spoke it and never wrote it before coming here, only read it... i apologize for that...

My deepest respect to you...

Thanks for your simple resume :

There is a chicken and egg problem in all of this, but it is likely solved by iterative and experimental testing.

@mahgister Thank you for your always enlightening posts.  They have been very interesting and I have enjoyed trying some of your ideas and experimenting in my listening space with good success.  My space is contrary to your suggestion that you need a dedicated room.  I don’t have or want a dedicated room.  I use an open living room (24x16x10) working off a corner diagonal.  Surprisingly the room acoustics and absorption are quite good when doing sound tests.   My 2 channel stereo and TV are in a wood hutch with speakers on both sides which I have to live with to maintain my living arrangements.

What worked well for me was:

adding 6’ sound absorbing panel in the corner behind hutch 

built an ardent 5’ - 3 tube Argent room lens  to spec placed right behind the hutch

added 5 shumann generators with shungite and diamond to enhance throughout room

 Built 8 Helmholtz resonators from various sized wine/spirits bottles with straws, experimented with placements and was shocked the sound stage and 3d effect they added.  (Have to store in closet when not in listening mode ;-)

Overall, better bass, enhanced clarity and highs, fuller sound stage, more 3d...all in a good subtle way.  

Family makes fun of me saying I have a bottle problem!

Thanks for sharing your expertise its been a fun play!

 

In life the only precious moment , save the moment passed with those we love, is to be of some help to someone...

I cannot thank you enough for your generous post toward me...

Thanks

tksteingraber

 

...

Good video, I've seen it and read a lot of what Mr. Toole says. Erin's Audio Corner is also a good resource to find objective measurements for speakers.

Good post mahgister but no amount of room treatment or equalizing will make a poor speaker sound good. And a good speaker will still sound better than a lessor speaker. Now if are talking about optimizing what you have or your room, I'm on board with that.   

NOTHING will ever transform a bad pair of speakers in a good one...

This is common sense and pure scientific provable evidence for sure...

But optimizing a "relatively" already good speaker to the sky of his PEAK quality working potential is POSSIBLE...

This is my method and experience with my actual relatively good speakers, Mission Cyrus 781...Not top high end speakers only relatively good one...( my old Tannoy had more potential than my actual Mission)

But acoustic will work with any good speaker...

No speakers even 100,000 bucks one can beat their room and defeat it... NONE...

Almost all upgrades at any price will never compare to a treated and controlled room either if the basic gear which ask to be upgrade is already "relatively" good to begin with.... My actual Mission which are a less high quality speakers than my old Tannoy beat them anyway in my actual room even if they had less S.Q. potential...

Alas! i never listened to my Tannoy for the 40 years i own them in a treated and controlled room adapted for them...

Thanks for your post and my deepest respect to you...

Good post mahgister but no amount of room treatment or equalizing will make a poor speaker sound good. And a good speaker will still sound better than a lessor speaker. Now if are talking about optimizing what you have or your room, I’m on board with that.

This all makes sense.

Nothing can transform a bad pair of speakers into good ones.
A good pair of speakers can be made better -- taken to their peak.
A very good pair of speakers can be made better -- taken to their peak.
An excellent pair of speakers can be made better -- taken to their peak.

Therefore, the better speaker you have, the higher the ultimate peak.

There will be diminishing returns, after a point, but there will be significant improvement from good to better to excellent.
 

Exactly...

And anyway a better pair of speakers in a non treated room and non controlled one may sound worst than low cost well designed speakers in a room treated and controlled and adapted to them...

It is the reason why boasting about branded name gear means nothing, pass the point to say that we appreciate what we own for this and that reason, like i appreciate my Mission even if they are not the end of the world...

All my posts are about some low cost homemade devices , and a simple method in the three embeddings working dimensions control...Not about the "marvellous" Sansui i own, or my "astounding" dac or my past alleged "superior" Tannoy or actual basically good Mission Cyrus...

Same thing for "tweaks" i dont like boasting about branded name ready made tweaks, especially costly one, i prefer to replicate some idea at no cost behind their design... Like in control of mechanical vibrations with springs...

I dont trust at all people boasting too much about their gear NAME...So good it is because in audio anyway the key is acoustic...And acoustic is more difficult to be done right than anything else in audio...Save designing a new amplifier or dac etc...Which are things i could not do anyway... Then plugging branded name costly products in the wall and calling this Hi-Fi experience is meaningless for me...

Small room acoustic is not a well explored "continent" till now because of the small demand from potential and actual customers, whose numbers of those owning a dedicated audio room is very small...And those with the will and time wanting to experiment with the tuning process even smaller... There is no market for the most important key : acoustic of dedicated small room...

 

This all makes sense.

Nothing can transform a bad pair of speakers into good ones.
A good pair of speakers can be made better -- taken to their peak.
A very good pair of speakers can be made better -- taken to their peak.
An excellent pair of speakers can be made better -- taken to their peak.

Therefore, the better speaker you have, the higher the ultimate peak.

There will be diminishing returns, after a point, but there will be significant improvement from good to better to excellent.

Post removed 

For those who are interested by Helmholtz control method...

This article refer to experiments and is from 2019...

I just stumble onto it...

Perhaps my mechanical equalizer is not a fool’s dream... 😁😊

And perhaps when i claim that Acoustic is the key and not upgrading without end , perhaps i am right...

The limited number of reactions in this thread reveal the complete desinterest by most about the most essential audiophile key...

People prefer it seems to boast about branded name in gear...

😁😉😊

Anyway i hope to be useful .....

By the way in this article they experiment with CLOSED box Helmhotz resonators only...

My mechanical equalization used Helmholtz DIFFUSERS grid also, made with different OPEN tubes of different size with one of the aperture covered by some fabric cloth of different thickness to create a filtering of the frequencies and a better diffusion...

I even used many tubes inside a tube....Or many tubes witrh some fabric  filter at one end or others with many little tubes at one end...Or a single  string cord of many feet made with diffrent sizeof straws or little tubes with the diameter of a straw or more... Etc...

The impact is staggering...

A single straw is AUDIBLE.... Yes... A single straw impact may be audible in a treated and controlled room...

 

 

 

 

 

https://www.researchgate.net/publication/331326071_An_experimental_study_on_the_optimization_of_the_production_and_efficiency_of_tunable_Helmholtz_absorbers_for_the_modal_control_of_small_rooms

 

Do we know what is sound ?

Not completely it seems but we made progress...

 

Do we know what is fire?

think twice we dont know yet all there is about fire...No more than with sound...

 

https://www.sanatan.org/en/a/2729.html

Now do you think that we audiophile know how to manage acoustic of small room ?

Not at all.... It is just why i start this thread after discovering this fact myself...

For sure science know many things..

But between theory and applications there is a great divide...

I am not a scientist at all...

I only experimented and discover that "Helmholtz diffusers", produce great impactful tuning effect, i created the name because i read nowhere about their extensive possible useful impact in small room acoustic...

"Helmholtz resonators" are more well known but not extensively spoken about in audio thread not much in acoustic threads either... Panels sellers dont use them in general...

Helmholtz diffusers are another animal...A new one...

The tubes i used are open at the 2 ends , save one is covered with various cloth fabric for a better diffusive effect...They are of various size and the size is determined by listening experiments...For example i use a regular straw string extending horizontaly to 6 feet over my speakers ...

 

The effect of the Helmholtz method of mechanical equalization is STAGGERING...

People buy most of the times new gear because of their complete ignorance of acoustic...

 

 

I am the first person to ever dare to say that in all audio thread in this forceful and direct way...

 

😁😊😊😊😊😊😊😊😊

 

 

 

 

All of my room correction is mechanical. Angles on a ceiling portion and angles on a soffit.  No foam in use only real sheeps wool behind cloth covered stretcher bars and only 5 of these in this large room. I use 1 each of the threaded inverted Audiopoints coupling discs screwed into 3 of my sound panels. These brass devices are located and tensioned by ear so as to extend the stage down the side walls and  maintain focus  closer to my space. These work and sound best by tightening by hand and then just backing off a 1/4 turn.  I originally used more but it was like watching a laser show of connect the dots. This was exciting but I decided it was not real..so only 3 remain. These are all.about the conversion of shear waves to the compressive.

With my recent speaker rebuild I needed to augment the bass but the real suprise was how it augmened the vocals and further enhanced an already wall to wall soundstage. Since this finding I have built more of these simple devices an located them to enhance laminar flow in the room. Think of an increase in laminar flow as a reduction of interfering energy air molecules collide but there are ways to make them smoother.

If you have speakers and a rack and furniture then laminar flow is disturbed while listening. I forgot I have 3 Argent Room Lenses a laminar device on the floor behind my chair and an active mothership contol device 10 ft behind my chair. Pretty much my boundaries are gone.. Experiment.

Tom

.

Thanks Tom for this interesting post...And for all your ideas...

This will give impulse to some to experiment ....

My best to you....

For those who doubt that my Helmholtz tuning method with a grid of tubes can tune a room here, what i call "mechanical equalization", here are some simple basic observations to read from a MASTER book i just discovered 5 minutes ago ...

I cannot reproduce images of the text here, nor the equations correctly, but the text say it all and give some basic understanding about an important fact in my grid of tubes : The more absorbing tubes and the more diffusing one, or the open/closed tubes and the open/open tubes and the case in between these 2 types, with mutiples littltes tubes inside a bigger one, and also some tube with  a cloth fabric filtering device at one end and the other end open... These are the 4 types of tubes of various size at different locations i used in my "mechanical equalizer"...

 

 

«2.5.3 Sinusoidal wave excited by a velocity source in an acoustic
tube.

In the last subsection sound waves were shown to be excited by a sound pressure
source at the entrance x = 0 of an acoustic tube. Another type of exciting source is a
velocity source.
Fig. 2.16 shows an image of an acoustic tube with an open end at x = L, and a
sinusoidal velocity source at the entrance x = 0.


The boundary condition can be formulated such that
p(x,t)|x=L = 0 (Pa) and ∂p(x,t)∂x ����
x=0
= −iωρV eiωt, (Pa/m) (2.54)
where
v = V eiωt (m/s) and − ∂p
∂x
= ρ
∂v
∂t
= iωρv (Pa/m) (2.55)
hold [1][7][13] between the sound pressure (Pa) and the particle velocity v (m/s) for
sinusoidal plane waves, and ρ (kg/m3) denotes the volume density of the medium.
Assuming the general solution given by Eq. (2.43) once more, then the solution
must satisfy
Ae−ikL + BeikL = 0 (Pa) and Ak − Bk = ωρV (Pa/m) (2.56)
under the boundary condition specified by Eq. (2.54). Solving the simultaneous equation in Eq. (2.56) for A and B, then the general solution can be rewritten as
p(x,t) = iρcV
sink(L − x)
coskL
eiωt. (Pa) (2.57)
Comparing the solution given by Eq. (2.57) with that by Eq. (2.46) for the sound
pressure source, the poles of the solution for the velocity source are located at lower
frequencies:
cosknL = cos
ωn
c
L = 0 or ωn =
c
2L
(2n − 1)π. (2.58)
The fundamental (n = 1) is lower than that for the pressure source by 1/1−octave.
The pressure response to the velocity source is purely imaginary. In addition, the
poles are composed of odd harmonics without the even harmonics. The difference in
the poles between the pressure and velocity sources can be interpreted as the difference in the boundary conditions for the acoustic tubeFig. 2.17 displays the two types of boundary conditions for acoustic tubes: openopen and open-closed end conditions [17]. The open-open tube represents the case
for the pressure source that makes the condensation or dilation of the medium at the
entrance. Assuming the impulsive condensation at the left end, then the pulse-like
positive pressure travels inside the tube. The pulse-like pressure wave is reflected at
the right end (open end) by the negative magnitude. The return of the negative pressure wave to the left end changes the sign of the pressure to positive, which goes
toward the right end. The periodic traveling yields the fundamental frequency.
In contrast, the propagation wave from a velocity source can be interpreted as
the traveling waves in an acoustic tube under the open-end boundary conditions, as
shown in the right panel of Fig. 2.17. Velocity excitation might be made by piston
motion of a “plate” at one end of the tube. As happens in the open-open tube, the reflected pressure wave with the negative sign comes back to the source end. However,2.5

Acoustic tubes with open-open and open-closed ends, where pulse-like waves propagate
between the two ends; from Figs. 4.1 and 4.5 [17].
no sign change occurs at the end because the end is closed by the piston plate, which
reflects the wave without a sign change. This traveling of the pulse-like wave is periodic; however, the period is two times longer than that for the open-open tube. The
longer period makes the fundamental lower by 1/1− octave than that for open-open
tube [17].
The two types of boundary conditions may represent the conceptual models for
a flute by the open-open condition, and a clarinet by the closed-open condition. The
difference of the boundary conditions might explain the difference in the fundamental
frequencies with their harmonics. However, the boundary condition for a clarinet
might be mixed rather than purely open-closed [5]. The harmonics can be composed
of even and odd harmonics even for a clarinet.»

 

Acoustic Signals and hearing by Mikio Tohyama 2020

 

Apart from classical passive acoustic treatment which seek to optimize the balance between absorbing and reflective surfaces and diffusive one,

Apart from the mechanical equalization of the room by modification of the pressures zone distribution and modification of the shear velocity of the waves in some location with different Helmholtz open/closed/filtered tubes which act as resonators and diffusers...

The most important addition to my room were the low cost grid of Schumann resonators modified and tuned with copper/shungite+quartz ....

But way less known and underestimated is the ionization effect on the room acoutiscal properties...

I used three type of ionizer, 2 low cost chinese ionizer for cars but that work well after a year of non stop use in my small room, a more costly one of french design which is the most powerful i put between my speakers and near listening position, and 3 himalayan salt lamp which are the less powerful device for sure but anyway work for me under my desk with a glowing orange light that create anyway  also by his beauty a placebo effect ....The effect of all these ionization is very audible and easy to verify when you shut them on or off...

 

But Ionization is the LAST so call "tweak" to add to a room...

It is the ice on the cake with the cherres in room installation ....

If you put it first BEFORE passive material acoustic treatment and with no mechanical control over the room the odds are you will be in the camp of those objectivist who mock any audible sound effect not measured yet because you will not hear it in a bad room... An effect which is audible but stay subtle is no less spectacular than a more evident effect like improving timbre or dynamic or bass ....The cherries distributed on a chocolate cake change the taste of the cake even a few cherries will do....

Then beware...

Acoustic embedding control has a list of priorities:

--Passive material treatment...

--Mechanical control after Helmhotz....

--Schuman generators...

--Ionization of the room....

Perhaps the title of my thread would have better been named : gear fetichism and consumerism conditioning over acoustical method and some other embeddings controls...

But the subject matter is so vast and complex anyway and acoustic and psycho-acoustic are the more underestimated matter in audio and at the same time the most important matter...

Only consumer conditioning and gear fetichism conditioned ignorance explain why the essential of hearing and listening experience is considered secondary to the gear choice and "taste"....

It is the audiophile paradox: Sound is associated with the name of a favorite brand over acoustic knowledge...

RCA victor dog entered DEEP  in our subconcious understanding... The dog listened music or his master voice  from the pavillion of a turntable or gramophone WITHOUT ANY ROOM between his ears and the gear...

Think about it....

 

CAN WE HEAR THE SHAPE or SEE THE SOUND  OF A DRUM ?

 

The mathematician Marc Kac treated mathematically all aspects of the relation between the form of a drum geometrically and topologically and the "sound" or waves patterns emergence...

But can we hear the sound of a room and his acoustical content ?

For sure i cannot treat this problem, but the analogy is striking me....

I use this analogy to illustrate the way we can "see" the sound and the way in which sound waves waited to be seen so to speak...

 

 

But perhaps why it is possible to see sound and hear shape in some way to some degree  is explained by one of the most important thinker in mathematic and physic nowadays Alain Connes...

His last discovery is to interpret the zero of the dzeta function to be spectre not of some frequencies in some dynamical unknown  space but to be  an expression of the spectre of time itself... His demonstratiion use the distribution of primes musically to metaphorically make us understand time evolution to be fundamental...

i am not qualified for sure to decide that he is a genius and his idea is true.... But.... My intuition say so... Think by yourselves....

 

 

You know then that phosphenic images in closed eyes and geometric hallucination by drugs and circle of whirling dancing dervishes or shaman are related... Congratulations! 😁😊

I burned some herb once.....okay, maybe more than once!

 

«My body is at the same times the clay tablet and the calame» -Anonymus  yogi

Just thinking about sound and how it behaves has been a lifelong fascination to me. Even today as I walk in the morning, sound is part of the observation.

 Unfortunately, most of civilization is polluted to me in this way. It is better to walk in the desert.

Mahgister, curious about the amount of time you have invested in solving these many room issues. I am not discounting your effort only curious if there exists some quick and easy steps. Thanks in advance. g

Thanks for your interest....

My goal in my posts and in this thread is to alert people who most of the times underestimated it about the huge impact of acoustic treatment but ESPECIALLY of acoustic mechanical control...

Alas! i dont sell acoustic panels here with a "general rule" to apply about their location...It is not so simple ...

It is more difficult...

Nobody teach me that, i am the only one i know to use the Helmhotz resonators and the Helmhiltz diffusers in a grid of devices mechanically adjustable each one of them... Their location is also a key element...

The tuning process cannot be applied AUTOMATICVALLY by a simple rule but i had to do it one piece at a time, optimizing each step by another step in a continuous listening process...

It takes me many months, it was fun, but not a simple act...

My goal here is speaking about the importance of acoustic, versus throwing our money in an upgrading sound obsession... The impact of tuning a room for specific speakers and specific ears is huge, more impactful than most useless upgrade... An upgrade of gear will not change the room...

And like already say an acoustician: no speaker beat their room....

There exist some quick and easy steps yes... Elementary acoustic passive treatment if you dont own a dedicated room, but if you are lucky enough to have a dedicated room, it is easy to create simple Helmholtz resonators and diffusers with discarded bottles, tubes etc using different straws with different lenght and diameter for neck in the case of resonators and different open tubes with different filtering devices at one end for the diffusers...

But tuning all that is not quick , it is not plug and play, you must listen and learn how to listen in the process... It was the more fun experience ever in my audio journey... Upgrading may be very deceitful, tuning a room is not, you are the designer yourself here...

Apart from my acoustic devices creation i make some discovery i will attempt to explain here soon about the psycho-acoustic geography of my room, or how i created my out of the head "headphone" intimate effect or listener envelopment/source width ratio (LEV/ASW in acoustic ) using one speaker like the "head" and the other speaker like the " tail" of my Helhmholtz grid " serpent" around the room ...

By the way i am not an acoustician, all my discoveries came from  listening experiments and from  a few basic known or well less known fact in acoustic science...

It is then difficult to explain it all for me in scientific way here... NO ROOM/ SPEAKERS relation is the same...The tuning process must be completely specific...

For example the way i modified my speakers each one of them is related to some way  i decided to experiment and  used mechanically some acoustic crosstalk and some acoustic crossfeed between the speakers tp suit optimally each one of my two  ears and make possible image acoustic source localization ...It is called  the precedence law or Hass principle in acoustic and also i use time modifying  control and level  modifying control in each speaker to do all that...

Being not an acoustician nor an engineer i must study AFTER the fact and AFTER my experiments WHY they are so successful...It is not easy to explain it all after all nobody ever explain it to me in the first place...  😁😊

i try my best here to convey the essential ...

But if someone is not excited by listening experiments it is useless...

I played with acoustic not knowing acoustic and i discovered the great power of acoustic principle while playing with them in a way not explained in most audio thread... People are used to buy, plug and play, or are willing to pay for costly acoustic devices... I never did that... Acoustic can be cheap cost if we know what we do or if we dare to experiment...

Most people really think that the cost paid for their gear give them the best possible experience... Most of the times even if there is for sure a possible improvement between 2 electronic designs choices on a quality/price  scale, the real huge improvement come AFTER acoustic tuning of the room /system... This is my discovery...

 

My deepest respect to you....

Mahgister, curious about the amount of time you have invested in solving these many room issues. I am not discounting your effort only curious if there exists some quick and easy steps. Thanks in advance. g

 

Thank you for the thoughtful response. Unfortunately today I don’t have the ability to dedicate a great deal of time to optimization of the room- but certainly appreciate the need to do so. Simple moves of equipment have yielded astounding results. But my space, while mine alone, is long and narrow. The footprint for equipment is pretty small. Again, my complete thanks and admiration. g

One remark...

Contrary to some saying, there is no so much  BAD rooms by their size and geometry...

There is only some room easy and other less easy to optimize...Most of the times.... Save some impossible room to optimize because of weird proportions...

Helmholtz resonators and diffusers exist precisely to modify the pressure zones distribution of the room...

For sure i am retired then i had plenty of time.... I did it each day for almost a year why?

Because each week it was better than the week before... It motivated me a lot...like someone upgrading his gear each week... It was fun... Not esthetical because i am not a crafty man  for sure but it was efficient...

Then your room will be perfect... After implementation of the mechanical control to tune them for your ears and system...

Now you know it, then  you will do it when the time come, i hope before your late retirement like in my case...i am 71 years old...

😁😊

 

My best to you from my heart....

Thank you for the thoughtful response. Unfortunately today I don’t have the ability to dedicate a great deal of time to optimization of the room- but certainly appreciate the need to do so. Simple moves of equipment have yielded astounding results. But my space, while mine alone, is long and narrow. The footprint for equipment is pretty small. Again, my complete thanks and admiration. g

 

 

One of the best listening experiences I had was in a large room without room treatments.  The size of that room and the fact he was using apogee diva speakers set up properly had a lot to do with the great sound, would have been better with room treatments who knows. Most of us don't have rooms large enough so we need room treatments to help get the best of the system.

You are right for sure...

But i think that because room treatment homemade and especially homemade room mechanical control is "ugly", in my case for sure, nobody with good looking gear in a living room will ever experiment the way i did for sure... 😁😊

They will think for ever that the sound they enjoy is very good , and it is good sound for sure, but not OPTIMIZED at the level it could be in a mechanically controlled room...

I know now that most people has never listened to their working gear at his utmost peak potential , this is one of the reason for half of the useless upgrades search...

We cannot replace acoustical method with a new "better" speakers at a higher price in an acoustically "empty" untreated room... Even if the new upgrading speakers are better in design in some case, compared to an old one which can compete with them BUT ONLY in a completely controlled and treated room dressed for them and for our own ears... This is my point...

My actual smaller Mission Cyrus 781 were a less high-end product than my past Tannoy dual Gold Concentric for sure, but guess which one has the better sound ever?

The less originally designed Mission at a lower cost  than the Tannoy yes, win  BUT  in a better controlled room...In an empty untreated  room they lost...

If it was not the case i will kill myself with remorse because i sold my two pairs of Tannoy ...I had no more the necessary space on my desk... 😁😊

I am not frustrated at all with the Mission Cyrus which are a notch under the Tannoy potential quality nevertheless ...

Thanks to acoustic science !

One of the best listening experiences I had was in a large room without room treatments. The size of that room and the fact he was using apogee diva speakers set up properly had a lot to do with the great sound, would have been better with room treatments who knows. Most of us don’t have rooms large enough so we need room treatments to help get the best of the system.