+1 Sy,
that's what i want to say when i wrote about the fall of the enclosure frequency near a notch in the band or in a notch of the bass crossover (or Fs). But don't understand the role of the subharmonics upper frequency maid by an enclosure. But they beam with less energy... My understanding is it's good to damping cabinets... even if some manufacters maid them with thin wood to play with that !
that's what i want to say when i wrote about the fall of the enclosure frequency near a notch in the band or in a notch of the bass crossover (or Fs). But don't understand the role of the subharmonics upper frequency maid by an enclosure. But they beam with less energy... My understanding is it's good to damping cabinets... even if some manufacters maid them with thin wood to play with that !
Eldam said:
SY said:
Indeed. Which is exactly what I have and what I used as I went. However I have no record of the results as I went as I never imagined I would need to keep results so I could prove the sand "burned-in", assuming you could even measure what you think, or dont think, you perceive ( hehehe ). Even if I had results in graphs i dont think some people would believe it anyway.
The output of a MEMS accelerometer using a op-amp to headphones was good and not hard or expensive to do as SY mentions. I made a wideband seismometer a year or so ago and so I had experience in detecting very tiny wideband vibrations. While I was testing the speaker I had a "Oh wait I know" moment and went and whipped it up one night. Its freaky listening to a cabinet. Really weird effect. YES the sand did seriously dampen the cabinet. Could i have detected it "burning-in" ? I donno about that. I would also need some sort of freq sweep I suppose, very careful recording of the data, and would need to be very careful to replicate the results. Also I was thinking doing 2 of them and setting it up as stereo on the headphones would be really really useful.
Im not willing to go thru all the effort of pulling the sand out, and setting up this science test. I am confident in what i heard and I am fairly confident i know why I heard it, despite many here saying i cant possibly hear it and that I should don a tin foil hat and believe in big foot.
BTW. I can handle any amount of forum abuse and not care and have excellent retorts BUT im just not willing to debate these subjects because its like debating religion. My arguments, no matter how well based in facts or cited with scientific links, will not result in anyone changing their minds. Cognitive bias and the dunning-kruger effect will rule the day in the end and it will all be pointless and a waste of time.
I think the below statement sums up this whole thread, accurately for both sides of this debate, and we *could* be done with it.
Yes Fonebones, I thought you were refering to my knocking on the cabinets with the sand. Yes I can see your point. But yes, despite my "miss knocking" the dampening material did also make a impressive difference. Not like the sand did, but I think it all combined nicely. Maybe the sand kinda pressed into the pliable surface of the Sonic Barrier Vinyl and that took a few days and that was what happened ? hahahaha....
Well im gonna go order some caps for making a analog power supply for my Oppo rather then debate this. If you guys are so passionate about this you should replicate this, use some mems accelerometers with some sweeps and see if there is a difference and post the resulting charts. Thats way more effort then I wanna do, hehehehe.. I got what i wanted.. My speakers sound great.. And they continue to burn-in, hahahahaha....
If you decide to do this I would specifically listen to the noise, not just the fundamental levels. Maybe measure distortion off the MEMS pickup from the cabinet. I would imagine you could hear all the harmonics of all the various lenghts of each bit of the cabinet. The spectrum of the noise would be interesting. Then moving the sensors around would be interesting as well. It is all really interesting, but I have other things i would rather do ATM.
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Setting aside the question of how accurate our hearing may be, let's consider what happens to the sand and its properties before and after "settling". Before a material settles there is room for it to move, it is not "locked" in place. Materials stop settling after they have compacted and run out of space for the individual particles to move. So, how might that affect a speaker panel?
I suppose a material with room to move about is not as rigid as one which has completed settling. It would exhibit frictional loss (damping) when particles rub together. After settling rigidity would be higher and frictional damping less of a factor. The material would be denser, although the difference might be very small.
Speaker panels react to sound waves by vibrating, and individual panels can have a large radiating area. Panels would not vibrate identically across the frequency spectrum, and panel resonances certainly can be audible. Adding mass, rigidity, and damping are all methods used to attempt to minimize or at least make panel resonances less obtrusive. Adding mass would tend to move panel resonance lower in frequency, and the added mass requires more energy to induce movement. Adding rigidity moves resonances up in frequency. Most music has less energy at higher frequencies, so there is less acoustic energy available to excite a higher resonance frequency. Adding damping makes resonances decay quicker. A panel filled with loose sand could very well have different resonant properties than one with tightly packed sand. After compaction, the speaker panel would be in its most massive and rigid state. It would also have the least damping, but if it is too heavy and rigid to set in motion easily that might not be a problem.
I suppose a material with room to move about is not as rigid as one which has completed settling. It would exhibit frictional loss (damping) when particles rub together. After settling rigidity would be higher and frictional damping less of a factor. The material would be denser, although the difference might be very small.
Speaker panels react to sound waves by vibrating, and individual panels can have a large radiating area. Panels would not vibrate identically across the frequency spectrum, and panel resonances certainly can be audible. Adding mass, rigidity, and damping are all methods used to attempt to minimize or at least make panel resonances less obtrusive. Adding mass would tend to move panel resonance lower in frequency, and the added mass requires more energy to induce movement. Adding rigidity moves resonances up in frequency. Most music has less energy at higher frequencies, so there is less acoustic energy available to excite a higher resonance frequency. Adding damping makes resonances decay quicker. A panel filled with loose sand could very well have different resonant properties than one with tightly packed sand. After compaction, the speaker panel would be in its most massive and rigid state. It would also have the least damping, but if it is too heavy and rigid to set in motion easily that might not be a problem.
More OT stuff removed. Repeated warnings make work for me. I do not like work. The next person who makes me waste keystrokes goes for a two week vacation in read-only mode .
Indeed, it seems to be a brilliant Idea to to keep the cabinet as silent as possible. However one will do that. Sand/bracing/whatever.
Yes of course: Sand will settle.
As always i can't remember the source but i seem to remember that in old days some people put vibrating plates under their cabinets when they filled their sandwich constructions with sand.
On the net one can find this Study "Technical University of Denmark (DTU) -Acoustic Technology Sound Radiation from a Loudspeaker Cabinet using the Boundary Element Method"
In this case the cabinet was not damped with sand but there are many ways to go to Rome.
http://orbit.dtu.dk/ws/files/51952164/Sound_Radiation.pdf
I hope I'm allowed to copy a small part of the studys conclusion here without being eaten for lunch. My sister me will be unhappy. Hm.. I'm not sure about that.
"The study revealed that just after a short period of time, the sound radiated by the cabinet is dominating in the decay of the loudspeaker’s sound. Despite that the SPL generated by the unit is much higher than that of the cabinet in a steady-state situation (i.e. when reproducing a stationary signal, such as broadband noise), as soon as the signal ceases, the sound pressure of the unit drops, while the cabinet keeps “ringing” for a longer time. At the natural frequencies of the cabinet, its SPL was found to be much greater than the unit’s during most of the decay process. Also in the time domain, the influence of the cabinet is more severe in the back than in the front. "
And yes, I'm very sceptical if one can make conclusions on sound without proper A/B testing.
As Symox I'm not the one for scientific studys. I'm an ordinary DIYer and there are so many other things to do so i leave that to scientists and OTOH i don't like sand so much because of its weight. I'm just in the process to think about my next and last speakers and it might be uncomfortable to ask the nurses to move them.
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I notice you are from Arizona, normally quite dry. Just heard from a a guy in Arizona that the "terrible time" has occurred, when his outdoor swimming pool has finally dropped below 80 degrees and is too chilly to be comfortable.
I live in New Mexico, average relative humidity where I live is normally in the 25 range, recent rains and flooding brought humidity up to over 55%.
All my still doors stick now, but less since RH has dropped to 39%.
Relative humidity (and temperature) will affect the resonant frequency of paper cones, their stiffness, the rigidity of MDF, and the damping properties of sand.
Temperature and humidity also have an affect on high frequency air attenuation, independent of the frequency response changes due to RH physical affects on the transducers and cabinet.
Barometric pressure affects soft tissue parts, and probably our hearing mechanism to some extent.
If your hearing is particularly acute (and attuned) you may have heard the effects of weather changes and HF air transmission on your cabinets during the days following the addition of the sand, as well as the effect of the sand settling in.
Having made the change of adding sand, then hearing further change, it would be easy to conclude that the sand was changing, when there are many other environmental changes that could account for the differences you heard.
Having measured the same cabinet response outdoors under different environmental conditions, I can attest to measurable changes.
At any rate, if you look at the past RH, barometric pressure and temperature record for your area, if you find it changed over the course of the days when the cabinet's response changed you will perhaps come to a different conclusion as to what caused the change.
Art
Hi Cal,
...or material for semi-conductor or ...windows !
Windows in a room are awfull for high frequency reflection but are a gift of god(s) for bass : they absorb it when the surface of the windows are large enough. Better thazn everything even bass trap... but you have to play with high frequency reflexion.
We maid research here about the air and sound reproduction : negative ion, positive ion, near the sea, at the mountain, dryness of the air, etc...
Bijojo here maid a bidule (=gadget) called the Ionostat to play with the caharge of the ions = more space, blabla, blabla . But if you have a poor system...I think it was a psycholigacal bidule. We can hear it, that's not the problem even if it's psychological...after all, God(s) bless America I'm listening the last Iggy Pop... I can hear him...believe me !
Idem with sand 40 years ago with Onken with sandwich enclosures in Japan, US, France, GB,...
I think this the place to talk about that. For example ;know that fhz with speakers in rooms around 120 to 150 are problematics with most of the room mod. Some designers do their crossover cut here,some try to paD ofF the resonanceS to approach that, and so on. Let's talk about sand but too enlarge the theory to understand if the first assertion is good or not (burn in). Maybe yes, maybe not, maybe a mix : something happen + psychological happen... and truly heard a difference. (nobodies here have a problem with this honest testimonie).
Sand, air,...known facts...but a question of priority : where I place sand in my priority to make a sound system. But I think it's very interesting to talk about that...again. Maybe the hope of an another section for Theory & research (like a hobby we are not at AES... but very impressed by the level of the people here !).
About plans under speakers : they have to isolate the wood surface for no vibration or you have a 4 ways : a super bass speaker under your feets. But in same time : the mechanical ref of the speaper has to be stable for te bass (I think medium has more relation with the cabinet himself and if we can go with one cabinet by driver ! ); maybe the spikes have to be in opposite position : the spike under the cabinet and not to the floor ????... Difficult for commercil sells !
Interesting thread, have to prioritize, but a question like an other !
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Interesting thread. I love it when it gets all existential.
I've never understood the psychoacoustics approach with regards to burn in though. While I would never debate my ear's abilities to deceive me or my brain's ability to deceive my ears, I don't think this is in any way a direct contradiction to the idea of burn in.
To say that my mind can fool my ears is in no way to say that burn in does not occur. Just because the world isn't flat doesn't prove that it revolves around the sun. Same field of study? Sure. Both true? Sure. But one does not directly lead to the other.
I've never understood the psychoacoustics approach with regards to burn in though. While I would never debate my ear's abilities to deceive me or my brain's ability to deceive my ears, I don't think this is in any way a direct contradiction to the idea of burn in.
To say that my mind can fool my ears is in no way to say that burn in does not occur. Just because the world isn't flat doesn't prove that it revolves around the sun. Same field of study? Sure. Both true? Sure. But one does not directly lead to the other.
Oh wow... Deleted posts.. Damn it, I hate when i miss things.. Well to whomever posted, I still love you , even if you went off on me or there was some rage I missed
All good posts..
My fav is
So what i need to do to get the best sound is to BURN-IN my speaker... With that in mind, it was clear what i needed to do...
Speaker BURN-IN - YouTube
Sand is a very weird material. Its surface is extremely irregular and random with a lot of sharp edges. I would venture to say that as sand settled it might become better at dissipating/absorbing energy as each piece would be touching each other piece, but not in a flat manner so it would dissipate energy any less.. What we need here is a super computer simulation. Thats really the only way to start to model this.. Even then knowing the surface of the sand is gonna be key.
Or of course we could just listen and be done with it for each person.
I also have another thought.. Does it even matter if it does burn in ? Is this part of a manufacturing process ? Is it something we need to take into account ? I mean truly - WHO CARES... Its just idle fodder really...
, even if you went off on me or there was some rage I missed All good posts..
My fav is
So what i need to do to get the best sound is to BURN-IN my speaker... With that in mind, it was clear what i needed to do...
Speaker BURN-IN - YouTube
Sand is a very weird material. Its surface is extremely irregular and random with a lot of sharp edges. I would venture to say that as sand settled it might become better at dissipating/absorbing energy as each piece would be touching each other piece, but not in a flat manner so it would dissipate energy any less.. What we need here is a super computer simulation. Thats really the only way to start to model this.. Even then knowing the surface of the sand is gonna be key.
Or of course we could just listen and be done with it for each person.
I also have another thought.. Does it even matter if it does burn in ? Is this part of a manufacturing process ? Is it something we need to take into account ? I mean truly - WHO CARES... Its just idle fodder really...
Or you could put some sand between the walls, stick on a couple of accelerometers, and get some actual data. Crazy notion, I know.
hI xYMOX1
I will be interested if you have measured with a micro at listening position before and after to "see" the hearing difference.
The problem with the measures : difficult interoretation...what did tou hear : the effect on the fifth harmonics, the notch that is good by chance in this room, the first harmonic DB reduction from the cabinet ?
Where did you put the sand ? In an another cavity,the first near the floor? In the bass cabinet ? Enough to change Volume and Q factor ? How much pounds,kilo, noix de coco unit ?
We know a fact (don't no how to say that in english) : mass/spring for sound energy absortion like bass trap : a plan with move and behind wool material to kill sound energy into heat (just a though).
Maybe the enclosure is the mass and the sand is the spring.
I always liked the idea of physical correction because look like profesionnal recording studio.
Have a look at my high/mid trap... it's a chair with polystyren little balls (very relaxing for music to)... I never had micro to measure with it oe without in a room ! But I would !
Imagine now the same bag chair with sand or a mix of "plein de choses" : wool, etc ! With five of it in a room.... ! Sand is easy to move and almost to remove. Imagine some of these "beautiful bags" near the wall behind the speakers near the behind and side wall ?!
Measures of cabinet and listener position would be a first step, maybe not enough. Maybe some french here can looking for at "La revue de l'Audiophile" if there were some experiments Or AES ?
I will be interested if you have measured with a micro at listening position before and after to "see" the hearing difference.
The problem with the measures : difficult interoretation...what did tou hear : the effect on the fifth harmonics, the notch that is good by chance in this room, the first harmonic DB reduction from the cabinet ?
Where did you put the sand ? In an another cavity,the first near the floor? In the bass cabinet ? Enough to change Volume and Q factor ? How much pounds,kilo, noix de coco unit ?
We know a fact (don't no how to say that in english) : mass/spring for sound energy absortion like bass trap : a plan with move and behind wool material to kill sound energy into heat (just a though).
Maybe the enclosure is the mass and the sand is the spring.
I always liked the idea of physical correction because look like profesionnal recording studio.
Have a look at my high/mid trap... it's a chair with polystyren little balls (very relaxing for music to)... I never had micro to measure with it oe without in a room ! But I would !
Imagine now the same bag chair with sand or a mix of "plein de choses" : wool, etc ! With five of it in a room.... ! Sand is easy to move and almost to remove. Imagine some of these "beautiful bags" near the wall behind the speakers near the behind and side wall ?!
Measures of cabinet and listener position would be a first step, maybe not enough. Maybe some french here can looking for at "La revue de l'Audiophile" if there were some experiments Or AES ?
Attachments
If you are not able to show that burn in happens scientifically using the knowledge and resources of your field, then it is simply an idea. It's at that point only a concept which you have created to explain some phenomenon. The difference here is that the vast majority of audiophiles will tell you a reason as to why burn in occurs. It's usually based on something scientific. When it cannot be proven or measured and yet they still use science to create products which have said burn in characteristics, you quickly realize something is amiss.
This biggest problem here is this: audio electronics are not special. Nothing about a speaker cable's copper's electrons are more unique than the electrons in copper wire in some other piece of electronic equipment. It is impossible to argue this since fundamental physics is founded on it. If burn in occurs, then how is there zero evidence of it occuring in any other field of electronics? For example, why is it that speaker cables and amplifiers can burn in, but powercord plugs do not? The cable, sure. The plug, no. CD players do not burn in. DACs do not burn in. Speaker internal wiring does not burn in. The wires inside your projector don't burn in. All of this stuff is made of the exact same material, so it should at least be replicable everywhere the same materials and signals are present. Yet, it's only noticed in some places. The question I ask then is simply why?
But this thread is about sand in loudspeaker cabinets. Why are you insisting on dragging it off topic? This will make work for the moderators and I'm not the only one who doesn't like work.
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