Speaker Cabinet Vibration and Measurements

Cabinets vibration can be measured.

MLSSA is the analyser that interprets the measurements. The are many other softwares that you can use. The actual tool used to measure vibration is known as interferometer. You can also use accelerometer.

One published measurements brought to my attention by a member here shows that the best resonance damping method is..Drum Roll Please...the el cheapo blu-tack placed between speaker stand and speakers. Not spikes or cones.

These measurements were actual vibration of the cabinets on different stands and cones, spikes or blu-tak.

It makes no claim as to audible difference but drew conclusion by conjectures why it can be so.

Despite having the tools at their disposal, why no measurement were taken to measure the actual freq. response speaks for themselves about the effect of stands and expensive cones.

Before changing a stand, make sure it is non resonant and adjust the height.

All other theories are pure snake oil.

The most relevant formula to understand how acoustic waves get transferred to another medium is based on acoustic impedance.

Not meant to offend others but we must put stop to bull shitting. It doesn't help people to enjoy music.

musicmusic wrote:


Despite having the tools at their disposal, why no measurement were taken to measure the actual freq. response speaks for themselves about the effect of stands and expensive cones.

Before changing a stand, make sure it is non resonant and adjust the height.

All other theories are pure snake oil.

For the benefit of other viewers reading this ... there is a serious need to correct the gross ignorance and ineptitude put forth by the starter of this thread.

http://www.stereophile.com/features/806/index.html


I dunno about the rest of you guys ... but i'd certainly have a healthy dose of faith and trust in John Atkinson's articles. He is, after all, the resident lab-freak and measurement tester expert for Stereophile Magazine for the longest number of years.

Oh and BTW, there is a clear and positive reference to (more drum roll please...) "Blu-Tack" in page-4 of the aforesaid article.



as quoted in the article:

What can the caring audiophile draw from these results? Certainly, I think I've illustrated that the speaker stand and the interface between the stand and the speaker influence the behavior of the loudspeaker's cabinet walls. As a rule of thumb, if you want to suppress cabinet resonances the least, you should support your speaker on upward-pointing spikes or cones. If you want to suppress resonances the most, you should use thin pads of Blu-Tack about the size of a nickel. If you want to arbitrarily boost some modes and suppress others, you should use some sort of reactive interface, of which there are a myriad. These results also imply that the choice of the stand itself will have a major influence on cabinet vibration, an effect independent of that of the interface.

musicmusic wrote:
The most relevant formula to understand how acoustic waves get transferred to another medium is based on acoustic impedance.

Not meant to offend others but we must put stop to bull shitting. It doesn't help people to enjoy music.

On the interesting subject of bullshits:

Well, lets see who's really bullsh!tting who now?
There are 3 kinds of bullsh!t.

Type "A" bullshit is the type some people try to give & pass on to other people. aka "The bullshitter".

Type "B" bullshit is the type some people GET or receive from the bullshitter. aka "the guy who kena con liao".

Type "C" bullshit is the kind of bullshit that some people (whether inadvertently or not) happen to profess junk and just end up bullshitting themselves only. Sort of a self-denying and self-deceiving kind of way. This one is definitely the most insidious kind. And the victim is none other than the starter of such bullshits by simply labeling this and that as snake oil, cacing etc....

Yes!!! My bait worked. Who said "this will be the last reply to musicmusic"?

Never mind, it is good to have someone with technical knowledge to debate with even though seemed a bit thick skinned to go back on his words.

Before jumping up and down and misquoting, read the entire 6 pages and the chart.

Don't read half way and give selected quote and shout like measuring PF of the wall of the main supply. I got scolding from TNB for nothing. Thanks to a smart aleck.

The cones were pointed upward so that they can measure the actual measurement of the cabinet without stand interference.

Nobody is interested in Jon Atkinson's interpretation. It is akin to one smart aleck's interpretation of impedance matching with the reflection coefficient formula to explain transfer of vibration between stands and speakers.

To know more about Jon Atkinson, you should ask him about his silence to Arthur Salvatore allegation.

Do you agree MLSSA is a software and got nothing to do with measuring vibration? What so specific of MLSSA analyser to measure speaker vibration?

And again how to measure PF of the wall main supply? Can or cannot? Why pass an opportunity to put down another BS?

In conclusion, A+B+C= Bull Shit

Since this is a new thread.... the game's afoot, and it is hereby put forth that musicmusic here has NOT one ounce of valid technical knowledge nor experience whatsoever in the realm of hi-fi, audio reproduction or any related field whatsoever. Of course, if he can so well as to exonerate himself in manner, it would be most welcome.
... but it's highly doubtful.

btw, who did u ask in TNB ? The guy in charge of placing the road cones on the street? ... My best guess is that birds of the same feather flock together. Let alone seeking advice from the road-cone guy.


To musicmusic:
Lets take a little wager shall we? ... if i can prove that "PF" CAN indeed be measured. What do you have to put into the ante ? C'mon, now's not the time to be a chicken here.


But actually, in your specific and particular case (and only to musicmusic alone) ... here's how u can measure PF. Take a metal prong, stick it into the wall socket, turn on the switch and "feel" the power factor. Remember to repeat the steps for all 3 openings in the wall socket. Guaranteed that one of them will give you the "best feeling" PF. Kid you not. Maybe you can post the findings here once you're tried it out yourself. Of if you didnt manage to "feel" any of the Power-Factor there .. ok, you win. No further objections from me. Deal ?

So far, you have not shown any ONE single ounce of valid technical fact on just about ANYTHING....

But thats not surprising, if you follow the ramblings of your Arthur Salvatore.... is that the one "who's out of business since 2001" ? Congratulations to musicmusic and the references he chooses.

mugenfoo wrote:
But actually, in your specific and particular case (and only to musicmusic alone) ... here's how u can measure PF. Take a metal prong, stick it into the wall socket, turn on the switch and "feel" the power factor. Remember to repeat the steps for all 3 openings in the wall socket. Guaranteed that one of them will give you the "best feeling" PF. Kid you not. Maybe you can post the findings here once you're tried it out yourself. Of if you didnt manage to "feel" any of the Power-Factor there .. ok, you win. No further objections from me. Deal ?

Please do not duplicate the above act which is to be performed by the professional in its field.

chua55 wrote:

Please do not duplicate the above act which is to be performed by the professional in its field.

So another snake oil myth is debunked.

Measeure PF of your main wall power supply by sticking metal pole.LOL!

Bro..stop klentong.

Stick to your advice to measure PF of the wall supply.

Is it relevant and measurable?
So you want to bet your Krell and throwing in your free XLO cable?


Why so evasive to answer a simple question?

OK, a new one. Why thin wall cabinet speakers cannot rock?

So if the loudspeaker got no cabinet, like the Pro Ac or Orion cannot rock?

More bull Shit and snake oil.

Go ahead .... PROVE IT that any of my factual postings are not true...

Don't just talk c0ck with snake-oil calling.

You guys are so technical and I must admit I do no understand a tiny bit of what I ahve read. When I listen to a system, I only draw a simple conclusion "I like it or I don't like it".

Please don't laugh at me as I do not have any in depth knowledge in this stuff as you guys do. Guess I need to learn from you guys.

Intresting but find no time in reading john's article. But i do agree with Harbeth recomendation of not using blue tack. I came across an old speaker with a damage bottom cause by blue tack stuck to the stand. As the speaker is made of mdf, glued particel wood, have to send to paint shop to plaster it.

Any other ways recommended without harming our beloved speaker?

Just a reminder. Good debate here, but KEEP IT CIVIL. I.e. no name callings and NO DIRTY WORDS or CURSING. I think if it can be kept civil and factual, everyone stands to learn a lot from this thread.

Yes, good call WongKN.

While I respect JA for many of his works, but in this article, please spare a bit of your precious times to think about the following; I will not say more, who am I as compare to JA?

Imagine your speakers is a Stradivari violin, the violinist firmly holds it down hard with his chin and hand firmly gripped the neck reminiscent to what Blu-tak would do to your speakers which sits on its stands, and guess how it will sound?

Resonant is a groase misunderstood topic in the field of hifi. When you think you know, you could be wrong. Blutak to couple speakers to stands is fundamentally wrong. I learned this and wasted many years of my efforts in trying to make my system sound right. When the fundamental is wrong, almost everything that we do is either compromised or wrong.

Chinrest is not done for no reason. Observe how chinrest is mounted. This is kindergarten knowledge.

Jo Ki

Violin is a good example.

Do you see damping in a violin or a guitar body like what you find in a speaker cabinet?

For musical instruments body resonance is important compared to speaker cabinet resonance?

JA's measured the cabinet vibration. He did not measure the actual sound.

It is impossible to measure stand's influence becuase you cannot find two identical (shape, dimension, height) stand.

Over hundreds of measurements I have done. Even a few milimeter difference changes the FR.

Yes, good call WongKN. Long overdue. I was attacked for pointing out snake-oil logic.


:~( crying
;_; crying He started it first.. :~( crying
;_; crying

Hi Jo,
I would appreciate if you can recommend an inexpensive but effective product that is available locally to be placed in between the interface of the speaker and an open-frame stand, the one that the Harbeth dealer provides. It has to be sufficiently small to sit on an open-frame stand. So far I only heard of the TAOC Tite-35S which some people have used to decouple their speakers from the stands, and these things cost quite a bit --about RM1,700 for a set of 8.

Thanks in advance.

……. the behavior of vibration within the speakers’s enclosure.

The sound(vibration) which coming from cone(woofer) hit the speakers’s enclosure and bounces back to the cone.

After hitting the speakers’s enclosure it radiates in multi direction unlike electricity which looks for the shortest (least resistant) path to the ground.

In music, the cones do not wait for all the vibration to stop before hitting the second note. The process is continuous.

The main problem for speakers designer is how to prevent the radiating vibration from disturbing the cone movement.


If you shout inside a bare room, you will hear echo. So if you are the cone(woofer) and the room is the speakers’s enclosure the same happens.

So how you prevent echo in your room? Do you put absorber outside your room wall or inside the room wall?

Which one will influence the echo the most?

Food for thought.

Couple of questions in my mind reading this interesting exchange of thoughts:

Coupling vs damping. Seems to me blutack damps out but does not couple/transmit energy from speaker to stand?

Also from perspective of holding the speaker absolutely still, the compliance in blutack will not achieve this?

I'm beginning to see this coupling/energy transfer from speaker->stand->earth as similar to the issue with passive pre's. ie output impedance of source should be << input impedance of pre; output impedance of pre should be << input impedance of amp, and finally for good damping factor, output impedance of amp should be << impedance of speakers thus the output trans of tube amp. Jo, this explains why LS3/5A with 15ohms is friendly to tube amps though not in terms of SET's small power output due to its low sensitivity?

So the parallel to impedance in electrical driving/loading is density in mechanical resonance energy transfer? So speaker density < stand density < earth density to setup some kinda 'density gradient' for truly 'grounding' out vibration energy whilst keeping speaker completely still?

But this train of thought whilst considering energy transfer hasn't looked into resonance frequency signature of the stand yet. Does this mean if speaker cabinet has a dominant node at xHz, we'd like to have a stand that also has a resonant node at xHz for maximal energy transfer?

Just my unenlightened thoughts. Kindly shine the light guys.

I use the antiskit transparent rubber feet found in Supermarket DIY corner...

I wonder how much evil it can make...

musicmusic wrote:
I was attacked for pointing out snake-oil logic.

and "those who think they know everything" tend also to be the ones to dismiss much as "snake-oil".

A healthy debate should not start with just labelling anything as snake-oil and left there alone. If you want to expose anything to be fraudulent, better be prepared to back it up with proof. Not just with motherhood statements left hanging.


On the use of Blu-Tack, the purpose it two-fold.
Firstly, it is to PROVE that the use of blue-tack does have and influence on the sonic reproduction of any speaker system. Whether its for better or for worse is another matter altogether.

Secondly, one should also not be so quick to write-off blu-tack or any such sticky temporary adhesive as it would all DEPEND on how the system being employed. As stated in earlier posts in response to Ryder's earlier enquiry about stands and Harbeths, adhesives would not be the choice and it would interfere with the speaker's intended design and mode of operation (ie. to let the cabinets vibrate themselves as part of the reproduction eco-system). This is due to the nature of BBC style thinwall designs and the way the cabinets are build to vibrate as part of the speaker's sonic characteristics.

But this does not and should not be taken as a total write-off for the benefits that temporary adhesives might impart of other differently designed systems.
Does one dare say that the use of such adhesives will ALWAYS be WRONG and not applicable in ALL Situations?

Spoiler:

Perhaps the only BOLD statement that I can think of for now is: "Don't take your normal home hifi system and install it submerged in your swimming pool so that you can listen to music while swimming."

As per JA's article, if you want to DAMPEN cabinent vibrations, please use Blu-Tack. If you want to MINIMISE the Damping (or get best Isolation between Stands & Speaker), please use upward pointed spikes. Anything in between, there would be a myriad of coupling/decoupling methods available.

And as such, there are a myriad of other "not so high-end" aka budget bookshelf speakers that benefit tremendously by damping cabinet resonances. Some stand mfgs even go so far as to create "clamp type" stands that hold the speaker in place for max performance. Case in point: Target stands for Wharfedale Diamonds in the late 80s.


Some speakers would work better with max damping. ie, Wilson cabinets which strive to make the cabinets as inert as possible.

Some speakers would include cabinet resonances as part of the sonic reproduction's system.

So who is absolutely right or wrong ? Alan Shaw vs. Dave Wilson ? They both sell truckloads of speakers. So back to the issue at hand .... the real answer really is that it "all depends".

On the matter of musical instruments vs. Transducers , the similarities can only go so far. Musical instruments are designed FUNDAMENTALLY to resonate and create its signature sound. Like a Steinway Grand or a Stravidari violin. Musical instruments are not so much constrained by the "economic factor" such that one accepts that if the instrument is built a certain way, that would be the way it sound. It might be more pleasing or less pleasing to the ear in terms of grade and built-refinement, but for all intent & purposes of hifi debates, the original instrument is the gold standard. (ie, an unpleasant sounding cheap junk guitar in real life, should sound just as unpleasant & nasty when reproduced by an HONEST audio system). Any deviation from this reference would be loss of fidelity and colouration already.

Loudspeakers on other other hand are designed to be as Neutral as possible within the given contraints of physics (material sciences, environmental factors, etc) and economics (price/performance ratio). So it will ALWAYS be a compromised situation. Now, how these manufacturers/designers go about to EMPLOY the physics & MANAGE the economics, then its another ballgame altogether. Dave wilson & the late great Jim Thiel would perhaps build such an inert and rigid cabinet such that the sound drivers perform closest to the theoretical ideal of a perfect pistonic motion. Alan Shaw might say that this is an exercise in futility, and would rather "manage" the vibrations of the cabinets and tune the entire speaker assembly to work in unison and present an honest APPROXIMATION of the source material. And for this is what they are famed for such lush and rich vocal reproductions.

They are all correct in their own ways. And they have their followings and commercial successes to prove their stand.



But what its totally counter-productive, would be to choose one extreme as the only true way and pushing the other points as snake-oil.

Again, if anyone wants to point out snake-oil logic (for example if its impossible to measure XYZ at the wall outlet? ) ... you had better be prepared to PROVE IT OTHERWISE. If you can decisively prove or dispell factual errrors, it is most welcome. But alas, this has not been the case yet...

Coupling vs damping. Seems to me blutack damps out but does not couple/transmit energy from speaker to stand?

In the context of vibration transfer discussed here,(risking being wrong here) damping converts kinetic energy to heat.

It is impossible to draw any conclusion from JA's measurement because he did not measure the stand's vibration.

How much vibration transfer from the stand to cabinets is unknown here.

Let us take one step at a time, let's discuss the echo example in room.

Then we can move to a more complicated area of stand, and blue tak influence.

A healthy debate should not start with just labelling anything as snake-oil and left there alone. If you want to expose anything to be fraudulent, better be prepared to back it up with proof. Not just with motherhood statements left hanging.

So, please show me how to measure PF from your main supply of the wall. Please.

I don't know anything.

So please show me.

musicmusic wrote:
So, please show me how to measure PF from your main supply of the wall. Please.

I don't know anything.

So please show me.

Well, if you can show that is is impossible, Please .... show proof.
(So who did you really talk to in TNB that said this is impossible? Not the road-cone guy i hope )


Otherwise, very difficulty lah bro... Its like asking how to show colours to someone who might happen to be colour blind ?
(Not referring to anyone in particular of course).

So maybe if someone else who is NOT colour-blind asking to talk about colours ... ok, perhaps can justify an answer then.

Well, if you can show that is is impossible, Please .... show proof.(So who did you really talk to in TNB that said this is impossible? Not the road-cone guy i hope )

As expected for a guy who writes long irrelevant formula, now so reluctant and hide behind colour blind shield.

I also ask the TNB jaga:-

Maybe, the road-cone guy is correct, after all.

f8. wrote:Couple of questions in my mind reading this interesting exchange of thoughts:

Coupling vs damping. Seems to me blutack damps out but does not couple/transmit energy from speaker to stand?

Also from perspective of holding the speaker absolutely still, the compliance in blutack will not achieve this?

Coupling (or decoupling) merely addresses how the vibrations from the speaker's cabinet will be transmitted to the speaker stand.

Its good not to confuse coupling with damping: Case in point here, if the speaker cabinet is heavily "coupled" to the stand, then the damping of the speaker cabinet resonances will be greatly influenced by the type of stand in question.

In the case of blutack that "glues" the speaker so tightly to the stand that means ALOT of the speaker's vibrational energy WILL be transmitted to the stand. This could work very well for certain peculiar speaker types, but may be horribly detrimental to other speaker types (perhaps like Harbeths & LS/35A monitors, for example). And if the stand happens to be extremely inert and acts as a very good drain sink , then naturally it will damp-out the speaker cabinets and drain away its vibrations.


On another extreme example: if the speaker is close to being ideally DE-COUPLED from stands by an infinitesimally sharp up pointing spike, then almost NO cabinet energy should be transmitted to the stands at all. Hence zero damping of the speaker cabinet due to mass-loading or coupling the speaker to the stands.
But as with all things in the real world, there is no perfect scenario. Even a magnetically levitated speaker on top of a stand's top plate would still have vibrational energy transmitted across the supposedly magnetic isolation barrier. Just that the transmission efficiency (between speaker & stand) would be extremely low especially in the higher order frequencies.

Blu-tack vs. clamps vs. mass-loading (placing a heavy brick on top of the speaker) vs. Spikes vs. or magnetic footers or sorbothane pucks are but extreme examples of coupling or isolation. And then there are numerous tweaks in the market fall in between (branded boutique stuff like Harmonix footers, Finite-Elemente ceramic balls, MonsterCable Footers, TAOC spikes and cups, homemade sandboxes, etc... ). These interfaces are similar to the elctrical high-pass or low-pass or band-pass filter networks. They would block the transmission of certain freqs, while allowing the transmission of certain spectrum of freqs.

For example: Sorbothane footers between 2 materials would be an analogy to a low pass filter. It probably wont damp out subsonics travelling between the 2 materials (speaker / stand), say at >200 Hertz, they are really effective isolators and will absorb or "eat-up" alot of the vibrations trying to pass from one medium to the next.

On this same example, putting puck-sized chunks of sorbothane footers between speakers & stands would drastically imprint a unique sonic signature onto the reproduced sound.


But this is only one side of the coin. There other flip side would be how Stands themselves resonate and transmit their own energies back into the speaker cabinets. This is more apparent in western countries where their floors are not concrete but soft creaky wooden planks instead. An example of Worse-case-scenarios would be a typical home hifi in the attic. Speaker cabinet vibrations being sent to the not-so-rigid floor, and in turn floor vibrations creep back into the analog turntable system. This colours the sound in which the coloured-sound is further pumped back into the source via mechanical transmission again. This is called a "feedback loop". Same thing happens on a mis-suspended Linn Sondek (as an example) if the suspension is sagged and is resting on the main plinth. Very obvious nasal sounding deck in this case.

So if the speaker would be so perfectly isolated from its stands ... then the accoustical feedback would be purely from airborne sound waves as opposed to mechanical transmission via tightly coupled speakers -> Stands -> flaky floor -> equipment rack -> turntable: & the loop recurs again.

musicmusic wrote:

Well, if you can show that is is impossible, Please .... show proof.(So who did you really talk to in TNB that said this is impossible? Not the road-cone guy i hope )

Asexpected for a guy who writes loa longrrelevant formula, now soreluctant and hihidesehind colour blind shield.

Maybe, the road-cone guy is correct, after all.

if u can't prove me wrong .... give it a rest. Obviously i don't need to justify anything to you.


Open invitation to the rest:
To anyone else who is keen to know how, pls PM me ... will gladly explain for the sake of knowledge sharing, and if it is indeed proven wrong or not satisfied with my answer, please feel free to post into this thread for all to see.

Cheers!

If soemthing is so certain and precise and relevantto JKKhoo's post, then why need to PM in private.

Can I PM, for the answer?

musicmusic wrote:

If you shout inside a bare room, you will hear echo. So if you are the cone(woofer) and the room is the speakers’s enclosure the same happens.

So how you prevent echo in your room? Do you put absorber outside your room wall or inside the room wall?

Which one will influence the echo the most?

Food for thought.

Another flawed analogy here....
If the person is akin to the speaker cone woofer , and the room is akin to the speaker cabinet: Then the person should be STANDING at the doorway, shouting out to the external medium. The room should thus be the sounding-board that reinforces the person shouting outwards ... (towards the hall or another open area, for example).

So far, i have not come across any speaker design in which the woofer happens to be totally recessed inside a sealed cabinet with no opening whatsoever. But as I dare not say it for certain that such designs do not exist as I have not come across all types of loudspeaker designs in the world, these could very well be the ones that musicmusic is playing in his system ....
(shrugs)

OK. If you want to be so precise.
Make it a 12 in woofer fitted in a room in a hole just like speaker.

You should know drivers not only send sound forward but also backward.

Hey, I still want to know how to measure PF of the wall main supply.

He who asserts must prove.

He who says earth is flat must prove.

musicmusic wrote:Hey, I still want to know how to measure PF of the wall main supply.

He who says earth is flat must prove.

For you, just use the prong method . You can prove me wrong afterwards if this doesn't work .....

I just double checked Harbeth webiste.

About thin wall it says "Whatever solution one arrives at, the best one can achieve is to suppress a panel's output and/or to steer it into a frequency band where it is either inaudible or benign: this implies at the bottom end of the audio spectrum."


About blue-tac it say "...A small ball of Blue-Tak (or similar) seems a much more elegant solution,..."

musicmusic wrote:OK. If you want to be so precise.
Make it a 12 in woofer fitted in a room in a hole just like speaker.

You should know drivers not only send sound forward but also backward.

So, your point being ?

musicmusic wrote:I just double checked Harbeth webiste.

About thin wall it says "Whatever solution one arrives at, the best one can achieve is to suppress a panel's output and/or to steer it into a frequency band where it is either inaudible or benign: this implies at the bottom end of the audio spectrum."


About blue-tac it say "...A small ball of Blue-Tak (or similar) seems a much more elegant solution,..."

Just a suggestion ... why don't you go and listen to some real Harbeth systems being used in real-life. Perhaps some Harbeth owners here can oblige you. Or the local Harbeth dealer's place. Go have a listen, then post your take on them. Instead of relying whatever website states (harbeth's included) or other people's opinion that Harbeths maye be good for this or bad for that. Agree ?
If they are so kind, u can also try some spikes , or blu-tack, or other sticky stuff or rubber footers.

Who knows, maybe you won't hear any sonic differences after all and the whole discussion is a moot point only and finger exercise for everyone. Agree ?

For you, just use the prong method . You can prove me wrong afterwards if this doesn't work .....

I respect the moderators request to keep this discussion civil.

Why you want to tell about measuring PF in private?

Want to make sure you are right before posting here.

Worried you may be laughed at.

You are one person who never let go an opportunity to bash when one errs.


So why so reluctant to show your superior prowess in Hifi.

Tell us how to measure PF of the wall's main supply.

So you now professing that no sound bouncing around in a cabinet?

So, your point being ?

The point is if the is so much unwanted waves in the cabinet..


What is the best solution.

Do you damp inside the wall

or outside?

musicmusic wrote:

For you, just use the prong method . You can prove me wrong afterwards if this doesn't work .....

I respect the moderators request to keep this discussion civil.

Why you want to tell about measuring PF in private?

Want to make sure you are right before posting here.

Worried you may be laughed at.

You are one person who never let go an opportunity to bash when one errs.


So why so reluctant to show your superior prowess in Hifi.

Tell us how to measure PF of the wall's main supply.

So you now professing that no sound bouncing around in a cabinet?

Awwww .. have a sense of humour here buddy....

"Why so serious ?" - the joker

But on a serious note, if I have err'ed here, please show where and when ?
I am all ears to your feedback, as always !

musicmusic wrote:

So, your point being ?

The point is if the is so much unwanted waves in the cabinet..


What is the best solution.

Do you damp inside the wall

or outside?

The above's comprehension of physics here is again, totally abysmal and its yet another flawed analogy. Loudspeaker Cabinet vibrations are primarily due to Newton's 3rd law of motion. The mass of the woofer pushing forward will impart the same backward force against the woofer basket assembly which is then securely fastened (or coupled) to the cabinet assembly.

Acoustic energies being radiated rearwards (which already passes through a fluid medium which in this case is the internal cabinet's air volume) would be subject to a speaker enclosure's internal wadding (via popular materials such as sheep wool, cotton wool, various fibrous materials, sponge, etc etc) and being intentionally damped , with its internal volume space and the presence of a tuned port in the case of a bass-reflex design, or purely internal volume alone for sealed enclosures.

The amount of speaker internal volume, damping employed, internal cabinet dimensions, tuned port or not, bracing and joint techniques would then be encompassed as the build and tuning aspect on voicing the sonic characteristics of the loudspeaker construction in question.


Back to the main point again. Speaker stands in their totality and how the loudspeaker cabinets are coupled (or decoupled) with the stand all WILL influence the reproduced sound. Period.

If the above is wrong, Please disprove otherwise.
JA's article already has shown CLEAR and MEASURABLE effects of the different loudspeaker/stand boundary effects already.

Local reputable audiophiles have already professed the point that such Interfaces are indeed significant audible in the use of tweaks and methods of "tuning" the stands, and also employing various ancillaries to mount the speakers (marble slabs, crystal slabs, spikes, footers, Harmonix stuff, etc etc)... the list goes on.



Lets save the realm of room acoustics for another thread. That topic deserves its own section entirely.

Re: Electricity effects on hifi?
by mugenfoo on Thu Sep 30, 2010 1:40 am

nice fluke meter...

But u forgot another very important aspect.... whats the PF (power factor) of your wall supply ? If your current waveform is 90degrees off from your your voltage waveform ... you're pretty much paddling up sh!t-creek ... with no paddle!

Let's start here. This is something new for me.


So how to measure?

You said thin walled speaker cannot rock.

So is the cabinet wall is the criteria for designing a loudpspeaker suitable for rock musical genre?

I am not saying you have erred but you made statement but refused to back it up.

Will continue on a day or two if I other reader show interest.

OK, just to whet your appetite ... what is the effective power delivered to a load if the AC current is 90 out of phase with the AC voltage being supplied to the load?

What is the electrical power equation for an AC scenario?


BTW, i never said that thin wall speakers cannot rock. It was Alan Shaw himself that said that his Harbeth speaker would not be so suitable for Rock music. That being said, I have still thoroughly enjoyed fast paced and dynamic music being played via someone's Harbeth 40.1 and Super HL-5 speakers on many occasion and find them to be quite musical indeed.

Have you gotten around to hearing some Harbeth's in real life yet?
Would highly recommend to do so.

OK, just to whet your appetite ... what is the effective power delivered to a load if the AC current is 90 out of phase with the AC voltage being supplied to the load?

I may not able to complete this post as my cab will be here anytime.

If there’s delay for a day or 2 don’t put a chicken picture and ridicule me.


About your PF so what the load at the wall power point?


Yes, heard it at AV show this year. I always thought it was meant for broadcasting.


I remember reading something about it here when he came down for a talk. It cannot be right. It is illogic. Need to go through every word he said About thin wall and rock.

Ok…cheers!

musicmusic wrote:

I may not able to complete this post as my cab will be here anytime.

Hasta la vista...

musicmusic wrote:

If there’s delay for a day or 2 don’t put a chicken picture and ridicule me.

dun worry, i won't. promise.

musicmusic wrote:
About your PF so what the load at the wall power point?

a bag full of rocks weighing in at around 50 kgs.

musicmusic wrote:
Yes, heard it at AV show this year. I always thought it was meant for broadcasting.

Try hearing in more real-world situations also .... as in a typical room or living setup.

musicmusic wrote:
I remember reading something about it here when he came down for a talk. It cannot be right. It is illogic. Need to go through every word he said About thin wall and rock.

Yup, be my guest...

musicmusic wrote:

Ok…cheers!

cheers!

musicmusic wrote:
In music, the cones do not wait for all the vibration to stop before hitting the second note. The process is continuous.

The main problem for speakers designer is how to prevent the radiating vibration from disturbing the cone movement.

If you shout inside a bare room, you will hear echo. So if you are the cone(woofer) and the room is the speakers’s enclosure the same happens.

So how you prevent echo in your room? Do you put absorber outside your room wall or inside the room wall?

Which one will influence the echo the most?

The point is if the is so much unwanted waves in the cabinet..

What is the best solution.

Do you damp inside the wall

or outside?

as mugenfoo has pointed out, the unwanted waves inside the speaker cabinet are damped out by wool, fibres, foam, etc. most, if not all, speakers have some kind of damping material inside the boxes.

Damping of the speaker box is done by the speaker manufacturer.

Damping of the (outside) wall i.e. the listening room is done by the owner of the speakers.

What is the best solution? i don't think there is a one-size-fits-all answer.

the audiophile buys a pair of speakers which already has damping materials inside the box, so there's nothing much he can do to change the situation.

as for the listening room, how many audiophiles have treated the walls and/or ceilings of their rooms with acoustic panels?

transfer of cabinet vibrations to the speaker stand and downwards to the floor/ground is another story.

how the material used to decouple the speaker from the stand can affect sound quality is also another story.

whether a speaker shld be coupled to or decoupled from the speaker stand is again another story.

I've got a question which is totally unrelated to speaker cabinet vibrations but could be related to driver vibrations or resonance nonetheless, so if someone in the know would be so kind as to oblige me then please, pretty please. But if I'm off topic kindly tell me and I'll post elsewhere.

Here's the question: I've seen some woofer baskets being made out of magnesium. Why would a speaker manufacturer choose magnesium over steel or cast iron or even aluminium?

Cheers y'all!

since you keep asking how to measure PF, pls see below the meter used. I have also mentioned before not onlypower factor, it can do tell you power quality.

http://www.fluke.com/Fluke/usen/Power-Quality-Tools/Troubleshooting-Power-Meters/Fluke-43B.htm?PID=56080

bimmerman,

magnesium is a light and stiff material that does not store energy well.

there are speaker units that use magnesium cones too.

Thanks Sflam. So by not storing energy it can result in not generating energy related by-products like resonance? Is that the reason for using magnesium? But on a separate matter, once the magnesium corrosion sets it, it can be such a biatch to deal with I tell ya.

BTW Sflam, I tried that earth quake pads you blogged about sometime back and it works a treat for resonance damping! Cleans up and tightens the sound aplenty. Kudos to you and thanks for answering my question.

chua55 wrote:since you keep asking how to measure PF, pls see below the meter used. I have also mentioned before not onlypower factor, it can do tell you power quality.

http://www.fluke.com/Fluke/usen/Power-Quality-Tools/Troubleshooting-Power-Meters/Fluke-43B.htm?PID=56080

So how do you use that to measure form the wall plug point?

Do you honestly thought I do not a Fluke power analyzer?

I refer to your Fluke 43B Single Phase Power Quality Analyzer.

In the manual it says "This function measures and displays the
following power readings: active power (W),
apparent power (VA), reactive power (VAR),
power factor (PF), displacement power factor
(DPF or cos ϕ) and frequency."

So what are the three values when you plug it to the wall plug without a load?

I like the term "coupling" ... it's sexy, no? ... Q

sflam wrote:

musicmusic wrote:
In music, the cones do not wait for all the vibration to stop before hitting the second note. The process is continuous.

The main problem for speakers designer is how to prevent the radiating vibration from disturbing the cone movement.

If you shout inside a bare room, you will hear echo. So if you are the cone(woofer) and the room is the speakers’s enclosure the same happens.

So how you prevent echo in your room? Do you put absorber outside your room wall or inside the room wall?

Which one will influence the echo the most?

The point is if the is so much unwanted waves in the cabinet..

What is the best solution.

Do you damp inside the wall

or outside?

as mugenfoo has pointed out, the unwanted waves inside the speaker cabinet are damped out by wool, fibres, foam, etc. most, if not all, speakers have some kind of damping material inside the boxes.

Damping of the speaker box is done by the speaker manufacturer.

Damping of the (outside) wall i.e. the listening room is done by the owner of the speakers.

What is the best solution? i don't think there is a one-size-fits-all answer.

the audiophile buys a pair of speakers which already has damping materials inside the box, so there's nothing much he can do to change the situation.

as for the listening room, how many audiophiles have treated the walls and/or ceilings of their rooms with acoustic panels?

transfer of cabinet vibrations to the speaker stand and downwards to the floor/ground is another story.

how the material used to decouple the speaker from the stand can affect sound quality is also another story.

whether a speaker shld be coupled to or decoupled from the speaker stand is again another story.

The flaw in the argument is no matter how much damping used it is impossible to control unwanted resonance especially the lower octave.

From Harbeth"It is self evident that if the 'raw' untreated panel is thin, that damping that applied damping will have a proportionately greater beneficial effect than if the panel is thick, where no amount of conventional surface damping can adequately suppress latent peaky resonances."

Also read http://www.linkwitzlab.com/frontiers.htm

mugenfoo wrote:

musicmusic wrote:

I may not able to complete this post as my cab will be here anytime.

Hasta la vista...

musicmusic wrote:

If there’s delay for a day or 2 don’t put a chicken picture and ridicule me.

dun worry, i won't. promise.

musicmusic wrote:
About your PF so what the load at the wall power point?

a bag full of rocks weighing in at around 50 kgs.

musicmusic wrote:
Yes, heard it at AV show this year. I always thought it was meant for broadcasting.

Try hearing in more real-world situations also .... as in a typical room or living setup.

musicmusic wrote:
I remember reading something about it here when he came down for a talk. It cannot be right. It is illogic. Need to go through every word he said About thin wall and rock.

Yup, be my guest...

musicmusic wrote:

Ok…cheers!

cheers!

Still cannot answer how to measure PF from of your supply from the main.

50kg!! When you are cornered you throw some fancy technical stuff.

Re: Speaker Cabinet Vibration and Measurements
by mugenfoo Today at 3:42 pm
..BTW, i never said that thin wall speakers cannot rock. It was Alan Shaw himself that said that his Harbeth speaker would not be so suitable for Rock music.

You said it. Now when you cannot explain the open baffle speaker system you say Alan Show said.


Looking at the kind of support you have here, there can be no useful exchange in this forum.

musicmusic wrote:
The flaw in the argument is no matter how much damping used it is impossible to control unwanted resonance especially the lower octave.

u r right, there is no such thing as 100% damping. even wilson's inert box is not that inert. even the box with braces will still vibrate.
but that is the way most speakers are made.

Musicmusic, if you feel that everyone seems to be 'against' you, perhaps you might want to take a step back and read carefully your first post on this subject, how it was worded and the thread it was written in. Effectively in that post, you more or less jumped in halfway into a discussion where everyone was sharing their knowledge and experience but then proceeded to insult someone who is very very widely recognized and respected for his hi-fi knowledge and abilities (worldwide I would add). Do note that your first description of his points was 'snake oil' (note: I am NOT talking about mugenfoo). To be honest, I myself didn't take that post very well at all.

By coincidence, 99% or more of the forumers here tend to share the same opinion and has the same experience as that person which is why to you it seems that everyone seems to be helping to defend mugenfoo. But the actual fact is that everyone is just addressing the topic objectively. Nothing was directed at you, everything is directed at the topic itself. Perhaps you might feel it a bit personal due to the tone of that first post I mentioned above ?

To be honest, I do know your actual intention of starting this thread. But I also believe I know what mugenfoo would want all the rest of us to do (i.e. allow him to answer questions directed to him, himself). This is why I went ahead and let this thread start eventhough it is effectively a 'showdown' between two forumers.

Bimmerman, don't worry, all proper questions are legitimate in this forum.

Thank you to everyone who responded and thanks especially to mugenfoo and musicmusic for obeying the rules of this forum and keeping this thread civil. There have been absolutely no personal attack, flames, vulgar words or other such undesirable things.

But at this stage, I do find that the debate is starting to become circular and the same things are being brought up again and again. Perhaps it is time for both parties to take a step back, come clean and maybe settle things and move on ?

(note that I am asking very nicely).