@ginetto61
Just to add that vibrations and (even more) resonances are capable of causing some "damage" to listening, as we all know.
The cabinet of a subwoofer is stressed both by the air that the cone of the woofer moves (back and forth) and by the same weight of the woofer basket and its magnetic assembly and therefore by the weight of the whole woofer itself.
And by the sound it itself produces, that's by vibrations that it itself produces.
Frankly, I don't think (but I'm not an expert) that the force generated by the cone of a woofer inside a box on the sides of the box, however large and heavy the woofer may be, is capable of producing enough stress to make a properly constructed cabinet vibrate and/or deform too much, especially if that box is well-built and dedicated to a single woofer.
Everything also depends on the size of the box, the materials chosen for its construction, the expertise of those who build it, etc.
I believe that even the choice of glue can be a discriminating factor.
Also because in my opinion the resulting SQ is the addition or subtraction of an infinite number of elements that sometimes contribute and other times compete.
Assuming that the cabinet of a subwoofer was absolutely inert and refractory to physical stress and vibrations and resonances, would the subwoofer sound better than any other option?
I don't know, and even if I knew I wouldn't be absolutely sure.
Dizzy Gillespie's trumpet sounded the way it did just because someone just fell on it. 😉
IMO
Just to add that vibrations and (even more) resonances are capable of causing some "damage" to listening, as we all know.
The cabinet of a subwoofer is stressed both by the air that the cone of the woofer moves (back and forth) and by the same weight of the woofer basket and its magnetic assembly and therefore by the weight of the whole woofer itself.
And by the sound it itself produces, that's by vibrations that it itself produces.
Frankly, I don't think (but I'm not an expert) that the force generated by the cone of a woofer inside a box on the sides of the box, however large and heavy the woofer may be, is capable of producing enough stress to make a properly constructed cabinet vibrate and/or deform too much, especially if that box is well-built and dedicated to a single woofer.
Everything also depends on the size of the box, the materials chosen for its construction, the expertise of those who build it, etc.
I believe that even the choice of glue can be a discriminating factor.
Also because in my opinion the resulting SQ is the addition or subtraction of an infinite number of elements that sometimes contribute and other times compete.
Assuming that the cabinet of a subwoofer was absolutely inert and refractory to physical stress and vibrations and resonances, would the subwoofer sound better than any other option?
I don't know, and even if I knew I wouldn't be absolutely sure.
Dizzy Gillespie's trumpet sounded the way it did just because someone just fell on it. 😉
IMO
This thread in particular: https://www.diyaudio.com/community/threads/planet10-hifi-minionken-plan-set-subscriptions.186350/
Doesn’t cover the freebies. Many have their own threads and have spawned many threads. Search Frugel-Horns, Pensils, microTower, Baby Labs, and Scott has added many sketches in this thread: https://www.diyaudio.com/community/...s-markaudio-fostex-tb-dayton-seas-etc.323051/
Then all the rest…
dave
Hi thanks but the " the woofer basket and its magnetic assembly " do not move so they cant generate vibrations
Their mass instead causes inertia To an extreme if the basket and the magnetic assembly had a very high mass there will be no vibrations
Instead the cone moves and having a certain mass generates vibrations
The cabinet can act absorbing those vibrations using mass or as i have been explained moving the resonances outside the speaker working range with bracing And actually i have seen sub boxes using more bracing that added mass
Instead if i had to treat the sats i would just add mass that moves the resonances lower in Hz This is very clear to me
In this way bracing a small 2 ways could be even detrimental moving the resonances in the speaker working range
this is a fundamental issue to cancel this problem I really do not know for sure
the mass of a big woofer could be up to 200 grams ? I am not able to calculate the forces generated by this mass moving back and forth with frequency
The only way is to excite the woofer with a strong sine and check
i can only think about musical instruments Their cabinet is designed and built to resonate and doing this adds something to the original signal from the strings that is not present in the signal THD and volume is added
The ideal speaker cabinet should be the exact opposite
I have completely solved the problem above lets say 200 Hz Just some lead will solve any vibrational issues
Below that is where things become complicated and challenging
Thanks again Unfortunately after watching the section about subs here in the forum i see that the aspect of cabinet vibrations is quite overlooked I could not find reports of measurements Maybe i should look better That would be very interesting
Everything moves. If the motor applies a force to the coil/cone, an equal and opposite force is applied to the basket/magnet. It's Newton's third law. And the vibration of the basket/magnet will be transmitted to the cabinet, so it will tend to act like a soundboard. This may well be the primary cause of vibration in the cabinet.
Yes i agree I meant that the not moving parts react to the force generated by the moving parts
In this sense the back to back solution is the best of course
The vibes plague more the single woofer concept
If a high cabinet stiffness is the primary design goal nothing beats metals
If i look at the stiffness of a metal plate and a wooden plate of same size and thickness there are orders of magnitude of difference A huge difference actually https://ars.els-cdn.com/content/image/3-s2.0-B9780128035818029441-gr4.jpg
Yes metals can ring but if the ring frequency is placed outside the working range of the speaker nothing happens
Like a driver will not emitt sound below its fs
Metals are not easy to work with unfortunately But they could be the ultimate solution for bass boxes in general
Someone used them i guess with great results (and with back to back woofers)
In this sense the back to back solution is the best of course
The vibes plague more the single woofer concept
If a high cabinet stiffness is the primary design goal nothing beats metals
If i look at the stiffness of a metal plate and a wooden plate of same size and thickness there are orders of magnitude of difference A huge difference actually https://ars.els-cdn.com/content/image/3-s2.0-B9780128035818029441-gr4.jpg
Yes metals can ring but if the ring frequency is placed outside the working range of the speaker nothing happens
Like a driver will not emitt sound below its fs
Metals are not easy to work with unfortunately But they could be the ultimate solution for bass boxes in general
Someone used them i guess with great results (and with back to back woofers)
Drivers do still emit sound below the driver Fs (or system Fc). Just less of it. But maybe still enough to matter? I'm not sure.
Hi thanks ! this is a very interesting question and i have no answer as usual
I have always seen the fs the wake-up point below which the driver is sleeping
I guess it can change once in the box i do not know But there is always a popular rule to use a driver from 2xfs Hz up
But the most important lesson for me is that increasing stiffness moves the resonances upward in frequencies and icreasing mass moves the resonance downward in frequency This is very important to me I was confused and now much less so
Metals cost a lot more than wood and this makes the option out of question
The driven cone/VC moves. It has a small mass. This mass’ monentum is transfered to the enclosure (but opposite polarity) primarily via where it attaches to the enclosure, but in a subwoofer, air pressure inside can cause ballooning.
Even thou the mass of the cone/VC is only a fraction of that of the enclosure it can still move it. The brute force way to counter this is more mass (that is where the idea that mss helps comes from), but active reaction force cancelation is a clever way to dramatically reduce what gets to the enclosure, Makes no difference in terms of ballooning.
Note: more mass means more money and a back that hurts, clever engineering can largely get around that.
Where they are more likely to get excited, if you add mass you want to also increase stiffness and move potential resonances up in frequency.
As often in diy there is often overkill. But budget is usuakky a factor, just enuff overkill to tame the issue and no more will be most cost effective.
And then either store it and release it later* or turn it into heat.
*(a quick release might be best, thelow level time smeared grunge coming from an MDF enclosure is something i don’t like — it buries low level detail (decreases DDR))
If the sat is crossed high enuff, moving (potential) box resonances below its bandwidth will certainngly work. But subs asopposed to helper woofers probably means the XO is too low. @waxx has done a WAW with MA A10.3 that takes this approach. IIRC XO int he 300 Hz range.
I have not (finished) drawing the woofer but this is what he did for the tops: waxx-a103-sat-220121.pdf
Due to its toxic nature probably something to avoid.
dave
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Hi, no problem, I would only like to answer the following: anything is capable of vibrating and therefore producing a sound.
The study and research of usable and extremely refractory materials serves precisely this purpose.
Please note that it seems that here you continue to interchange the meaning of the verb to move with that of the verb to vibrate, but this shouldn't be done.
I've repeated the difference several times, but at this point it becomes your problem alone. 😉
However, also please note that the weight of a basket and the magnetic assembly of a basket of a let's say professional JBL woofer (I loved them!) is certainly capable of deforming a panel that is not adequate to support its weight itself.
Deformation can also be an element that accentuates a resonance and therefore a vibration, otherwise why would one make so much effort to use rigid and non-deformable materials?
Furthermore, I don't know how to repeat again that movement and vibration are two different things, which however happen at the same time.
But they remain different.
Even contemporary.
Frankly, I don't see anything too complicated about it. 🙂
On the other hand not even the parallel between musical instruments and loudspeakers shouldn't even be thought of at all. IMO
Since the acoustic musical instruments produce and propagate a sound.
The loudspeakers reproduce a recorded sound.
Between to produce and to reproduce there is the ocean.
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One only needs to put the mechanic's stethescope to the wall of a playing subwoofer box to understand how untrue the above is.
dave
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I didn't rule it out at all (and you didn't quote everything). 😉
I just said it might not do too much if it's well built. 🙂
On the other hand, if this were not the case it would be a real mess, and no one would be able to build anything good, as happens instead.
So the cabinet will certainly be stressed, but not so much as to make the sound bad, if well built.
That's what I said...
And if sealed, EQ is often added to extend its response (like a Linkwitz Transform). I have seen sealed pro woofers that only operate below Fs. If the box has a hole in it that is difficult since the woofer unloads below tuning.
A metal enclosure can work well, you can use much thinner material. There are some very pricey commencial loudspeakers doing so.
dave
I do not agree with this, and a lot also depends just on the context.
Please note that some definitions out there are ambiguous, however, I prefer the following: "vibration is a mechanical oscillation about a fixed reference point".
https://www.diyaudio.com/community/...field-with-2-way-speakers.390217/post-7121815
IMO What should be distinguished in the meaning is a subtle but substantial difference in language and concept.
In other words, if by "movement" you mean that it moves from one place and arrives at another place, it does not apply to "vibration".
Its English. As i said vibration is a movement, a movement may not be a vibration (most often isn’t) but in the context of this discussion when when says move, it means vibrate, because any movement of the box walls is a oscillation.
dave
At the end of the day that's exactly what I said if you follow the path of replies:
A deformation of a panel due to also woofer itself weight can also be very slow, a very slow movement.
But, when I talked about the movement of the woofer cone and the vibration of the air that sound produces, I really meant to differentiate the two things that in that context are not interchangeable.
thanks again I understand quite well that adding mass to a big bass box will move the resonances lower in Hz but still inside the speaker working range
Someone mentioned that resonances in the bass range could be less audible ?
another issue could be a way to find the resonance point of the system woofer plus cabinet and check if it is in the less critical part of the spectrum
Bracing is a nightmare for me One thing is to add some weights another to design cut and assemble bracings
I do not have the tools and the skills needed
Luckily for the sats i will be able to get away just adding mass
yes bracings have mass Metal bracings could be the very best for both stiffness and weight
i am thinking to cut at around 200 Hz even if someone prefer a lower cut for a 3 ways with mid cone
If the mid will be dome then the only problem will be the bass box
The 3 ways are another nightmare for me ... dome or cone mid ?
i do not like to use a big 12" close to 1kHz And for good bass woofer size matters
thank you very much for the link I will study that project with attention
lead has great properties to tame vibrations It is very very good But also very toxic
I wonder if slabs inside a box could represent a risk for the health For the sats i mean
BBC did research that suggests that. That is were their thin-wall construction came about.
dave
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