This is a good point. There are many things a loudspeaker needs to get right before enclosure stiffness and damping are worth worrying about.
A smooth flat on-axis anechoic frequency response is the single biggest determinant of a good-sounding speaker. The second biggest determinant is an off-axis response which closely follows the on-axis response.
Get those two things right first, and the rest is, as they say, small potatoes.... secondary issues.
Based on the comments from my first attempt at defining the enclosure requirements, here is Revision A. These requirements apply to speaker enclosures, and are not applicable to open baffle or dipole radiator systems.
What are the requirements for a loudspeaker enclosure?
1) The box must have the right volume of air for your woofer, and if you are designing a vented system, the port must have the right dimensions to achieve the desired tuning frequency. Numerous free tools help with this.
2) The box must isolate the back radiation from the front radiation to avoid cancellation and absorb it so that it does not color the sound by being re-radiated through the cone diaphragm. The discussions about midrange transmission lines are aimed at preventing this, although most of us believe that can be handled by simply filling the box with fiberglass insulation or polyester stuffing, or acoustic foam, or other absorptive material. Sometimes acoustical ceiling tiles or heavy felt is used to line the cabinet.
3) The vibration of the box must not add any acoustic output which is audible on program material. Box structural resonances are the primary source of box signature. All of our discussions about stiffness and damping relate to the prevention of a box signature.
4) The box must have a baffle shape and driver locations which minimizes diffraction. Another approach is to design a baffle geometry which is tailored so that the baffle diffraction and the crossover work together to achieve an acceptable frequency response. Several software programs are available for free which help model this behavior.
5) The box must meet the end users physical and aesthetic requirements. There are often height, width, or depth restrictions. Sometimes there are weight limitations. A large heavy box may not meet the needs of someone with a small space, or someone who needs a portable speaker. A simple plywood cabinet painted with gray latex paint may not meet the aesthetic needs of someone who is going to place the speaker between fine furniture, and under a work of art.
6) If the box must contain the crossover components, or for active speakers, the electronics, it must do so safely and comply with appropriate standards, such as UL or IEC.
7) The box must provide access to allow repair. Oftentimes the woofer hole is sufficient for this, but other times the rear baffle is made removable. This can complicate the control of box resonances.
What are the requirements for a loudspeaker enclosure?
1) The box must have the right volume of air for your woofer, and if you are designing a vented system, the port must have the right dimensions to achieve the desired tuning frequency. Numerous free tools help with this.
2) The box must isolate the back radiation from the front radiation to avoid cancellation and absorb it so that it does not color the sound by being re-radiated through the cone diaphragm. The discussions about midrange transmission lines are aimed at preventing this, although most of us believe that can be handled by simply filling the box with fiberglass insulation or polyester stuffing, or acoustic foam, or other absorptive material. Sometimes acoustical ceiling tiles or heavy felt is used to line the cabinet.
3) The vibration of the box must not add any acoustic output which is audible on program material. Box structural resonances are the primary source of box signature. All of our discussions about stiffness and damping relate to the prevention of a box signature.
4) The box must have a baffle shape and driver locations which minimizes diffraction. Another approach is to design a baffle geometry which is tailored so that the baffle diffraction and the crossover work together to achieve an acceptable frequency response. Several software programs are available for free which help model this behavior.
5) The box must meet the end users physical and aesthetic requirements. There are often height, width, or depth restrictions. Sometimes there are weight limitations. A large heavy box may not meet the needs of someone with a small space, or someone who needs a portable speaker. A simple plywood cabinet painted with gray latex paint may not meet the aesthetic needs of someone who is going to place the speaker between fine furniture, and under a work of art.
6) If the box must contain the crossover components, or for active speakers, the electronics, it must do so safely and comply with appropriate standards, such as UL or IEC.
7) The box must provide access to allow repair. Oftentimes the woofer hole is sufficient for this, but other times the rear baffle is made removable. This can complicate the control of box resonances.
What you would hear in an anechoic room isn't exactly what you'd call sound. So where's the good in a no-sounding ( speaker)!?
Why? Because it lacks of the fundamental body of a sound which is determined by the presence, body...all determined by the localization in space.
Apart from this, the off-axis is important for the stereo image as the head sits in the between of the two sources, at a certain distance, so there must be some deviation from the (semi) axis.
Oh...that's the revision? 😱
No crossovers inside
No electronics inside
They are separate components ( different duties): the speaker box is a very crude environment, why would you mix & mess the two things?!
I am not sure of your point. I am attempting to paraphrase Floyd Toole's very excellent research into a single sentence or two... Based on listening tests of hundreds of speakers, the ones which rated highest had this defining feature: They had a smooth flat response when measured in an anechoic chamber at the NRC, and the off-axis response was similar to the on-axis response (except of course the very high frequencies which always decrease off-axis).
Of course we do not listen to speakers in an anechoic room... but we measure them in an anechoic chamber or with a gated response to simulate an anechoic chamber.
Does this make sense? perhaps I misunderstood your statement.
Really? It's hard to imagine that light weight speaker can sound as good as similar sized heavy weight speaker when their FR is matched with EQ...
Let's make sure we are talking about the same thing... two speakers, both with the same drivers, same baffle shape, same crossover, and it is a good crossover that results in a good smooth flat response. One pair is has a heavily constructed, well braced, and the cabinet is pretty inert. The second pair is made of thinner material and little bracing. In this case, the sound quality difference between these two pairs will be small. You may have to listen for a while before you can tell them apart.
Now let's do another thought experiment where we take two pairs of identical heavily constructed cabinets which are very inert. In one pair we install high quality low distortion drivers, and a well designed crossover. In another pair we install mismatched drivers and a poorly integrated crossover. I bet we can hear a huge difference after the first 10 seconds of listening. The great cabinet does nothing to redeem the poor design.
So that is what I meant by " There are many things a loudspeaker needs to get right before enclosure stiffness and damping are worth worrying about. "
Floyd Toole's large body of research showed that frequency response on and off axis is the most important factor in whether a speaker sounds "very nice" or "merely good" or "meh" or "terrible". Other things like harmonic distortion, power compression, cabinet resonances, yes these things matter, but not nearly as much as frequency response. Assuming we have achieved a flat smooth response, it is those secondary factors which differentiate between "very good", "excellent", "world class", and " OMG I am weeping it is so good"...