Most spec sheets come with the dimensions and the bolt hole parameters.

We saw that earlier in the sketches I provided.

And you should use this in planning your design and also the mounting

configuration. You always want to mount the transducers

from sorry about that, mount all the transducers from the outside of the

enclosure. if you mount them from the inside you end

up with some diffraction and you know, round the opening of the box itself.

And you know, some added dynamics that, that are not desirable.

So you always mount the the transducers from the outside of the box.

So, you know, they'll have a, a flange on them if you, if you imagine the cutaway

of the box looking something like that. the speakers will have a flange and the

flange will sit on the outside. And then of course, they'll fit inside

the whatever opening you that cut in the box.

But mount, mount them on the outside of the box here, so this is the interior of

the box, all right? So with that those basic guidelines those

should apply whether you're designing ported enclosures or you're designing an

enclosed box. But we're going to start today talking a

little bit more about closed box design. And so for the moment we're going to go

back to our old discussion of the Helmholtz resonator.

And if you recall when we put a speaker in a box, the enclosed air in the box

actually adds stiffness. So if we have a speaker with a diaphragm

of a given mass and it'll have its own spider and suspension system.

So this is the tranducer, these two components are fot the transducer on its

own. But once you set that transducer in a

box, you ger an added stiffness that's associated with the enclosure and I've

kind of sketch that over here. you know, where we've, I, I show the box

and the transducer itself, and of course there's a, a stiffness associated with

the speaker. The, the spring doesn't sit up here on

top of the transducer, I just sketched it symbolically.

And then we have some stiffness associated with the enclosure, the box

itself. but it turns out that the the total

stiffness of the box. Or I mean the total stiffness for the

design is going to be the sum of the stiffness of the speaker itself plus that

of the box. And so, if you can calculate a new,

natural resonance frequency associated with the box or you know, the speaker

designed in the box. Based upon the mass of the vibrating

diaphragm of the speaker and then of course the total stiffness in the box.

Now, box stiffness we already covered earlier, but I'll, remind you again with

the equation here that the box stiffness depends upon, you know, some basic

parameters. Such as the density of the air, the speed

of sound in air, the volume of the box and then, of course, the radius of the

driver. so you should remember, for a given box

size/volume, the stiffness really depends upon the area of the transducer, or the

radius of the piston. So a fixed box size doesn't have a fixed

stiffness. A fixed box size has a stiffness that's

dependent upon The radius of the speaker, okay?

And so if you end up with a smaller radius, then you're going to end up with

a higher stiffness. If you end up with I mean, a smaller

stiffness, if you end up with a larger radius, you're going to end up with a a

larger stiffness. So they're proportional but, you know,

it's proportional in terms of the square of the radius and then the square of the

area. it's an important part of the design

consideration. Some basic Thiele-Small parameters

required for design basically are the speaker or transducer, free-air

resonance. This is with no box and then Qt, Q sub

ts. the ts is a subscript just known to

represent the total Q of the driver at resonance.

And again, the Q can be thought of an amplification factor at resonance.

The greater the Q, the sharper the resonant peak.

So I, I shown this here in a diagram that I generated for increasing Q.

And you can see that, you know, basically our our resonant peak is in this domain

here. And as Q increases, and that's what this

arrow is here. The, the peak gets taller, so the

response becomes sharper, if you will, around that frequency.

And you know, we can debate over which curve might be an optimal curve if we

were looking at the response of of of a speaker itself.