Speaker Design – from scratch – Rev3 – Parametric!

Ok, Figiured I’m spending alltogether too long on the doodling, so lets make a fully parametric grid upon which I can ‘draw’ the enclosure and start extruding a bit to define the waveguide………….After much googling and figuring out a bit of Fusion’s formulas and parameters…………..

Speaker Parametric 1

 

 

and, the below shows how the guide is dimensioned –

Speaker Parametric 2Speaker Parametric 3

The Above image shows the grid upon which the waveguide ‘maze’ is being placed.

Its dimensions are simply made up of small squares of wall thickness and larger squares of waveguide height. This will allow me to highlight rows and toggle them from being construction lines to full lines … after which I select the whole square and extrude it upwards!

The purple image on the right is a rough representation of the speaker front and rear….

Starting from the Top

  • Fx 110 – this is the speaker cabinet width –
    • Defined as Waveguide width + wall width + wall width
  • 100 – Speaker diameter
  • 80 – Speaker cutout
  • 60 – Speaker cone diameter (you have to manually derive this from the speakers SD
  • fx 100.00 – Waveguide width chosen
    • I originally derived this from the speaker cutout size but lots of experimentation suggested to leave it independant and manually adjustable
    • since this is a simple box, the waveguide’s maximum width will be the space between the two sides of the enclosure!
  • fx 38.3 – This waveguide width is derived from a formula
    • ( ( ( SD_Speaker * 100 ) / ( Guide_Width / 10 ) ) / 10 ) * 1 mm
    • Since we know the speaker cone’s surface area (SD in cm2) and if we know one dimension of a rectangle of the same area, we can derive the second dimension….
    • In this case we know 28cm2 = 100 mm width x ? height
  • fx 10 – This is simply the chosen box / enclosure wall thickness.

 

Just to show how well the parametric stuff works, lets set the wall thickness to 40! (note how large it’s become compared to the fixed sized speaker outline!)

Speaker Parametric 4

And, for my final act, a wall thickness of 1mm!

Speaker Parametric 5

 

It’s early days yet – I still need to figure out how to measure the length of the path of the airflow – Right now it’s about 33 waveguide widths and 34 wall widths, which on the 10mm wall width version gives

  • (28.3 * 33) + (10 x 34) = 1273.9 – or,  roughly 127cm….Significantly longer than I need!

Now i’ve figured the math out, it’ll be back to optimising the waveguide path somehow – I’d really like to keep the speakers to not much larger than the ones I currently have

which are roughly 140 h x 90 w x 120 depth

I say roughly those dimensions as right now I can’t find my ruler and have used a standard credit card for scale –

in credit card terms, my existing speakers are dimensioned thusly

1 stood vertical + one stood horizontally high x just over 1 wide x 1 and the top part of my thumb deep

 

 

Author: Bleugh

Early Fourties, Wife, two kids in primary school. Both of us work full time...5 years now we’ve been Back in Blighty after a decade away...It's a new country for everyone! Still finding time to tinker!

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out /  Change )

Twitter picture

You are commenting using your Twitter account. Log Out /  Change )

Facebook photo

You are commenting using your Facebook account. Log Out /  Change )

Connecting to %s

%d bloggers like this: