Advice on designing a spherical speaker

[Chris Roemer]

Yup: 0.02cf (about 600cc), 5/8"id by 3"long (straight section) port, but I'd add at LEAST an external R.O.
Fb near 110Hz. F3 near 100. 6wRMS Xmax lim. down to just under 100Hz, at about 90dB.

[zx82net]

Yup: 0.02cf (about 600cc), 5/8"id by 3"long (straight section) port, but I'd add at LEAST an external R.O.
Fb near 110Hz. F3 near 100. 6wRMS Xmax lim. down to just under 100Hz, at about 90dB.

Sorry, what's an R.O.Fb?

[Chris Roemer]

RoundOver
Fb is the Frequency the vented bOX is tuned to.
F3 is the -3dB "down-point" (essentially where the bottom end rolls off).

[Geoff Millar]

I agree it needs some kind of foot or supports. Three legs, or a poppet-valve sort of foot are what I'd consider.

As Curt Campbell says in his write-up of his "Exclamations" speakers, don't put them on a flat surface, as they will roll away......

Geoff

[TN Allen]

"I'd probably go to 0.1mm layer height for the finished unit..."

Is this the wall thickness? .1mm =~ .004" ? Just curious.

[zx82net]

"I'd probably go to 0.1mm layer height for the finished unit..."

Is this the wall thickness? .1mm =~ .004" ? Just curious.

Unfortunately, there's not really a simple answer to that.
Layer height is how much vertical height the printer lays down in one pass. Within one pass, the "line thickness" is determined by the nozzle diameter, which is typically 0.4mm. The vertical wall thickness of the finished part will effectively be a multiple of that. The slicer programs used to generate code for 3D printers will automatically place cavities inside the walls, unless you tell them otherwise. This means when it comes the 3d printers, you'll hear a kinds of talk about wall thicknesses and infill densities. I designed this model with inner and outer walls of 2mm, each will take 5 passes of the 0.4mm nozzle. The reason for reducing the layer height on the finished unit is to get a smoother finish on the curved surface near the front. Thick layers produce what looks like contour lines on the finished part.

[TN Allen]

I'm familiar with 3D printing, but the printers are older and the filament thickness as it builds is probably closer to .2mm to .4mm, though I should check that, and the surface is comparatively rough. A smoother surface, without sanding, would be a significant improvent.

[3rutu5]

I'm interested project, I didn't have much fun with those drivers, but would like to see them put to good use

[zx82net]

I'm interested project, I didn't have much fun with those drivers, but would like to see them put to good use

I'll keep you posted. I'm expecting the drivers to be delivered later this week. I'm going to try them sealed, ported and with the PR, in the same enclosure, see how they come out.

[zx82net]

I've started a little test box to try the driver out with 1 or 2 passive radiators or a port. I've printed filler blocks so i can vary the volume between 500 and 300cc.

[zx82net]

Cross section, with all the fillers in place: