Anyone fancy making their own passive radiators?

[zx82net]

I made a parametric toolkit for 3D printing passive radiators of any size. Believe it or not, they actually work pretty damn well.

You can get them here:
https://www.thingiverse.com/thing:4825265

[Fishchris]

Hey, this is pretty cool Considering how simple a PR is, I can imagine, they would work pretty well This makes me wonder why all (that I know of) PR's are designed with baskets and spiders, etc. Why do we need to pay for all that fanciness ? Hey, if you want to make some more, you can make me a couple 18"s. Im running two 15"s ... but should have went with 18"s to begin with. It would be awesome to have a PR like the blue one on the bottom of your pic (rectangle with rounded corners... whatever that shape is called, of about 18" x 30" to use in my 5cu ft box, with my 18" sub

[zx82net]

Hey, this is pretty cool Considering how simple a PR is, I can imagine, they would work pretty well This makes me wonder why all (that I know of) PR's are designed with baskets and spiders, etc. Why do we need to pay for all that fanciness ? Hey, if you want to make some more, you can make me a couple 18"s. Im running two 15"s ... but should have went with 18"s to begin with. It would be awesome to have a PR like the blue one on the bottom of your pic (rectangle with rounded corners... whatever that shape is called, of about 18" x 30" to use in my 5cu ft box, with my 18" sub

Yeah, I think for most driver manufacturers there is an element of just reusing an existing driver design, and they certainly work well. If you look at a lot of the portable speakers and the Tang Band modules, the radiators are just a weighted disk in a single membrane. The trick is keeping the center of mass in line with the membrane, so it doesn't sag. I made a double membrane version to offer perfect symmetry, but I think its actually overkill. I made some THD measurements VS a Peerless 830878, using a microphone positioned close to the PR, see attached.

[tomzarbo]

This is interesting stuff for sure. What do you think about the longevity of the flexing parts considering it's 3D printed stuff? On a few of those in the pic there looks to be a LOT of flexing material and very little actual 'cone' area. I guess this helps as the larger 'surround' would spread out the motion over a greater area. I've seen TB do this as well with their tiny PR's.
How big to you think you could make a PR with the material you print with? Would it be feasible to create most of a PR and then have a section printed for a 3/4" disc of MDF for example to bump up the mass?

TomZ

[zx82net]

This is interesting stuff for sure. What do you think about the longevity of the flexing parts considering it's 3D printed stuff? On a few of those in the pic there looks to be a LOT of flexing material and very little actual 'cone' area. I guess this helps as the larger 'surround' would spread out the motion over a greater area. I've seen TB do this as well with their tiny PR's.
How big to you think you could make a PR with the material you print with? Would it be feasible to create most of a PR and then have a section printed for a 3/4" disc of MDF for example to bump up the mass?

TomZ

I think I get about 5mm of linear travel per 10mm width to the surround. A 20mm surround seemed to work fine for the circular PR, but using it with the rectangular one, the straight sections kind of "flapped about" for want of a better term. This showed up very clearly in the distortion measurements, I could also see it as harmonic peaks in a live spectrograph. I think the heavy rubber material and the weird folded shape Tang Band use probably helps them combat this. Unfortunately, it isn't possible to reproduce those with an FDM printer, I'm basically limited to a pleated design.

The size limit will be the bed of the printer, so I could print a 12"x12" square surround, and yes, you could glue whatever material into the middle.

[Wolf]

The double-damper will combat the rocking of the mass and actually support more weight. It's always been said a PR with spider (or secondary suspension) is better than one without.

Later,
Wolf

[zx82net]

The double-damper will combat the rocking of the mass and actually support more weight. It's always been said a PR with spider (or secondary suspension) is better than one without.

Later,
Wolf

Yep, can't dispute the fact that it is mechanically superior.

[3rutu5]

oh hello there zx82net so i've been wanting to try this for a while and have some polyflex ready to have a go, was it worth it mate?

[zx82net]

oh hello there zx82net so i've been wanting to try this for a while and have some polyflex ready to have a go, was it worth it mate?

Absolutely, I think they work really well, totally appropriate for a sub-woofer. For a full range it probably warrants a bid of investigation to see how much HF passes through the surround, but it seems reasonable so far. I'm going to do some side by side tests with an ND65PR in my P-CUBEs

[3rutu5]

Absolutely, I think they work really well, totally appropriate for a sub-woofer. For a full range it probably warrants a bid of investigation to see how much HF passes through the surround, but it seems reasonable so far. I'm going to do some side by side tests with an ND65PR in my P-CUBEs

fantastic, i dont have fusion, but i'll see if i can suck all your hard work into autocad so i can incorporate one into my designs

[zx82net]

I put a drawing of the membrane cross section in the images, so you can just copy that and revolve it, or sweep it along a path, the rest is simple.

[zx82net]

here it is

[3rutu5]

cool, thats quite a thin membrane on the gussets. I tried 0.7mm with curves, but i dont think it really worked well, doing it like this makes more sense.

[zx82net]

Yeah. Note, the angled walls are 0.4mm across their horizontal intersection, not 0.4mm thick. I've printed over a dozen of these now, and I've found a single one to have a leak. I have a flex profile based on this:

https://www.bondtech.se/knowledge-ba...x-on-prusa-i3/

[3rutu5]

Yeah. Note, the angled walls are 0.4mm across their horizontal intersection, not 0.4mm thick. I've printed over a dozen of these now, and I've found a single one to have a leak. I have a flex profile based on this:

https://www.bondtech.se/knowledge-ba...x-on-prusa-i3/

What printer are you using for yours?

[zx82net]

What printer are you using for yours?

I print the flexibles on something that used to be a Flash Forge Creator Pro, now it has a Duet controller, Bondtech extruder and Mosquito hotend. I call it the Franken Forge :-D