DIY midtweeter planar with flexible PCB membrane, a recipe for disaster?

[WrineX]

i thought you where not making a ribbon ribbon, like unsuported on the sides ? if so you dont need any reinforcement, i would say corruagte a foil , and see how well it holds?

 

[OllBoll]

i thought you where not making a ribbon ribbon, like unsuported on the sides ? if so you dont need any reenforcement

I'm not, or at least I don't think I am.

My plan is to basically do this

but:

1. lengthen to 160 cm.
2. Swap the foam to TPU rubber which may have small teeth to help keep the corrugations + hold the shape.
3. Mainly use a 3d printer to make the frame, although I will use laser cut wood and metal reinforcements where needed.

 

[WrineX]

aah ok, but not the curved one i guess so you will go for the low resonance non stretch thingy

 

[OllBoll]

I seem to be the master of confusion

I'm currently only planning to build a single set of planars. All the crazy ideas are just musings of different designs of how to either improve performance or make it more easy to manifacture.

So yes, the above mentioned planar would be curved. And yes exactly with the low resonance from being non stretchy. Mostly because I'm not sure how I'd actually manifacture a 160 cm long curved planar that is properly tensioned. So if I can skip the tension and still get good results then it seems like an a good place to start.

 

[solhaga]

Exactly.

Since my driver will be so tall (160 cm) I believe I'll need to not just rely on the aluminum itself to keep the corrugations. My current plan is to print toothed TPU gaskets which then locks the corrugations in place.

In the easy case where I have lengthwise magnets I think it should be simple as long as the corrugations are consistent, to handle shift errors I can just make the membrane a few mm longer and allow it to shift up or down to slot into the teeth.

But if I orient the magnets sideways I just realized I would be able to have pretty big corrugations without impacting xmax. That is, if I could ensure that the corrugations only protrude in the area not covered by the magnets. Big corrugations would also make it a lot easier to ensure alignment since printing too small teeth in the TPU gaskets would be a problem.

I think it would be doable but it would probably require me to get creative when corrugating the foil. A normal roller would probably accumulate errors but say if I did a jig that creates a single corrugation and then do them all by eye manually. I could add extra guide lines on the outside of the membrane to help align everything. As long as my error is say within half a mm and independent on all the other existing corrugations then I think it would be feasible.

I've had the same idea, but I thought TPU is still to stiff.
Have you tested it yet?

Nice with the Silhouette Cameo 4 by the way. I'm currently waiting for my second machine, a Silhouette Cameo 5.
A nice thing about that machine is that you can cut on narrower material (5"/12,7 cm).

 

[OllBoll]

I've had the same idea, but I thought TPU is still to stiff.
Have you tested it yet?

Nice with the Silhouette Cameo 4 by the way. I'm currently waiting for my second machine, a Silhouette Cameo 5.
A nice thing about that machine is that you can cut on narrower material (5"/12,7 cm).

I have not tested printing the TPU yet. I did order the foaming VARIOSHORE TPU which can print with a shore hardness down to 65A which I hope will be soft enough.

About the Cameo 5. I didn't know that it was much better on narrower materials so based on that I sent a cancellation request for my Cameo 4 so that I can reorder and get a Cameo 5.

 

[solhaga]

VARIOSHORE TPU, that's interesting!

I guess that you'll have to wait a while then, especially if you want the black one; they are on back order.
Cameo 5 are also more expensive than 4