3d printers recommendations for printing horns and waveguides

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#43
#44
Don`t confuse mpp with a perforated panel. The microperforated panel is sub mm size holes compared to a more conventional perforated panel.
There's different functions in play, sort of. This seems to be the agreed upon origin to the mpp https://pascal-francis.inist.fr/vibad/index.php?action=getRecordDetail&idt=PASCAL7588507573


The tweeks one can do is amount of sub mm holes/surface area, the depth of the back chamber, and also depth of the actual hole.
https://www.researchgate.net/public..._thick_micro-perforated_panel_sound_absorbers
 
#45
Nissep said:
Don`t confuse mpp with a perforated panel. The microperforated panel is sub mm size holes compared to a more conventional perforated panel.
There's different functions in play, sort of. This seems to be the agreed upon origin to the mpp https://pascal-francis.inist.fr/vibad/index.php?action=getRecordDetail&idt=PASCAL7588507573
Click to expand...
perforated panels are pretty much the same as microperforated ones as i understand it, both are based on helmholtz resonators...... the only differences is that the micro hole size allows for another variable, which is velocity change from baffle to microhole which gives a little additional absorbtion

tho i would get my hopes too much up making MPP's with a FDM 3d printer, you are probably lucky if you get "close to perfect" 0.5-1mm holes
 
#46
I’m having a hard time remembering how small I tried to go. But smaller than 1mm that I’m sure about. I used drill bits for circuit boards to check. I think it was 0,3 0,5 0,8mm in the model.
1739807323632.jpeg

1739807451797.jpeg



On this one we can simply count the layers, there suppose to be 0,2mm
1739807596782.jpeg
 
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#47
ah doesnt look too bad ! what is this part of?

i guess best case would be 0.1-0.2mm with a fdm printer

i think the velocity change thing on microholes is something gradually increasing (with decreasing size), so even 1mm holes could already benefit a bit from it
 
#48
N

Post in thread 'Acoustic Horn Design – The Easy Way (Ath4)'

I’m not going to distract to much, but I’m continuing the work on making my tiny 4” coaxial with controlled directivity.

I have since the last time tried adding a center tube in the back chamber that is a press fit against the magnet with micro perforation like example C in this paper. https://mdpi-res.com/d_attachment/a.../acoustics-03-00031-v2.pdf?version=1625566551

So there’s three rows with 36 0,9mm holes close to the open back, then there’s 3x36 0,7mm, 3x36 0,5mm, 3x36 0,3mm.
The tiny holes is one layer thick on my 0,4mm nozzle. In the...
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