When you knock PP or TPU (>60D) they are quite dead (low E). You can also experiment with structure - sand inside, fibers, multimaterial CLD. You can print HIPS with thick wall and and infill like surf board and it will still resonante a lot.
Can we define here and now good scientific test?
Can we define here and now good scientific test?
I wouldn't be using a printed horn by itself....maybe for the finish side if its surface is that good but surely you guys are adding layers of epoxy (or something) to the back sides of these waveguides?! I thought of PETG as choice because its the one with lowest amount of warpage/shrinkage
Last edited:
The only deterministic (ie not based on feelings, intuition or any subjective input) way to design a non resonant part (horn or anything else) is through modal finite element analysis (FEA) factoring in both shape, materials, joints, bondings, constraints at external interfaces etc. This is the way any Mechanical part is designed with a guarantee that it will have no mode in its usage band (or controlled modes, ie modes either not excited or withblow Q etc.)
The only way to assess that a real part has modes or not is to attach accelerometers and hit it with a purpose-made hammer. The modal spectrum should 100% match the FEA, or some part of the design or manufacture has been done wrong.
I use this process daily at work, and could do it for mabat’s horns (fea on desgin, impulse response on actual part)
The only way to assess that a real part has modes or not is to attach accelerometers and hit it with a purpose-made hammer. The modal spectrum should 100% match the FEA, or some part of the design or manufacture has been done wrong.
I use this process daily at work, and could do it for mabat’s horns (fea on desgin, impulse response on actual part)
I quite agree with that. Using rectilinear infill, createas a somewhat porous web structure which I find quite damping. Haven't tried filling the horns with stuff yet.
Another thing I've seen people do with old metal horns is to coil rubber tubing around the back of the horn.
ag2 has it!!
I suppose this have to made specifically for each horn design in order to be optimal. But would it be possible to make a more generic solution from which a few design rules could be drawn, that if followed would giva say 80% performance? To be valid for the pattern of e.g. axisymetrical WG with a rollback?
- material properties
- wall thickness
- guides/stringers/cavities...
- etc...
//
I suppose this have to made specifically for each horn design in order to be optimal. But would it be possible to make a more generic solution from which a few design rules could be drawn, that if followed would giva say 80% performance? To be valid for the pattern of e.g. axisymetrical WG with a rollback?
- material properties
- wall thickness
- guides/stringers/cavities...
- etc...
//
