Acoustic Horn Design – The Easy Way (Ath4)

I don't remember, I tried different settings but the BD graph didn't change much (above I posted the original IR from ARTA). There are two main issues here - insufficient reflection-free time (limited space in my workshop) and the response not being EQed to flat - I just didn't bother at this point. I show the decay because if I didn't people would think I don't want to show it for some reason 🙂
 
Here is mine, also from PETG. 0,1mm layer height and solid infill.
Solid infill, that's really extreme, I can't imagine printing it like that, the more so with such a thin layer. That sounds just crazy, in a good sense of course.

Do you think it has an advantage over say 50% infill?

BTW, these prints really call for a bigger nozzle, it can save a considerable amount of time. I use 0.6mm with 0.24mm layer and typically with a quite sparse infill (certainly no more than 20%). But I'm really considering printing some two-part molds. The problem is of course the exotherm during casting and curing but there are materials that don't heat up that much.
 
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A few things to note about printing etc.
1. I have found PETG to become brittle at high infill especially near 100%. Most of my experiments were using settings to make PETG see though. So very slow, +100% infill and HOT!
2. For moulds and prototypes resin might be ok. Long term stability of resins is still an issue IIRC. it is my understanding that long term stress causes them, to deform especially at elevated temperatures. I may be a little out of the loop on current resins but that was my understanding approx. 5 yrs ago when I was working much more with them.
3, Larger nozzles can go a bit faster, but the difference is not that much until you get a fair amount faster and have rather large layer heights. What time you save in printing you will spend in filling/sanding. If it is just for prototyping you will find that some slicers allow you to vary the layer height for different parts of the print. Perhaps not super useful for petals but might be helpful for the throat. I dont think there is really a lot to gained here unless you are doing large batches of prints. 1 offs / prototyping / stereo pairs you wont see much of an actual difference in saving 20-40% of time off a print unless you have your alarm clock synced with your printer. 😉
4. In my experience printing for casting I usually print the device I want, finish to a high standard (putty/paint/sand/etc - then gloss finish) put on the release agent make the mould from the part (fibreglass/silicone etc). Now finish the mould to an even higher standard, release agent etc. Now mould the part. This allows the use of materials that can hold the heat / stress etc. https://www.youtube.com/@easycompositestv has a few hours of videos worth a watch if you are interested. 😉
 
0.6 mm nozzle can reduce print time to almost a half compared to 0.4 mm, and give you a stronger print. Of course you can still consider that negligible 🙂

With the petals, the only area that may really gain from using a thinner layer is the top - the last inch or so, and there you can easily set it to e.g. 0.1mm without much time penalty, as it's a pretty small area.
 
4. In my experience printing for casting I usually print the device I want, finish to a high standard (putty/paint/sand/etc - then gloss finish) put on the release agent make the mould from the part (fibreglass/silicone etc). [...]
I should finally try that some day, i.e. the proper way of doing it. It just feels that too much know-how and skills are required to not only waste time, money and effort... These are large devices.
 
If I am going for speed I find my prints tend to be flow limited. I get around 30mm2/s with the 0.4 and 45mm2/s with my 0.6. I use the 0.2mm later height with the 0.4 and 0.3 with the 0.6 nozzle. Using the same number of walls and top/bottom layers. Lower infill with a larger nozzle I can get issues where the infill is too sparse to properly support the outer layers. They tend to warp a little especially where later time is small and there is a curve flattening to horizontal. All these things make my speed difference between a 0.4 and a 0.6 for an equal quality print. My older printers that were more limited by movement mechanics saw more of a difference between nozzle sizes. I just had a chuckle thinking about how one of my bedslingers would look printing a petal standing up at the accel/speed my Voron can run at. 🤣🤣🤣
 
I should finally try that some day, i.e. the proper way of doing it. It just feels that too much know-how and skills are required to not only waste time, money and effort... These are large devices.
It is a lot of work but a part from a properly made mould can require an incredibly small amount of work to finish. If you have the know how the magic number where is it worthwhile to put the work in is probably just above 2. I.e. the amount of work in making the mould is probably just a fraction more than properly finishing 2 printed ones...
 
... Using the same number of walls and top/bottom layers.
The point is that with 0.6mm you need only 2/3 of the walls as compared to 0.4mm for the same thickness. There's no reason to keep the same numer of walls, and then of course you don't save as much time as you could.

But if you are already flow-limited, that can be the barrier.

I just had a chuckle thinking about how one of my bedslingers would look printing a petal standing up at the accel/speed my Voron can run at. 🤣🤣🤣
I don't quite understand this, but it must be something funny 🙂
 
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Just for the sake of putting the data out there, here is the DFM 2535 on A520G2 response REW auto EQd flattish and the corresponding burst decay plot with a 40dB range on y-axis (based on the impulse responses provided in above posts)
1724168215946.png

1724168295231.png
 
I have no idea about the relative audibility of things from above plot.. 😀
But atleast for comparison, here are my EQd flattish measurements of the BMS 4550 & SB audience Rosso 65CDN-T (with throat insert) on the EXAR 400 horn
and the corresponding burst decays with a similar 40dB scale on y axis
1724170306893.png

1724170391882.png

1724170410370.png


The SB audience Rosso 65CDN-T (with throat insert) on the EXAR 400 horn is something that I use on a daily basis and have no issues..

Now copy-pasting the DFM 2535 from above
1724170577880.png


So may be the above burst decay plot with even the break up resonance related issues well suppresed and 30 dB below out to 14+ kHz should be really good I guess (atleast to the eyes.. 😛 )
 
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Solid infill, that's really extreme, I can't imagine printing it like that, the more so with such a thin layer. That sounds just crazy, in a good sense of course.

Do you think it has an advantage over say 50% infill?

BTW, these prints really call for a bigger nozzle, it can save a considerable amount of time. I use 0.6mm with 0.24mm layer and typically with a quite sparse infill (certainly no more than 20%). But I'm really considering printing some two-part molds. The problem is of course the exotherm during casting and curing but there are materials that don't heat up that much.
I do not know as I do not have a version with 50% infill to compare to. However, I can easily say, this is an inert horn. I will be measuring soon (within this week) and sharing data (which you already have, I guess).
 
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