Crazy question... I'm looking to try my hand at a Synergy-style "rectangular" horn, but as a 180x60 config. Yes - side walls are basically the regular front baffle, with only upper and lower walls each at 30 degree off center axis. Is this something that could be modeled? In terms of assembly it would be a regular front baffle with two slanted flat boards (obviously with the 30 deg chamfered edge) attached right up to the tweeter surround.
And, on top of that, would it be possible to model the effect of some acoustic absorption? Or is that something only Akabak can do?
And, on top of that, would it be possible to model the effect of some acoustic absorption? Or is that something only Akabak can do?
Printing ABS Style with reduced cooling basically immediately runs into problems the moment cooling is being reduced.
I guess its mostly the material being used (Sunlu PLA+) is impossible to deal with this kind of geometry.
Sunlu Meta PLA looks promising to me, as it is printed at already 20° less. Cooling should be less of an issue.
In general i may benefit from designing an improved cooling assembly for my printhead...
I guess its mostly the material being used (Sunlu PLA+) is impossible to deal with this kind of geometry.
Sunlu Meta PLA looks promising to me, as it is printed at already 20° less. Cooling should be less of an issue.
In general i may benefit from designing an improved cooling assembly for my printhead...
Marcel, you mentioned a while back you got an SLA printer. Have you had much luck with it? As you say, only the z height affects the time it takes to print with SLA. However, how thick can it print before you get issues with curing the resin inside the part? Maybe it doesn't matter if it's encased in cured resin? But then what is the strength?That will take a few days
- That's the beauty of SLA printing, it takes the same amount of time no matter how big or complex shape is printed, only the height is what counts. The printer I have is too small for the whole 2" plug, I would have to print it in several parts (not sure I want to do that, maybe I will try).
I will have access to an SLA printer soon and I am considering experimenting with printing the throat and maybe phase plugs. I remember Earl stating multiple times that for OS waveguides, the most precision is required in the throat so that seemed a good candidate for an SLA print combined with filament prints further out in the profile.
Dan
For phase plugs, SLA is most certainly the way to go, but for waveguides I don't think it's necessary (in fact, I don't think that the precision is that much of an issue). I use a 0.25mm nozzle on a small FDM printer instead and for e.g. the ring inserts it works very well. I just found SLA too messy. But there are guys here who made the whole waveguides with SLA printers.
The printing was quite good (PLA). I had no success with filling the light epoxy, too dense to fit between the internal infill (5%) then, although I used slow-drying epoxy, the mixture heated up and somewhat deformed the profile of the horn, nothing that cannot be fixed, but I have to find another successful formula. We continue investigating....
mabat, thank you for your reply in post 14,430. Based on that I'll use your R-OSSE formula. I really like your ATHEX idea to make printing on a small printer easier not to mention enabling 6 beveled boards to make a hexagonal enclosure.
While the other ATHEX zip files I looked at had STEP files in the zip, the 460-25-7.2 (which I assume best fits a DE250) has only the ASC and not the STEP file. Could you add the STEP file or tell us the R-OSSE parameters to make our own? (I assume the R-OSSE profile is along the corners). My mesher will transition from the round throat to a flat so I only need a single profile though I have considered programming in your segmentation formulas. Again many thanks for your contributions even if you decide you need to keep that stuff proprietary.
For the folks above trying to fill their print cavities, there is a low viscosity, low shrinkage, low exotherm, epoxy that goes by the name of Stycast. It's expensive though. Alternately you might try going to a craft store and getting the epoxy they pour in sand paintings to stabilize it. I've used it in the distant past for that purpose and it was pretty low viscosity and I didn't notice shrinkage or exotherm. Maybe by now they have a cheaper Acrylic version. Another option is go down to your boat store and get West System epoxy 105 resin and 206 hardener which is also reasonable viscosity, but it is very mass sensitive so mix in small batches or the exotherm will melt things.
For myself my plan is to 3D print an envelope of the ATHEX above the straight transition line and make multiple petals from that mold in latex concrete which doesn't have rocks, just sand along with the binder. Have you ever tapped concrete? There is zero ringing and the stiffness (Youngs Modulus) is reasonably high. It cracks easily in tension and has moderate shrinkage, so I'll post how that turns out. At worst maybe I'll end up printing an envelope per petal and use the envelope as the tension member. Latex Concrete is less than 1/10 the cost of filament or epoxy.
While the other ATHEX zip files I looked at had STEP files in the zip, the 460-25-7.2 (which I assume best fits a DE250) has only the ASC and not the STEP file. Could you add the STEP file or tell us the R-OSSE parameters to make our own? (I assume the R-OSSE profile is along the corners). My mesher will transition from the round throat to a flat so I only need a single profile though I have considered programming in your segmentation formulas. Again many thanks for your contributions even if you decide you need to keep that stuff proprietary.
For the folks above trying to fill their print cavities, there is a low viscosity, low shrinkage, low exotherm, epoxy that goes by the name of Stycast. It's expensive though. Alternately you might try going to a craft store and getting the epoxy they pour in sand paintings to stabilize it. I've used it in the distant past for that purpose and it was pretty low viscosity and I didn't notice shrinkage or exotherm. Maybe by now they have a cheaper Acrylic version. Another option is go down to your boat store and get West System epoxy 105 resin and 206 hardener which is also reasonable viscosity, but it is very mass sensitive so mix in small batches or the exotherm will melt things.
For myself my plan is to 3D print an envelope of the ATHEX above the straight transition line and make multiple petals from that mold in latex concrete which doesn't have rocks, just sand along with the binder. Have you ever tapped concrete? There is zero ringing and the stiffness (Youngs Modulus) is reasonably high. It cracks easily in tension and has moderate shrinkage, so I'll post how that turns out. At worst maybe I'll end up printing an envelope per petal and use the envelope as the tension member. Latex Concrete is less than 1/10 the cost of filament or epoxy.
I've been using a dental plaster called Magic White, and I find it quite easy to handle. It heats up a bit but not to the point of being problematic, even when I've ambitiously casted large volumes in one go to hollow PLA parts. I wonder how this plaster would perform suppressing vibrations if, for example, the backside of petals of an ATH Exar were made by an open and deep honeycomb structure, and then this plaster was applied/massaged to fill it.
If not pouring, maybe a feasible way would be to use a standard tube of e.g. polyurethane glue/putty/sealant and fill sparsely (5 - 10%) infilled parts simply using pressure. Just two holes, for filling and an air outlet, would be needed for that. Maybe some 2K stuff, I don't know. These typically don't get too hot and cure moderately fast.
BTW, EXAR 400 has been updated.
BTW, EXAR 400 has been updated.
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Actually, I'm making a big concrete horn: https://www.diyaudio.com/community/...-design-the-easy-way-ath4.338806/post-7468717
I was able to make only the first one last year, I want to finish them this spring or summer.
It's not as dead acoustically as I imagined (it still rings somewhat), but otherwise I like it pretty much, it's nice to work with.
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I would guess that filling the parts with something like that must make for a pretty good damping, kind of CLD, because with the gyroid infill there's a net of thin walls through the whole interior of the part. Deforming the part will flex these walls and this must create shear forces and kinetic energy damped as heat in the filling material. At least that's how my imagination works 
I'm still trying to figure out what's actually happening in an extended-throat horn.
This is the throat impedance of such a device -
The real part is more than an order of magnitude higher around 700 Hz than for a "regular" waveguide.
How does this work? Is there a way to understand this intuitively?
This is the throat impedance of such a device -
The real part is more than an order of magnitude higher around 700 Hz than for a "regular" waveguide.
How does this work? Is there a way to understand this intuitively?
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This has been known for a long time, but I mean getting more of a "feel" for what's happening is more physical sense.
I believe some time visualization would be helpful, unfortunately that's out of capabilities of my tools at the moment.
Moreover, impedance is a steady-state concept, as far as I know. Probably not very telling in this regard.
Something is obviously resonating. It's just not clear to me what is in resonance and with what.
https://at-horns.eu/release/R-OSSE Waveguide rev7.pdf
I believe some time visualization would be helpful, unfortunately that's out of capabilities of my tools at the moment.
Moreover, impedance is a steady-state concept, as far as I know. Probably not very telling in this regard.
Something is obviously resonating. It's just not clear to me what is in resonance and with what.
https://at-horns.eu/release/R-OSSE Waveguide rev7.pdf