Thanks for the catch/advise @Patrick Bateman Not a chance this is a project I was going to hit print on so early in ownership of this printer. I just pasted it in to get a very rough print time, filament and cost estimate, have a look at it in my print volume and to see if anything else objected. I dont have the filament to take that on yet anyway. You are right of course, minimising contact/surface area with the bed is advised, once past the threshold you need for adhesion I guess and making the length of pull across a long part shorter like that seems wise too, less length = less contraction, which I expect is much less than pictured here, or perhaps even just tilt the part a little off the bed, say 5-10 degrees and leave it that way up if that will fit? (attached is tilted over 15 degrees (supports are not at all optimised). that could require less support material. Upside down with some supports would definitely work though. Print could take considerably longer with that much support. Some scale experiments on different materials up first and other prints are well before something this big. initially i'm printing carbon fibre nylon extrusions and mounts, so much less demanding shapes.
The first sizeable print i'm doing will probably be an impeller for a quick fume extractor. I live in the space the printer is and that itself would be the first reason I would avoid ABS. I'm building a big sort of extractor box to put the whole printer in ideally, so I can shut the door on that and erm ... pull it out to the outside world (no neighbours nearby, outside space is not so much a luxury as inside). it is enclosed and HEPA filtered, but still I would like to solve that problem for when more aggressive materials are being used. If there were more straight edges in this shape you might consider trying to angle it a little bit just for surface quality and strength, but as the shape is somewhat organic already I dont think it would matter as much for quality—or strength—just printability; as you say. The large prints ive seen so far in this thread and others look great at even larger nozzle sizes, but yes, buckling does seem a theme for this size at least in open printers. I think my hot-end will go up as far as 1mm nozzle, stock, but I will probably print this at 0.6 or 0.8. I'm a relative novice here in practical terms, but fairly well researched. Its something ive been gazing from afar at for years though and the tech (filaments included) passed a threshold of usefulness directly in engineering terms ie, printing end use parts at a level I could afford/justify, just recently. Buying a printer instead of buying a set of prototype parts, ie getting someone else to do the print or machining became a very real possibility vs the cost to do so say 5 years ago. The print quality you can get after a bit of finishing is really quite impressive and it has become more acceptable to the end user, post pandemic as you see it all around you now.
The first sizeable print i'm doing will probably be an impeller for a quick fume extractor. I live in the space the printer is and that itself would be the first reason I would avoid ABS. I'm building a big sort of extractor box to put the whole printer in ideally, so I can shut the door on that and erm ... pull it out to the outside world (no neighbours nearby, outside space is not so much a luxury as inside). it is enclosed and HEPA filtered, but still I would like to solve that problem for when more aggressive materials are being used. If there were more straight edges in this shape you might consider trying to angle it a little bit just for surface quality and strength, but as the shape is somewhat organic already I dont think it would matter as much for quality—or strength—just printability; as you say. The large prints ive seen so far in this thread and others look great at even larger nozzle sizes, but yes, buckling does seem a theme for this size at least in open printers. I think my hot-end will go up as far as 1mm nozzle, stock, but I will probably print this at 0.6 or 0.8. I'm a relative novice here in practical terms, but fairly well researched. Its something ive been gazing from afar at for years though and the tech (filaments included) passed a threshold of usefulness directly in engineering terms ie, printing end use parts at a level I could afford/justify, just recently. Buying a printer instead of buying a set of prototype parts, ie getting someone else to do the print or machining became a very real possibility vs the cost to do so say 5 years ago. The print quality you can get after a bit of finishing is really quite impressive and it has become more acceptable to the end user, post pandemic as you see it all around you now.
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Or pony up for printing it with carbon or glass loaded filament, which increases lateral stability. here is the next size printer up from mine being used for large ABS parts sitting on the bed.
check at 28minutes
Multimaterial printing, which mine doesnt have either. Mine is the newer, with autobed levelling though. this was another grand and I couldnt bring myself to go quite that far on first printer.
check at 28minutes
Multimaterial printing, which mine doesnt have either. Mine is the newer, with autobed levelling though. this was another grand and I couldnt bring myself to go quite that far on first printer.
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It’s interesting that given the benefits of a heated chamber we didn’t see more aftermarket DIY projects addressing this in the prior 5 years. I have a folgertech I haven’t finished assembling and went down the upgrade rabbit hole and burned myself out and while I have seen projects that enclose the printer, today is the first I’ve heard about a heated chamber.
I probably just haven’t been paying enough attention.
Regarding the woofer placement revision; it was my above motivational issues getting the 3D printer setup that has prevented me from forging ahead with printing Bill’s latest iteration. Otherwise, I’ve had all the drivers and crossover components for the pair (and enough Baltic birch to make at least one enclosure). Sadly I am becoming one of the afflicted here, with drivers and “roadmaps” and little time or space to follow through.
I’m finishing two speaker jobs at the moment. They are both large pairs that will free up a lot of workspace when they are completed and delivered. Let’s see what can be done.
I probably just haven’t been paying enough attention.
Regarding the woofer placement revision; it was my above motivational issues getting the 3D printer setup that has prevented me from forging ahead with printing Bill’s latest iteration. Otherwise, I’ve had all the drivers and crossover components for the pair (and enough Baltic birch to make at least one enclosure). Sadly I am becoming one of the afflicted here, with drivers and “roadmaps” and little time or space to follow through.
I’m finishing two speaker jobs at the moment. They are both large pairs that will free up a lot of workspace when they are completed and delivered. Let’s see what can be done.
As you guys are mostly trying to print it in PLA, you dont want a heated chamber, its probably a mixture of bed adhesion, actual drafts and wrong temp/uneven bed temperature across the bed that is causing issues. Most people print in PLA on their lower end printers as its cheap and available. That alone would lower the number of potential projects/mods for heated chamber and you would also have to make sure that all the components (caps etc) are specified for the higher operating temp. There are a few if you look though. I just wanted one that was ready to go, so I didnt bookmark those, sorry.
A well enclosed chamber gets you most of the way there if you want to use other materials like ABS and nylon. My printer only comes with an enclosed chamber stock, not heated and it is a later model, designed specifically for printing carbon loaded nylon (higher temp than ABS), but is easy to add a little boost and better insulation to the chamber. Just enclosing the printer properly and using a higher bed temp means the chamber gets up to around 60C during printing anyway, so I expect it only really needs to boost to around 80C for even higher melt materials like PEKK/PEEK and some higher temp nylons; from what i understand.
indeed, lets see what can be done!!
A well enclosed chamber gets you most of the way there if you want to use other materials like ABS and nylon. My printer only comes with an enclosed chamber stock, not heated and it is a later model, designed specifically for printing carbon loaded nylon (higher temp than ABS), but is easy to add a little boost and better insulation to the chamber. Just enclosing the printer properly and using a higher bed temp means the chamber gets up to around 60C during printing anyway, so I expect it only really needs to boost to around 80C for even higher melt materials like PEKK/PEEK and some higher temp nylons; from what i understand.
indeed, lets see what can be done!!
Wont see a lot from me for a bit though. my first project is building a larger drybox filament system and buying a food dehydrator (the purpose built stuff is $$$$) as the materials I want to use like the nylons are very hygroscopic, so i'm not even buying bulk filament until Ive got a better way to use and store it..
for those that might be looking at a higher performance printer, dont mind a bit of a closed system, have a bit to spend (a grand) and dont mind going down the rabbit-hole a bit, because its relatively untested, you might have a look at this rather impressive kickstarter. Bambu Lab X1 check out the carbon version too. its a bit small for my purposes and no distributers on my side of the pond. i'm watching this space with interest though, as its just too cheap, even at the full price.. The Voron is very interesting too, but also too new for me to buy, at version 0.1
and a note, the thing that makes this so fast with PLA is the massive fan pointed at the build plate just below the nozzle by the looks. so cooling the pla as soon as its attached itself to the layer below looks the way to print PLA well, completely different to ABS.
saw a video of it printing a benchy last night. the thing is blisteringly fast. printing at 220mm a sec ... and that isnt even its 'ludicrous mode' yes, it has a ludicrous mode ... lol.
here it is. if I lived in the US, I would have just bought one as a second machine. I'll wait and see what their support is like and for a larger machine (preferably with heated chamber).
and a note, the thing that makes this so fast with PLA is the massive fan pointed at the build plate just below the nozzle by the looks. so cooling the pla as soon as its attached itself to the layer below looks the way to print PLA well, completely different to ABS.
saw a video of it printing a benchy last night. the thing is blisteringly fast. printing at 220mm a sec ... and that isnt even its 'ludicrous mode' yes, it has a ludicrous mode ... lol.
here it is. if I lived in the US, I would have just bought one as a second machine. I'll wait and see what their support is like and for a larger machine (preferably with heated chamber).
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Interesting thread. I'm still reading it. But, I think what was said is that the shape (maybe corners rounding) of the speakers affects sound waves and extends directivity control. If a speaker is mount in-wall (soffit mounted), then such advantage is lost. If one builds baffle walls for LCR speakers, I think that most will soffit mounted them, if possible.
After playing around with these waveguides for a while I just could never get them to not scream at me. I always blamed it on my terrible crossover skills (I never tried Bill's crossover, always active with a miniDSP), but I've come to the conclusion that it's really the midrange drivers that create so much 'honk' for lack of a better word (be it Homs or diffraction distortion, time domain artifacts or whatever it is) that I can't fix.
Just listening to the mids on their own with no crossover (but some eq to get rid of the out of band artifacts) they really sound awfully screamy and distorting. When I compare that to 'normal' speakers with 24dB filter slopes at around the same crossover points as the natural bandpass of the MEH mids (i.e around 300 and 1300Hz) the sound is waaaay cleaner.
So I'm really questioning the concept of having midrange taps at these wavelengths for a truly clean and transparent speaker. Now the positive qualities of having a point source are significant and they sound really engaging and lively with great plasticity as if one's "there". But there's just this screaming quality that never goes away unless I listen really quietly (which is what people like Earl Geddes have been saying forever, that Homs and such effects become more noticable with volume).
This became double apparent once I had the prototype of the SEOS-30 MEH running, which is crossed at around 500Hz for now. The 12-inch woofers playing through slots at 500Hz sound just fine, whereas the little midrange playing through holes at 1300Hz really scream. I think there's a reason why Genelec in their coaxials are really invested in having as little diffraction as humanly possible for the mids down to about 400Hz, but then let the woofers play literally from behind the waveguide with zero direct sound.
I don't know why, but something seems to change in perception regarding diffraction artefacts between 1000Hz and 500Hz that's bigger than the doubling of the wavelength might suggest. Anyway, just some thoughts on this.
Just listening to the mids on their own with no crossover (but some eq to get rid of the out of band artifacts) they really sound awfully screamy and distorting. When I compare that to 'normal' speakers with 24dB filter slopes at around the same crossover points as the natural bandpass of the MEH mids (i.e around 300 and 1300Hz) the sound is waaaay cleaner.
So I'm really questioning the concept of having midrange taps at these wavelengths for a truly clean and transparent speaker. Now the positive qualities of having a point source are significant and they sound really engaging and lively with great plasticity as if one's "there". But there's just this screaming quality that never goes away unless I listen really quietly (which is what people like Earl Geddes have been saying forever, that Homs and such effects become more noticable with volume).
This became double apparent once I had the prototype of the SEOS-30 MEH running, which is crossed at around 500Hz for now. The 12-inch woofers playing through slots at 500Hz sound just fine, whereas the little midrange playing through holes at 1300Hz really scream. I think there's a reason why Genelec in their coaxials are really invested in having as little diffraction as humanly possible for the mids down to about 400Hz, but then let the woofers play literally from behind the waveguide with zero direct sound.
I don't know why, but something seems to change in perception regarding diffraction artefacts between 1000Hz and 500Hz that's bigger than the doubling of the wavelength might suggest. Anyway, just some thoughts on this.
Hmm, I haven't noted that problem, using 2" or 4" mids with sealed backs they still sound clean to me even at neighbor bothering volume. I have run into extreme harshness a few times that I was able to trace down to the cone or surround hitting the surface the midrange is mounted on, there has to be good clearance on the mounting surface. Had that problem with woofers too. Not saying that's what you're hearing, but worth checking.
I didn't know 'honk' was a technical term in this context. 
@bwaslo I doubt that's the case as I've used some sealing foam strips on top of that brittle cardboard gasket the TF041MR midranges have which creates some extra distance. I also tried some Faital 4FE35, which fit your design as well and while the effect feels a little attenuated, it's also hard to tell as they're open back and I've never built an enclosure for them. So the rear signal is always there, which really disqualifies any real judgment.
I'm pretty sure the drivers work fine and then the issue for me is with my (or anybody's) perception and the audibility of diffraction and at which wavelength this becomes a non-issue.
@bwaslo I doubt that's the case as I've used some sealing foam strips on top of that brittle cardboard gasket the TF041MR midranges have which creates some extra distance. I also tried some Faital 4FE35, which fit your design as well and while the effect feels a little attenuated, it's also hard to tell as they're open back and I've never built an enclosure for them. So the rear signal is always there, which really disqualifies any real judgment.
I'm pretty sure the drivers work fine and then the issue for me is with my (or anybody's) perception and the audibility of diffraction and at which wavelength this becomes a non-issue.
IME it's the throat + mouth termination that 'ruins' a technically correct horn design, so recommend wrapping a plush bath towel around the mouth to quell its eigenmodes and if that helps, but doesn't cure it, then lightly stuff an open cell sponge down between the mids/throat to quell any internal reflections and if this works, then need to rethink the design.
Note that the air trapped between the horn/driver is a low pass filter and the MI chart notes/implies that this BW may need to be suppressed, so wondering if the added gasketing isn't the culprit.
Note that the air trapped between the horn/driver is a low pass filter and the MI chart notes/implies that this BW may need to be suppressed, so wondering if the added gasketing isn't the culprit.
There's your answer, right there.
I started building Unity horns seventeen years ago and it took me about five years of obsessive work where I could come up with a crossover which was somewhat functional.
On top of that, a lot of the 'secret sauce' of the crossover is nowhere to be found in the patents.
Danley has dropped a few hints in various diyaudio posts. But I think most people have fixated on the physical aspects of the horn itself, when That Point Source Magic requires sorting out the xover. In particular, you have to be conscious of how the drivers are delayed by the xover.
A big part of the reason I never finish Unity horn projects is because I hate making crossovers.
Hi Vathek,
Kindest regards,
M
For me, this is just a confirmation how differently we perceive sound. I have heard several different Unity/Synergy incarnations, and I have never experienced anything similar to what you describe.
Kindest regards,
M
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