Can you describe more detail how the sound changes with the vertical dispersion when you stand up and sitting on the listening position to the various distance (for example, 5 to 12 feet) from the speaker? I wanted to know if it will work on my living room and the listening distance is 9 feet to 11 feet. Thanks.
It is a very slow progress, but eventually, everything will be shared. Now I am trying to print the back enclosure for the AMT. I will look through my notes and answer your questions later.
@drumdoctor The current (inner) dimensions of the horn including the printed part down to the AMT membrane are: 530 mm width, 290 mm height, 320 mm depth. The -3 dB point is around 300 Hz with open backs, I thing I should get a lower response when I put the back covers on the mids. I estimate somewhere around 200 Hz crossover point should be possible. 300 Hz is actually good enough for my purpose (with a separate midbass unit below it).
@magic44ken I have only one unit built at the moment. The dispersion in the HF should be 30 degrees, which gives theoretically roughly 175 - 205 cm high window at the distances you specify. I would say that most of the perceived changes in sound would be from the reflections, not from direct sound. But I may be wrong.
@magic44ken I have only one unit built at the moment. The dispersion in the HF should be 30 degrees, which gives theoretically roughly 175 - 205 cm high window at the distances you specify. I would say that most of the perceived changes in sound would be from the reflections, not from direct sound. But I may be wrong.
A little progress. The AMT back cover is finished, the glue needs to dry, damping material will be installed and foam tape for sealing it. The parts are printed on different printers from different materials, that is why they do not align perfectly, one of the printers is not really calibrated for dimensions and prints slightly smaller things.
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I think I should try to go 3 way when the 2 way crossover is finally finished. The 8" Fane I bought for another project would fit fine🙂
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I have mixed feelings about the results. The sound is really great, no doubt about that, but it feels all quite impractical and I am not sure if I mind the narow vertical or not. Now I plan to built a large 3way Synergy with a traditional compression driver. And maybe then again one with an AMT - the arrangement around the throat must be done in a better way. Since I always wanted to try a proper open baffle speaker, the AMT will be used with a Deltalite II 15" in a minimal baffle test arrangement.
An AMT synergy is really something special, but I think I need to gather more practical experience to do it correctly next time. I still have an idea or two and I plan to use the GRS planars as test units, since they are easier to mount. Still, I consider the Heil AMT the best sounding HF unit for my ears...So good that I will most probably build a second quick and dirty impractical unit for listening before the large synergy is built.
An AMT synergy is really something special, but I think I need to gather more practical experience to do it correctly next time. I still have an idea or two and I plan to use the GRS planars as test units, since they are easier to mount. Still, I consider the Heil AMT the best sounding HF unit for my ears...So good that I will most probably build a second quick and dirty impractical unit for listening before the large synergy is built.
I was thinking a bit more about this and tried fitting things together in 3D and actually, it will be possible to build a large 3 way MEH with the AMT. Using slightly lower crossover than now, one 4NDF34 firing from the top, and (most probably) a 10CL51 firing from the bottom, both sealed. All this with 90 x 40 pattern and 75 cm internal mouth width, single flare with the option of adding the secondary if needed.
@pelanj I don't know if you're still active in this project, but I've been following along with some of your experiments and have done a few of my own. I recently mocked up a tractrix horn with the Heil AMT and a 3d printed adapter somewhat similar to yours, and I got some pretty interesting results. Here are a few photos of the horns I've been testing as well as the frequency response changes.
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Which curves are which? As I recall, ESS AMT-1 in a flat wall synergy was one of the best sounding speakers I have ever heard.
That looks pretty nice! My most recent experiment with the AMT is here https://www.diyaudio.com/community/...eter-faitalpro-3fe22-mids.400527/post-7844045 - slightly larger horn and a larger midbass driver - I had mixed feelings about that one - the midbass is too far away from the throat in this arrangement, so I cannot really make a nice crossover for it. I also do not really like the narrow vertical pattern - the cinema speaker next to it is 90 x 90 CD horn and it covers the room much better - especially sitting vs. standing (as expected). The midbass issue could be relatively easily solved with using a smaller driver closer to the throat. I do not think I can solve the narrow vertical pattern - only learn to live with it and listen seated only.
@xrk971 Top pink curve is the large tractrix, the green is the smaller white 3d printed waveguide, and the bottom is the bare heil.
I will admit I have no idea what I'm doing - a lot of the electrical pieces of speaker design are still a bit foreign to me, but I'm very good at 3d modeling and fabrication so I'm going for a "build and test" route instead of modeling with Hornresp.
In fact, most of what I picked up about this came from threads with both of you on it, so thank you for putting all of this information out there in the world - it is really helpful for amateurs like myself to enter the hobby.
@pelanj that conical synergy horn is really interesting! Joseph Crowe did a speaker a while back that had a multi-entry horn throat, this project here: https://josephcrowe.com/blogs/news/co-entrant-horn-no-1416
A lot of this came from the fact that I picked up the Heil for relatively cheap (I think 125 a driver) and wanted to see what the fuss was about. I'm thinking about doing a two-way, hopefully high efficiency, with a simple-enough design that I could do a passive crossover as I have a 2A3 tube amp that has been collecting dust because of my (currently inefficient) speakers.
I will admit I have no idea what I'm doing - a lot of the electrical pieces of speaker design are still a bit foreign to me, but I'm very good at 3d modeling and fabrication so I'm going for a "build and test" route instead of modeling with Hornresp.
In fact, most of what I picked up about this came from threads with both of you on it, so thank you for putting all of this information out there in the world - it is really helpful for amateurs like myself to enter the hobby.
@pelanj that conical synergy horn is really interesting! Joseph Crowe did a speaker a while back that had a multi-entry horn throat, this project here: https://josephcrowe.com/blogs/news/co-entrant-horn-no-1416
A lot of this came from the fact that I picked up the Heil for relatively cheap (I think 125 a driver) and wanted to see what the fuss was about. I'm thinking about doing a two-way, hopefully high efficiency, with a simple-enough design that I could do a passive crossover as I have a 2A3 tube amp that has been collecting dust because of my (currently inefficient) speakers.
I'd also like to build a really "pretty" speaker - something like the big model from A for Ara or Oswalds Mill Audio. Like I said - my design and fab skills are way better than my speaker design skills, so I'm aiming to either work with something somewhat time tested and work through my speaker design sins with DSP.
Do you mean the round blue one? Yes, that one was a fun experiment - the biggest shortcoming of it is the lack of roundover at the mouth causing diffraction - I had plans to make a horn with curved walls like Joseph Crowe, but in this size it would require too much wood and work - it might still happen one day. The A for Ara horns are pretty nice, I dig the large 3 way MEH and I wish I had enough space for such a pair of speakers. The B2 is also cool and I still have a speaker build of this type somewhere down my future project list🙂
I'm curious - how much value did you find in the "coherence" of a MEH compared to a traditional speaker? I'm asking because as I go down this rabbit hole I realize to achieve the low cutoff frequency of such a horn it might get...large, quick. A more traditional 3 way with an upper horn might be easier scale-wise but I'm still in the "exploration" phase
The tractrix provided substantial gain and bass extension. This should reduce distortion by allowing you to play with less diaphragm movement. Whatever you did as the transition from Heil to the tractrix worked. I don’t see any notches. Can you share more images of that transition adapter? Or is it just tape?
Nice work!
Btw, I see your shop is loaded to the gills with Festool (routers and the like) so you are well equipped. 🙂
Nice work!
Btw, I see your shop is loaded to the gills with Festool (routers and the like) so you are well equipped. 🙂
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Yes, I've gathered quite a collection of overly-expensive but oh-so-sweet tools over the years! They're expensive but man are they worth it.
I have a couple of screen grabs of the 3d model and a section from above to show more or less what it is doing. I didn't get fancy with the throat adapter - it has square walls on the side with an top and bottom to match the heil vertical angles. I just taped the adapter to the tractrix horn with some duct tape and it was honestly pretty poorly crafted - I hot glued it together 20 minutes. If I ever decide to build a permanent pair of speakers I'd likely mill it out of a solid piece of wood. I'm trying to decide where to go with this - I have a 2A3 tube amp collecting dust that I'd love to hook up to it but I don't think I have the chops to design a passive crossover; I always use DSP.
I have a couple of screen grabs of the 3d model and a section from above to show more or less what it is doing. I didn't get fancy with the throat adapter - it has square walls on the side with an top and bottom to match the heil vertical angles. I just taped the adapter to the tractrix horn with some duct tape and it was honestly pretty poorly crafted - I hot glued it together 20 minutes. If I ever decide to build a permanent pair of speakers I'd likely mill it out of a solid piece of wood. I'm trying to decide where to go with this - I have a 2A3 tube amp collecting dust that I'd love to hook up to it but I don't think I have the chops to design a passive crossover; I always use DSP.
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Interesting that a straight parallel wall throat has such a nice response and even had gain. Great 3D modeling job!
@xrk971 - thanks! I am a design architect so I spend about 80% of my working days using Rhino to model stuff in 3d, so thankfully my professional life and personal hobbies here overlap pretty well.
To be honest I'm a bit humbled that you answered my post! I have been into the esoteric speaker design world for a while and I was looking back at some earlier plans I had put together for a Karlsonator - and it turns out you had also been the one who was largely responsible for that design update as well. I have to say of every community I've ever been a part of, the DIY audio community is some of the smartest and most generous people I know.
To be honest I'm a bit humbled that you answered my post! I have been into the esoteric speaker design world for a while and I was looking back at some earlier plans I had put together for a Karlsonator - and it turns out you had also been the one who was largely responsible for that design update as well. I have to say of every community I've ever been a part of, the DIY audio community is some of the smartest and most generous people I know.
I always try to answer posts with a question directed to me, but I would comment on yours nonetheless for the excellent work you show and nice smooth response. If you want, posting an STL file (or other stanrdard CAD format) of that ESS AMT-1 throat adapter would be very useful for folks.
Great to know that you are a design architect. Will keep that in mind - industrial/commercial or residential?
Great to know that you are a design architect. Will keep that in mind - industrial/commercial or residential?