after a long period of complex testing because I don't have a pi 5, here is a working script, don't use the previous one... thank you m-a for your tenacity in the tests!
I will open a dedicated thread when I have time
Thanks for your great work and persistence in fixing every little issue I had with the script. It now works perfectly on my Raspberry Pi 5!
I’ve built one speaker and spent some time listening to it, thinking about what improvements I want to make before building the next version.
Overall, I’m amazed by how it sounds. It’s incredibly clear and lifelike, with a three-dimensional quality, even though I’m only listening to one speaker in mono. It feels like the musicians are right there in the room. With my limited HiFi experience, this is a huge upgrade.
That said, the sound can sometimes have a certain dryness. It’s probably something I could live with, but I’m curious if I can tweak the design to make it sound less dry.
I also find the speaker’s dispersion quite narrow, and measurements confirm this:
Changes for the next version:
The throat – I’d like wider dispersion for the high frequencies. The quadratic throat adapter seems to make it too beamy, so for the next design, I’m switching to a conical throat instead of an exponential one.
The Second Flare – The first prototype has a smaller second flare than most MEH designs. The Synergy Calc sheet recommends a final horizontal first expansion width to overall horizontal width ratio of 0.6–0.7, whereas my design is around 0.85. I wonder if I’m missing out on something by having a smaller second flare, so for the next version, I’ll use a 0.65 ratio. I’m keeping the same angle for both the horizontal and vertical second flare so that it aligns neatly with the chamfered MDF enclosure walls.
The mid chambers – In the previous design the total mid chamber volume is just 1L. I want to increase this and lower the crossover to the subs. The tight space also made the mid rear chambers hard to mount properly, leaving them slightly loose, which might be causing rattling and increased distortion at lower frequencies. With this change, the crossover will be ca 100 Hz, and the mids will still reach 105 dB before hitting xmax. I’m skipping the mid rear chambers and using a divider wall to separate the mid and sub sections of the enclosure.
Mid entry ports – The entry ports will be larger, increasing from 8 cm² to 16 cm², and positioned further out in the horn to lower the crossover point. My calculations suggest 800 Hz, but the Hornresp simulation indicates I might be able to cross over higher.
Smaller mid front chambers – I’ve reduced the space between the mids and the horn, slightly decreasing VTC.
Wider dispersion angle – I’m changing the horn’s dispersion from 80°×60° to 90°×60°.
Overall, I’m amazed by how it sounds. It’s incredibly clear and lifelike, with a three-dimensional quality, even though I’m only listening to one speaker in mono. It feels like the musicians are right there in the room. With my limited HiFi experience, this is a huge upgrade.
That said, the sound can sometimes have a certain dryness. It’s probably something I could live with, but I’m curious if I can tweak the design to make it sound less dry.
I also find the speaker’s dispersion quite narrow, and measurements confirm this:
Changes for the next version:
The throat – I’d like wider dispersion for the high frequencies. The quadratic throat adapter seems to make it too beamy, so for the next design, I’m switching to a conical throat instead of an exponential one.
The Second Flare – The first prototype has a smaller second flare than most MEH designs. The Synergy Calc sheet recommends a final horizontal first expansion width to overall horizontal width ratio of 0.6–0.7, whereas my design is around 0.85. I wonder if I’m missing out on something by having a smaller second flare, so for the next version, I’ll use a 0.65 ratio. I’m keeping the same angle for both the horizontal and vertical second flare so that it aligns neatly with the chamfered MDF enclosure walls.
The mid chambers – In the previous design the total mid chamber volume is just 1L. I want to increase this and lower the crossover to the subs. The tight space also made the mid rear chambers hard to mount properly, leaving them slightly loose, which might be causing rattling and increased distortion at lower frequencies. With this change, the crossover will be ca 100 Hz, and the mids will still reach 105 dB before hitting xmax. I’m skipping the mid rear chambers and using a divider wall to separate the mid and sub sections of the enclosure.
Mid entry ports – The entry ports will be larger, increasing from 8 cm² to 16 cm², and positioned further out in the horn to lower the crossover point. My calculations suggest 800 Hz, but the Hornresp simulation indicates I might be able to cross over higher.
Smaller mid front chambers – I’ve reduced the space between the mids and the horn, slightly decreasing VTC.
Wider dispersion angle – I’m changing the horn’s dispersion from 80°×60° to 90°×60°.
Yeah, could agree more, that's what I've found with the MEHs one dialed in.
The second prototype is ready! The new version is slightly bigger, measuring 36 cm wide, 50 cm tall, and 29.5 cm deep. It has a 90x60 dispersion and is conical from throat to mouth. The changes have made it much better for my needs. It now has a wider spread and sounds more even within the coverage angle.
Here are the polars using a crossover at 1100 Hz. The dispersion is wider than in the previous model, and now the dispersion from the compression driver lines up with the dispersion to the mid driver. There is a notch around 1750 Hz. Half a wavelength is approximately 10 cm, which is ca the distance between the mid entry ports.
It is currently crossed over at 1100 Hz, but after looking at the polar chart, I wonder if it would be better to cross it over around 1750 Hz, where the mid and compression driver overlap, to see if that eliminates the notch. 1750 Hz is much higher than I originally planned for the crossover, and I wonder if it breaks the quarter-wavelength principle. A quarter wavelength of 1750 Hz is 4.9 cm. The distance between the mid entry port and the throat is slightly longer, but maybe it works out fine.
Here is the raw mid and compression driver response.
And the measurements within the horn:
While writing this, I decided to test the 1700 Hz crossover. It sounds much better than the 1100 Hz crossover I had before. Previously, I could hear the sound changing as I moved between different points in front of the speaker, but now it sounds much more even. I have tried many different crossovers, and this is by far the best one.
I spent some time listening to the new speaker in mono and really enjoyed it. But the biggest change so far has been hearing both speakers together in stereo… WOW! One of my main reasons for building these speakers was simply to experience how MEHs sound, and it feels great knowing all the effort was worth it. The room was filled with beautiful sound. It felt like drinking exceptionally good wine, with nuance and detail that took me on a journey. I played some random songs on Spotify, including tracks I have heard many times before, and it felt like I was hearing them for the first time. I wonder if I will get used to this and start perceiving these speakers as “normal,” making everything else sound bad in comparison. I can still hear the dry character of the other speaker, but with this new one, it is like it is not even there, just music filling the space all around.
Right now, they are in my 50 m² work studio, where they fit perfectly. But they will not fit well in my small living room, where they are meant to be. Even the first version, which was smaller, was already pushing the size constraints. I would have needed to buy or build a new TV bench to make them fit, and this version is even bigger.
So, I have been planning Prototype 3, where the main limitation will be a maximum width of 24 cm so it will fit perfectly on my current TV bench. With Prototype 2, I confirmed that the drivers can cross over close to 100 Hz if the mid rear chamber is large enough. That way, I can put the subwoofer in a separate enclosure.
One issue with Prototype 2 is that because of the larger mid enclosure, the sub enclosure is too small. The subwoofer does not keep up with the other drivers, even though I am pushing the Aiyma A70 amp to the max. So, it would be great to put the subwoofer in a separate enclosure that is the correct size.
Here is my main idea:
This rendering has a 80 horizontal x 100 degree vertical coverage.
As you can see, I am breaking my original design constraint of keeping the mid drivers straight to avoid cone sag. This is mainly to position them as close as possible to the exit of the mid port. I am not too worried about cone sag with this 25-degree tilt and 4-inch drivers.
I have also been exploring the idea of using larger mid drivers, like the Faital Pro 6FE100 or 6FE125. Here is the response comparison (blue 6FE100, red 4FE35) .
And it has much higher max SPL than the 4FE35. A part of me regrets not getting the 6FE100 or 6FE125 when I started this project, but then I had a different design idea in mind at the time.
I have also explored a design with a circular conical horn that is slightly oversized, extending beyond the baffle. It is a bit harder to build but could be fun. One version has the horn centered using the 6FE100, and another is off-center with the 4FE35. I am not completely convinced by this design, but I am considering another idea: making the throat circular from S1 (horn throat) to S2 (plane of mid entry ports) and then gradually transitioning to a square shape at S3 (where the inner flare and outer flare meet).
Now I am leaning toward using the 4FE35 in a rectangular horn. I would add a rear port to extend the bass. They would reach around 103 dB at xmax, and I hope that is enough for my needs.
Here are the polars using a crossover at 1100 Hz. The dispersion is wider than in the previous model, and now the dispersion from the compression driver lines up with the dispersion to the mid driver. There is a notch around 1750 Hz. Half a wavelength is approximately 10 cm, which is ca the distance between the mid entry ports.
It is currently crossed over at 1100 Hz, but after looking at the polar chart, I wonder if it would be better to cross it over around 1750 Hz, where the mid and compression driver overlap, to see if that eliminates the notch. 1750 Hz is much higher than I originally planned for the crossover, and I wonder if it breaks the quarter-wavelength principle. A quarter wavelength of 1750 Hz is 4.9 cm. The distance between the mid entry port and the throat is slightly longer, but maybe it works out fine.
Here is the raw mid and compression driver response.
And the measurements within the horn:
While writing this, I decided to test the 1700 Hz crossover. It sounds much better than the 1100 Hz crossover I had before. Previously, I could hear the sound changing as I moved between different points in front of the speaker, but now it sounds much more even. I have tried many different crossovers, and this is by far the best one.
I spent some time listening to the new speaker in mono and really enjoyed it. But the biggest change so far has been hearing both speakers together in stereo… WOW! One of my main reasons for building these speakers was simply to experience how MEHs sound, and it feels great knowing all the effort was worth it. The room was filled with beautiful sound. It felt like drinking exceptionally good wine, with nuance and detail that took me on a journey. I played some random songs on Spotify, including tracks I have heard many times before, and it felt like I was hearing them for the first time. I wonder if I will get used to this and start perceiving these speakers as “normal,” making everything else sound bad in comparison. I can still hear the dry character of the other speaker, but with this new one, it is like it is not even there, just music filling the space all around.
Right now, they are in my 50 m² work studio, where they fit perfectly. But they will not fit well in my small living room, where they are meant to be. Even the first version, which was smaller, was already pushing the size constraints. I would have needed to buy or build a new TV bench to make them fit, and this version is even bigger.
So, I have been planning Prototype 3, where the main limitation will be a maximum width of 24 cm so it will fit perfectly on my current TV bench. With Prototype 2, I confirmed that the drivers can cross over close to 100 Hz if the mid rear chamber is large enough. That way, I can put the subwoofer in a separate enclosure.
One issue with Prototype 2 is that because of the larger mid enclosure, the sub enclosure is too small. The subwoofer does not keep up with the other drivers, even though I am pushing the Aiyma A70 amp to the max. So, it would be great to put the subwoofer in a separate enclosure that is the correct size.
Here is my main idea:
This rendering has a 80 horizontal x 100 degree vertical coverage.
As you can see, I am breaking my original design constraint of keeping the mid drivers straight to avoid cone sag. This is mainly to position them as close as possible to the exit of the mid port. I am not too worried about cone sag with this 25-degree tilt and 4-inch drivers.
I have also been exploring the idea of using larger mid drivers, like the Faital Pro 6FE100 or 6FE125. Here is the response comparison (blue 6FE100, red 4FE35) .
And it has much higher max SPL than the 4FE35. A part of me regrets not getting the 6FE100 or 6FE125 when I started this project, but then I had a different design idea in mind at the time.
I have also explored a design with a circular conical horn that is slightly oversized, extending beyond the baffle. It is a bit harder to build but could be fun. One version has the horn centered using the 6FE100, and another is off-center with the 4FE35. I am not completely convinced by this design, but I am considering another idea: making the throat circular from S1 (horn throat) to S2 (plane of mid entry ports) and then gradually transitioning to a square shape at S3 (where the inner flare and outer flare meet).
Now I am leaning toward using the 4FE35 in a rectangular horn. I would add a rear port to extend the bass. They would reach around 103 dB at xmax, and I hope that is enough for my needs.
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To wrap things up with the previous design, l'm posting some details on how l'd approach it if I were to build a V3. The main issue with V2 was that the subwoofer rear chamber was way too small, so the subs struggle to go deep and loud. V1 has a slightly bigger rear chamber for the subwoofers, and the difference is noticeable. It would make a lot of sense to make them floor-standing so the subwoofers have enough rear chamber volume.
I'm not planning to build that at the moment, but I've been exploring a two-way design, which I'll write about in the next post.
I have a parametric Fusion360 file for this design, so it's easy to change various parameters like the size of the horn, the cabinet, the coverage angle, mid port location, etc. If anyone's interested in playing around with the file, just message me and I'll send it over.
I'm not planning to build that at the moment, but I've been exploring a two-way design, which I'll write about in the next post.
I have a parametric Fusion360 file for this design, so it's easy to change various parameters like the size of the horn, the cabinet, the coverage angle, mid port location, etc. If anyone's interested in playing around with the file, just message me and I'll send it over.
The smaller WAF MEH has evolved. I’ve been developing the bookshelf speaker mentioned previously. The current design measures 240×380x350 mm and will have a rear tube. I’m planning to build a subwoofer in a separate enclosure.
I started experimenting with ATH. After hundreds of different tests and simulations, I ended up with this waveguide, which I think suits the design quite well. I like the shape, especially the valley above and below the throat, which helps keep the throat port length for the mid drivers relatively short.
The Faital 4FE35 were too limited in this design, so I began looking for alternatives that would play louder and deeper in this configuration. The SB Acoustics SB13PFC25-8 meets the criteria: it’s inexpensive, small enough to fit, and offers more cone area and xmax. The only downside is that the woofer isn’t designed to be mounted front facing towards the horn. Still, I think it will be possible to design around that and use gasket tape.
Although not in the rendering, I’m planning to add a rear tube. I'm planning to follow the principles in this thread.
I still have some fine tuning left before starting the build. Also, I haven't bought the drivers yet, so if anyone has suggestions for 5inch drivers that would be even better than these, then I'm open to all suggestions.
Here is a rendering of the design:
Here is a Hornresp simulation at xmax:
Polars from ABEC simulation:
One of the goals has been to be able to print the the whole waveguide on 3d printer with 256x256x256mm build area. I took this in account when designing, so now it just about fits on the build plate:
I started experimenting with ATH. After hundreds of different tests and simulations, I ended up with this waveguide, which I think suits the design quite well. I like the shape, especially the valley above and below the throat, which helps keep the throat port length for the mid drivers relatively short.
The Faital 4FE35 were too limited in this design, so I began looking for alternatives that would play louder and deeper in this configuration. The SB Acoustics SB13PFC25-8 meets the criteria: it’s inexpensive, small enough to fit, and offers more cone area and xmax. The only downside is that the woofer isn’t designed to be mounted front facing towards the horn. Still, I think it will be possible to design around that and use gasket tape.
Although not in the rendering, I’m planning to add a rear tube. I'm planning to follow the principles in this thread.
I still have some fine tuning left before starting the build. Also, I haven't bought the drivers yet, so if anyone has suggestions for 5inch drivers that would be even better than these, then I'm open to all suggestions.
Here is a rendering of the design:
Here is a Hornresp simulation at xmax:
Polars from ABEC simulation:
One of the goals has been to be able to print the the whole waveguide on 3d printer with 256x256x256mm build area. I took this in account when designing, so now it just about fits on the build plate:
Interesting. At this point in the design phase, I think you’ll find a good ol vertical MTM with Scanspeak midwoofers and tweeter will outperform the compact MEH……say a pair of 5 1/4 class mids and an offset ring radiator. Bass extension will easily get you down into the modal region to mate up with a subwoofer and have provide some midbass slam.
Speaking for the OP and myself -- MEH has much wider VHF dispersion & sweet-spot than the tweeter. Where I (likely) assign a "demerit" to mine is lack of soundstage depth -- coherent time and phase aligned speakers (1ch or 2ch) would project the musicians beyond the wall, rather than in the room; also a "holographic" sense of "air" and venue space. I hope @m-a DSP filter achieved this.
Fantastic! I love your way of exploring different horn shapes quickly! A part of me wishes that I had built my 2 prototypes out of foamboard so I would have been able to make adjustments quicker. These 2 speakers have taken me quite some time to build, and I'm not 100% happy with them yet. I have learnt a lot in the process, so I guess that's part of the game.Inspired by @m-a and everyone here, I got the HF108 to go with 4" Faital (in-cab so not sure which) and this past week prototyped a Minimalist MEH passively filtered. Cross-fertilization ideas & comments appreciated!
What I’m hoping the small MEH will offer over an MTM is the virtual point source effect, where all the drivers sound like a single full-range driver.
When I listen to my two prototypes in stereo, I can clearly hear the benefits of Synergy Horns. The soundstage is large, and with some recordings, it feels like the artists are there in the room playing live.
It would be interesting to compare them with some good MTM speakers once they’re ready.
Okay. My half-baked Minmeh (2nd-order with notch) was more dynamic and slightly more vivid; musicians in the room. My half-baked "more coherent" offset T/MM (1st-order with same notch) has musicians better focused and just beyond the wall. I couldn't directly L/R compare them (by repeating same music segment quickly swapping channels at amp input) because I've misplaced the other pair of mids....
(Just 0.5cm offset between HF108 rubber-padded faceplate and 4FE35 surround crest -- guessing that's inside the Admark LDA-401.)
In what configuration could the two midwoofers in an MTM arrangement ever be placed within 1/4 wavelength of each other?
The exploration continues.
I decided to pause the small ported MEH idea and explore what I could do with the 4FE35 mid drivers I already have.
After reading the extended throat waveguide essay on at-horns, an idea started brewing… what if I placed the mid taps on an extended throat? My hope is that, after EQ and active XO, the output from the throat will have a flat response that reaches down to at least 150 Hz (at home SPL levels) and doesn’t have any notable off-axis dips or peaks. Without doing much research on whether this would actually work, I went ahead and modeled a concept in 3D and sent it off to the printer.
For the mid ports I decided to go for small slits measuring 3x40 mm. The extended throat has the same 1-inch opening at both ends. The distance between the center of the mid entry port and the CD entry is ¼ wavelength of the intended 1300 Hz crossover.
I had already removed the drivers from the first prototype, so that was the only horn I could test with. It’s far from perfect, I’ve learned a lot since starting this project, but it was good enough for this experiment. I taped over the old mid entry ports in case they affected the measurements (turns out they didn’t have much impact). Because of the enclosure, I couldn’t fit the mid rear chambers, so I had to run the test with open-back mids.
The measurements were surprisingly good! There are some peaks and dips as expected, but much better than what I was preparing for..
After EQ and XO, they sounded great, even without the mid rear chambers.
For the next test, I’m going to make a freestanding waveguide in ATH using the R-OSSE formula. That way, I’ll also be able to test it with rear chambers on the mids.
I decided to pause the small ported MEH idea and explore what I could do with the 4FE35 mid drivers I already have.
After reading the extended throat waveguide essay on at-horns, an idea started brewing… what if I placed the mid taps on an extended throat? My hope is that, after EQ and active XO, the output from the throat will have a flat response that reaches down to at least 150 Hz (at home SPL levels) and doesn’t have any notable off-axis dips or peaks. Without doing much research on whether this would actually work, I went ahead and modeled a concept in 3D and sent it off to the printer.
For the mid ports I decided to go for small slits measuring 3x40 mm. The extended throat has the same 1-inch opening at both ends. The distance between the center of the mid entry port and the CD entry is ¼ wavelength of the intended 1300 Hz crossover.
I had already removed the drivers from the first prototype, so that was the only horn I could test with. It’s far from perfect, I’ve learned a lot since starting this project, but it was good enough for this experiment. I taped over the old mid entry ports in case they affected the measurements (turns out they didn’t have much impact). Because of the enclosure, I couldn’t fit the mid rear chambers, so I had to run the test with open-back mids.
The measurements were surprisingly good! There are some peaks and dips as expected, but much better than what I was preparing for..
After EQ and XO, they sounded great, even without the mid rear chambers.
For the next test, I’m going to make a freestanding waveguide in ATH using the R-OSSE formula. That way, I’ll also be able to test it with rear chambers on the mids.
What I would assume is the benefit of a MEH is that the drivers can be placed within 1/4 wavelength of each other and that would be harder to achieve in an MTM configuration. So a MEH would have less off axis dips.
The waveguide in post 48 is made using the OSSE formula in ATH. I’m not sure if it’s possible, or a good idea, to use it only for the second flare, since it’s intended to be used in the whole horn, from the throat to the mouth.