I built a pair of unique speakers designed by DiyAudio member claudiogan (the design is discussed here: 34c9 a MDD full range speakers.)
I was attracted by the unusual look and simplicity of build, not talking about low price. I made some slight changes to the construction so I could use various bits and pieces I had at hand.
I ordered the 3FE22 speaker, since it was in stock in CZ. As a bonus, it is also smaller and lighter - so I did not need a hole in the base. The Al pipes are 20x20 with 1.5 mm wall thickness, they were ordered online already precut to correct lengths. I made the pipe holder from a piece of pine plank. Also, instead using plumbers putty, I cut four little triangles out of 5mm plywood and glued them into the corners to create surface to mate the speaker to. For looks, it was sprayed black and covered in vinyl self adhesive wallpaper (to hide my wood working skills
).
There are two M5 threaded inserts for mounting to the L bracket. The screws are also holding the pipes by screwing in and pushing the pipes against the opposite wall. The mounting is shown in the pictures.
The bases are again a piece of 18mm pine plank with a small riser, so that the bottom of the magnet has some free movement.
I decided to arrange the pipes into a spiral after a test of both arrangements (in the pictures) since there was no difference in sound and measured FR. The pipes are glued together with contact cement.
Now when the pair is finished, I will experiment with a little of foam in the open ends, the initial test shows a slight improvement.
The sound is truly omnidirectional and there is a wide listening area. There is lack of bass as with any 3" speaker, which will be solved by an active subwoofer.
And this was the first pair of speakers that my wife actually wanted to put into the living room (and I had to say no ) I highly recommend anyone to build this speaker. It is really fun to listen to.
Update: 3D printed base pictures in post #36
I was attracted by the unusual look and simplicity of build, not talking about low price. I made some slight changes to the construction so I could use various bits and pieces I had at hand.
I ordered the 3FE22 speaker, since it was in stock in CZ. As a bonus, it is also smaller and lighter - so I did not need a hole in the base. The Al pipes are 20x20 with 1.5 mm wall thickness, they were ordered online already precut to correct lengths. I made the pipe holder from a piece of pine plank. Also, instead using plumbers putty, I cut four little triangles out of 5mm plywood and glued them into the corners to create surface to mate the speaker to. For looks, it was sprayed black and covered in vinyl self adhesive wallpaper (to hide my wood working skills
). There are two M5 threaded inserts for mounting to the L bracket. The screws are also holding the pipes by screwing in and pushing the pipes against the opposite wall. The mounting is shown in the pictures.
The bases are again a piece of 18mm pine plank with a small riser, so that the bottom of the magnet has some free movement.
I decided to arrange the pipes into a spiral after a test of both arrangements (in the pictures) since there was no difference in sound and measured FR. The pipes are glued together with contact cement.
Now when the pair is finished, I will experiment with a little of foam in the open ends, the initial test shows a slight improvement.
The sound is truly omnidirectional and there is a wide listening area. There is lack of bass as with any 3" speaker, which will be solved by an active subwoofer.
And this was the first pair of speakers that my wife actually wanted to put into the living room (and I had to say no
) I highly recommend anyone to build this speaker. It is really fun to listen to.Update: 3D printed base pictures in post #36
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I'm glad I shared my MDD projects and that the author of the first replica published is satisfied with the result and recommends its construction. I confirm my willingness to provide directions through the DiyAudio forum to members who wish to engage in building other prototypes.
What pelanj wrote is not enough to associate the "fun to listen" with MDD technology, for now it is enough for me to confirm the omnidirectional emission and the large listening area.
Compared to the prototype in the picture I can suggest some possible variants.
The resonance of the impedance at low frequencies is about ʎ / 4 of the length of the longest barrel, increasing the length extends the response to low frequencies but complicates the construction. It may be easier to use an active subwoofer.
Changing the wiring of the speaker wires as shown in the photo avoids creating a loop with ferromagnetic material inside and distortion due to the hysteresis generated by the radius of the basket. I propose to those who use 3FE22 (3FE25) speakers to do a test.
A little damping material inside the barrels reduces the peaks to ʎ / 2 in the course of the impedance and the phase.
Thanks to Pelanj for trusting in a decidedly unconventional project
claudio
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Hi Pelanj
in my 34c9 measurements (with the 3fe25 loudspeaker) there are a little more bass. In the graphs you can see the effect of the geometry of the room. The left channel is near a corner. The right channel in front of the flat wall. Even the L-shaped desk top with the peninsula on the left probably influences the differences. The room in the picture is about 4 x 4 x 3 m and the microphone in front of the monitor, I use the speakers even while working on the PC.
If possible you can say something or take a picture of the arrangement of the boxes in the room. When I have time I will do a free field measurement to understand the influence of wall reflections on low frequency response.
In my 34c9 measurements is shown both the graph with foam rubber and without, you under what conditions did you measure?
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My room is ca 3.3 x 4.5 x 2.1 m and the speakers are placed near to an opening to the garrage. Definitely not ideal
But I can enjoy the room filling effect partially in the garrage as well
I need to take them to my ordinary listening room for some better measurements.
There is one interesting effect to these speakers. The soundstage is2D in the horizontal plane. For example, if a HiHat "image" is placed at ear height close to the left speaker, when I stand up, it is in the same 2D plane and feels like I am listening to the HiHat at that point in space/plane no matter where I am standing and how high my head is. It is like I have a miniature model of the band in the room. Traditional speakers do not have this feature.
I need to take them to my ordinary listening room for some better measurements.
There is one interesting effect to these speakers. The soundstage is2D in the horizontal plane. For example, if a HiHat "image" is placed at ear height close to the left speaker, when I stand up, it is in the same 2D plane and feels like I am listening to the HiHat at that point in space/plane no matter where I am standing and how high my head is. It is like I have a miniature model of the band in the room. Traditional speakers do not have this feature.
I'd love to try that method. Would schedule 40 pvc be needed vs thinwall pvc?
Did Sapkowski really achieve a broadband effect with his K-tube like patent - ? - or just wishful thinking ?
https://patentimages.storage.googleapis.com/9c/20/b4/35d7939fdc3996/US5552569.pdf
Did Sapkowski really achieve a broadband effect with his K-tube like patent - ? - or just wishful thinking ?
https://patentimages.storage.googleapis.com/9c/20/b4/35d7939fdc3996/US5552569.pdf
From the build page referenced above: “A series of 7 rigid PVC waveguides used in electrical installations with a diameter of 25mm and 1 mm of thickness...”
Even Schedule 20 has a wall thickness greater than 1 mm at 1” diameter so thin wall should work.
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Very nice, Claudio. I wonder if this could be scaled to say 15" woofer. The size would be a bit impractical, but it could make nice organ-like speakers. I will try to simulate multiple length tubes in Hornresp and add them together. It kind of worked for the double backloaded horns, so I think it is worth trying.
Edit: Or maybe better, learn to use Akabak.
Edit: Or maybe better, learn to use Akabak.
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Hi Pelanj,
for 15" woofer i suggest a radial structure as 66c9 project, using cardstock for the prototypes and wooden or rigid PVC structure for final model.
I don't use simulators, i can't say.
I think this project deserves a better looking finish. Since I got into 3D printing lately, the alu waveguides will get a new 3D printed speaker holder. I will also try to make the surface of the waveguides look better by sanding with high grit sandpaper.
Ultimately, I think I will build another pair with round copper plumbing tubes polished to high gloss in 3D printed holders for a high end look
Ultimately, I think I will build another pair with round copper plumbing tubes polished to high gloss in 3D printed holders for a high end look