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34c9 a MDD full range speakers.
34c9 a MDD full range speakers.
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Old 21st August 2019, 08:27 AM   #1
claudiogan is offline claudiogan  Italy
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Default 34c9 a MDD full range speakers.

MDD (Multi Delays Diffraction) is an innovative technology for loudspeakers.

MDD uses acoustic diffraction to emit coherent secondary sound waves, delayed by a few milliseconds at different points in space.
The 34c9 project is the first compact version made with MDD technology. Other features of the 34c9 project:
- zero internal acoustic reflections,
- sound insulation from the floor in the audio band,
- omnidirectional emission on the horizontal plane over the entire audio band,
- no damping material,
- 3FE25 speaker from Faital-Pro.

More information at links:
Claudio Gandolfi - MDD
34c9
Pin by claudio gandolfi on 34c9

Thanks for the attention
Claudio
Attached Images
File Type: jpg 34c9 left Phase FR.jpg (73.2 KB, 701 views)
File Type: jpg 34c9 mic d 07.jpg (146.4 KB, 714 views)
File Type: jpg 34c9 L 12.jpg (71.8 KB, 722 views)
File Type: jpg 34c9 L sotto 17.jpg (204.5 KB, 719 views)
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Old 21st August 2019, 04:17 PM   #2
carlthess40 is offline carlthess40  United States
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This is a pretty cool project
Whats the largest driver you have used ?
Whats the size of the driver you used for all of these? Could we try a 6.5 driver? There are so many great 6.5 drivers out on the market today. Do you think using a 6.5 or a 8 driver and using 3 down to 1 pipes would work? The larger pipe for lower hz and the smaller tubes for higher hz
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Old 21st August 2019, 08:54 PM   #3
claudiogan is offline claudiogan  Italy
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Quote:
Originally Posted by carlthess40 View Post
Whats the largest driver you have used ?
Whats the size of the driver you used for all of these? Could we try a 6.5 driver? There are so many great 6.5 drivers out on the market today. Do you think using a 6.5 or a 8 driver and using 3 down to 1 pipes would work? The larger pipe for lower hz and the smaller tubes for higher hz
I only did tests with 3" drivers but the MDD technology can work with bigger speakers. The problems that occur with 6.5" and even more with 8" are mechanical. It increases weight and you need to find a fairly strong bracket to have an adequate subsonic resonance, greater weight requires a more stable base to avoid accidental falls.

Side-by-side waveguides must have the same section. There is the advantage of obtaining some guides from a single long tube, reducing the waste of material.

The rule I used in the prototypes is to have the sum of the area of all the sections of the waveguides equal to about the area of the speaker cone.

The resonance frequency depends on the length (no section) of the guides and I recommend having the shortest one half the length of the longest. The number can also be different from 9, it is important that the lengths are calculated so that the increments are logarithmic. 
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Old 22nd August 2019, 02:28 AM   #4
carlthess40 is offline carlthess40  United States
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What about using a 3 point spring mount?
So your saying that the tubes or pipes need to equal the same amount as the area of the driver ? so is a driver has a total of 20 in. or 10 cm of cone Area, then the pipes or tubes should equal to 20 in. or 10 cm ? Am I way off base on this? I really want to try this
I have some old full range drivers from the 50s though the 70s that came out of Console tube stereo systems, LOW power
Most of them are from 8 up to 15 drivers
And Id like to use round pipes, like ones used in church organs. Id really like to use as large as a 10 down to 1 pipes. And all copper or brass
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Old 22nd August 2019, 08:37 PM   #5
claudiogan is offline claudiogan  Italy
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Quote:
Originally Posted by carlthess40 View Post
What about using a 3 point spring mount?
The system with 3 springs can work, it must oscillate to a few Hz also ensuring stability. In the 34c9 project with a 3" loudspeaker that weighs 525 grams you get to a complete 2.2 kg system. An 8" driver weighs 2 kg, I think the total weight with the guides easily reaches 10 kg. Everything becomes more complicated to manage.

Quote:
Originally Posted by carlthess40 View Post
So your saying that the tubes or pipes need to equal the same amount as the area of the driver ? so is a driver has a total of 20 in. or 10 cm of cone Area, then the pipes or tubes should equal to 20 in. or 10 cm ? Am I way off base on this? I really want to try this
In the 34c9 project the external section of the guides is:
20 x 20 = 400 mm (single guide)
400 x 9 = 3600 mm = 36 cm (total).
The internal section of the guides is:
18 x 18 = 324 mm (single guide)
324 x 9 = 2916 mm = 29 cm (total)
The area of the cone up to the center of the foam gasket is:
radius = 32.5 mm
Area = 3318 mm = 33 cm

If the cone area is 20 in. you can use 9 guides from 2.22 in. but it should work well even with values between 2.0 and 2.5 in.
If the cone area is 10 in. you can use 9 guides of 1.11 in. (1.0 - 1.25)

Quote:
Originally Posted by carlthess40 View Post
I have some old full range drivers from the 50’s though the 70’s that came out of Console tube stereo systems, LOW power
Most of them are from 8” up to 15” drivers
And I’d like to use round pipes, like ones used in church organs. I’d really like to use as large as a 10” down to 1” pipes.
I used rigid pvc round guides in the 227h project .
The easiest configuration to make is with seven guides, one in the center and six on the diagonals of a hexagon. In each diagonal three guides are aligned, in this configuration in a 6" driver you can use 2" guides, with a 15" you can use 5" guides (You can complicate the configuration using different diameters). With seven guides I suggest using this logarithmic series for the lengths: 552, 610, 673, 743, 820, 906, 1000 mm.

Quote:
Originally Posted by carlthess40 View Post
And all copper or brass
Copper and brass tubes (smooth inside) are suitable to work as acoustic waveguides, if you have them available it's fine. Given the value of the metals I would do before tests with rigid PVC which is less expensive. The system can be made adjustable by sliding cardboard tubes inside the rigid ones. Once I found a satisfactory configuration I would pass to the definitive one in metal. 
Attached Images
File Type: jpg 227h 77 20190501_115758.jpg (80.2 KB, 654 views)
File Type: jpg 227h 77 20190501_115841.jpg (76.8 KB, 124 views)

Last edited by claudiogan; 22nd August 2019 at 08:43 PM.
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Old 23rd August 2019, 11:28 AM   #6
twocents is offline twocents  South Africa
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34c9 a MDD full range speakers.
Wow Claudio, this is indeed a radically different FR design, unlike anything I have seen on this forum. I would love to hear what it sounds. You chose a great driver very affordable and sounds fantastic in the right enclosure. This should be a very cheap build. Aluminum is mined here, so the tubing is at least cheap in our country.

I am interested to see how this develops, and surprised that you have not received more interest, attention or comments here.
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Old 23rd August 2019, 12:27 PM   #7
pelanj is offline pelanj  Czech Republic
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Very nice and well documented! This goes definitely to my project to-do list and subscription

I always wanted to try omnidirectional speakers, these actually look as easy to build and also the tower form is beautiful.
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Old 23rd August 2019, 08:29 PM   #8
claudiogan is offline claudiogan  Italy
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Thanks for the first "Wow" in a comment, I'm glad you appreciate the originality of the 34c9 project.

Since 2013 I have been building FR trying to optimize the emission of coherent secondary sound waves, delayed at different points in space. This is not easy if you also try to have a good frequency response and low distortion. I found nothing that documents similar research, I invented the acronym MDD to describe the technique.

At the moment I'm the only (maybe) who works on MDD technology, who wants to listen to it will have to be very patient. Alternatively, you can decide to experiment in a field where only my documentation is published. Until someone replies the 34c9 project, I will gladly provide clarifications on specific aspects of the implementation.
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Old 26th August 2019, 10:13 AM   #9
pelanj is offline pelanj  Czech Republic
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I have first two questions - just to be sure how it is made (to clear my understanding of your description).

1. the square holder for the pipes has no bottom, the speaker is screwed directly on to the sidewalls. And the holes around the frame are sealed by a sealant - what would you recommend to use? I think silicone or hot melt glue should work.

2. the polyurethane ring at the base is a fit on the magnet, so when the whole thing swings, it slides on the magnet, to create a kind of seal. Is that correct? Do you have any suggestion where to get this foam from?

I put the pipes into an online alu dealer calculator (I can get only with 1.5 mm thickness) - and the cost will be slightly less than a pair of drivers, so that is not too bad, since there will be only a little wood and woodworking.

Thanks!
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Old 26th August 2019, 12:03 PM   #10
nas3000 is offline nas3000  Lithuania
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Quote:
Originally Posted by claudiogan View Post
MDD (Multi Delays Diffraction) is an innovative technology for loudspeakers.

MDD uses acoustic diffraction to emit coherent secondary sound waves, delayed by a few milliseconds at different points in space.
The 34c9 project is the first compact version made with MDD technology. Other features of the 34c9 project:
- zero internal acoustic reflections,
- sound insulation from the floor in the audio band,
- omnidirectional emission on the horizontal plane over the entire audio band,
- no damping material,
- 3FE25 speaker from Faital-Pro.

More information at links:
Claudio Gandolfi - MDD
34c9
Pin by claudio gandolfi on 34c9

Thanks for the attention
Claudio

very original project!


btw, you are mounting 3fe25 from the bottom - for this mounting you should try Lavoce drivers, they are suitable for this AND italian (!!!)
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