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MDD Multi Delays Diffraction (Multi TL, omnidirectional, single drive, ...)
MDD Multi Delays Diffraction (Multi TL, omnidirectional, single drive, ...)
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Old 13th January 2020, 02:11 PM   #51
claudiogan is offline claudiogan  Italy
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Default MDD neutral cabinet

I made the second version of the 22C71L8 project, I fixed the spiral guides to a wooden table and rigid guides. It is now transportable and usable for a series of measurements with the microphone at the exit of the flexible guides.

With the graphs it is possible to calculate the mathematical average of the frequency responses which highlights the neutral behavior of the loudspeaker at low frequencies.

More photos at the address: 22C71L8
More information on the neutral cabinet at: acustica MDD projects
Attached Images
File Type: jpg 22C71L8 146 right.jpg (110.5 KB, 270 views)
File Type: jpg 22C71L8 142 umik1.jpg (212.3 KB, 203 views)
File Type: jpg 22C71L8 FR Z 1-8 right.jpg (75.5 KB, 197 views)
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Old 19th January 2020, 10:17 AM   #52
pelanj is offline pelanj  Czech Republic
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MDD Multi Delays Diffraction (Multi TL, omnidirectional, single drive, ...)
Default MDD attachment for compression drivers

I wanted to try out 3D modeling of the MDD as a proof of concept. I yet have to think about how to make the spiral, but the steps look OK. I printed that scaled for a 1" compression driver, the overall length is 85 mm. Once I have some measurements, I will post them.

As another idea, I wonder if MDD type fullrange speaker could be used in a trunk of a car, where the openings would be placed above the back seats. I need to try that one day too.
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File Type: jpeg 17C2C7FF-03EC-402B-B63C-99E7DFCD180E.jpeg (124.6 KB, 167 views)
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Old 19th January 2020, 05:06 PM   #53
claudiogan is offline claudiogan  Italy
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Default MDD tweeter

Quote:
Originally Posted by pelanj View Post
I wanted to try out 3D modeling of the MDD as a proof of concept. I yet have to think about how to make the spiral, but the steps look OK. I printed that scaled for a 1" compression driver, the overall length is 85 mm. Once I have some measurements, I will post them.
For those wishing to try the MDD technology on multi-way systems, I propose a drawing of a possible two-way configuration. The vertical waveguides (12) mounted in front of the tweeter (5) make the speaker omnidirectional on the horizontal plane.

A possible complication could be created by positioning too high that sends the energy of the high frequencies above the listener's head.

One condition to be tested (I have no tweeter available) is the possible lack of rear primary emission. It could be avoided by making holes at the base of the waveguides, a primary wave in phase with delayed waves would be emitted. Given the times and costs of 3D printing, I would first test with rigid PVC pipes.
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File Type: jpg fig10.jpg (9.1 KB, 154 views)
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Old 19th January 2020, 05:41 PM   #54
claudiogan is offline claudiogan  Italy
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Quote:
Originally Posted by pelanj View Post
As another idea, I wonder if MDD type fullrange speaker could be used in a trunk of a car, where the openings would be placed above the back seats. I need to try that one day too.
For those wishing to test MDD technology in the car, a starting point can be the one in the drawing. The structure is the same as in the 22C71L8 project.

A closed box contains the FR speaker. The box is mounted under the trunk panel.

The frontal waveguides in rigid PVC exit directly into the passenger compartment through holes in the panel.

The rear spiral sheaths come out of the box, can make the necessary curves inside the trunk and exit into the passenger compartment through holes in the panel.
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File Type: jpg carAudio.jpg (38.4 KB, 55 views)
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Old 17th March 2020, 08:26 AM   #55
claudiogan is offline claudiogan  Italy
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Default MDDHX135 an MDD project with the HX135 driver

In the MDDHX135 prototype I apply MDD technology to a discontinued Ciare HX-135 speaker. With previous projects I think I have reached the limit of the potential of the excellent 3FE25 of the Faital-Pro, I decided to experiment with the best speaker I have available.

The HX-135 cost about 10 times more than the small 3FE25 and at first glance you can perceive the difference. The first impression is that of a greater extension to the ends of the band, less distortion and greater listening pleasure. I plan to take a series of measurements within ten days.

Most of the time it was used to build a frame that supports the MDDBL rear acoustic load made with spiral sheath for electrical systems. The frame also supports the horizontally mounted speaker and the MDDFL frontal acoustic load, which is very simple to make.
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File Type: jpg mddhx135-06.jpg (178.9 KB, 36 views)
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Old 26th March 2020, 08:56 PM   #56
claudiogan is offline claudiogan  Italy
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I published the measures of the MDDHX135 project.

link:
Claudio Gandolfi - MDD (Multi Delays Diffraction Loudspeaker)
MDDHX135
MDDFL
MDDBL
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File Type: jpg MDDHX135 FR THD left.jpg (89.7 KB, 21 views)
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Old 1st April 2020, 01:50 PM   #57
claudiogan is offline claudiogan  Italy
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Default MDDHX135-LV (Lockdown Version)

I made the measurements on the MDDHX135 prototype in my studio, I found myself in the situations of those who move to a better place in the theater but are worse off because of the presence of annoying neighbors. In my case I was annoyed by the excessive dimensions (1000 x 760 x 360 mm) in a 4 x 4 m room, also after 15 days the smell of the solvent contained in the impregnating agent was still excessive. I reconnected the 22C71L8 prototype and continued listening to music with that.

For the impregnating agent, I left the prototype outside without the speakers for another week. For the size I arranged. Stuck in the house for the covid-19 emergency, I could not buy and have the wood cut to size, I had finished the electrician clamps. I cut parts of the frame freehand and instead of the clamps I used rigid copper cable.

I used the only abundant resource: time. If I hadn't been stuck in the house I wouldn't have used a couple of days to get a result like the one shown in the pictures, a prototype destined to be dismantled with the normalized situation.

I moved the speaker cube back and moved the waveguides back. It is clearly seen that the frame is undersized to support all the spiral sheath. The only bulky part of the prototype is the rear one which is positioned close to the wall. The visual footprint is much smaller than before.

How does she feel? Well very well.

I will not make measurements on a prototype destined to be dismantled (I hope soon). Those already published on the same page remain valid, they also contain measurements with the microphone positioned at the outlet of each waveguide.

More photos at the links:
MDDHX135
MDDHX135
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File Type: jpg mddhx135-35.jpg (111.6 KB, 18 views)
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Old 6th April 2020, 02:36 PM   #58
claudiogan is offline claudiogan  Italy
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Default MDDHX135-42

The MDDHX135-42 prototype uses the same drivers and waveguides as the previous ones. It is more compact, the base measures 42 x 26 cm, the height of about one meter. It now has a suitable footprint for use in my studio. The construction method is that of the previous LV version, I reused what I had available: woods and rigid wire.

The sound is very good, like the previous MDDHX135 prototypes.

More photos at the link: MDDHX135
Attached Images
File Type: jpg mddhx135-l52.jpg (135.3 KB, 9 views)
File Type: jpg mddhx135 FR BL waveguide.jpg (69.3 KB, 9 views)
File Type: jpg mddhx135-BL12.jpg (33.2 KB, 8 views)
File Type: jpg mddhx135 FR FL waveguide.jpg (68.9 KB, 8 views)
File Type: jpg mddhx135-FL07.jpg (41.7 KB, 11 views)
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