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34c9 a MDD full range speakers.
34c9 a MDD full range speakers.
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Old 31st August 2019, 06:48 PM   #21
claudiogan is offline claudiogan  Italy
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Quote:
Originally Posted by L.rivera92172 View Post
Can you get more into this 2 way with the tweeter and cardboard it's hard to tell how it's made from the pics can you please post pics of it so I can get a idea how it's done thanks in advance
In the 34c9 project the diffraction is used for two objectives: to generate delayed and coherent secondary waves, to make the diffuser omnidirectional. Normally in the design of the speakers there is a tendency to minimize the diffraction, I have not found on the internet suggestions to maximize it.

My previous thread is an invitation to experiment with the phenomenon of acoustic diffraction. On the Lavoce website I saw a high frequency compression unit on the home page, it reminded me of a possible 2-way drawing. Up to 1 Khz almost all electrodynamic loudspeakers are omnidirectional, if you want to detect the effect on the directive emission it is better to carry out tests with a tweeter.

By placing a sound wave guide (a pipe) in front of any speaker, sound waves are generated by diffraction on the opposite side. It is not a Hi-end system but it allows to verify the omnidirectionality of the issue. On the contact page there are links to pdf files and Pinterest pages, you can take inspiration from dozens of photos and drawings with waveguides of my projects. It is always full-range but the same guides also work with tweeters.

To make tests, any rigid or semi-rigid tube positioned in front of a loudspeaker is fine. To increase the acoustic diffraction holes or slit can be added. If a tweeter is not available, tests can be performed with a two-way facing upwards.
Attached Images
File Type: jpg 665g.jpg (85.9 KB, 196 views)
File Type: jpg diffrazione.jpg (62.7 KB, 194 views)
File Type: jpg ondeSecondarie.jpg (117.5 KB, 186 views)
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Old 3rd September 2019, 01:49 PM   #22
pelanj is offline pelanj  Czech Republic
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I did some cutting and glueing yesterday - and I have severely broken the rule "measure twice, cut once". Therefore no pictures yet, there is some serious filling and sanding needed and even then, it will not be perfect. Most probably, I am going to put self adhesive wallpaper as finish so that it looks at least acceptable.
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Old 6th September 2019, 07:19 AM   #23
pelanj is offline pelanj  Czech Republic
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Just to illustrate, these are the tube holders before sanding - I just used leftovers I had, but I cut them too narrow - so the edges will not be perfect 90 degrees. I will select the best surface as the front and try to cover up with the self adhesive wallpaper.

I also did not install any mounting for the holding screws yet (by mistake) - I plan to use M5 threaded inserts, I hope they will hold the load.

In the lower inner corners, I will glue in some small triangles, so that the whole bottom forms a baffle so I will not have to use any putty, just weather seal strips. These triangles will also serve as holders/spacers for the tube assembly.

Claudio, I just wonder what is the reason to have a hole in the base for the magnet - is it to bring the assembly as low as possible? Would it work the same way with the speaker magnet above the base without any hole? Also, is the 5 mm distance between the tubes and the speaker critical? Would 8 mm be any significant difference? Also, what is the thickness of the steel bracket you use?
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Old 6th September 2019, 01:00 PM   #24
claudiogan is offline claudiogan  Italy
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Quote:
Originally Posted by pelanj View Post
Just to illustrate, these are the tube holders before sanding - I just used leftovers I had, but I cut them too narrow - so the edges will not be perfect 90 degrees. I will select the best surface as the front and try to cover up with the self adhesive wallpaper.

I also did not install any mounting for the holding screws yet (by mistake) - I plan to use M5 threaded inserts, I hope they will hold the load.

In the lower inner corners, I will glue in some small triangles, so that the whole bottom forms a baffle so I will not have to use any putty, just weather seal strips. These triangles will also serve as holders/spacers for the tube assembly.

Claudio, I just wonder what is the reason to have a hole in the base for the magnet - is it to bring the assembly as low as possible? Would it work the same way with the speaker magnet above the base without any hole? Also, is the 5 mm distance between the tubes and the speaker critical? Would 8 mm be any significant difference? Also, what is the thickness of the steel bracket you use?
I saw that you made the support at least twice as long as my prototype, better you have more possibilities to fix the bracket.

The triangle instead of the sealant is fine. A further possibility is to build a flange as in the 54m42 project.

I don't think the distance between tubes and speaker is critical. The steel bracket section is 2.5 x 20 mm. The oscillation frequency also depends on the distance of the base.

I thought the hole for the magnet to avoid any interference with the base. These are minimal differences. The aesthetic improvement is evident.
Attached Images
File Type: jpg 54m42 08 left basso.jpg (179.4 KB, 138 views)
File Type: jpg 34c9 LS 20.jpg (112.4 KB, 28 views)
File Type: jpg 439h R staffa 20190428_121016.jpg (124.8 KB, 29 views)
File Type: jpg 227h staffa R 20190501_115442.jpg (118.5 KB, 32 views)
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Old 6th September 2019, 01:12 PM   #25
pelanj is offline pelanj  Czech Republic
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Thanks for the answers. I will most probably try it on a temporary base without the hole first - I am not sure if my bracket is ideal, it might be too soft.
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Old 12th September 2019, 04:39 AM   #26
amthanhkhangphudat is offline amthanhkhangphudat  France
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I am quite interested in the idea of your project. Can you advise me on an idea for new products? I am doing business on full range speakers and karaoke speakers. This is my website 96+ mẫu loa hội trường cho san khấu ngoai trời gia rẻ 08/2019
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Old 14th September 2019, 07:43 PM   #27
pelanj is offline pelanj  Czech Republic
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One unit is ready for measurements The bracket is a bit soft, but still looks fine with the frequency of movement. The tubes will be glued by contact cement and polished, the bases will be covered by self adhesive wallpaper. I think I will not make a hole in the base, the smaller Nd magnet does not look too bad.

I hope to plot some curves tomorrow.
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Old 14th September 2019, 08:36 PM   #28
claudiogan is offline claudiogan  Italy
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Quote:
Originally Posted by pelanj View Post
One unit is ready for measurements The bracket is a bit soft, but still looks fine with the frequency of movement. The tubes will be glued by contact cement and polished, the bases will be covered by self adhesive wallpaper. I think I will not make a hole in the base, the smaller Nd magnet does not look too bad.

I hope to plot some curves tomorrow.
I'm glad the project is almost ready. I usually use the prototypes a couple of days trying to guess the result of the measures in advance. I measure later as confirmation.

I am very interested in your opinion on the effect of delayed sound fronts. There are no measurements about it, I am waiting to hear your impressions after the break-in (of the drivers and the ears).

claudio
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Old 14th September 2019, 09:03 PM   #29
pelanj is offline pelanj  Czech Republic
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The first measurements will be just to confirm I did everything right and to see the overall in room balance and low cutoff. I put together also the other one really quick, I am excited to listen to them tomorrow. I will try my two best SS and tube amps.

It aleady makes me think how to apply this principle to load a compression driver, it also reminds me the K-tube I always wanted to try.
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Old 15th September 2019, 03:15 PM   #30
danb11 is offline danb11  United Kingdom
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This sounds like a fascinating project. I'm interested in trying the 439h, which seems to have a good response down to 41hz, which appeals to me from my favourite driver 3fe22. I have a few lying around.
This version uses a lot of piping, which becomes quite expensive in steel, here in the UK. PVC box profile pipe is much better value.
Is there any reason you've used metal over plastic?
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