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A Study of DML's as a Full Range Speaker
A Study of DML's as a Full Range Speaker
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Old 28th December 2020, 12:20 PM   #2631
chdsl is offline chdsl
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Join Date: Oct 2020
^^
That is not the idea of distributed mode. The vibrations are supposed to move along the surface of a plane, not through a polystyrene rod to give sound. As the rod is round, the vibrations won't go along it's surface, for the cross section of a round rod is quite stiff.

Instead of a pagoda looking structure, if you put all those disks on top of each other, glue them to each other, you'd get a better sound. But, not bass as you get from a 8" woofer.
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Old 28th December 2020, 12:48 PM   #2632
xrk971 is offline xrk971  United States
Got Foam?
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A Study of DML's as a Full Range Speaker
Quote:
Originally Posted by irishpatrick33 View Post
I built the PGodas. No scientific testing whatsoever was done though. My ears confirmed some ideas and fears. No matter how many discs I add, there just isn’t excellent bass with exciters. In this case I used Visaton exciters, which unfortunately look to be made in China. I also think that matching disc sizes creates more interaction nulls/peaks. They sound like speakers for sure, not super great though. They do solve my pet peeve about exciters, the super brightness is tamed.

These get top heavy quick even when using styrofoam. Despite the lightweight of material, a lot of leverage is created by the vertical length and double sided tape doesn’t want to hold while doing temporary testing. I think this might be worth pursuing for someone else. I only want full-range speakers—no subs.
Very creative and out of the box thinking.
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Old 2nd January 2021, 09:57 AM   #2633
mRRk is offline mRRk  Spain
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Join Date: Mar 2018
Quote:
Originally Posted by irishpatrick33 View Post
I built the PGodas. No scientific testing whatsoever was done though. My ears confirmed some ideas and fears. No matter how many discs I add, there just isn’t excellent bass with exciters. In this case I used Visaton exciters, which unfortunately look to be made in China. I also think that matching disc sizes creates more interaction nulls/peaks. They sound like speakers for sure, not super great though. They do solve my pet peeve about exciters, the super brightness is tamed.

These get top heavy quick even when using styrofoam. Despite the lightweight of material, a lot of leverage is created by the vertical length and double sided tape doesn’t want to hold while doing temporary testing. I think this might be worth pursuing for someone else. I only want full-range speakers—no subs.
Hi
From the pictures It seems to me you are using polyethylene foam, and not styrofoam (polystyrene)
Styrofoam is made of little balls you can take apart. It is the kind of foam that came with a new TV, and it is much more rigid, even with reduced thickness it is quite rigid.
I noticed you are using a very big thicknesit is beter to use reduced thickness.
PE foam is not that rigid, it is used to protect from drops and vibrations (bad!) so won't work that well
M
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Old 3rd January 2021, 05:24 PM   #2634
moldie is offline moldie  South Africa
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Location: Cape Town
Default First attempt

Finally got around to building something. Went out and did it without much experimentation or good design... Your suggestions welcomed! Sound is listenable, but nothing to write home about. Driver seems too low powered for panel. Will experiment with adding more drivers at a later stage.

Goal was to get output closer to 50Hz. Roughly inspired by Burntcoil's design. Clamped the bottom of the plywood between rubber pads and 3D printed wedge to bend it and increase stiffness lengthwise. Bend proved insufficient to keep the ply stiff. Ended up sawing a bit off the top (which was good since the ends were water damaged) and adding an adjustable tensioner (attaches a the top). Hopefully tensioning can keep the wood from deforming over time because of moisture absorption (avoiding painting as it changes the colour and decreases WAF).

Materials:
Dayton Audio DAEX32EP-4
3.5mm Commercial plywood
3D printed wedge (PLA)
Vibration absorbing rubber matt (used on floor underneath heavy machinery)
M8 and M10 hardware
Brake disc as base (with felt pads to protect floor)

Frequency response:
Click the image to open in full size.
Impulse response:
Click the image to open in full size.

Click the image to open in full size.
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Old 5th January 2021, 12:33 AM   #2635
Miguel_AC is offline Miguel_AC  Spain
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Default Another dml video

Quote:
Originally Posted by kaptajnThomsen View Post
I did a youtube search with a 1 month filter for dml speakers / flat panel speakers as i figured more people would be tinkering lately. I found a few:

tiny balsa panel on a box
YouTube

slim and tall ply panels:
YouTube

plywood with resin (i think)
YouTube

basic 3 mm ply
YouTube

sand on a plate
YouTube

tonewood (idk, sound seems pretty terrible)
https://www.youtube.com/watch?v=uFnWQgmuwUo

guitars in stereo (older)
https://www.youtube.com/watch?v=eN5gihTm5lk
https://www.youtube.com/watch?v=n7WIrFeCwK0
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Old 5th January 2021, 09:51 PM   #2636
raph1978 is offline raph1978  Poland
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Join Date: Dec 2019
Location: Warsaw
Hey everyone,
I've been slightly out of the loop as work has been keeping me occupied. I wanted to share with you my experiments. During the pandemic I tried working with all sorts of canvases as art shops were the only shops open in Warsaw.
I tried all sorts of canvases: Linen, Cotton and Polyester. What I found out was, that the thinner the material, the fuller sound it produced, but the key to getting a deep sound was not only sticking a wooden “plate” onto the canvas, but also drilling a hole in the piece of wood. It didn’t make a difference whether you drilled 1 or 10 holes. The size of the hole mattered the most. Since I couldn’t get any double sided tape during this time, I only pressed the excited to the wooden plate. My further observations were:
1) Linnen was too thick and the sound was simply muffled.
2) Cotton was decent, but I couldn’t get a universal speaker out of it.
3) Ikea painting was GREAT! Unfortunately I salvaged only 1 painting from my office and it was the largest size that Ikea had. I must say that it was fantastic, but I kept getting some buzzing sound with a lot of base. I can bet that with a smaller sized painting things would have been a lot better

I planned on priming all of them with 50/50 wood glue & water, but never got around to it as I had to commit all my free time to my business and also because I hooked up my Kenwood ls-880 ‘s and they just sound so good that I never had the motivation afterwards

Just my $0.02 that I wanted to add to the conversation.



Click the image to open in full size.

Click the image to open in full size.

Last edited by raph1978; 5th January 2021 at 09:59 PM.
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Old 6th January 2021, 11:00 AM   #2637
moldie is offline moldie  South Africa
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Location: Cape Town
Quote:
Originally Posted by raph1978 View Post
I tried all sorts of canvases: Linen, Cotton and Polyester. What I found out was, that the thinner the material, the fuller sound it produced, but the key to getting a deep sound was not only sticking a wooden “plate” onto the canvas, but also drilling a hole in the piece of wood. It didn’t make a difference whether you drilled 1 or 10 holes. The size of the hole mattered the most. Since I couldn’t get any double sided tape during this time, I only pressed the excited to the wooden plate.
Hi raph1978

Which hole sizes did you find work best?

Any idea what type of canvas the Ikea painting uses?

Regards
Dirk
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Old 6th January 2021, 02:27 PM   #2638
raph1978 is offline raph1978  Poland
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I took a standard size 6 drill as that's the only one that I had. I tried making 1 hole, 2 holes, 5 & 10 and actually the more I made, the flatter the sound became.

I'm sorry but it seems that I forgot to add the part that Ikea canvases are made out of Poliester. They were the thinnest ones of the whole bunch.

The thicker the canvas, the more muffled the sound.

My recommendation would be to get a small / medium size Ikea painting when they're gonna be on sale for a few bucks and give them a go. When I'm gonna have some extra free time I might actually prime the one that I have and gonna try to put some windows seals where they canvas meets the metal frame.

Unfortunately I don't know when I'm gonna have the time to do that, as I'm currently preoccupied with other things.

Hope this helps.
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