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Repeat the treatment on the other side until both sides of the panel are treated twice. To make this process go faster, use a hair drier to quickly dry the treated panel. To finish rounding the corner, use an electric palm sander and 100-grit sandpaper by sanding right up to the marked lines.
Hi, I'm in the process of building some dml speakers but in my initial testing I get only very low output levels out of my panels. I'm using 4x DAEX25FHE-4 , two wired in series for each channel and two acryllic pannels, sized 50cm x 37cm x 1cm . The Amplifier is a Yamaha R-S202D, 100W per channel. The sound I get is ok quality wise, but much too quiet and even when the sound starts to break up noticably it's still not loud at all. I don't think it's the pannel size/thickness as I get the same quiet sound when I use a larger cardboard pannel.
Filling Large Spaces With Sound
Project Update- I have added 500uF bipolar capacitors from the output of the crossovers to the drivers to stop low frequencies below 50hz overloading the drivers. I used uF caps connected back to back in series with each of the drivers and found this improved the sound. Digital Signal Processing can be a little involved. Certainly more than I can cover in this introduction.
They throw a huge soundscape that just fills the room. Even tiny 14.5” x 12” panels absolutely fill the room with delicious flat panel sound. If you didn’t know that the tiny panels were speakers you would have little clue where the music is emanating from. Choosing the right material will greatly affect how a DML speaker sounds.
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On smaller panels, I prefer light suspension as there is more “air” and detail in my opinion. Generally, I would say that opt for the least amount of suspension but a panel free of resonance/panel noise. For most panels, I place 2 small pencil erasers under a thick, soft, tri-folded piece of fabric so that the panel is really only touching the fabric where the erasers are .
I noticed this going between cardboard, treated cardboard, thin ply, untreated and treated XPS and EPS. You start to get a feel for how certain materials sound just based on their physical properties (hard vs soft, light vs heavy, the sound of just brushing your hand across the panels, etc.). For the easiest build, use 2’x2’ Project Panels from Home Depot (Owens Corning FOAMULAR® 150 rigid XPS foam insulation). These are cheap, require no cutting, and will give you a good introduction to DML panel sound. However for better performance, a panel 24”x32.5” would provide better low and high frequency response.
A Study of DMLs as a Full Range Speaker
A pair of simple stands will need to be made to hang them on. Slow fading of sound away from the speaker allows it to fill a room with a very even sound. Bipolar which also limits sound interactions with side walls.
Where higher output may be required, a multi-panel array is a solid solution. Look for updates in the Flat Panels section of the Speaker Projects area of the Parts Express Project Gallery for a DML multi panel array design. You will need 2 sheets of 5mm thick 20×30 inch foamboard and 2x100mmx3mm thick MDF discs which you can buy at art supply shops. They need to be drilled first for the 4 nylon mounting bolt holes and after marking the position of the driver drill 5mm holes around the disc-I found this improved the treble. Prime the center with PVA glue to improve adhesion of the driver then stick on after drying. Mount these to the panels slightly off center with the bolts and nuts but DO NOT glue them on.
Without any type of damping at the edges some energy will be released at the edges instead of all the energy being focused on the front or back of the diaphragm. You really can not make a claim as to which exciter is “Best” honestly. Personal preferences also play a huge part as well. Place the exciter on the panel in the marked position. The exciters come with 3M VHB adhesive pre-applied to the exciter.
I don't mind making something as I do have a table saw, drill press, and the like. 2nd- There has to be an option of some kind that surface treats in white or some kind of opacity. I am currently experimenting with diluted gesso and acrylic paints to make DML’s presentable to anyone besides the Man Cave or Dorm Room markets. 220 is wonderful for shaping, gets the “rind” off very quickly, and doesn’t gouge and rip the panels the same way as low-grit paper.
Different materials will produce different ranges of frequency response. Ideal materials are things that resist compression while also allowing the panel to flex. Flexibility and compression resistance are key when creating an efficient DML speaker. I know this may be difficult, but do you know what these ceiling tiles are? We hear energy that is transferred to air in the form of sound pressure. Transferring energy into a surround doesn't help us.
This, to me, is the reason for the improved detail. This improved detail comes, unfortunately, at the expense of a more rolled-off high frequency response due to the larger voice coil. Building the panel is simple and can be completed in 1-2 hours. It is important to sand off all of the panel “skin”. The sanded surface should be dull, soft and velvety feeling, with none of the original sheen still present.
DML speakers can be a very attractive option when considering a sound system. If you're willing to couple the DML speakers with a DSP and a subwoofer, then you can create a system with really amazing sound. The large size of these speakers can be a negative in small spaces, although the ability to hide them inside walls or as artwork can easily overcome this limitation. The distributed sound waves do not penetrate walls as much as normal speakers. It's possible to list to them quite loudly before the neighbors will complain. By emitting sound over a large area directional sound and speaker separation are maintained, while also mitigating room modes that may cancel out certain frequencies within a confined space.
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