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  • Cahudson42
    replied

    Advice on DML panel dimensions appreciated!


    I'm confused on dimensions. It seems many of this thread make 'squarish' panels - 24x24", 24x32", sometimes 12x24..

    What confuses me is that the Magnepan panels, across the board, are much narrower rectangles. The single-panel MMGW, for wall mount - is 10x38". The two-way MMGi floor mount, with 2 vertical panels apparently 48" tall, have a total width of 14.5". The .7 2-way 2 panel is 54 x15". Why such a difference between Maggie's and the DMLs here?

    Is it because of the 'problems' of a single point Exciter operating over such a narrow vertical panel? Or what?

    Specifically, may I ask what panel size you would recommend for the following:

    .. panel of 1" Formular EPS, corners 4" radiused, edges eased, glue coated.

    ..panel mounted in frame with compliant surround of Frost King foam, or foam tape.

    ..Exciter, DAEX25FHE-4 (or if you recommend, upgrade to DAEX30HESF)

    ..Exciter fixed mounted on crossbar

    ..Intended use - a simple 2 channel stereo, as a Left and Right speaker, floor mounted, flanking a 50" flat tv. Simple 'home theater' - no subwoofer, no center channel. Speech intelligibility important. Occasional classic music no-tv use.


    Any suggestions in addition to dimensions always appreciated! Panel material, panel mounting (or not) , stacked separate panels for each channel, Exciter choice/mounting/positioning, multiple Exciters - or not..

    Thanks for your help!
    Chris

    Leave a comment:


  • Unbiasedsound
    replied
    Originally posted by Cahudson42 View Post
    Formular Coating...

    After sanding the Formular faces, most seem to coat with 50/50 or 70/30 diluted white wood glue.

    Much less messy and durable would be Zinsser spray shellac. Alcohol based, dries instantly, does not dissolve the panel as laquer might.

    Is this as good? Any disadvantages?
    Just as long as the coat is very thin and light...….thicker coats of anything will make the panels become heavier and dampen the panels reducing spl and even sound quality.

    Leave a comment:


  • Cahudson42
    replied
    @unbiasedsound

    Ah! Always great to learn something! Thank you!

    I will continue with my 'Maggie Alternative' project - with an open back. 😊

    Chris

    Leave a comment:


  • Unbiasedsound
    replied
    Although it can be done you are going to change the sound of the DML panels.....DML panels are meant to be open baffle type since they radiate sound in a bipolarish fashion as they use the back walls to reflect sound for a open livelier sound signature.....Dr.Jose Bertagni states that it uses the reflected energy off the walls to combine with the front for increase in bass, openness with a 3d like imaging and soundstage.

    Its been further concluded by Dr. Shelly Katz (who worked on the Podiums) in which he stated that conventional speakers are designed and tested in anechoic chambers for the least amount of room interactions, while the podiums are completely the opposite where they need as much room interactions as possible.

    I have tried using a acoustic suspension (mdf wood) with my DML panels and it took away that 3d like magic imaging so I prefer the standard open baffle type of DML panel.

    I also used XRK's foam core enclosure and although I prefer it way more then the mdf wood material it still cant compete with the open baffle 3d like sound signature that I prefer the most.

    You can try it yourself and see which one you prefer as its all personal preference.

    Leave a comment:


  • Cahudson42
    replied
    Formular Coating...

    After sanding the Formular faces, most seem to coat with 50/50 or 70/30 diluted white wood glue.

    Much less messy and durable would be Zinsser spray shellac. Alcohol based, dries instantly, does not dissolve the panel as laquer might.

    Is this as good? Any disadvantages?

    Leave a comment:


  • Cahudson42
    replied
    Acoustic Suspension DML?

    Has anyone built an Acoustic Suspension DML, so that any effects of back-side radiation are eliminated, the DMLs can then be wall-mounted, etc?

    What I have in mind is an approximately 24 x 38 Formular panel, suspended in a frame all around with a highly compliant fabric or foam tape surround. But the frame is the rabbeted front of a closed back box, providing Acoutic suspension for the Formular panel. (Exciter would be fixed mounted on an internal cross member immediately behind the panel).

    Thoughts? Box depth/volume?

    Leave a comment:


  • Unbiasedsound
    replied
    Great job....you can lightly paint the panels to match your room color.

    Leave a comment:


  • Alphas
    replied
    Alright the update of the flat panel exciters are here. With Dolby Atmos receiver, front surround, top and rear surround, the sound effects are spread all around and phenomenal. The panels are stuck on the spacers with adhesive velro, this allow the panels to be removed when necessary.

    Before


    After
    The exciters are position with a 3/5 and 2/5 rule and diagonally. I found the double sided tape on the exciter's coil will tend to peel off after a week or so, therefore I removed the tape and glue with UHU general adhesive. This will fix the peeling issue and prevent it from dropping. The impedance of the exciter is 4 ohm, so I had the exciters in series to get 8 ohm total impedance. The panels are mounted vertically, which I find give a wider sound stage.


    The front surround are wired with 2 panels on each side, each panel has two exciters. The center is the 98cm width panel


    Top panels are fixed into the ceiling by washers and screws.


    Rear surround panels (extruded foam) are fixed with adhesive velcro tape.

    Enjoying the movies with realistic sound effects and cinema quality, my own cinema theatre. :s12::D

    Leave a comment:


  • Unbiasedsound
    replied
    Not sure if I mentioned this before or on another site but here is a tip to tighten up the sound of the panels so they don't sound so diffused. Its a simple technique Ive been using for the past 2 years. All you need is some type of soft foam/rubber. I use Frost kings rubber foam tape. Cut a piece off the size of the magnet of the exciter you are using. If your panels are free floating (without a spline) stick the foam directly on the magnet of the exciter. If you are using a spline stick the foam on the spline. With a spline you have more placement options as you can use multiple damping pieces all along the spline to fine tune the sound to your taste.



    Leave a comment:


  • Alphas
    replied
    Extruded foams are cut with foam cutter, the dimensions are 60x30cm, edge rounded at 10cm. The local stores only carries it in blue color, all of them are edge rounded and buffed to give a clean look.


    Next was the spacers, I used wood block and acrylic to make them. The total thickness is 3.0cm, so the exciters can be glued on the panel surface and the panel will be mounted on the spacers with velcro.

    Leave a comment:


  • Unbiasedsound
    replied
    Plywood is not one of the better sounding woods most likely due to the glue dampening the wood which also hinder spl levels.........I prefer Balsa, spruce or bass woods, but they are more expensive.

    For the most COHERENT sound only 1 exciter should be used per panel....multiple exciters used per panel will increase spl levels but you wont get the same coherent sound when using only 1 exciter on each panel as there is no way one can completely stop the waves from overlapping each other on the same panel....The only way to completely stop the waves from overlapping is to use multiple separate panels to create one big panel like in a line array.

    Leave a comment:


  • Alphas
    replied
    Had been busy with work past few weeks but I managed to get some parts done. The wooden plywood are cut with laser machine and curved to remove harmonics. The 5mm thickness plywood has the dimensions 60x30cm. The longer piece is for the center speakers, 98x30cm, all edges rounded at 10cm. The lightweight 3-ply plywood is flexible and should provide a good frequency response to the high range.


    Leave a comment:


  • Unbiasedsound
    replied
    I hope those aren't the DAEX30HESF-4 exciters....because if they are I am totally jealous right now. LOL....Those are IMO one of the best exciters that P.E. has to offer.

    What type of wood are you using and what is the size and thickness?

    Leave a comment:


  • Alphas
    replied
    Hi Everyone, I am from Singapore. Recently I did a home renovation and decided to create a cinema home theatre with Xiaomi UST laser projector and flat panel exciters.

    Next, av receiver for the home theatre setup wtih the Xiaomi wemax projector. I got Sony DH-790 7.2ch Dolby Atmos receiver. Going to setup 7.1 home theatre 7 exciters not speakers. The exciters are here and I will be using wooden panels for the sound. Let see how this goes!




    Come back again for updates!

    Leave a comment:


  • Unbiasedsound
    replied
    Benji, you could even make your panels a octagon shape if that would please you more aesthetically....Also I prefer 70% water and 30% glue mixture as its not as thick as the standard 50/50....I find that anything too thick can add extra weight and dampen the panels.

    Leave a comment:

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