DIY Flat Panel Speaker Love

[Cahudson42]

@unbiasedsound

Ah! Always great to learn something! Thank you!

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

Chris

[Unbiasedsound]

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.

[Cahudson42]

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

[Unbiasedsound]

Conventional cone speakers are very pistonic in motion so the higher the motion and the bigger the cone area equals more bass.....Exciters are more modal in motion but certain exciters do have more pistonic motion then others but its still very limited compared to most normal conventional cone drivers.

Because pistonic motion is very limited with exciters they need bigger panels to produce more bass, hence why most DML panels need to be at least 16inches or larger to produce adequate bass....If bass is not your concern and you are using a separate powered subwoofer then you can make the DML panels smaller but I still would not go smaller then 12inch in width minimum.

The reason why most people make squarish panels is because that is the panel material (pink formula hobby panels) that is readily available in that shape/size.

I prefer rectangle shape, but there is a limit to how long the rectangle shape can be because just like you said exciters radiate from a point outward......Panels that are very long require more then one exciter on the panel....the only down fall to using multiple exciters on one panel is that you will lose coherency as there is no way one can completely stop the vibrational waves from crossing each other....Its like throwing a single pebble into a pound it will produce a nice uniform circle but when you throw in more then one stone at the same time the waves overlap and cross each other therefore reducing that single uniform coherency.....There are some ways and techniques to control how much the waves overlap but you cannot completely stop it.

So any panel size just as long as its over 16inches. in width and length....The pink 24X24 panels are a good size but you can cut it to 24X20 for a rectangle shape which is what I prefer. Ideal thickness is 1/2-1/4 inch but most readily available XPS/EPS are 1-2 inches thick....Unless you have a large hot wire cutter it will be hard to cut a panel evenly.

Round the corners of panels.

Sand both sides of panels (make sure you wear some type of mask) The back of the panel were the exciter will reside use 70%water to 30% glue mixture while the front of the panel use oil based paint of your color choice....spray lightly from at least 2ft. away and dry indoors or in a shaded area... Do not dry in sunlight as heat seems to increase corrosive properties of oil based paint....The reason for oil based paint is that its harder/stiffer.

Mount panel in frame using frost king rubber/foam tape to connect panel to frame......Where to attach frost king foam to panel? In the back of panel all along the edges all around the panel....now do NOT use one continuous strip of frost king foam tape all around the panels as that will over dampen the panel.....what you do is CUT them into 2 inch pieces and space them 2 inches apart all around the back edge of panel. When spacing frost king foam around the panel make sure you do not space them apart at the corners as the corners NEED to be covered with the foam tape. So cover all 4 corners with foam tape first and then start spacing them 2 inches apart all around the panel....Also the FK foam tape adhesive is weak so you will need to use wood glue on both sides of the foam to attach panel to frame. Do not clamp just use a light weight on top of panel until the glue is set in about a couple of hours.

When attaching the exciter to panel use the 5min. 2 part epoxy glue...do not use the 3m adhesive that comes with the exciter, peel it off.

mount exciter to spline....exciters without mounting holes should be glued with 2 part epoxy glue. (magnet part)…...To tailor the sound you can use strips or pieces of FK foam tape all along the back of the spline to your personal taste.

Both of those exciters are good but if you want higher volume/spl levels then the bigger exciter is the way to go as it will play louder and handle more power but if not the smaller exciter is one of the best bang for the buck exciter that P.E. has to offer.

One exciter per panel is the most coherent but you can use multiple panels and stack them together and wire the 4ohm load in series for 8ohm load as most receivers are usually 8ohms.

Placement of exciter on panel I prefer dab smack in the middle but sometimes I am around 1-2mm off. LOL Its up to you where you want to place them as you could do the 3/5-2/5 or wherever you think it sounds best.

Build some stands directly on to the frame like this pic> https://img.usaudiomart.com/uploads/...0-speakers.jpg The stands should raise the speakers at least 4 inches so your total panel height would be roughly around 28-30 inches...you could make them taller to around 35inches which is closer to ear level.

Use some type of dampening material (I use yoga mats from Ross's LOL cheap 5 bucks.) and put it directly under the stands with at least 1 inch lip sticking out all around the stands edges....For the most bass response all panels should be placed directly on the floor like floor standing speakers....when you raise the panels off the floor the higher you go the less bass.

Placement...Panels should be placed at least 1ft. away from the back walls or 1-1/2ft to 2ft. ideal....toe in is not really required unless your panels are very far apart as the soundstage and imaging is spectacular. They do need WALLS to reflect sound.

For aesthetics you can buy terminals , speaker frame and grill cloths etc.

[Cahudson42]

Unbiasedsound

Thank you very much for the great tutorial and explanations!

May I ask two quick questions?

1. Am I correct that the panel edges are left simply rounded/sanded, no glue or paint? As leaving this keeps reflections back into the panel less (provided better Damping)? Or are the edges painted or glue covered?

2. I am having trouble visualizing what is the mounting 'spline'. I see the exciter simply glued to a frame cross member, which I would place diagonally (forming a triangle to resist frame racking - old Carpenters rule - make triangles). In woodworking, a 'spline' is a rectangle that joins two larger rectangles that are slotted and joined by the spline. A woodworking ''bisquit' is a form of spline. Can you explain how the spline is used here in mounting the exciter? Also, is there any 'trick' to use when glueing the exciter so that the voice coil is not offset from it's home position (pushed in, pulled out?

Thanks again for all your help
Chris

[Unbiasedsound]

1. no glue or paint on the edges...but what I forgot to mention on that part is to use frost king foam all around the edges of panel....the reason for this is that some vibrations likes to escape from the edges but the foam keeps the vibration in so that it comes out from the front of the panel instead of escaping to the sides/edges.
..
2. Spline is just a single piece of material (any type of material like wood , aluminum , metal etc.) to hold and support the exciter in place attached to the frame like in this picture https://img.usaudiomart.com/uploads/...0-speakers.jpg The thinner and lighter the spline the easier it is to work with when attaching.

As for the off set of home position, Now that is the tricky part that even I have a difficult time with as you have to make sure its not pushing nor pulling....I glue the exciter to the panel first then I glue the spline to the back of the exciter then I glue the sides of the spline to the frame....gluing the spline to the frame last lets you adjust it by eye so you are not pulling nor pushing which is the reason I use 5 min. epoxy so it sets pretty fast...do this with the panel standing up instead of facing down as this way there wont be any weight from the spline pushing down just make sure you keep it level with no sag and you will have to hold it by hand UNTILL the epoxy hardens which is about 5-10 min. when holding the spline try not to push or pull just support it with your hands....One reason to use frost king foam is that it does have some slack/give to play with as its flexable so even if you are a little off from the home/center position the foam can adjust to it over time or you can stretch the foam a little yourself...I am sure pros like DrJose Bertagni or Dr.Shelly Katz know of a better way to align it perfect so its not pushing or pulling but I cant find any info on there techniques.

Although it seems like a lot to take in this is just the intro for a beginners design.

[Unbiasedsound]

Check out this Russian company called SheetControl and there DML panel design called Mescalito pro.

https://www.youtube.com/watch?v=HfYI1fRmymI

https://www.youtube.com/watch?v=-vtt29mbyX4

IMO my panels still sounds better....If they were to use some of my secret techniques there panels could sound just as good as mine or better. But I aint telling LOL

[Cahudson42]

Got it. I will report back when I construct my panels. It likely will be late May or June, when I am back in the Adirondacks and have access to my Woodshop up there. Meantime,I will get the Exciters, Frost King foam, Formular EPS panels, etc. and get ready.

Thanks Again!
Chris

PS - on the ' mounting exciter to spline w/o pushin/pushout' - after glueing the exciter to the spline and panel, I am going to mount the spline to the frame with biscuits, but with the biscuits 90 degrees to horizontal, not vertically along the ends of the cross member as they usually would be. This will allow the cross member when dry-fit mounted, to move slightly in the horizontal plane. I will then actuate the exciter, perhaps with 100/200 Hz, 'to see where it settles' - then glue the spline in place. The settling point should be at the voice coil home position exactly.

[Unbiasedsound]

This guy is on the right track....He utilized one of my advanced methods which is carving out the EPS panels so that they are different thicknesses throughout the panel....I can tell by the shape that he took that from either Bertagni or yamahas ear designs.

The misconception of thicker panels producing more bass is false....Thinner panels produce better, tighter more accurate bass, which is why I recommend 1/2 inch -1/4inch panels for my beginner design.....My advanced design can use 1-2 inch panels because the panels will have various thicknesses through out the panels with some areas being as thin as 5mm.

https://www.youtube.com/watch?v=haKoMOiOqho&t=225s

Panels need to be stiff but yet flexible at the same time hence why thinner pieces of EPS and Honeycomb material are around 5-10mm thick....Thinner the panel equals more flex while thicker panels barely even flex...The main reason small panels of the same material don't have as much bass is that smaller panels do not flex as much as larger panels. That is why one needs thin but larger panels to get the most bass response.

[Cahudson42]

May I ask the method to use to remove the 3M sticky tape from the front of the DAEX25FHE-4 exciter w/o damaging it? Box cutter/lift/scrape? A solvent? Or?

On shaping XPS - can you do a ''creme brulee' with a blowtorch - carefully? Make an oval parabolic dish, large, exciter in middle? Stiffest in center, feathering out the collapsed foam layer so it becomes thinner and more flexible toward the edges... No need to coat?

Route a deep channel around the outside of the oval, creating a surround. Do coat the back of it for a bit of strength with thinned rubber cement...(?) Mount rectangular panel directly to frame. No need for Frost King foam...

Thanks!
Chris

[Unbiasedsound]

The method I use to remove the 3M tape is with a tweezer. Peel one section off then hold with your finger on the plastic coil while you remove the rest of the tape.

HECK NO NEVER USE A BLOW TORCH......You can use a router or even a Dremel with router bit (it gets very messy so a shop vac while you sculpt comes in handy)....Or if you have the luxury of owning a hot wire cutter that would be one of the best options...…..you can make an oval or octagon shape with exciter in middle......yes thickest in center so that it becomes thinner and more flexable toward the edges...coat back side with 70%water and 30% glue mixture and the front lightly with oil based paint.

Not exactly sure about your last question but are you saying to use rubber cement to mount panel to frame?....The EPS panel cannot touch another hard solid object as they will produce distortion which is why there needs to be some type of rubbery foam material to attach them to the hard solid frame.

[Cahudson42]

Thanks again, Unbiasedsound. Got it.

On my last question, I was thinking of a simplified method of mounting panel to frame by cutting out a deep channel around central oval Sharpie drawn on the rectangular panel (which I am thinking maybe 20x 32 for initial shot). If the panel was 1/2" Formular (8x4 sheets are at my local HD) I might make the channel 1" wide and 20mm deep, leaving 5mm of material. Then coat the channel with shellac so the 5mm doesn't melt in the nextstep -: thinned rubber cement in the channel and channel edges. This suspends the oval in a remaining rectangular frame, which now can be directly glued inside a frame.

Even simpler might be the create an oval with spider legs - completely cut away the channel except for 3 or 4 'legs' connecting to the outer rectangular shell around the oval.

Thoughts?

Chris

PS - I was thinking of making a wire cutter, but thought to cut the panels out of the 4x8 sheet, I would use my drywall framing square, and an 8cm 'breakaway' replacement box cutter blade copper wire wrapped to my soldering gun tip. To make a channel, I would wrap a copper wire loop to the soldering gun tip...

I also have - in the Adirondacks unfortunately, a Dremel with the new Veritas (Stew-Mac like) plunge base, which would allow cutting to depth.. but will need to wait until late May when I am back..

I do tend to over-think these things..😊

[Unbiasedsound]

My advanced design is basically a modified version of Bertagnis SM100 2 way loudspeakers. I am still not exactly sure what you are trying to say but you could try it out and see if your method works.

Here is a pic of Bertagnis speakers and how my design is very similar.>
As you can see the oval part is the thinnest, its thicker in the center where the exciter resides but gets thinner as it goes outward until it reaches the edge, while the rest of the panel triangular shaped are the same thickness...the grooves and channels is what separates the thickness.

Yea I seen a video on youtube of one making a hot wire cutter out of his soldering tool...I was going to try that but I have only 1 soldering tool so I didn't want to chance it in case I broke it....Plus I am not sure if my soldering tool is powerful enough to heat a long wire....I seen the router (with a loop) hot wire cutter from the hotwirefoamfactory with a good power supply but it cost around $100.00.

[AEIOU]

My advanced design is basically a modified version of Bertagnis SM100 2 way loudspeakers. I am still not exactly sure what you are trying to say but you could try it out and see if your method works.


Yea I seen a video on youtube of one making a hot wire cutter out of his soldering tool...I was going to try that but I have only 1 soldering tool so I didn't want to chance it in case I broke it....Plus I am not sure if my soldering tool is powerful enough to heat a long wire....I seen the router (with a loop) hot wire cutter from the hotwirefoamfactory with a good power supply but it cost around $100.00.

You can make or buy a hot wire foam cutter quite inexpensively. Do a web search for "hot wire foam cutter" and you'll see all sorts of options. Making your own would be the best option for having total customization.

[Unbiasedsound]

Another video of the Mescalito pro DML loudspeakers> https://www.youtube.com/watch?v=rd8yU2XwxIM

Behind them you can see a pair of BMR speakers with a tweeter....Anyone that likes the sound of a BMR driver should look into DML loudspeakers.....Current available BMR drivers cannot even compete with DML panels as the largest readily available BMR driver is 3.5inchs.....Unless they make a 6.5 inch or larger full range BMR driver I wouldn't even fathom of buying a small BMR driver ever again.