DIY Flat Panel Speaker Love

[Roadsterdriver]

I just finished my last dml flat panel today which was the sub panel.......Sub is 21inchX16inch

How did the sub workout? How did you build it? Material, driver, etc?

[Unbiasedsound]

It worked out pretty good...Still some kinks that need to adjust but all in all its to my preference.. After using 4 different conventional cone subwoofers I kept on going back to my DML sub.....A DML sub will not hit as hard, go as low or play as loud as a conventional cone subwoofer because of there limited pistonic movement....The reason why I prefer the DML sub is because IMO it blends the best with my DML panels keeping that DML signature sound....The DML sub IMO is also very articulate and detailed unlike some one note subs.

My designs are basically a modified version of Bertagni loudspeakers....Standard Design foundation would require a frame that would hold the diaphragm material in place with a spline to hold the exciter magnet in place as one unit like a conventional speaker basket similar to a BMR driver.

Material of choice is High density (EPS) Expanded Polystyrene. Preferred thickness 1/2-1/4 inch.....size ideal around 20-24inch X 16-18inch.

Frost King rubber foam to attach diapharam material to frame.

Driver recommended for sub application> https://www.parts-express.com/dayton...-4-oh--295-240 https://www.parts-express.com/dayton...4-ohm--295-238 If you need a 8ohm>https://www.parts-express.com/tecton...citer--297-206

Any type of sub amp. One with a 30hz boost or eq is a good option to have as most exciters low frequencies start dropping at 100hz

Tips> DML sub panel should be placed horizontally on the ground and inbetween the Left and right main/front channel speakers.

Using some type of acoustic foam pads like Auralex isolation pads under the DML sub will tighten up and increase bass response.

Using XRK's (DIYAUDIO forum) foam core enclosure on the DML sub will also increase bass.

You would still need to do the basics like sanding panel and treating the panel with 50/50-70/30 water glue ratio and rounding the corners painting the front side etc. you can read up on that on this topic.

[dawnut]

I'm a big fan of the DML, and have actually read through this whole thread. Being an old guitar player/builder I tried something a little different. Did a pair of dreadnought size acoustic guitars with the exciters mounted under the bridge area. I use these routed from my computer through a 6n3 YuanJing preamp and an older modified Lepai 2020A+ I'm using these in my 15'x20' sound room so volume doesn't have to go that loud.. Did my first listening session about a week ago with one mounted on a floor guitar stand and the other just propped against a chair. Amazing sound with details high and midrange that I have missed even with the PreSonus Eris E8 studio monitors I use with my DAW. Heavy bass at louder volume will get a little muddy and boomy so am working on a solution to that. with inline high pass and a small subwoofer. Still need to install my 1/4" strap peg jacks and hang them from the ceiling. I'm convinced these will be the speakers I'll be listening to just to relax by.

[benjicon]

"You would still need to do the basics like sanding panel and treating the panel with 50/50-70/30 water glue ratio and rounding the corners painting the front side etc. you can read up on that on this topic."

Love this thread.. SOOO much to digest.

Do you know if anyone has tried coating XPS panels in a thin layer of epoxy resin ? If I had to guess this might add a little more weight to the panel, but 'm curious if its a viable option. I am an artist and considering putting artwork directly on the XPS panel, if its been tried with no success I'll reconsider my options. If no ones tried I'll roll my sleeves up and have a go.

[Unbiasedsound]

Coating the whole panel of XPS will not only add some weight to it but dampen the panel reducing volume out put and sound quality....unless you can dilute the epoxy to where its similar to the 50/50 water glue mixture....That would probably require some type of thinner like acetone or laquer but those type of solvents do not do well on polystyrene due to there corrosive properties.

[dawnut]

Love this thread.. SOOO much to digest.

Do you know if anyone has tried coating XPS panels in a thin layer of epoxy resin ? If I had to guess this might add a little more weight to the panel, but 'm curious if its a viable option. I am an artist and considering putting artwork directly on the XPS panel, if its been tried with no success I'll reconsider my options. If no ones tried I'll roll my sleeves up and have a go.

An alternative could be a water based rattle can spray paint. I know Krylon makes a water based spray paint just for plastics that you could give a thin even base coat with. They also make a primer just for foam products. https://www.krylon.com/products/craft-foam-primer/ That might be a viable alternative to the glue/water mix.. they also make a spray gesso https://www.krylon.com/products/gesso-spray/ . One of the nice things about working with the XPS panels are that they are inexpensive enough to experiment with. Grab a 4'x8' piece cut up some panels and go for it. I used regular spray paint on one of my experiments but you must keep the can a good ways away from the panel and use very light coats or the solvents will eat into the XPS.

[Roadsterdriver]

My designs are basically a modified version of Bertagni loudspeakers....Standard Design foundation would require a frame that would hold the diaphragm material in place with a spline to hold the exciter magnet in place as one unit like a conventional speaker basket similar to a BMR driver.

Material of choice is High density (EPS) Expanded Polystyrene. Preferred thickness 1/2-1/4 inch.....size ideal around 20-24inch X 16-18inch.

Frost King rubber foam to attach diapharam material to frame.

Oh, thin material...interesting design.

Do do you have any pics

[Roadsterdriver]

Acoustic guitars, awesome. I thought of that too. Glad someone did it. Guitars should be roughly same range as human voice. Interesting.

[dawnut]

Acoustic guitars, awesome. I thought of that too. Glad someone did it. Guitars should be roughly same range as human voice. Interesting.

Trying to get the whole setup together pairing them with a small sub, when done I'll dig out a couple of my mic's and try to capture some decent sound video of them to share.

[benjicon]

Coating the whole panel of XPS will not only add some weight to it but dampen the panel reducing volume out put and sound quality....unless you can dilute the epoxy to where its similar to the 50/50 water glue mixture....That would probably require some type of thinner like acetone or laquer but those type of solvents do not do well on polystyrene due to there corrosive properties.

Thanks for the suggestions and nuggets of knowledge. There is a new type of resin available called "Art Resin" very low toxicity and easy to work with. I can thin it out by placing each of the parts (2 part epoxy) in a hot water bath which will reduce the viscosity of the combined solution. I don't know yet if it will match the viscosity of a 50/50 wood glue solution.. I'll be sure to share the results.

[benjicon]

dawnut Thanks for the tips on the water based spray paint, I'll keep them in mind as an alternative option. Definitely viable for the artwork.

[Unbiasedsound]

Oh, thin material...interesting design.

Do do you have any pics

I don't have any pics right now but my panels design is very similar to Bertagni's design > https://img.auctiva.com/imgdata/1/6/...1777455_tp.jpg

[Roadsterdriver]

I am also interested in ways to power them at the source so a signal can be pushed wirelessly.

Ideas?

Same here. This looks like a possible integrated solution. Probably Lo-fi, but I’m going to try it out for non-critical listening games rooms.

https://www.parts-express.com/dayton-audio-wf40a-multi-room-wi-fi-2x20w-amplifier-with-ir-remote--300-3820

[Limbo]

I have one exciter on a standup bass (double bass) and another on an acoustic guitar, both on floor stands in a L/R stereo configuration. Sounds outstanding for classic music, especially string quartets and chamber music. Also sounds nice for instrumental jazz. What really made me smile was listening to the classic "Dueling Banjos." It was recorded and mixed with true stereo separation (one instrument per channel). It feels like a ghosts are playing the instruments while you are looking at them, the sound comes through so well, and the separation is so exact. I augment the low end with a small subwoofer for other types of music.

This solution is not ideal for vocals. The voice components have too much echo within the instrument body. It may help if I play with the placement of the exciters. I plan on adding a couple flat panels with exciters and drive them from the Front-B outputs on my beefy Marantz SR7500. This will bring out the vocals and improve the sound of rock music. I can turn off the A speakers (string instruments) when listening to rock music.

[benjicon]

I hope this is ok to post here. I'm not the OP for this thread but I felt it will be more useful to people that find their way to this thread than if I start another one.

So I found some time over the weekend to start my flat panels, with the goal to make speaker panels out of the optimum material that will also let me use them to create art works on. The core challenge for me is going to be finding a balance between surface preparation and final finish with my artwork applied to it without effecting or compromising the sound quality too much.

It seems generally accepted that the best and most cost effective material is XPS (extruded polystyrene)... Home Depot in Canada has 2'x2' panels for $8. I grabbed a couple, some sandpaper, xacto blade, wood glue. The first step was for me to shape the edges of the panels to minimize any distortion or splashiness.. this guy (https://www.youtube.com/watch?v=zdkyGDqU7xA) recommended rounding the edges for best results so thats what I started with.

Sanding is a delicate process, I used my xacto blade to bevel the edges then sanded them gently until they were about where I wanted them. I used 220 grit and not a lot of pressure, if you press hard while sanding this stuff it starts ripping holes in it .. so go slow.



Gave them a rinse, let them dry and coated them with a couple of coats of glue / water mix.. Once they dried after the second coat they were a little toothy, so I gave them a light sand with 300 grit sand paper, then I made the mistake of giving them a quick rinse with water to get all the dust off.. this reactivated the wood glue so I ended up with very sticky panels that I couldn't stand anywhere for a a while til it re-cured.







This is after the wood glue water has re-cured, surface it nice and even and ready for painting.