A Study of DMLs as a Full Range Speaker

Yes it is a cheap car sub. I should try it with a coroplast but the biggest i have is about 18x24". I guess it won't hurt for experimentation. Or, I may just screw them to my loathsome "home entertainment center" ...

That reminds me...I need to call my shyster, ahem, attorney :cool: ... I was offered (and accepted) a "pre trial agreement" which apparently means I pay fines, do minimal community service (20 hrs) and the charges go away. Apparently the signs WERE there illegally but I was in the wrong to remove them ("petty theft"). None the less, 2016 beckons and we shall see...
As can be seen in the photo of post #41, modding an ordinary driver into a DML exciter, the difficulty is in connecting the VC to the panel.

The VC of a cone driver is deep under the frame, one has to extend it long enough to be higher than the front surface of frame. So it'd be better if the frame is cut to free up the VC.

And then, to mount it on the panel, it needs additional external support to float above the panel. Some soft gasket on the existing frame might work (if not being cut), but not ideal. Those are going to be damping points and too close to the VC.

Eventually, I think it's not very cost effective to do such mods. It can be done and it'll make some sound, of course. But for better performance, proper exciters are worthy. And, actually they are cheap enough.
Hi Guys, Interesting discussion re: home made exciters. Seems to me to be a lot of work for an uncertain result since PE has exciters that are so cheap. Some of the best are 8-14 dollars and one per panel is all you need. I have been playing with this stuff since 2009. Most important is the panel material. Current best is EXP or EPS but only if sanded and treated with thinned PVA glue. If this is done natural sound is the result. If not it sounds like plastic. ( I doubted it too) but sanding and treating is a must. If you want full range sound the panel needs to be large. A decent exciter and properly treated panel will give you sound that once you get used to the different presentation will cause you to dump your horns, various boxes and OB's. I would urge you not to dismiss years of experimentation available over on Audio Circle-- Open Baffle--NXT Rubbish Think Again. Thin ply can sound good too. Sorry X but foam core seems to be over damped and doesn't have the stunning clarity.
Hi Jim,

Thanks for the tips.

As to foamcore, it needs treatment to sound good, too. PVA coated, curved, and driven at the front surface (as my latest build) can bring life to it.

Before attaching driver to the panel, tapping on it and listen to the sound would be a simple test.

It should be clean and crisp, without excessive ringing. Think of those thin wood boards on various musical instrument, without the resonance of the box.
Hi , CLS Is there a link to your latest build?
xrk971 Yes the pink XPS is good. Here it is 3/4 inch thick and available in 2'x8' pieces. Sanding and PVA a must. Sanding makes a mess so would be nice if not necessary but there is no way around it sonically. There is a thread on the go at PE tech talk forum pg 2 --DIY Flat Panel Speaker Love. They are making the pink XPS black with ink and some interesting mounting methods for the panels. Worth a look.
Great suggestions.

I was thinking coroplast with a sheet of mylar glued to it.

Or some fiberglassing composite. I have access to fiberglass and resin on the cheap, having done a couple of surfboards with a buddy.

And just in time, I thought, as Parts Express introduced cheaper economy shipping for international customers, but their system doesn't ship to a PO Box nor support Chinese characters, as my address is impossible to translate in English (not in a way that the package would actual reach me!).

Amazon ships to PO boxes, so I'll have a look there!
I wanted to add a sheet of Mylar to make it a bit more resonant.

Anyway, just ideas popping in my head.

I was also planning to try sheets of thin ply available here.
Glue the sides to a mesh and suspend the whole thing within a frame, should be able to resonate freely.
According to the experiences of members in AudioCircle, it's said natural materials would be better (wood, paper... etc.) than plastic. I tend to agree.

Foamcore is sort of compromise for convenience.

I've tried corrugated cardboard which is nice and natural sounding. I gave up because I couldn't get large enough area and couldn't make it look good.
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Thanks for the flurry of interest! My "WTF" trial now has the 12" sub glued to the 18x24" coroplast. I used 4 small pieces of wood as offsets to glue the speaker flange to the coroplast. Good point about the damping problem: you really can't avoid it can you? The "exciter" must be attached at the driven point (voice coil = cat food tin, in my case) and the non-driven (basket -> flange) points too. Or does it?

This is an interesting trial: A 12" sub is probably overkill but (with much EQ to flatten the response), there is a good bit of bass. Since I didn't cut the cone nor damp the backwave in any way, a lot of what I'm hearing is doubtlessly reflected rear sound. My room is mostly hard, flat surfaces. I'll have to crank it up loud and find out if it will pull itself apart :)

The DML is an interesting concept and based on my somewhat sketchy knowledge of it, seems to offer the best DIY combinations of being cheap as well as demanding tweaking and experimentation which is why we are all here :)

Now will someone show me an easy way to make a Walsh type fullrange just using an old driver and an ice cream cone :clown:
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