Sure thing. It really is nothing special in design terms. I used one exciter per panel in the classic 2/5 offset position attached using the 3M tape fitted to the Dayton drivers. The board is a very cheap qtr inch/5mm with three plies of board. The inner ply is thicker than the outer two and possibly a softer wood. The wood is far from a high quality, there are knots visible and the surface is rough, straight off the ply lathe blade at a guess. I will see how I can get a video with decent sound for you all.
Someone with more experience with DML’s will be along in a minute but from what I understand you need low mass but high stiffness. A 2mm thick sheet the size I have ( 600mm by 1200mm) might be too flexible but give 2mm a whirl. The exciters are cheap as is board that thickness. Providing the panel size is not too big in order to maintain stiffness it should work. You will have less low frequency with a smaller panel.
Just to add there was no special insight behind 5mm, it was just the thinnest panel I could get in MsrBricolage down here in the Cherante.
Just to add there was no special insight behind 5mm, it was just the thinnest panel I could get in MsrBricolage down here in the Cherante.
I guess you meant Charente... 
Ok, I have a local shop that has both 2mm and 5mm.. the cheap stuff as well... not called Mrs Bricolage though! ha ha!
I just need to get my hands on some exciters.
Been wanting to try DMLs for a while.
Going on vacation soon, but I'll get on it when I come back.
Ok, I have a local shop that has both 2mm and 5mm.. the cheap stuff as well... not called Mrs Bricolage though! ha ha!
I just need to get my hands on some exciters.
Been wanting to try DMLs for a while.
Going on vacation soon, but I'll get on it when I come back.
I guess you meant Charente...
Ok, I have a local shop that has both 2mm and 5mm.. the cheap stuff as well... not called Mrs Bricolage though! ha ha!
I just need to get my hands on some exciters.
Been wanting to try DMLs for a while.
Going on vacation soon, but I'll get on it when I come back.
Though I haven't tried this yet.... I have some Dayton 25s. Possibly a thin material slightly bent over a long radius might do. Something like a 6' by 2' with a slight bow along the long axis.
Thanks for the reply. My measuring gear is in London, I am in France, stupid I know. From what I can see the exciters have a metal spring for suspension, a spring steel disk with circular cuts to produce a planar spiral which is why I thought I should ask. It’s only been 24 hours but the sound has changed. This could be good news or could be signs of failure?
It could be the plywood? Humidity plus temperature variation of a large panel suspended freely in air.
A good starting point would probably be to look at how a commercial exciter is made.
The cone/diaphragm and perhaps some of the basket should be removed.
Then comes the problem of mounting the voicecoil former stub to the DML panel, and still harder how to mount the remainder of the basket to the panel.
With the last you are really doing a secondary spider of sorts, so a lot of flexibility in the movement axis of the voicecoil, but as little as possible in any of the rotational axis. The most important being the one hinging around the voicecoil former attachment point, being pulled by the weight of the magnet.
You might need an additional wire(s) supporting the magnet.
You might also consider thinning out the main spider as its stiffness will get added to the new one and to the stiffer membrane, lowering Qts significantly.
The cone/diaphragm and perhaps some of the basket should be removed.
Then comes the problem of mounting the voicecoil former stub to the DML panel, and still harder how to mount the remainder of the basket to the panel.
With the last you are really doing a secondary spider of sorts, so a lot of flexibility in the movement axis of the voicecoil, but as little as possible in any of the rotational axis. The most important being the one hinging around the voicecoil former attachment point, being pulled by the weight of the magnet.
You might need an additional wire(s) supporting the magnet.
You might also consider thinning out the main spider as its stiffness will get added to the new one and to the stiffer membrane, lowering Qts significantly.
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The exciter I use has a steel spring spider which has a strong restoring force. I don’t know if other exciters have similar arrangements but this restoring force might be a requirement. Why not look at a few patents online to get a better idea of how exciters work. The general view is that exciters are ‘just’ a speaker motor assembly without the cone, however it might be a bit more subtle than that. It may well be possible to DIY an exciter but they are very cheap and unless you are experimenting with a new principle it might be a better to buy one?
Have a look - $3 starting prices and $10 is a decent one. Cheap as chips.
Exciters & Tactile Transducers in the Speaker Components Department at Parts Express | 18
I wouldn’t bother making one from salvaged conventional driver. I have tried and it’s not as good sounding.
Exciters & Tactile Transducers in the Speaker Components Department at Parts Express | 18
I wouldn’t bother making one from salvaged conventional driver. I have tried and it’s not as good sounding.
On another note has anyone experimented with mid/side stereo?
Either with one panel parallel to the listener and another sticking out from the mid point of the first at a ninety degree angle (not touching of course, but close)? Or with two ninety degree splayed panels, pointing inwards or outward from the listener?
The characteristics of the DML panel would seem ideally suited to the idea.
IE back and front sound being practically symmetrical and the radiation pattern being very homogeneous.
Either with one panel parallel to the listener and another sticking out from the mid point of the first at a ninety degree angle (not touching of course, but close)? Or with two ninety degree splayed panels, pointing inwards or outward from the listener?
The characteristics of the DML panel would seem ideally suited to the idea.
IE back and front sound being practically symmetrical and the radiation pattern being very homogeneous.
Just reporting back that after 48 hours I am getting much more bass from the panels such that I am reconsidering if subs are really needed. I am getting very good output down to 30 hz. So instead of a sub I am now thinking about a large panel suspended behind and between the two main panels with either four exciters with two mounted left and two mounted right or using bass shakers. If I get the exciters through in time before I head back north I will update you then. I am also getting good output up to around 18k according to a spectrum analyser app I downloaded. The spectrum looks reasonably flat now, better than the first day when there was a downward slope from around 12k. I will post some results tomorrow via screen grabs from the app.
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It would be cheap and quick to check this out. The panels I am using do have null points at the side ( or maybe it’s not a null but just a lack of output) but this region is very narrow, between 5 to 10 degree max.
I promised some feedback on frequency response of the cheap as chips panels I threw together last week.
I have attached an image on the overall spectrum made using an online white noise generator below.
Several notes of caution on the image.
Firstly it’s recorded on an iPhone using an app called dB meter. As the iPhone microphone has a limited response below 250hz by design please ignore the spectrum below this.
I recorded the white noise at a distance of one meter from the panel but make no claim for huge accuracy, it’s just a quick and dirty look see with what I have to hand.
There is an obvious dip at around 3k. From this point there is a gentle falling response out to around 18k after which it falls off a cliff.
After that I used an online frequency generator to test the audible range I can hear from the panel. More caution. I am not able to hear much above 12k these days and yes, that’s exactly what I got. Blame me, not the panels.
The bottom end was more interesting. These panels definitely reach down to 50hz but there wasn’t much below that. This is not as deep as I ‘thought’ I heard, e.g. a Low E from an open bass string was heard, but that might have been the ‘missing fundamental’ effect in action.
So maybe I need that subwoofer, be it a big panel or a decent box.
In the meantime Dire Straights 'Alchemy' is playing and I am at a rock concert. Fabulous sound.
I have attached an image on the overall spectrum made using an online white noise generator below.
Several notes of caution on the image.
Firstly it’s recorded on an iPhone using an app called dB meter. As the iPhone microphone has a limited response below 250hz by design please ignore the spectrum below this.
I recorded the white noise at a distance of one meter from the panel but make no claim for huge accuracy, it’s just a quick and dirty look see with what I have to hand.
There is an obvious dip at around 3k. From this point there is a gentle falling response out to around 18k after which it falls off a cliff.
After that I used an online frequency generator to test the audible range I can hear from the panel. More caution. I am not able to hear much above 12k these days and yes, that’s exactly what I got. Blame me, not the panels.
The bottom end was more interesting. These panels definitely reach down to 50hz but there wasn’t much below that. This is not as deep as I ‘thought’ I heard, e.g. a Low E from an open bass string was heard, but that might have been the ‘missing fundamental’ effect in action.
So maybe I need that subwoofer, be it a big panel or a decent box.
In the meantime Dire Straights 'Alchemy' is playing and I am at a rock concert. Fabulous sound.
