[gragra]

I will try this http://www.laminil.com/eng/laminil.htm

[sedge]

Oral3
You will probably be better off using zygadrs vh eps if you can get hold of it,but I would go for the cheaper option of the 25mm which is easier to get hold of at most diy shops ,in the UK that is.
You can then chop it up and sand it down without worrying about the cost,and it will sound just as good, if not better? You can usually buy it in 8x4ft panels for about 7pounds ,which ever you choose good luck.
Gragra
Do not use anything with paper coating it will sound bad.
Steve

[gragra]

ok thanks

[sedge]

Gragra
Sorry that was a bit abrupt ,I should explain,the panels look very much like foamcore which is a very over damped panel,if you can get hold of the panels without the paper coating that would be a good material to start with I use something that looks similar in 5mm thickness and a 2 x 3 ft panel size ,and I would recommend using a LF driver up to 300 or so HZ ,you can run them full range if it's convenient but I would roll them of at say 100HZ or so ,the panels I use sound pretty good if you follow the methods explained on this thread.
Steve

[sedge]

these are some of the panels I have tested over the years , I did not get the big panels out, and a lot of the others  I have already thrown away, but looking at a couple of these ,I may have to have another look at to see if the new mods can improve the sound.
the second from the left which has wood bracing might be improved , the bracing was to improve the LF below the 300 HZ point, but the openness of the panel sound always seemed to suffer .

[Odal3]

Sedge, Many thanks for posting the pictures and the advice. That's quite a collection!  From a panel shape point of view, do you still considering the rectangular shape to be best? How does e.g. the guitarr shaped board I see in the picture compare (curious on the effect on high frequencies)?

[Odal3]

Jesus..........just look at that.....at the bottom....

http://science.wonderhowto.com/how-to/make-paper-plate-speaker-actually-works-for-under-1-0141522/

....Guys, I feel now an irresistable desire to play with those wires and magnets...
Ziggy, I swear now I'll find a way how build an ultimate exciter to drive the plywood... 
A fast look on the market gives me all I need - a lot of cheap chinese neodymium discs and rings. And large steel washers. As for the voice coil, I wound some to repair, isn't a problem. The theory of the perfect driver is simple: the voice coil must be single layered and a whole one must be placed in magnetic flux as stronger as possible. Ok, let’s go….

Curious if you pursued this further?

[zygadr]

 ..................sedge, sorry, not impressed, ........you don't seem to be giving this speaker technology a serious go          ..........just kidding!!..................

Odal3, making a true ''exciter'' as such is not easy, but I encourage you to give it a go. It has been tried before but there has, to my knowledge, been no breakthrough or success as far as I'm aware.

I think that NXT had spent a lot of time and money on this type of driver that does not just simply resemble as a simple cone type loudspeaker with it's basket removed and an extension with a  ''foot'' placed at the end of the voice coil. The ''spider'' is where the secret lies I believe  I could be wrong??

The NEW DAYTON ''THRUSTER'' EXCITERS HAVE ARRIVED!!!!!!!.........my wife wants to confiscate them for the purpose of a Christmas present.............so far we are both recovering in hospital from multiple bruising.

Rob.

[sedge]

Oral3
Changing the shape seamed a good idea at first ,minimize standing waves and direct reflections, but at the end of the day you just end up moving things around ,swings and roundabouts.
It would be great to have a computer program that tells you the best type and shape of panel for the best sound quality with real music, and how far do you push the panel into nxt type mode with a stiffer material or bracing or go the other way with a less rigid panel with more of a point source effect.
When you change the shape or rigidity or any other property's of the panels you risk setting off another set of problems , from experience it is far easier to get a good sound from a larger panel than a small panel ,the energy(sound)on a large panel is more easily dispersed ,on a small panel it instantly comes back and bites you.
For an easier build keep it simple and as large as you can handle this will probably give the best sound up to a point, unless you don't mind large amounts of hair loss.now where did I put that wig.
Steve

[sedge]

Rob
If I remember rightly didn't nxt use a silicon type gel to support the coil and exciter? This was a few years back and it seems to have disappeared I think, the best spider would be no spider if I had my way.
I did try but not very hard, to mount a coil on the panel with the magnet mounted separately without a spider ,too many variables with weight ,materials ,expansion with temperature maybe? And so on ,basically I gave up as its too easy to just glue on an exciter.
This is why when I saw the thin film piezo speaker I thought ,no spider just glue it straight onto the panel,and no coil .
From what I have read about the problems of coil size and more power , larger magnets and so on, is the trade-
offs in HF,swings and roundabouts again I'm afraid.
I'LL  leave all that to someone else as I am running out of hair.
Steve

[zygadr]

Steve, don't worry about it too much. This technology, as far as I have surmised, is out to fool you in to believing that it is "rocket science".........which it is not. Why do I say this?.........because through all these years of experimentation, what is supposed to happen usually never does!   

What we have created here on this massive forum is a very cost effective method of reaching panel speaker nirvana! Yes, we are constantly seeking ways of improving the performance of the DML, but many , such as myself, are happy with what we currently have and are allways amused at the response of fellow audiophiles or even total strangers who can not believe that a small "thingymagig" (Aussie slang ) mounted behind a piece of foam can produce such a realistic concert hall/ jazz venue with such clarity and fidelity for next to nothing in cost!!!!. This is what drives this forum.................no surprise to all that have joined in and believed in the impossible ! 
Rob.

[zygadr]

I have had and still am having a very busy weekend, but have managed to try the new "thruster" 40w Dayton exciters compared to the standard 25 w version.
I must stress that this was a quick 60 second (with the exciter held up to the EPS panel) try as a matter of interest.
Before that even, the new exciter felt a lot heavier than the others and as soon as a signal was connected to the exciter.........I knew that something weird was happening........massive vibration while holding the bare exciter.
The new exciters were packed in a moulded foam/shaped to fit the exciter standard brown box, but was a step up from the usual cheap and nasty packaging of other exciters.......this time there was an air of class about it.
As soon as the "thruster" touched the panel..................................

[zygadr]

I have had and still am having a very busy weekend, but have managed to try the new "thruster" 40w Dayton exciters compared to the standard 25 w version.
I must stress that this was a quick 60 second (with the exciter held up to the EPS panel) try as a matter of interest.
Before that even, the new exciter felt a lot heavier than the others and as soon as a signal was connected to the exciter.........I knew that something weird was happening........massive vibration while holding the bare exciter.
The new exciters were packed in a moulded foam/shaped to fit the exciter standard brown box, but was a step up from the usual cheap and nasty packaging of other exciters.......this time there was an air of class about it.
As soon as the "thruster" touched the panel..................................

[zygadr]

Well, this is a totally different exciter to what we are accustomed to..........I am pretty sure about that.
The title "thruster" is well and truly appropriate. There is an obvious force or "shove" increase that truly surprised me.
When placed against the EPS panel with the standard Dayton exciter quickly disconnected for comparison reasons - back and forth, the output of the thruster version was very noticeably greater! This was not by any small amount either!

Stay tuned for further tests as they come to hand.

[Odal3]

So how does it sound?

[zygadr]

So how does it sound?

These exciters may well redefine the efforts of this very specific, and specialised community of panel loudspeaker builders!
I confess that it has been pointless to permanently mount these units to a pair of smallish, crappy/damaged poly sheets (the last two pieces I have left!!) .
However, just by holding the exciter against the panel with the sound destroying peel off paper still attached to the VHB adhesive rings, drops my jaw with the increased sensitivity and "shove factor".
I will not bother to mount them to a couple of 4mm thick marine grade ply sheets I have, as I am certain that we have the better panel material ( EPS) - after treatment ( or not.......as I have discovered..... Your choice ! )

A word of caution and advice for all of my friends and followers...........the exciter you choose DEFINITELY has a  lengthy "BREAK IN" Period..........I have heard this time and time again.It even relates to piezo cones as well.
I compare this to Black Gate Capacitors, which I laughed at in the first instance I read this, until it happened many weeks/months of use.

Where do I stand at this point in time.?.........I have never been so excited as we have a TRUE high power exciter that has a high "force factor" and consequent higher sensitivity which has been the downfall of our efforts in the past.
In my opinion, we are free from the detrimental "multi exciter" necessity to obtain an acceptable power rating and output volume that exceeds "elevator music" without cooking our transducers.

EPS - the VH variety will, according to my tests via numerous recent listening sessions be the best panel material after all compromises have been evaluated.
There may be something better as we progress, I have no doubt, but for the present, I am hearing great gobs of detail which has not been present in the past use of so many different materials even when treated.

I have raved on enough my friends, please be patient and by all means add any comments or technical information should you see fit to do so.

Rob.

[oldschoolVlad]

Someone asked what will happen next?...

[Odal3]

Rob thanks for the info. New is fun. Btw: how do you mount the heavier exciters? Haven't been able to find thin Eps yet - only 3/4" so still on my birch plywood.  Still like it a lot on lower levels, especially after I thinned the edges like a piano soundboard (thicker in the middle with a taper out to pretty thin edges)

Oldschoolvlad - looks like a great weekend project!

[j gale]

Hi,   3/4 EPS is fine. It will be as if it's not even there. It!s very important to sand off the skin that is a result of they way they were cut. Back, front, and edges. If you don't it sounds like plastic. After sanding apply a coat or 2 of PVA glue (  thinned )which in essence gives the panel a new skin without the plastic sound. I have also had good success with a coat of shellac especially on the back or exciter side. I have avoided coating the edges so don't know the effect of that. Credit Sedge for the idea to remove the skin. Before doing that I could not stand the sound of EPS and always went back to plywood or cardboard. Now I know you can tailor the sound of EPS to your taste. Changing the skin is the key. EPS is so cheap that all of us can afford to experiment.  Jim

[Odal3]

Alright - off to the store tomorrow! BTW: What size is your favorite so far - Width, height, thickness? These will be in the basement so there will be no WAF. And is one exciter the consensus for best sound or is the moncor (or other) placements still in the running?