[zygadr]

Yes,...........careful here guys...........this is a new area of product...............I had to physically examine a few samples before I found the right stuff.

It looks like normal white poly, but is noticeable harder and a bit rougher on it's surface.

Regarding SPL ...................THIS STUFF REALLY ROCKS!

sedge, one exciter can be used..........no problem. What is deadly is the power output of your amplifier when cranking up the volume in a larger room like mine.

Remember, a single standard exiter is rated at 6-10 watts by Billionsound (manufacturer's data sheet), so you don't have much margin to play with. That's why multiples are mainly used(Podium) so that the panels can cater for larger power inputs etc.

Anyhow, the very low mass/weight of this stuff is a delightful cahnge to the much heavier materials we have been struggling with.
Maybe only 2-3 exciters will be enough on huge panels?............who knows

[jonners]

sedge -

Is this the stuff you are looking for? Max thickness seems to be 6mm.  http://www.plasticstockist.com/index.cfm?Page=cHJvZHVjdHM=&sector=MTE=&Group=NzA=&SubGroup=NzA0MQ==&jump=31

Also on eBay, but only up to 4mm:  http://cgi.ebay.co.uk/4-0-x-1372-x-660mm-White-High-Impact-Polystyrene-sheet_W0QQitemZ180478891468QQcmdZViewItemQQptZLH_DefaultDomain_3?hash=item2a056155cc#ht_500wt_754

sedge and zygadr -

 Your doubts about this stuff were well-founded: The density is 1.05g/cc - which is more than most wood!

[Tinnitus]

Ok, I've made the first of a pair of tensioned sheet panels (crude, especially the scaffold, but even these take quite a bit of effort to make, so I want to see if there's any promise to the approach before investing more serious time).
I've used a ratcheting 'ladder strap' to tension the panel to the point that when flicked with a finger it sounds a little like a timpani (even drumming my fingers makes this sound), they seem like they could provide high SPL.
I plan to sew the exciters to the fabric using the 5 little holes found around the foot of the device and some very strong thread supplemented with RTV sillicone sealant.
But I'd like to solicit some opinion on the best placement of the exciters from the members of this forum.
At a later date (if this shows some promise)I hope to turn one of these panels through 90 degrees and Try Pol's single panel stereo configuration, but I'd like to try conventional seperated stereo panels to start with.
The complications of this approach are legion but of particular concern to me are the edges of the panels.
The sheet is currently undamped (I've yet to apply any substances) and the long edges are free to 'flap' which may cause problems, but we'll see.
The short edges may 'reflect' waves back into the panels as they are effectively 'clamped' by the scaffold pole around which they are wrapped, again, we'll see.
I hope to use a little Tripath TA 2020, and also a Musical Fidelity 75W amp to drive the exciters.
I also may try opposed exciters sewn to each other on opposite sides of the sheet (set up so that one pulls while the other pushes).
But I'd like to start with maybe between 1 and 4 exciters (per panel) all driven by the little T-amp.
So, would anyone more knowledgeable than me care to help me out with some advice on numbers/placement/wiring?, bearing in mind that once sewn on the exciters would be time consuming to move!.
Sorry about the pic' quality.

[sedge]

Zygadr
Had a little play around with a 20x24inch styrene panel of 8mil thickness[this was a piece of old packing I had lying around ] it has a good fr response up to  10 k .
What I noticed was the panels self noise ,this is easily noticed when playing loud music and then pressing pause ,the panel makes a thong type noise after the music has stopped .
I then painted on some shellac only a thin layer and only up to 2inches from the edge on both sides to see if it had any effect ,I do not have a lot of shellac and did not want to waste it ,then left it to dry over night.
What was surprising was that now the panel stops with the music[no thong sound]and sounds a lot fuller.
Looking at the fr plot it gives good output down to 40hz [near field resp]I can also hear the rumbling from the pink noise 10ft away,not bad for a 20x24inch panel I think .   
The hf was only slightly improved but the overall sound was much better,this looks promising .
Hope this info is of some use ?
Tinnitus
I can see you have put a lot of hard work into this project .
The exciters produce most of the hf from the centre of the 1inch foot ,so if you basically stick them together in push pull mode you are covering up the hf area.
I have played around with this sort of panel [but not this tight ] but gave up ,they sounded ok at low volume but went to pot when turned up louder.
Prolonged notes or test tones sent the panel into resonance .
Hope you have better luck than me
sedge

[zygadr]

Guys............

jonners............yep, that's correct............some materials resemble opaque perspex and weigh a ton, so NEVER order anything unless you see and feel it first........VH POLYSTYRENE is unmistakable............light as a feather..........looks and feels like foam, sounds noisy when rubbed or handled.

Tinnitus, your concept is interesting and I would like to know how an exciter would sound on the tensioned sheet.
However, sedge is right........DO NOT bother with any form of push/pull exciter mounting. Also, FORGET this blasted sewn on exciter thing!

I suggest that you make a free standing brace(with firmly held exciter/exciters) that can be shifted in to place behind the stretched panel and contact made with it and the exciters using thick/clear double sided tape as I have recommended in the past.

Stick to the just off centre of panel arrangement in a vertical array, evenly spaced arrangement(if you are going to try more than one exciter).

This way we will be able to judge the panel's performance to what has been done here in the past.

sedge, glad to hear that shellac will kill the poly self noise. I have noticed this self noise too and have found that this is obviously due to unwanted resonances and can be cancelled out simply by holding or touching the panel at various points at the edges of the poly (which I hope silicone mounting points will do also ).
I will coat one of my panels with shellac this week and see what happens.

''Self noise in panels'' is noticeable in all materials used as a DML........Gatorfoam has it, Balsa wood has it, C.C. has it, glass, metal, plastics............and so on....... ............the trick is to get rid of it...........and I think we are getting there..one way or another.

Here's another thing..........when a free standing polystyrene panel is placed on the floor, supported by small blocks of soft foam rubber at the base, a lot of resonaces are killed.........except the top of the panel.
As the top is basically unsupported, it can buzz and visibly ''FLAP'' ..........wildly!......like a whip!

This is no doubt due to two main factors: 1. : the extreme low weight of poly, 2. : the fact that the poly is not super rigid (mounting the panel at various points around it's perimeter/edges will sort this out).

Either way, we can now shellac the poly, thus providing a dampened coating.
Mount the poly accordingly, and there will be little self noise or resonances to worry about.

[DanTheMan]

Ziggy, with this 10mm stuff, have you tried carving it--like rounding over the edges?

Thanks,

Dan

[zygadr]

Dan, ............nope............but you have a good point..............that might stop the ''buzzing'' which seems to eminate from the ''CORNERS''
I'll give it a go and see what happens.

[DanTheMan]

Let us know!

Dan

[mikadosan]

Dan, ............nope............but you have a good point..............that might stop the ''buzzing'' which seems to eminate from the ''CORNERS''
I'll give it a go and see what happens.

My bet is that you can get some serious results...

[DanTheMan]

The question to me is "how?" I mean what do you use to cut it.  I suppose for a prototype, pretty doesn't matter, but for a permanent install, I'm sure we'd all like it to look good.  So is there a way to cut the length w/o making it look bad?

Dan

[zygadr]

I'm gonna use a small amount of C4.................

[zygadr]

Seriously though.........................how about a chainsaw ..........still joking

If you want to cut the final ''finished product/panel'', the only correct way is to go to a foam supplier. Mine has the special cutting equipment that does everything including shaping, carving etc.I believe it's a heated blade or wire.....something like that????

For a prototype, a fine saw blade will probably do the job, but the cut will need to be sanded as those little left over pieces can buzz..........which is what we are trying to get rid off in the first place

[zygadr]

  ..................hmmmmmmmmmmmmmm  :for the last few days, the single exciter held to the poly with another form of 3m double sided tape(same as the original Sonic Impact cardboard discs), which has never been problematic before is FAILING

I have not used the 9473PC rings yet from NXT as this is experimental work.

I have a very bad feeling in my gut that the poly may ( )be incompatible with the adhesive on the tape and could be reacting with it causing adhesion failure.

It's only a suspicion at present, but I will have to thoroughly clean the exciter and poly surface and use the proper adhesive ring (9473PC) to find out for sure.

If this starts letting go also....................we have a serious problem

[zygadr]

O.K.............removed the gummy mess and half hanging off exciter from the poly last night.
Cleaned off all the residue off the exciter foot and applied the 3M 9473PC '''foot ring'' to the exciter and then to a clean section of the rear of the poly.

The foot was gently pressed around it's perimeter with a small wooden spatula to ensure even adhesion(important) and then the whole panel was laid flat, face down on the floor, with the exciter resting in it's position on top.

I left it this way over night as the tape/adhesive has a short ''curing time'' according to 3M.

I need to highlight the fact that all the VH EXPANDED POLYSTYRENE experiments so far have been with double layers of 3M tape of a different variety(can't recall the number).

This is the first time that the ''PROPER'' adhesive tape/ring has been used

The result?............there is allways a surprise with this crazy technology ..........

When fired up this morning, the sound was noticeably LOUDER and the HIGHS!! ........came out like a bat out of hell! .........the difference was far from subtle..........obvious improvement, crystal clear

Verdict and recommendation?................the alternate tapes........even 3M varieties(and there are many), Scotch tape, etc. have the potential not only to fail in warm conditions and exciter forces, but also to TOTALLY STUFF UP THE SOUND...................especially the SPL and high frequencies

I just hope that the ''proper stuff'' holds to the poly permanently and that something sinister isn't at work behind the scenes

[zygadr]

BTW...................is anyone alive out there?...............or have you all given up???????????????

[DanTheMan]

I'm alive, but not seeing a way forward at present.

Dan

[zygadr]

Dan, dissapointed that you feel this way.

On the home front, I have ordered two  6 foot X 2.5 foot sheets of 10mm VH EPS.

These will carry 4 standard exciters...........this time on a frame with back brace..........no exciters hanging off the back crap anymore.

The object will be to see if the gain in efficiency is worth the effort, and secondly to check on high frequency output and tonality/any buzzing of the material after silicone sealeant attachment to the wooden frames.

If this fails, it's all over for me...............if they won't work with low powered SE amps, they will be of no use to me...........at all

[mikadosan]

Hi there, my recommendation is that you should always use the 3M VHB rings for the adhesive between the exciters and panel. Other tapes are not more than a huge headache and wasting of time...

When you have found a good position for the exciter(s), I recommend that you will glue them on. I have tried lots of different types of glue and the best one is sold in Finland under the Plastic Padding -brand (Henkel). It is Plastic Padding Extreme Repair -glue. A small black tube with some yellow graphics on it.... I´m not sure if this available in other countries but it is very good glue for this indeed... The glue will not harden completely, it will remain a little elastic, but only a little...not as silicone or foam tapes...it´s not totally hard but not too elastic either... Hard to descripe it in foreign language then... 

Regards

-M

[captainjack115]

Hey Guys,

I found another set of PE exciters, that makes 15 pairs or 30 exciters in my possession
Still $35.00 for the lot, add shipping for USA.
Jack

[DannyT]

my PE exciters will come today  where can I find 3M 9473PC tape cheaply? The cheapest I found online is $75 for a roll of 2" by 60 yards. If someone here bought a roll and want to sell part of it then I am interest