[Nickolay V]

Hi Zygadr !
I still dont understand you final conclusion concerning  kind and sort diaphragm material?
What is really best HV:  Extruded or Expanded  Polystyrene.  What is exact market name finally selected material ?
(What look for and buy)
What best density ? Thickness ?

Many Thanks !

[cologner]

Hi everyone, I´m from Cologne in Germany and work as a freelancer in multimedia and physical computing. It took me almost one day to read the whole thread  but it was worth the time. 

My first contact with NXT was in 1999 when it was introduced over here along with "speaking pictures" and "acoustic walls", more or less art presentation with invisible ambient sound. That was fascinating but not for everyone unless having a budget to pay >300 $ for a wall picture (speaker) with sound  So even if you try to get a license to sell NXT, the final product isn´t saleable at all.... Over here, the idea is dead and former license holders gave up. But with some of these cheaper and freely available exciters, things might change in future...

Originally it was "KapaSound" because Kapa is the most common material producing displays and signs. You can print on it, laminate pictures, build displays etc. It all started here (formerly known as Alusuisse):
http://www.alcancomposites.com/
I was confused when I read here that Kapa has a bad sound.... Maybe the difference is the core of Kapa is Polyurethan (which makes it more flexible to cut and handle), than cheaper EPS boards made of expanded polystyrene (the stuff zygadr ordered). You can get EPS over here pretty cheap 1 Euro 10 sq.feet used for home insulation indoor / outside, but the surface is pretty rough. Found something similar called Foamboard, again with the expanded polystyrene core, but paper coated, used like Kapa...

I´m definetely going to give it a try, I´m working with a company producing signs, displays etc. with direct printing and laminating on all sorts of material from cardboard, Kapa, acryl glass to Dibond.
For me, until now, NXT was basically the "ambient sound experience" in the Lo-Fi range, but there is so much input here to improve perfomance - great  However, give your NXT board the experience of ambient sound one day (print some relaxing landscape view on it, or use your slide projector or beamer ), this is what I like sitting in front of my PC... 
http://www.sagebrush.com/winchime.htm

Finally I want to add something for the math and just make sure, from what I read, if this is correct:
Assuming the board is rectangular and *a* the long side, *b* the short side, we have ratio 3:7 (a = b x 2.33), 4:9 (a = b x 2.25) or 5:13 (a = b x 2.6). If not, please change the values…
With 4 exciters on a 900 x 400 pixel board, we place the units at 180 pixel position (long side) x 200 pixel (short side) each?

[sedge]

Rounding corners or not?
Using my various  free floating panels I have experimented with different types of dampening on panel corners ,the most easy to use being blu-tack (easy to put on and take off)it is also very effective.
I felt the self noise was reduced and the over all sound was cleaner and clearer
If you were thinking of cutting off your corners I would recommend you try this first (very difficult gluing corners back on )as it gives good results.
As zygadr is mounting (I think) his panels in the corners with silicone he is probably half way their already,plus if you add damping (mass) to these areas it could solve buzzing and sound problems in one go but without effecting the performance in other areas .
When rounding the corners was first mentioned  some time ago ,the first thing that popped into my head was I wonder if this could be the best place to mount the panel?
If you cut off the corners you will also have the problem of finding somewhere else to mount the panel to the frame which could cause other problems ?
If anyone else tries this could they let me know what they think,good or bad.

sedge

[sedge]

cologner
If foamboard is the same as foamcore in the uk it will have a very dull over damped sound .
foamcore is more of a sponge type foam ,eps is made of little expanded polystyrene beads all stuck together ,the more expanded the beads are the softer the panel.
sedge

[cologner]

foamcore is more of a sponge type foam ,eps is made of little expanded polystyrene beads all stuck together ,the more expanded the beads are the softer the panel.

Officially "foamboard" is expanded polystyrene coated with cardboard, but who knows, these shops are just selling it, you can´t ask in detail most of the time..
Today I talked to a local manufacturer of EPS, they offer expanded polystyrene beads in different dimensions and I was invited to grab some board samples for free when I described the project  hm what size of beads, expansion range and thickness of board should be asked for? Maybe Zygadr can help

[jonners]

Here's a table of EPS grades and densities that might be helpful: http://www.longvalley.co.uk/epsblock.htm

[sedge]

jonners
thanks for the link.
sedge

[cologner]

Jep, excellent EPS survey for insiders
Would be great to know if zygadr has information in detail about his VH EPS specifications. The manufacturer here told me they also keep EPS in large blocks and cut them according to customer needs.

[emailtooaj]

Would be great to know if zygadr has information in detail about his VH EPS specifications.

I would imagine he is using the "115 (EHD/FRA)Very small bead FRA*" or something very similar to it.
I am currently tracking a vendor here in the states to order material from. I am very familiar with XPS foam boards, as that is what I have been experimenting with. Which is still excellent by the way!!! I have found that in XPS boards you want to shoot for 25psi rating in the .5 inch thickness.
15psi rated boards in .5" thickness sound ok, but a little more hollow sounding. Sound seems to stay at the back of the panel insted of coming through it If that makes scense

EPS foam is manufactured in another way, which gives it it's "brighter" and "up close" sound. It's the density of these panels that will help give a tight, crisp sound!! Along with deilvering better low end Fq. Of couse, the panels overall size has a major factor in the sound.

This is just my opinion...but i think EPS will be, and is, very suitable for moderate to loud listening enviroments. Which will deliver unquestionalbe clarity!!
Getting from Loud to Extremly Loud(Stadium or arena) enviroment...I think XPS will be the transition matieral. But that will come when exciters start to mature and can handle higher wattages!!! Hopefully in the near future!
Just my thoughts 


 

[jonners]

Here's a bit more data. It appears that grades HD, EHD etc. are also known as EPS100, EPS150, etc. : http://www.pacspackaging.co.uk/DATASHEETS/Polystyrene.pdf
http://www.styrotech.uk.com/pdf/construction.pdf

[cologner]

Hi emailtooaj, XPS is extruded polystyrene. After reading all these comments, it looks that expanded material (so everything that has a less compacted structure inside) is better from "the acoustic point of view" 
I´m not sure, just in theory. Today someone offered 3 Foamboard panels 10 x 1400 x 1000 mm (which is paper coated EPS) for 50 $ in the local advertising journal, maybe another thing to think about, but first I´ll take a look at the local manufacturer.
My idea is to order the Dayton DAEX25
http://www.intertechnik.de/index.html?lang=de&artnr=1381991
together with Dayton DTA-1 amplifier
http://www.intertechnik.de/index.html?lang=de&artnr=1381993
Getting the 5 $ pair of exciters from the US to Germany is probably expensive (shipping & customs).

[zygadr]

Guys, good to see some interest generated on the latest material find.

I have already posted a link on this thread before relating to the West Australian supplier of expanded VH grade polystyrene sheet : FOAM SALES.

I am using uncovered/uncoated 10mm thick,  185 cm X 75 cm EPS sheet with 4 exciters per panel.
In this size sheet, the exciters are spaced at 37cm distances ''EQUALLY'' from top to bottom (185cm didvided by 5 =  37cm)

The sheet of this size is far from ''RIGID'' but from what I am experiencing, it makes absolutely no difference what so ever.....................very surprising

It's crystal clear, loud, very quick in dynamics,when there are deep bass notes, they are subterranean! and in the tonality department.............able to easily distinguish instrument timbres and sounds with great ease.
It's a sound that's so unique and special.............nothing that I have heard comes close to it

I have not cut any of the panel corners so far......... I may leave that to my experimental sheet.

On mounting the panel........................silicone may be an option, BUT, ............I have another idea and supplier of a strange, spongy rubber material that may be better and can dampen where necessary - far better than silicone. There are many choices here, but I don't think that panel mounting will be a great problem....................certainly nothing like the problem with what panel materials to choose !!

Be careful with ''FOAMCOR''..................especially the paper coated stuff!
Here in Australia, the art shops sell it and the foam and general quality totally SUCKS!
I have seen these Foamcor sheets, warped, bent and the paper peeling off.....................great stuff huh???

What you should be looking for is the highest quality EXPANDED POLYSTYRENE(raw sheets that feel a little rough, not smooth!) that has the highest compression rating and density rating. If you have this, you have the ''right stuff''

[emailtooaj]

My idea is to order the Dayton DAEX25
http://www.intertechnik.de/index.html?lang=de&artnr=1381991
together with Dayton DTA-1 amplifier
http://www.intertechnik.de/index.html?lang=de&artnr=1381993
Getting the 5 $ pair of exciters from the US to Germany is probably expensive (shipping & customs).

Cologner, The Dayton DEAX25 exciters are fairly decent. The only thing I didn't like about them, if you plan to disassemble them, the wires leading to the voice coils are very  very thin. But still a great exciter! I love that they are 8ohms and seem to have a little better sensitivity to them compared to the $5/pair from PE.

Like Zygader mentioned already... I too would advise not to waste money on paper backed FOAMCORE panels. They just will not compare to raw EPS Polystyene. Save your money and spend some time to find a EPS dealer near you. I would advise to talk to some residential/commercial building suppliers in your area for help.
I'm sure once we all nail this polystyrene down, one of us fine gentleman , on this thread will post links to all the supply lines to get EPS or XPS polystyrene in small quantitys

And now, for the news on the new material I've been working with..... Depron!
Well...in short....


IT SUCKS!!!!!! I'm soooooo disapointed in it!!!!!! I ordered 4 sheets in 6mm thickness, coated one of them with epoxy to stiffen it up some, and it still SUCKS!!

The one positive of Depron is vocals sounded pretty damn good
So if your thinking of using it for a center channel on a surround system, I can some what recommend it.
Ohhhh Wellllll.....Live and Learn 
Lucky for me it was a small expense

I think I found a good supplier of EPS poly here in the states. The problems I'm running into is either you buy all or none!!! I can't for the life of me find a small order distibutor, and all the manufacturers are to far for me to drive to

If worse comes to worse, would any one here be interested in doing a bulk order for EPS in the U.S.

[zygadr]

emailtooaj..................I only charge $1,000 U.S. per sheet(free shipping!)

Seriously, bad luck with the Depron.............never mind, worth a go wasn't it?...........that's what we're here for !!

Just another reminder................try and stay away from ''EXTRUDED'' poly. I don't know if the stuff over there is different in some way,maybe I'm wrong, but extruded poly here is not as good as ''EXPANDED''..........no comparison.

Agree with the Dayton exciters. As we only need 4 pairs, it's worth the extra cost, which isn't that much overall.

[cologner]

Hehe, congrats for NOT "still haven´t found what I´m looking for"...
I will forget about the foamboard and contact the local manufacturer http://www.nafab.de/ (sorry, only in german) to get a sample EPS-panel dimension 185 cm X 75 cm, 10 mm thick, like zygadr. Good to talk about high compression and density with the manufacturer himself, he was pretty interested when we talked on the phone today.
Also found Depron on several sites, sounded good from reading - sorry to hear it was a waste of money... It looks like the cheapest stuff is still the best material for NXT
zygadr, do you think 3 exciters per panel would also do the job? Reason is, the Dayton amplifier can handle 15 Watt per channel, and I have an offer to buy the DTA-1 with 3 pairs of DAEX25 for 100 Euro (which somehow is my limit for the "try-out"...)

[zygadr]

Hi cologner, you can use 3 exciters, but remember that there will be an odd impedance with the 8 ohms each exciters.
3 in series is 24 ohms, 3 paralelled is 2.667 ohms.
 You cant series/paralell an odd number as power distribution will be uneven

Just try two exciters if you can't get a fourth one(you will have 4 ohms or 16 ohms depending on wiring of course).

I would also cut down the sheet to 150cm X 75 cm for a 2 exciter per panel configuration.

Hope it works out for you

[cologner]

Hi zygadr, you´re right about the odd number, I´ll take 2 exciters each and reduce the panel size. 
Do we have another ratio when scaling down the panel? 185 cm X 75 cm is factor 2,5 - and 150 cm x 75 cm is factor 2, or is it of no matter?
Last question - the amplifier can handle 4 & 8 ohms, exciter is 8 ohms. So 2 exciters paralleld is 4 ohms, series is 16 ohms. What is the better choice here (I´m not familiar with wiring ...)?

[el`Ol]

I still have no answers concerning the 0.5 kg/m² spring steel wire cloth. If someone from the US wants to try:
http://www.thomasnet.com/nsearch.html?cov=NA&what=Wire%20Cloth%3A%20Spring%20Steel&heading=95162608

[zygadr]

cologner, the panel ratio makes no difference in my experience, so go for whatever looks better to you.

I would go 2 exciters paralelled : 4 ohms.................so,dividing by 3, your first exciter will be spaced 50cm down from the top of the panel and the second - 50cm up from the bottom of the panel.

As the DTA-1 amp puts out 10watts per channel realistically speaking, the two exciters would be rated at a total of around 20watts max......................should be a resonable match.

Don't try to shake the windows with very high levels though

[emailtooaj]

Zygadr....
I came across some EPS sheets I can get a "somewhat" small order from.
The highest density is 3 lbs, with a compressive rating at 40-45 psi.
Is this similar to what you received? I tried to find some detailed specs from your source, but couldn't find any?
You mind posting your panel ratings.
Thank you!!!!!