NXT.......rubbish??....THINK AGAIN!

el`Ol · « **Reply #900 on:** 18 Mar 2010, 09:56 pm »

Hello all!

Some time ago since I last tried something with DMLs (my failure with Lamera Hybrix). I had given up, but today I googled around again for new materials and I found something interesting: Phenolic foam is not a structural hard foam (not stiff enough) and so is only used for insulating. But with added lignin (the stuff in wood) it becomes suitable for structural applications. And if it was as linear as the phenolic spiders of vintage drivers, oh la la. I couldn't find a finished product, however. But when it comes out I will be back again.

Oliver

jonners · « **Reply #901 on:** 18 Mar 2010, 11:05 pm »

I've found a UK seller of extruded polystyrene foam board on eBay. (His username is 'easy-foam09'). It's described as 'Styro Insulation Board', and is said to be much stronger and more rigid than the beaded polystyrene foam. The density is 2lbs/cubic foot. He is advertising various sizes, including 4ft by 2ft by 1" thick boards, and he said in response to my enquiry that other sizes and thicknesses are available. (4' by 2' max, though. He has thinner stuff but doesn't advertise it on eBay because the boards don't lie flat.)

zygadr · « **Reply #902 on:** 19 Mar 2010, 02:15 am »

Firstly....................jack!................you pullin' the plug????

Secondly, PHENOLIC FOAM has a density of 55kg/m3............much more than EPS which is only a few kg/m3(can be more depending on grade, but still much less than other materials).

Even Gatorfoam has a density of 30kg/m3.

Compared to EPS sheet of 10mm thickness, everything else seems to weigh waaaaaay too much

9473PC tape can be requested in ''sample rolls'' just short of 1 inch wide from your local 3m rep.

If you can find the right type of glue.........then go for it

For the record....24 hours later............exciter still firmly attached to the EPS and sounding better than ever

captainjack115 · « **Reply #903 on:** 19 Mar 2010, 03:38 am »

Firstly....................jack!................you pullin' the plug????

Nope!!!

I bought tons of exciters and set plenty aside for myself.

I have a friend in Canada that was manufacturing bending wave loudspeakers and even custom made his own exciters. He was using a diaphragm technique that is very far removed from what we're doing on this forum. I'm going to give his design a try and report my findings. Forgive my hesitation for not giving out details, I see no point in all of us trying something as a collective that may be worthless.
Let me say this; I have feeling that this design won't have much spl, but it may sound pretty good........Who knows?

Jack

zygadr · « **Reply #904 on:** 19 Mar 2010, 06:10 am »

.....hmmmmmm.....sounds interesting.
Keep us informed

el`Ol · « **Reply #905 on:** 19 Mar 2010, 01:04 pm »

Quote from: zygadr on 19 Mar 2010, 02:15 am

Secondly, PHENOLIC FOAM has a density of 55kg/m3............much more than EPS which is only a few kg/m3(can be more depending on grade, but still much less than other materials).

The paper about the new structural foam is not freely available, but I found this in a patent for phenolic foams:
"the density of theresulting foamed phenolic material can be controlled from about 1.5 to 77 pounds per cubic foot."

pol_bct · « **Reply #906 on:** 20 Mar 2010, 08:40 am »

Hello All
For those who once had the idea to make a pulsating sphere
I did it with a DML, no big thing !

http://img24.imageshack.us/img24/3641/p200310sphere.jpg
why ? because the vibrations come not from the center
but from a point on the sphere and spreads over the entire surface
Before returning to the point of departure,
http://img411.imageshack.us/img411/5950/p200310spher2.jpg
as echo chamber it is excellent, but not for a HiFi loudspeaker

though bandwidth for a sphere of 75cm is 140Hz-3400Hz
the distortion is very strong, Because the echo
-30dB below 1kHz, increasing to 100% a 3kHz

that's it, an idea to return on the book-shelf

POL

Tinnitus · « **Reply #907 on:** 20 Mar 2010, 07:33 pm »

Quote from: pol_bct on 20 Mar 2010, 08:40 am

that's it, an idea to return on the book-shelf

POL

Damn, that's not how I hoped it would behave.
I wish I understood the physics involved with reverberant/resonant enclosures.
I wonder how something like the body of a stringed instrument avoids this echo chamber effect?.
Does the hole play a part?, or does the body deliberately exploit the echo effect in some way?
As usual, all I have is questions rather than answers, for the moment.
Once I've tried finishing my fabric panels (awaiting parts) I might try building vessels from cardboard and butterfly tape to see how they might sound.

Quote from: captainjack115 on 18 Mar 2010, 01:59 pm

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

Would you consider shipping to the UK Jack?

If Jack's willing to ship overseas would anyone else in the UK want to split?
Would you want any more John?

Sedge,
thanks for clarifying the 'push-pull' hf drawback for me, I had been assuming that the hf was distributed throughout the panel in the same manner as the other freq's, in light of this I'll not bother with this approach, I don't think there's any point trying the 'push-pull' thing for bass reinforcement if I'd just have to add another single exciter for hf.
It's disappointing to hear that you've tried fabric and found it wanting, but hopefully high tension and/or damping/stiffening the panel with resin or similar will control unwanted resonance, I'll try this before moving on to other approaches if I fail.

Has anyone out there tried a single skin(paper,metal,foil whatever) stuck to one side of a sheet of poly or whatever?
I've found a manufacturer in the UK who makes Alu' ,Stainless steel(and titanium!)foil in thickness's from 10 microns up to 1mm and will supply 'non industrial' quantities to craftspeople.
Anyone tried a single skin panel?
Long post, sorry.

captainjack115 · « **Reply #908 on:** 21 Mar 2010, 01:20 am »

Quote from: Tinnitus on 20 Mar 2010, 07:33 pm

Would you consider shipping to the UK Jack?

If Jack's willing to ship overseas would anyone else in the UK want to split?
Would you want any more John?[/b]

The reason I specified USA only, was shipping costs. I know nothing about VAT and whether or not it's worth it to someone over seas to purchase a fairly inexpensive item. Can anyone bring me up to speed? I don't know the exchange rate, but aren't we talking about just 16 or 17 pounds? plus shipping?

Jack

Tinnitus · « **Reply #909 on:** 21 Mar 2010, 12:47 pm »

Capitan Jack,
I think that VAT is only incurred upon items that have a value of £18 or more so shipping would be the only other expense.
It cost me around $50 for express shipping a tray of 20 from parts express, but the exciters that I already have will keep me going for a while so I'd not require the fastest shipping available.
If you're up for sending to the UK who would your preferred carrier be?.
Rodney (Tinnitus).
I'll also send this PM

el`Ol · « **Reply #910 on:** 21 Mar 2010, 02:13 pm »

Another interesting thing:
The production of Swisscell has been running for a year now. This stuff has similar properties as Nomex honeycomb at a lower price. If it's still cheaper after shipping to Australia - I can't say.
http://www.the-wall.ch/cgi-bin/main.cgi

jonners · « **Reply #911 on:** 21 Mar 2010, 06:24 pm »

I've begun my first experiments, thanks to the help of our UK importer Rod/Tinnitus.

Cardboard seemed not very promising - lacking in treble and tiring to listen to.
My first listenable results have been with two sheets of MDF, 4' by 2', by 3mm thick. Two exciters per sheet, wired in parallel and mounted side by side near the centre of the sheet.
I don't remember seeing MDF mentioned on this thread, but it's so long I could easily be wrong. There are some graphs on the Slovenian forum showing a good frequency response. (I don't understand the language but a graph is a graph...).
Some recordings sound really good - ECM jazz goes well for example - and there is good treble detail, space and atmosphere. A string quartet can sound a bit thin at the moment but I haven't spent much time optimising things yet. I improved the bass a lot by putting the panels well apart, close to the side walls in order to get some reinforcement. There is a decent amount of volume, but I don't listen at headbanging levels.
MDF is cheap and easily available - surely someone else here has tried it? (The Slovenians also tried Dibond which again is readily available, though quite a lot more expensive - about the same price as Gatorfoam).
Edit: After a bit more listening it's obvious that there must be some unevenness in the treble since strings don't sound right. Perhaps coating the panels in shellac or magic juice could make a difference?

cometarossa · « **Reply #912 on:** 27 Mar 2010, 12:46 am »

ok I have received today my 4 brand new exciters. Begin testing

I'm talking about these: the Dayton DAEXSFH, the well known Steered Flux High Shove Exciter

I'm waiting for Nomex and aluminium honeycomb.
Have a nice day!

cometarossa · « **Reply #913 on:** 27 Mar 2010, 09:53 pm »

Quote from: mikadosan on 18 Mar 2010, 09:04 am

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...

Something like this?

Should be the italian version....

mikadosan · « **Reply #914 on:** 29 Mar 2010, 01:11 pm »

Yep...indeed the same glue...

emailtooaj · « **Reply #915 on:** 4 Apr 2010, 05:38 pm »

Hello!!
I am new here and would like to share my journeys!

In the pursuit to find a thin panel speaker for my garage workbench, I came across PE's exciters, bought them and when they arrived I have stuck them on everything!!

I tried cardboard, wood, Tupperware, metal cans, plastic cups, just about everything in the garage!! To my surprise the best sounding material is polystyrene foam packaging... IMOO. The sound was loud, crisp and clear. Only problem was the sample i had was to small...got it out of a 4" speaker packaging box that protected the speakers.
So then I went to WalMart and looked, pinged, tapped, scraped different material...I came across Elmers 20x30" foam board, and was amazed at the sound the transducers produced!!! After that moment...
I am hooked

Trying to find some more info on the net I came across you guys!!
Read though the whole forum from beginning to date. I see you guys have been on the same path as I have and would love to participate.
I hope to contribute on the quest for the perfect flat panel speaker

As I was researching polystyrene a little bit, they say ABS is a compressed polystyrene. Has anyone tried this yet? I don't remember anyone mentioning they have tried it yet. I know that ABS sheet can get as thin as 1/16"(1.5mm) up to 1/2" or more!
My thought was that possibly mating a ABS sheet to High Impact Styrene Foam my be a good combo?
Any thoughts, concerns, ridicule would be appreciated

Sorry post is so long, but excited to see that that crazy person named Karma brought me to this thread!

DanTheMan · « **Reply #916 on:** 10 Apr 2010, 12:53 am »

Anyone still experimenting out there?

I finally got mine on some cardboard boxes. Definitely not ideal, just wanted to hear.

Dan

zygadr · « **Reply #917 on:** 13 Apr 2010, 04:06 am »

DannyT · « **Reply #918 on:** 14 Apr 2010, 04:13 pm »

holly.............baffle

zygadr · « **Reply #919 on:** 14 Apr 2010, 11:53 pm »

Interestingly, these speakers are from the early 70's?................yet they clearly have ''EXCITERS'' as seen in the diagram.

So, when the hell did these exciters become available to manufacturers?..........everything I have read indicates at least two decades later?.....................notice the EXACT similarity to what is available today from Parts Express