[sedge]

Pol-bct
I thought I would wire my 4ft by 4ft panel as a stereo panel ,just to see what would happen .
The panel sounded quite good ,with a nice central image .
There was plenty of Lf  and I was wondering what 4ft by 8ft would sound like with wider spaced exciters ,when suddenly the tape holding the panel up gave way ,ripping one of the exciters off.

Time to compare  a 4x4 panel with one exciter  with a 2x4 with two exciters !
To my surprise the panels responses were practically identical except for a bit of a 60hz hump in the lf  on the 2x4 panel and a very slight more volume on the 4x4 panel.
Lf was very strong on the these panels playing together ,felt as well as heard .
I think I prefer the sound from the large panel ,it sounds cleaner  and clearer .
If nothing else falls down and breaks I will let you know what I think after a long listen.

As for the one panel for stereo ,if I can order  an 4x8 panel and wire it up as a stereo panel ,then cut it in half  to compare the sound ,I will.
IT would be very interesting  to compare a 4x8 panel with two 4x4 panels almost touching .
which would give the better sound mmmmmm.
That’s for another day.
sedge

 

[panomaniac]

If you are hoping that the poly sphere will radiate like a pulsating sphere, you are going to be sadly disappointed

Naw....  I don't expect that, being NXT and all.  Really don't know what to expect.  But it might radiate OK all over the hemisphere with the exciter at the apex.  Did you actually try a hemisphere or sphere, or just the 2x2 panel?

Even if a 16" doesn't do much bass, it might make a fun mid/hi driver.

[Nickolay V]

Carsbro nLIGHTn  China-retail-FOB is only 149$/pc.
That means that diaphragm price (and material price) is not high.
We have tried to get diaphragm material specification from  Carlsbro.
They refused to provide any.
Though the speakers were discontinued.
May be any of you, guys,  know what the material exactly is ? 
And who produces it ?

PS: We know for sure that material is Chinese .

[pol_bct]

Pol-bct
I thought I would wire my 4ft by 4ft panel as a stereo panel ,just to see what would happen
.....
I think I prefer the sound from the large panel ,it sounds cleaner  and clearer
 .....
As for the one panel for stereo ,if I can order  an 4x8 panel and wire it up as a stereo panel
.....
sedge
 

YES, bigger is better, no matter what small panels may say !!!!

and a happy new year to all DML fanatics !

POL

[j gale]

Sedge    Here in Canada can't find the hi density stuff Zygadr has. We have the regular white stuff used for insulation and a higher density one with smaller beads called type 2. Thinnest is 25 mm. The surface is still a bit rough like the lower density. I'm wondering if your 25mm is same/similar? Can you comment a bit more on sound from undamped vs damped on your present panels?  I'm going to give the 25mm higher density a go any way. I'll start with 2 exciters at the 1/3 position. Have already tried gatorboard ,single and double cc. The corrigated cardboard has had the most natural sound so far.

[sedge]

J gale
What size panels are you going for, are you going to use an Lf driver for the low end?
Don’t worry about the 25mm thickness of the panel,it will sound  as if it does not exist.
If it’s a 4x8 ft panel you may have to turn the lights out to convince yourself of this .
Initially play music with live acoustics as echo machines can sometimes sound OTT.

I think my poly panels are the cheapest you can get (£7 for a 4x8 f panel) so I can not say what the higher density might sound like.
Plus, a lot of the problems I was having were coursed by the tape on the rough surface, but using glue fixed this. 
But what you could do is use the method I used to glue the exciter on, including applying the glue an inch or two around the exciter.
You can then listen to the sound of the panel before applying the thin coat of damping over the rest of the surface. If needed (which I think it probably will)
All panels have a sound ,but I think that zygadr’s very high density panels could be more or less self damping,so would not rush to damp them, as it could ruin them!
I did try damping a high density 40x 40cm 10ml sample panel (maybe too heavy a coat) but I liked this panel naked .
Personally I would glue one exciter per panel ,then listen to the sound .
If it sounds bad ,damp one panel ,then listen again,and compare .
Don’t forget to leave the panel for a day or two as the glue will harden and the sound will change.so do not rush (like I do) and save yourself a lot of grief .
Only damp the exciter side of the panel!!!
I found one coat on my panels was enough ,If too much is used it will sound smoother but slower and you will loose db’s.
the beauty of the polystyrene panel is it’s lightness and speed. 

When you have sorted out the damping, you can add the second exciter to one of the panels, then compare, please let me know what you think of the difference between one and two exciters? That’s if you do it this way.
Hope this information is of some use .
Good luck
sedge

[j gale]

Hi Sedge,   Panels are 2'x6' hung inside a frame I used before with elastic bands in each corner.  I used 2 exciters because I have the cheap (but excellent quality) 4 ohm ones from Parts express and want an 8 ohm load. I attached the exciters with the vhb tape. I have a can of minwax wood hardener used for preparing rotten wood for filling. It contains a bit of acetone and methanol and presumably some plastic. I found that it just begins to attack the polystyrene if you gently wipe it over the area you want to attach your exciter to, leaving it smooth and coated. It doesn't attack the polystyrene if you don`t linger too long. Anyway I believe that I have a good bond with the tape. I tried lacquer thinner to smooth the polystyrene but found it to be far too aggressive. It will probably a couple of days before I get to hear what I have got. These panels come in 2'x8' and cost $6 each. They have a green tinge and if squeezed don't feel as spongy as the cheapest. I will try your damping technique soon after I hear them. Might try a 2'x 4' later since I have a couple of 15'' woofers in H frames.

[Nickolay V]

 Phenolic Paper Honeycomb much BETTER  and preferable than EPS and ALL range of Amina used materials.
 Exactly!!!

http://www.amina.co.uk/downloads.html

[el`Ol]

Maybe of interest for the thread starter: Paper honeycomb from Australia:
http://www.atlcomposites.com.au/atl_composites/products/cores/paper_honeycomb

[sedge]

Nickolay v

In What way, do you think phenolic paper honeycomb is better than eps?


J gale

If you do not follow the instructions for making the panels ,I can’t guarantee the sound .
When the pva is dry it is so thin you  would not know it was there ,it does not attack the panel material and bonds very well (tightly to the panel).
You are using two layers of material ,one soft( tape ) one hard (wood filler ) plus a lacquer, you could have peaks in the response or poor hf  or both .
the sound is everything !
Alter things a little and you will change the sound a lot.
I’ll keep my fingers crossed .

sedge

[Garytr]

 j gale

I previously asked about a Canadian source for HD 3lb EPS, where did you source yours?

garytr

[j gale]

Sedge,  You miss understood.  :?The minwax hardener has the consistency of water and a fingertip on a cloth 1 1/2 inch circle on the panel. It just attacks the poly enough to smooth it. Does not leave anything descernable behind. Just to facilitate bond. The VHB tape is thinnest. Half as thick as zygadrs. No cushion there. No lacquer either. I only mentioned lacquer thinner to warn that it is too aggressive to do what the minwax stuff does. Don't believe I have changed the game.  Jim

garytr,  Home Depot. They call it hi density. It has a slightly greenish colour. Largest I saw is 2ft. x 8 ft. Seems to be type 2 about 25% denser than type 1. Plasti.Fab brand.

[sedge]

J gale

Sorry about the miss understanding.
But you are still using tape ,which is unpredictable with eps .
If the panel is going to be covered in glue anyway, why not use it to glue the exciter on,
And then you can remove one of the variables.
When I measured the panel after about 8 hour of drying time, including at least 30 mins with a hair-dryer, to a high temperature.
 I found the hf was struggling to get over 10k,luckerly the next day it reached 20k.
Even though the glue felt and looked solid It was not good enough to do the job.
So maybe you can understand my concern about not having the exciter mounted as close and as firm a mounting as possible.
NXT may recommend using tape ,but from what I have seen of nxt panels, they struggle to get over 10k anyway,looks to me as if they worry about patents not sound!
I will keep my fingers crossed anyway,and hope all goes well.

Nickolay v
On heavier panels the exciter has to do a lot of hard work to move the panel,but with the poly panel ,the panel does all the work and the exciter hardly moves.
So even the smallest of sounds ,like someone quietly breathing in the back-ground can be heard( this makes the hair on the back of my neck stand on end)!
I managed to get a fantastically flat frequency response from my thin metal panels ,and they sounded very  good,but in the end I found them lacking!
It took so muck to drive them it felt(sounded) like something was getting lost.

sedge

[Nickolay V]

sedge
In What way, do you think phenolic paper honeycomb is better than eps?

By my opinion and my ears:
Phenolic Paper Honeycomb have neutral , biting expressive sound ( ! almost 100%  identical live insruments and vocal )
Polypropilene/Polystyrene cardboad and EPS have more shallow  and excessive ringing sound than natural.
Paper honeycomb polyester skin  have moderately expressive , but excessive ringing sound than natural.

[j gale]

Would love to try some phenolic paper honeycomb but can't find it for sale.

[sedge]

Nickolay v
Have you made your own panel speakers and tested these panel materials, if so could you give details, or are they nxt  products such as nlightn and amina?
 
sedge

[Nickolay V]

Sedge

We tested factory made Carlsbro , few Amina models  , Wharfedale and  отнеr british and italian made.
I look  panel construction in  J.GALE gallery . It like Podium , is not  technological pure NXT.
NXT must have ALL perimeter damped diaphragm.
Therefore by my opinion Podium type constructions (partial damped) on bass freq. work  in  some pistonic identical mode.

Our next experiments will be with self made  ROHACELL diaphragm speakers.
And now we looking for Carlsbro like  Phenolic Paper Honeycomb

[sedge]

Nickolay v

The name of this thread is a little misleading.
this is not an nxt thread.
Mkstat  on page  58 did try and tell you.
The panels do have nxt properties but then ,so does every other cone speaker,so you are right when you say this is not a pure nxt.
They have been described as a flat horn and from the sounds I am hearing I can well believe this .
But to be honest I think the panels have a little bit of everything in them.
I myself have never heard an nxt panel I liked .that is including  the new mission dml’s.
For the first 30 seconds or so you think, yes these sound great, then you think, oh dear there’s something wrong, they sound restrained and spatially flat.
Zygadr has spent over two years getting to where he is with his excellent sounding  full range poly panels( I  only got hooked on exciter panels a year or so ago)
So saying we must do what nxt do (clamp a frame to the panels and so on)is like a red rage to a bull,I am sure zygadr would have had more to say ,if it wasn’t for the fact he’s probably  thrown his computer out the window !
So please ,as zygadr has said ,can we get back on track!
sedge


 

[bobloblob]

sedge-

While I think the main focus of this thread should be in the direction that you and Zygadr are going, it is nice to see what others are doing and thinking occasionally when it relates.  I would like to see where this takes Nikolay, but without his criticism at present of the poly panel approach - that is, as long as it doesn't yank the whole thread in a new direction.

In the meantime, I am more interested in your project.   I can easily find the material you are using locally, and it sounds as though it's working well for you.  By the way, I don't think you mentioned whether you mounted the exciters to a spine or just mounted them unsupported on the panel.

Happy New Year to you and Zygadr and all

[irishpatrick33]

Actually I'm really intrigued by the foam spheres that Patrick posted.  The big ones are $$$, but the 16" could be fun to try.  I have a 16" globe, and that's a pretty big sphere.  It has more surface area than a 2x2' panel (one side at least.)

Since they are split in 1/2, you could put an exciter in the apex of both and close it up to make a sphere or use them open to hear the difference.  It looks like the 16" size includes shipping, over that requires a shipping quote.

I personally think the 3rd dimension has been completely ignored. If this were a typical open baffle speaker, the baffle is merely a divider to prevent cross cancelling. No reason to epically mess with "flat" in that case. But with these NXT open baffles, the baffle is producing the sound--not just a separator to prevent cross canceling. So I think the 3rd dimension is worth a look. Which I already have. I have already attempted a 20 something inch EPS cone. I had surprising results, but I will not reveal them because I have no baseline to judge them. I am using different drivers than I used in my old Zigxtaplanars.


3 PANEL ENTER.... 1 PANEL LEAVE (PLUS A BLANK FOR THE BASELINE)




So why not knock two birds out with one stone. I need a baseline panel to gauge my 3D cone panel, and I am interested to find out whether voids in the panel will significantly change performance. I have 4 panels. 3 panels with designs and a baseline blank. They will be suspended by rubber bands within the roughly constructed wood frame. Driver placement will be judged as well throughout each panel. One driver per panel during testing (the Dayton 25mm high shove premium model). The driver will be temporarily secured to the panel with double stick tape. Results to follow.