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

Jah-Hey! · « **Reply #1120 on:** 13 Aug 2010, 08:46 pm »

Three posts in a row by one person; it's official: talking to myself! And when I said I'm going "full bore" on the
EPS/exciters...I must have 'bored' you all. jstkidding.

Still though, if anyone cares to chime in with ideas on best cutting a 4' x 8' EPS sheet for a stereo pair, or if
the info has been stated, please tell me the page.
I haven't found it yet.
Si quieres puedes.

sedge · « **Reply #1121 on:** 19 Aug 2010, 04:57 pm »

jah-hay
the size of the panel depends on the size you can fit into your room.
If you want to experiment with the panels you could go for the 4x2 x4sheets using 2 exciters per panel.
I think zygadr is using 6x2 (or 6x2.5)with 6 exciters.
The bigger the panel the lower fr,you could try the 4x4 and if it was too big change it to 2x4.
how about 2 6x2 then you have a 2x4 to compair them with?
It is your choice.
have fun.
sedge

vaugi · « **Reply #1122 on:** 20 Aug 2010, 02:31 pm »

Hey UK people, if you got your VH grade EPS panels, where did you get them? Can't seem to track it down that easily in 10-12mm format, just fat 25mm for construction industry or small expensive bits for model making.

Cheers,V

Jah-Hey! · « **Reply #1123 on:** 20 Aug 2010, 06:22 pm »

Thank you Sedge,
Zygadr wrote that 2x4 w/ four exciters is optimal,
But your suggestions make sense too; especially, I like the 2x6 option! GBOBH...go big or etc.
I *was waiting for pics of his*final version using EPS in a frame.
Has he posted them?
The edge treatment seems isn't clear to me either.
I wasn't sure how to. Do I just round them?
The buzzing that zygadr noted is eliminated after edge
treatment so, it's an important step.
I'll reread his posts; trying to be sure about it before
committing to cutting/framing.

jonners · « **Reply #1124 on:** 20 Aug 2010, 07:22 pm »

Quote from: vaugi on 20 Aug 2010, 02:31 pm

Hey UK people, if you got your VH grade EPS panels, where did you get them? Can't seem to track it down that easily in 10-12mm format, just fat 25mm for construction industry or small expensive bits for model making.

Cheers,V

I haven't actually bought mine yet, but I was thinking of trying here: http://www.packagingandmuchmore.co.uk/Polystyrene-+EPS-+Sheet%2C+Mouldin.htm

Nickolay V · « **Reply #1125 on:** 22 Aug 2010, 10:06 pm »

! ALL for DISCUSSION:
1)Rohacell RHC.31 or Rohacell LS
http://www.cstsales.com/Rohacell_31_IG.html
2)

pol_bct · « **Reply #1126 on:** 5 Sep 2010, 12:45 am »

Cologner and others

" I have two other questions concerning exciter positioning and possible stereo effect on a single panel. Do 2 lines of exciters (equal in distance to each other and the panel dimension) make sense, anyone tried this? "

it was a couple of months ago I did those tests, and I am now sticking with a single stereo panel setup, which will stay FOREVER.
I can put better transducers or better panel material, but the global design wont change, NEVER.

It goes like this:
take one single biggest panel you can get
if your room is 2.4m high dont go above 1.8m heigh
if the room is 4m wide dont go above 3m width
mark the 2/3, 1/3 points, in both directions
in this example, 0.6m & 1.2m from ground
and 1m from left & right sides
put one single exciter at each of these 4 places.
wire them 2 by 2 (serie or //)as LEFT & RIGHT. (I prefer //)
in the center of the panel, stick 4 (yes four) transducers
as close as possible to each others.
wire them 2 by 2 (serie or //) exactly as you did for the L & R.

now watchout carefully:
insert the center transducers together in the return path of L&R elements.
This means that wiewed from the amplifier you have
left output -> 2 drivers L
right output-> 2 drivers R
common point of return goes through the center group of 4 drivers back to amplifier ground.
respect the polarities amp>(+(L_or_R)-)>(+C-)>ground
this design is about half a century old, but it is very effective.

let me know about your listening sessions

POL

j gale · « **Reply #1127 on:** 5 Sep 2010, 05:04 am »

Is the panel suspended? If so how high from the floor? Do you have a picture? Does the stereo image have depth? With your single stereo panel can you describe what you hear vs 2 panels in terns of sound stage and stereo image? I would suppose that your arrangement is more coherent. It seems to me that it's interaction with the room would be most important. Can you tell us more about the placement of your panel? If I understand correctly you use 8 exciters, 4 right,4left?

pol_bct · « **Reply #1128 on:** 5 Sep 2010, 03:08 pm »

Quote from: j gale on 5 Sep 2010, 05:04 am

Is the panel suspended? If so how high from the floor? Do you have a picture? Does the stereo image have depth? With your single stereo panel can you describe what you hear vs 2 panels in terns of sound stage and stereo image? I would suppose that your arrangement is more coherent. It seems to me that it's interaction with the room would be most important. Can you tell us more about the placement of your panel? If I understand correctly you use 8 exciters, 4 right,4left?

When I started my tests I found clever to suspend all my designs to the ceiling
with the lighest panel I could get, to catch the ultimate efficiency.
with 8 transducers on a single styrofoam panel it went easily in Hi_efficiency territory, but the sound was ... awfull, deep valley & hi_mountains, very difficult to listen for a long time, and the worst, lots of ceiling reflexion.
After a lot of cut&try I went back to CC, single or double layer, simply standing on the floor by itself, , efficency is lower but sound is more natural, and the (quite) heavy weight damps peaks&valleys. (no picture for the moment I am not at home).
this config with L_center_R spots is the one who give the best coherence, close to ambiophonics config, if you know what it is.

With conventionnal stereo, I always felt unsatisfied with the center hole
I turned to ambiophonics more than 2 decades ago, but it it difficult to live with a central separation, total unWAF, so I was in search of a more acceptable setup.
This one act like a "paravent", it can be decorated, painted, etc etc ...
one can hide the TV & gears behind the panel

about interaction with the room, this config is probably the one where there is the more to win. In the past I never felt than bandpass or distortion was SO important to me. Those parameters were only the 2 that we best know how to measure, that does not make them, automatically the more meaningfull.
A constant radiation at all frequency means much more to me.
Do you get what I mean?

actually this config is built with 8 transducers, 2xL_2x2xcenter_2xR, but a simple 4 drivers setup, at 1.2m from the ground, gives allready plenty of sound, because the huge surface of radiation fills the room at a constant level a any distance. I think surface of radiation is the criterium n°1 in sound reproduction, not distorsion or bandpass.

regards , POL

Nickolay V · « **Reply #1129 on:** 6 Sep 2010, 06:42 am »

NXT theory stipulate obligatory EDGE DAMPING !!!
I have read many patents for this item and can conclude.
Best material for in-frame damping is LDPE foam tape around all perimeter (!not any Rubber and not any foam) .

bobloblob · « **Reply #1130 on:** 8 Sep 2010, 02:35 am »

POL,
Interesting post, as always. CC = corrugated cardboard, right? Do you use this as one large flat piece, or is it folded slightly, like say a tri-fold, into thirds with the end pieces folded slightly in or out? Do you think that three similar-sized panels each one one-third the size of your one panel and wired the same way as you have done would work as well, or is there something about having all the exciters on one single panel that makes a difference? Have you tried the material ZYGADR uses?

Interesting, interesting.
Bobloblob

pol_bct · « **Reply #1131 on:** 8 Sep 2010, 10:19 am »

Quote from: bobloblob on 8 Sep 2010, 02:35 am

POL,
Interesting post, as always. CC = corrugated cardboard, right? Do you use this as one large flat piece, or is it folded slightly, like say a tri-fold, into thirds with the end pieces folded slightly in or out? Do you think that three similar-sized panels each one one-third the size of your one panel and wired the same way as you have done would work as well, or is there something about having all the exciters on one single panel that makes a difference? Have you tried the material ZYGADR uses?

Interesting, interesting.
Bobloblob

bobloblob, thank you for your interest
yessss, CC = corrugated cardboard
my next try should be with this thin CC (2 or 3mm) the one they use for post-packet , but difficult tu get with a big surface.
I placed my panel slightly rounded, for 2 reasons, to get a selfstanding panel, and to keep the 3 radiating spots at about the same distance of the central listening place. the main objectiv is coherence, so we have to preserve it all along the process.
I think that a big panel is better than 3 smaller, the 2/3, 1/3 trick is supposed to cancel 1/4 & 1/2 waves interferences, but there may be an exception, if the panels are tall, this could be an interesting setup in order to avoid thoses interferences between transducers in the horizontal plane, but it wont get as low in frq. In my setup the bass comes from the central group of drivers and make use of all the surface, 5.4m² , remember muscle-cars, you can't beat cubic inches...
About the material used by ZYGADR, I'm a little lost amoung all the threads and I don't know about his latest best choice.

best regards, POL

Nickolay V · « **Reply #1132 on:** 8 Sep 2010, 09:13 pm »

So guys , what about Rohacell ? Yours opinion ?!

zygadr · « **Reply #1133 on:** 9 Sep 2010, 03:19 am »

irishpatrick33 · « **Reply #1134 on:** 10 Sep 2010, 05:08 pm »

Quote from: Nickolay V on 8 Sep 2010, 09:13 pm

So guys , what about Rohacell ? Yours opinion ?!

I think $65 for shipping if just a tad too pricey. Just a tad.

Nickolay V · « **Reply #1135 on:** 10 Sep 2010, 10:47 pm »

Rohacell price only 1,4Euro/m2

mkstat · « **Reply #1136 on:** 11 Sep 2010, 01:08 pm »

Hi Nikolay V!

you may find this interesting:

http://ip.com/patent/US7564984

it's one of the latest NXT Patents and describes some aspects you can take into account if you decide to place multiple exciters in a linear arrangement on your panel.

I suspect (according to your former posts) you are heading for a useful soundreinforcement/ installed sound design?
I'm afraid your way of looking at this kind of technology will most certainly not be very much apreciated in this forum.

with kind regards
m

irishpatrick33 · « **Reply #1137 on:** 12 Sep 2010, 01:02 am »

Quote from: Nickolay V on 10 Sep 2010, 10:47 pm

Rohacell price only 1,4Euro/m2

Assuming what ever USD value you have suggested is reasonable... that is not the problem. The obscene amount they are charging for shipping is.

I'll do my experimenting on some cheap foam core. When I have my ultimate design, I will probably try hexacomb. At least I know I can pick that up locally, and it's environmentally friendly.

ragna · « **Reply #1138 on:** 15 Sep 2010, 01:50 pm »

Hi all,

I just finished reading the thread. It was so thrilling, that I couldn't go to sleep last night, at least no very early.

@ Cologner: Hallo nach Kölle, meiner Heimatstadt.
You said, you ordered EPS in Germany. Is this from the NAFAB GmbH, you mentioned earlier?

I found this thread, because I was searching for a material for a paneel. Since now, my favourite was grain balsa with some kind of coating like epoxyd or aluminium foil.

Because my listening room is very small, I want to build a DML with small Paneels, like 25cm x 70cm. So I'm wondering, whether the thickness could be less than 10mm (depend on the supplier). To make it more stable, I want to glue a thin alu foil on the EPS. A few years ago a loudspeaker manufacturer was using this as cone material (Görlich Podzdus). What do you think?

Regards
Rainer

zygadr · « **Reply #1139 on:** 24 Sep 2010, 03:45 am »