[zobsky]

Zobsky-

I believe "slam" is usually a function more of the mid-bass, as you are pointing out, and also that sometimes cutting off the deep bass gives the perception (false) of an increase in "slam".  Is that your observation too, or am I mis-remembering my own speaker systems of the past?

Exactly.

[pol_bct]

Hi !

BLOBLOBLOB

I am afraid this won't work,
when exciters are set on a line, they radiate inphase in two directions, perpendicular to the line,
and they interfere randomly in all other directions, because of the wave lenght between them
with the cheap transducers about 5cm center to center this give a upper cutoff around 7kHz
and any small and rigid bar wont change this...
By putting transducers at random on the panel or on a line ,
we can spread interferences and get into the real DML

POL

[pol_bct]

SEDGE

this was my first test, to put an exciter just in the middle of the panel, and it works !
but with bigger dip and valley, exactly like any loudspeaker set at the center of a plan baffle

POL

[ondesx]

Then, how can we hope high acoustic power output ? Most of these exciters have a poor 75 dB/W/m... We need a lot of them to reach decent levels. Now, we know that several can be used and how, more or less, we must "distribute" them on a panel (vertically or/and horizontally)...
Then the next question is how can they be "arranged" to deal with more than the 10 or 15 W they normally accept and connect say a 100 or 150 W amp ?

[bobloblob]

pol-

I'm not sure I understand the concept here.  I realize that when the exciters are set in a line, there will be interference between them.  My point was that if they are attached to a bar, if the bar were rigid enough there should be little energy radiating through it between the exciters.  Instead that energy should be transferred through the bar as though it were a single exciter, thus eliminating the interferring nodes.  Remember the bar would be between the exciters and the panel, not outside of the exciters.  The thought here is to link them mechanically so they function together as a single unit.  It would act very differently from the exciters mounted freely on the more flexible panel, especially if the exciters were mounted so they nearly touched each other.  I think the only way to approach this is to test the idea and see whether or not it works.  It may not work.  On the other hand, it may.  The major obstacle is finding a light enough and stiff enough bar.

I started thinking about this because of Zygadr's comments.  First, his problem with the exciters overheating at medium sound levels when played for some length, and second, when he suggested, as have others, that maybe a single exciter would give the best results.  For those who have bought several of the less expensive exciters, I'm sure the idea of tossing them and buying a pair of the expensive ones is frustrating.  Why not give it a shot, or try Tinnitus' suggestion of using a round plate?  Easy enough to try four this way on a single panel for anyone who bought some extra ones that are not being used.

I apologize for suggesting this and not testing it myself, but nearly everything I own is packed away in a storage unit for awhile.  Life takes very strange turns.

[sedge]

Zobskt
Thanks for the info ! this explains a lot
Pol
I have just made a quick test with a mic on my knocked up panel 2x4 single layer cc.
The response from 200hz to 15k is very similar excep for a  peak at  at about 8 or so k with the 3/3 spot.
In the 200hz and bellow there are some changes ,the main one being at about 60hz.
In the center it is a dip in response but at the 2/3 spot it is a peak , close mic shows a good response in this region but as you move away the overall response drops away except for the 60hz ,which stays there.
On pink noise you can hear it rumbling away  in the room ,
As I say pol this was a quick knock up and I was hindered by the shellacking I had done on one side of the panel only.
Having the shellac on the front seemed to drop the hf at about 10k which I was not expecting but having the shellac on the back gave a good response again ?
Have to look into this further, front side ,back side , both,small part or all ?
EMERGANCY
I have been trying to look at  zygadrs  more powerful exciter but he has deleted himself from the site or at least from my computer?
Hope its nothing I have said?
I had a sudden thought are these exciter units like ours or are they resonators that vibrate inside their case, I only ask as it says you can detach them from a ring that holds them on the panel?

[jonners]

Many of zygadr's posts are now in the Intergalactic Wastebin. What happened? 

[ondesx]

It seems this happened in another forum...

[zygadr]

It was of my own doing.....................and it DID NOT happen on another forum........the posts are still there.

[ondesx]

@ POL :

Please see PM,

[sedge]

metal panels
my metal panels are two 11 thou ali sheets [don't know metric]glued together with spray mount,my freind thought this was my  best sounding panel  so far but it is not as efficiant as cc[at least 6db less].
 they are about 2ftx2ft they do not go low say 250 hz .
larger panels do go a bit lower though.
I have spreed myself a bit thin with all these panels.
maybe I should set up a pair as a ref and see if I can get a more efficiant  one to sound as good ,its easily said but I have changed these around so many times that I think my heads going to fall off
I Just remembered I have some 2inch or so styrene panels in my loft 
I think it has  paper on each side ,will this kill the efficiancy of styrene[at least 6db better than anything so far?
oh well hey ho here we go again!

[pol_bct]

ONDESX

done ... & answered  )

[BowerR64]

Has anyone looked at the "mission M-cube" a guy on another forum had a set that failed and wanted some help with replacing his setup. Once i looked into his setup i noticed in one of the images this system uses NXT technology.

What are they doing here? The little cubes measure 3-4" what is the panel material they are using? How are they getting any kind of decent sound using such a small panel?

Are they using the stands some how to help carry the sound?

In the image, the red part of the cube is cloth that you can change the colors of to match room decor. So is this part of how the sound gets out? Using the front panel as direction, and then the back of the panel to spread the sound outward?

This thing is interesting 

[ondesx]

ONDESX

done ... & answered  )

Thanks ! 

[mikadosan]

metal panels
my metal panels are two 11 thou ali sheets [don't know metric]glued together with spray mount,my freind thought this was my  best sounding panel  so far but it is not as efficiant as cc[at least 6db less].
 they are about 2ftx2ft they do not go low say 250 hz .
larger panels do go a bit lower though.
I have spreed myself a bit thin with all these panels.
maybe I should set up a pair as a ref and see if I can get a more efficiant  one to sound as good ,its easily said but I have changed these around so many times that I think my heads going to fall off
I Just remembered I have some 2inch or so styrene panels in my loft 
I think it has  paper on each side ,will this kill the efficiancy of styrene[at least 6db better than anything so far?
oh well hey ho here we go again!

Hi,

If you can get your hands on some thin aluminium sheets you can try the following... Use either a spray glue or contact cement and make a composite with 4mm Rohacell 71 foam sheet and thin aluminium skins. If you can make a good bond between the sheets and the foam core and keep it straight while the glue is drying, you can get some very nice panel for your DML loudspeakers...  

I also made a composite of 2mm pressed cork sheets with thin aluminium skins and it was also very interesting panel. It is of course quite heavy if compared to the foam cores and honeycombs but it has a very nice overall balance anyway with 32mm balanced exciters from PE as cork has a very good internal damping factor but aluminium skins will increase the stiffness of the panel...

-M

[vaugi]

NXT outing some more cardboard speakers (the original ones were the SoundPax cardboard "cones", which helped bring the Sonic Impact t-amp about I think).

http://www.engadget.com/2010/02/18/wowwees-paper-jamz-fake-guitars-make-the-jump-to-2d-gain-some/

With re: to the mission m-cubes, I think the cloth is literally just that, something to make the unit look more wife friendly and to be changed to suit decor, and don't think the stands do anything sonically (but might be mistaken!). 

[sedge]

the two thin sheets of ali glued together do have a very clean sound and as you say a good over all balance .
the panel itself is very well self damped,if you tap the panel it sounds dead ,but it also has a good hf responce when playing .
Am not sure if using any other internal filler would help[over damp and destroy hf]

[irishpatrick33]

Has anyone looked at the "mission M-cube" a guy on another forum had a set that failed and wanted some help with replacing his setup. Once i looked into his setup i noticed in one of the images this system uses NXT technology.

What are they doing here? The little cubes measure 3-4" what is the panel material they are using? How are they getting any kind of decent sound using such a small panel?

Are they using the stands some how to help carry the sound?

In the image, the red part of the cube is cloth that you can change the colors of to match room decor. So is this part of how the sound gets out? Using the front panel as direction, and then the back of the panel to spread the sound outward?

This thing is interesting 

I owned them. I gave them to my father. I go through speakers at an unbelievable pace.

I wasn't impressed by them. The sound is very different. They are very withdrawn or restrained. You really have to turn the volume up to get considerable sound levels.

[sedge]

irishpatrick33
restrained is a good word,I have heard these cubes at audio shows playing loud but with no dynamics,very restrained .
I find this sound very anoying so can only last a few mins before I have to leave the room!

[DanTheMan]

check out these links:
http://www.wvier.de/texte/NXT_Tonmeistertagung.pdf
http://www.soundcontrol.tudelft.nl/Personnel/Rinus%20Boone_files/RB_AES2000.pdf

Sorry the first one is in German only,

Dan