[el`Ol]

Have you tried the taksboard?

[el`Ol]

A funny exciter would be a rectangular antenna coil (red) glued on the surface of the panel with a neodymium bar in the open space inside the coil. The coil wouldn't move back and forth, but be tilting. Without a closed magnetic circuit the flux densitiy would be about a half, but there is no additional mass for voice coil former or spider. Unfortunately I only found suppliers of antenna coils at alibaba for quantities of min. 10.000 pcs.


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[zygadr]

Hi guys, the exciters we are talking about are pretty much all the same in efficiency.
Why?..........because I have a list and specifications of many models made in China, including some of the more powerful/expensive P.E. types sold in the past.

Most are in the low to mid 80db's. The most powerful is 89db and can ONLY handle 10-15 watts before burning out...........sometimes much less

All exciters clip on loud music such as drum blasts if played at ''realistic'' levels. ''Realistic'' level is way below what I expect (even with many exciters on large panels).The surround around the exciter's ''foot'' gets loose also and makes matters worse.

You CAN NOT use high powered amplifiers with these exciters and crank up the volume...........they will get hot and fry and/or detach from the panels. This has happened to me so I know.

NXT panels are only good for medium volumes and are great with small jazz groups or classical ensembles.

If you really want to try exciters at this point in time, buy the ''balanced'' type which have a device that holds the exciter to prevent voice coil droop. The italian website mentioned above has the first two that are what I am talking about. They also have 32mm diameter voice coils which is GOOD!

I have gone back to my horn speakers for some time now and do not listen to the panels anymore.
That does not mean that I have trashed the idea, it's just that until a true ''HIGH POWER''/''HIGH EFFICIENCY'' exciter is made, there is no point in continuing to try to get real volumes out of them.............they just can't do it.

[tino84]

You CAN NOT use high powered amplifiers with these exciters and crank up the volume...........they will get hot and fry and/or detach from the panels. This has happened to me so I know.
I have gone back to my horn speakers for some time now and do not listen to the panels anymore.
That does not mean that I have trashed the idea, it's just that until a true ''HIGH POWER''/''HIGH EFFICIENCY'' exciter is made, there is no point in continuing to try to get real volumes out of them.............they just can't do it.

we came to the same conclusion. I build something with visaton bg13p and woofers in OB, it's not the same thing..

yes, NXT (and now also BMR from Cambridge audio, as their Minx systems) have good points (a natural sound, very real), but lacks power, decibel,bass and got clipping.

also now clipping is present, but you can clearly hear it's not speakers' fault..

I hope something more in BMR tech

[el`Ol]

Someone is knocking on the stuff in the second video, interesting sound:
http://www.taskboard.com/index.html

[Abelma]

[

[tino84]

Hi, I think my room is something around 4x3 mt.
NXT were lack decibel (I think sensitivity had gained at maximum at 83db) with every thing I tried,that wasn't a real problem in that way (my denon has some power to deliver), but this brought some distorsion in some difficult moment (f.e. when a track raise near clipping).

problems all gone away when I changed to my new wideband system...

[Abelma]

[

[tino84]

ear some "holes"in some frequencys, next to experiment.

something around 150-220hz I think.

to test same distorsion I heard, try these (it's an acoustic guitar intro, some notes goes clipping. this is a black metal song)

http://www.youtube.com/watch?v=yvE1pMvxELo

or here (clipping on female voice, first 30-40 seconds)

http://www.youtube.com/watch?v=1Hdgb53QVaY

I think it's a problem coming above all from track, but this is an example of a situation (bad registration..) that NXT maybe won't handle (and this is not a very real problem I think, but would be better to keep it in mind).

[Abelma]

[q

[tino84]

Thanks Tino.
I was thinking in a dsp equalisation. I have a MiniDSP system to assemble and test. I believe that it will help a lot for this panels. What do you think?

that would help a lot, I think 

About clipping, only when is really loud in my case, and the volume is so high that i cannot enjoy the music. I am using a tripath based amplifier, digital of 150 Watts per channel and it works fantastic.

so your Visaton are better than NXT from PartsExpress. would keep in my mind for the next time I'll try something with NXT 

I have some pictures of my panels, i will post them later.

 

[Abelma]

[

[papasteack]

...Hi, i'm trying for fun to design a servo-controlled acoustic-excited music prototype instrument  with a dayton puck and a hiwave HIAX19C01-8 inside and lot of other crazy things

You should test the use of a transducer pickup to add negative feedback to your panels.
It will need only a mixer with volume control and phase shift.
You can use a bband AST 1470 for example, it is used in some 5 string bass guitar so it go really low. 
Negative feedback will correct automatically/unniversaly the bandwith problems.
It has not been tested yet, but "servo control" functioning seems me to suit perfectly to correct exciters problems.

Real good idea or not ? I would like to test myself, but don't have enough time at the moment...

Damien

[papasteack]

Oh, and...you should too take a look on acoustic instrument...exciters works like the brigde on guitar. It transmit vibrations. So big thick box with hole should hallow exciter to benefit of bass-reflex effect...like in double bass for example. And you should think about linear renforcment like under a guitar table. That should maybe help transmission of vibration...

Why not a flat box with exciter on one side panel, that to allow the other panel to vibrate by "sympathy" like the back of guitars...
And why not perpendicular small panel to get more surface to radiate like radiators ?

I think that there is still a lot of things to do with those exciters. I don't know if nxt are really better than modified cheap good speakers...
Some tang band speakers with good BL factor should be good guinea to do the trick  : http://www.tb-speaker.com/detail/1230_04/w3-1750s.htm
lol...sorry i've got lot of stupid ideas, but maybe some should works...

[Abelma]

H

[tino84]

Dont know if better. I had the HiWave from PE and they had same quality reproduction in my panels. But, the Visaton have the possibility to bolt them.

I also screwed mine NXT, and got those little problem with songs I linked 

On the images. I added some weight with lead on the exciters. Attached to the panels with velcro to support them vertically . The velcro do not transmit vibrations to the panel and vice versa.
Added some damping on panels to test. Not sure of the results yet, need more test.

I got very good results with Ikea Lack table, and on another forum, other people told me they got a very good sound. The strange thing is that Lack isn't so little or light as other materials (lie balsa) but seems to reproduce a great sound with NXT.

Anyway, nice try, they seems my first NXT panel  nice idea using velcro 

[zygadr]

Hi guys!!!!!..................I'm baaaaaaaaaaaack!!!

Yes, I have just made two 4 foot X 2 foot VHEPS panels left over from my last encounter with the Podium clone loudspeakers.
I have been doing considerable research and have been ''reading between the lines'' on the many reviews on the Podium Loudspeakers.

Firstly, I was totally wrong in stepping away from this technology. My methods of construction were also wrong even though many members here were doing it correctly in the past.

I have found the following to be true and accurate to date :

1. the VH EPS panel is still the best type of material to use............no competition.

2. the panel MUST NOT be held or suspended around it's perimeter except for four small points of ''rubber like'' solid tube at the edges of the panel.These points are positioned by experiment until unwanted resonances or self panel noise is reduced or eliminated.In other words the panel is ''tuned''.

3. the panel basically floats on the exciters' feet, therefore ensuring maximum efficiency.

4. under no circumstances are the exciters to be mounted freely and hanging off the panels without support.

5. Parts Express sell only one of their many exciters that is suitable for this speaker system.

6.high ''BL'' or ''FORCE FACTOR''(SHOVE) is essential in the successful implementation of making large panels.

7. higher powered exciters are now available in conjunction with high BL.

8. multiple exciters must still be used to ensure higher power handling and output

On listening to the panels again, there is no doubt that they produce a very unique, high resolution sound that can be eerily real................just like live music.

So, where do we start?..............................I'm ordering larger panels with rounded corners and the timber will be ordered soon after.
Which exciter?......................there is only one!

[Abelma]

H

[tino84]

Hi Zygdr

have you seen these

http://www.avguide.com/blog/radical-bmr-drivers-make-cambridge-audio-s-minx-system-different-better

and cambridge Bmr technology?

[zygadr]

Hi Abelma. I can link a source for the EPS but it is an Australian one which won't be any use to you most likely.
From way back, VH grade EPS is like normal polystyrene foam except it is much harder and more dense. This makes it stiffer and stronger for a given size than the standard stuff.
However, normal EPS will do fine at 10mm thick.
At the moment my panels just have two equally spaced exciters down the middle of the panel...........nothing special and they are not supported by a spine or anything like the Podiums. They were quickly slapped together just to test the sound quality again.
The real pair I will be building will have diffferent and much better exciters on a large panel.

Tino84.................no I haven't come accross these. They look interesting but are not full range panels.......they use a subwoofer which is not the way I want to go.

After all this time, how many of you still have working panels that you use as your main speakers?