PIEZO NXT type panel

[el`Ol]

Originally posted by jzagaja
el`Ol,

How we manage to change exciter position? I mean don't we destroy delicate coil centring?

They recommend pressing the exciter to the panel with the double-sided glue covered until the ideal position is found and remove the covers only for final placement. I glued one exciter on the panel and forgot to remove the cover of the voice coil. I had to remove the exciter and the result was that most of the glue of the feet was gone and one food went off spontaneously. So better don´t make any mistakes.

[Ziggy]

The positioning of the exciter as Dayton specifies only relates to a solid structure such as a table top, window( ), door etc.

When you start with ''free'' panles and suspensions, we are entering a different world where placement is not dictated by NXT principles as much.

[WrineX]

is here someone who ever measured these kind of speakers? im folowing the thread for weeks now, but opinions are a bit vaag. then they sound incredible and the next day they suck. day after they sound superb again. also i find it hard to believe that a panel driven at a few spots can sound good and realistic although one exiter has to drive all this mass, wich is even wobbly as well. even the so called high end versionsposted on moons audio , are to be found total crap by most people that heard it on the shows.

[Ziggy]

Measurements mean nothing. The type and size of the panel will have VERY different measurements if you are talking about frequency response.
A normal small NXT panel(picture size) will have a frequency response from 100hz to 15khz on average.The sensitivity will be low because most only use a single exciter per speaker, thus the need for multiple exciters in ''serious'' versions.

The reason for some inconsistent opinions(including my own) is that they are source revealing/dependant and are affected by the way they are mounted, not mounted, positioned.....whatever.
The slightest error with a loose, hanging or touching wire at the back and you will hear it - no problem.

This is a very different breed of animal to your usual monkeys and lions at the zoo.

The reviews I have read have been mostly positive, not negative.

First impressions at ''shows'' has very little to do with the actual thing in your own home, connected with painstaking care to the correct source equipment and set up correctly.....this is critical with this type of panel loudspeaker.

The room plays a vital role in the resulting quality of sound so , it would be unlikely that a showroom would be anywhere near good enough to display the speaker's ability.

I have found out the hard way about all this and am still amazed to this day how a speaker like this can tell you instantly that you have made a correct or incorrect choice of cable/connector/amplifier, cd player and so on.

Yes, the Gatorfoam I use is not entirely rigid and can be ''wobbly'' as you say, but this does not stop 6 evenly spaced vertical exciters moving massive amounts of air from a gigantic surface, totally full range, no crossover - a real experience........believe me, or just believe that they are crap.....please yourself

[jzagaja]

I've found foam-x or kapa quite cheap EUR 10,00/m2. Looks similar to gatorfoam. 10mm thickness is 0.85kg/m2.

[pol_bct]

I have made some measure on a starbass driver, another kind of DML
http://eazy-world.com/images_et_son/...C-STARBASS.htm
here is a wav.zip attached, it's a convolution of logsweep, so you can examine amplitude response, harmonic distorsion and phase and so on. The wav has been resampled to 44/8bits to fit in a small file
The dip at 10kHZ comes from the standing waves in the thick board I used, (my computer board)

I should get 10 pairs of DAEX25 next week...
more to come

POL

[jzagaja]

Here it is.

[pol_bct]

Jzagaja, what software do you use for this presentation?
I like it very much

POL

[jzagaja]

Hi Pol,

ARTA + Photoshop. Noise taken before main pulse. If you examine this wav file you will see harmonic distortion as a main pulse and echoes so I truncated in Adobe Audition.

Regards,
Jack

[pol_bct]

Jzagaja
ok I thought it was ARTA but I did not get the fotoshop trick

in this .wav you find a main pulse at the right, this is the response
and a suite of smaller pulses to the left, those are not echoes
but harmonics (distorsion), from this transducer (and microphone)

This is related to the FARINA's method of capturing a logsweep
and doing a convolution with the inverse of logsweep.
http://www.melaudia.net/zdoc/sweepSine.PDF
This is by far the best, easiest and more complete method
of one shot measurment on a transducer or gear.

POL

http://pagesperso-orange.fr/pol.bct/exemples/DIY.htm