In this forum posted, ziggy started making dml panels in 2008 using piezo drivers to excite the panels.
Every now and again I mention piezo's as maybe another option especially as piezo drivers are more powerful nowadays.
I do not get upset if no one is interested in this way of driving their panels.
I would have to experiment myself and prove it viable.
I came very close to purchasing piezo exciters and a piezo amplifier for testing.
But in the end my wallet would not open 🫣
You cannot expect others to do the work for you.
I find the idea of not having a spider and all it's problems very interesting.
Maybe starting a new forum on flat coils is the way to go.
But you will probably have to do some testing of your own to prove how well it works.
I would always keep an eye on such developments, to see if anyone comes up with any new ideas.
All the best .
Steve.
Hello Steve,
I have in mind that piezo driver are limited in displacement. What about their compliance?
Christian
Hello Eric,
Very interesting.
With that do you have more "classical" placements like 2/5, 4/9, 3/7 which may show how they make a balance between 1.1 and 1.3 modes?
Christian
Hello Christian.
I would think that a panel being driven by a piezo would be a dml or bending wave panel in its purest form ?
With no pistonic movement involved.
I have seen some small piezo drivers that have a good response down to 200hz .
Probably not good for heavier thicker panels.
But maybe eps or thin ply or veneer may work well ?
Steve.
I would think that a panel being driven by a piezo would be a dml or bending wave panel in its purest form ?
With no pistonic movement involved.
I have seen some small piezo drivers that have a good response down to 200hz .
Probably not good for heavier thicker panels.
But maybe eps or thin ply or veneer may work well ?
Steve.
Hi Christian,
I've been very tempted to use piezos for HF boost.
Actually, some of the original old designs, decades ago, used piezos as drive elements before the more modern magnetic exciters came along.
The nice thing about the piezos is that they are capcitive loads and they run on voltage, not current so much, so they present very light loads to the amp.
They are also very light in mass. Almost zero inertia. Stratospheric HF response.
Compliance... I'm not sure about that, but being so light-weight, and not being connected to a magnet or back-brace, I don't think it's a problem.
The original old DML designs used arrays of piezos. 20 to 30 of them if I remember correctly. Thing is, piezos bend according to a driving voltage, and they do not react to a fixed magnet. So I think displacement/excursion is a moot point; One will not get the same measure of panel "flap" as one gets with magnetic drivers.
I'd imagine that one could use arrays of piezos in different configurations and polarities to take advantage of the bending action. It's something worth messing with. But that's a long rabbit trail anyway.
One would probably use a normal exciter, and add a few 50mm/30V piezos in conjunction with the correct inductor, to form a tuned resonant circuit in series with the capacitance of the piezo element, to fill in the top end of such an exciter-driven panel and STILL retain the panel's DML action. This is important.
Nice thing about this is that the piezo driver does not influence the impedance curve of the panel, and you can tune the resonant frequency and the Q of such a circuit, to match the HF dip in the FR of whatever panel you're battling with.
I do think it's cheating a bit though... Yar well...
Thank you André. I didn't know the bending movement of a ceramic glued on a substrate.
Here are some links with illustrations
Everything you need to know about piezo speakers
Piezoelectric Speaker Technology
Dragonfly speaker
Dragonfly datasheet
Note in the data sheet the test is made on a 30x60cmx2.5mm ABS panel.
Also some records in the links.
Thank you Christian.
There is a lot to read and it is half past1 in the morning 😴
I must go to bed.
Plenty to read tomorrow.
Steve.
There is a lot to read and it is half past1 in the morning 😴
I must go to bed.
Plenty to read tomorrow.
Steve.
These are good examples of ways to do it,
However IMO they make it seem more difficult than necessary, either by using vacuum, or going for the last excessive gram of glue. This could put people of trying to make a panel yourself.
Gluing the two skins in one go, and using fumed silica to thicken the glue (and create micro fillets by scraping the nomex over the skin) seems to work well.
Working with epoxy is not my favorite way to spend time, but I found making this panels easier than I had thought.
https://flora.tech/piezo-speakers-unveiled-the-future-of-high-end-audio/
Although both the recordings are pretty awful on this link, they do give an idea of how the sound of the two speakers compare.
The vocals sound better to me on the dml panels.
But the room is so appalling it is hard to make a judgement on the overall sound.
I wonder what the other piezo companies are coming up with ?
Steve.
Although both the recordings are pretty awful on this link, they do give an idea of how the sound of the two speakers compare.
The vocals sound better to me on the dml panels.
But the room is so appalling it is hard to make a judgement on the overall sound.
I wonder what the other piezo companies are coming up with ?
Steve.
This is the text my friend sent me regarding the panels and exciter used.
Hi Steve Teax25c10-8/hs. 25mm RS8765269. Discontinued. But still on the Web page for data sheet . 3mm Corrugated cardboard sheet 5ply. Hope that's enough info. Alan 👍
OK.
These operate in a different way than I expected .
They are mounted in the centre by a small pad .
The rest of the piezo is left to vibrate in free air along its length.
That is how I see it anyway?
Is this better than a piezo disk or strip wholly glued directly to the panel surface, I'm not sure ?
You would definitely get a higher output.
Would it be better to have the free ends rigidly mounted to a sub frame 🤔
https://flora.tech/shipping-box-diy-speaker/
Steve.
These operate in a different way than I expected .
They are mounted in the centre by a small pad .
The rest of the piezo is left to vibrate in free air along its length.
That is how I see it anyway?
Is this better than a piezo disk or strip wholly glued directly to the panel surface, I'm not sure ?
You would definitely get a higher output.
Would it be better to have the free ends rigidly mounted to a sub frame 🤔
https://flora.tech/shipping-box-diy-speaker/
Steve.
"Would it be better to have the free ends rigidly mounted to a sub frame 🤔"
Probably yes? It looks like the exciter is now pushing the panel by its inertia. Maybe the exciter will break when mounted solidly though.
The longer the "wings"are, the bigger the curve can get, so more excursion ?
On the product page halfway down there are audio samples. Not very encouraging. Musicians and PA sound engineers will recognize the distinct "ping" from cheap piezo acoustic guitar pick-ups.
BTW I The mounting of the exciter is diametrically different in this link
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The Flora piezo offering isn’t too bad, though the price is a bit steep—one could easily purchase a television with a built-in piezo sound system for that sort of money. It’s one of the reasons why so many intriguing ideas fizzle out before they even get off the ground, much like the NXT speakers -- that the 'inventors' are hoping to become rich overnight. On the other hand, one could always salvage a piezo speaker system from a broken telly. After all, copper wire (or Litz wire) and neodymium magnets are far more affordable and...
On the matter of dismantling piezo speakers...
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Although I would not recommend doing this to my panel.
This shows how durable these piezo units are.
This type of flat piezo is more like what I would be interested in.
Gluing this to an efficient eps or veneer panel would be quite interesting .
The piezo would for me be preferably mounted on the front of the panel, something that would cause problems with a standard coil exciter.
Steve.
This shows how durable these piezo units are.
This type of flat piezo is more like what I would be interested in.
Gluing this to an efficient eps or veneer panel would be quite interesting .
The piezo would for me be preferably mounted on the front of the panel, something that would cause problems with a standard coil exciter.
Steve.
I could not find this for sale in the UK, or America for that matter.
This is always the problem when trying to by good audio piezo units.
Sonitron looks good but postage doubles the price as usual.
And I would probably have to take it apart for what I want to use it for.
Steve.
This is always the problem when trying to by good audio piezo units.
Sonitron looks good but postage doubles the price as usual.
And I would probably have to take it apart for what I want to use it for.
Steve.
Interesting word salad, "By leveraging the panel’s vibration, Dragonfly amplifies the input sound and delivers immersive and dynamic audio experiences."
In fact, it is the panel itself that amplifies the sound through surface-bending waves, with the quality of the audio being contingent upon the surface and its inherent quality.
Once you purchase a piezoelectric speaker or a standard exciter, if the resulting sound doesn’t meet your expectations, you find yourself needing to buy another, and then another. However, if you’ve simply wound the coil yourself, you have the flexibility to redo it. Instead of committing with glue from the outset, you can use tape to test the sound first. You can also adjust the size of the coil based on the dimensions of the neodymium magnet available, or vice versa. The DIY spirit to the fullest.