Hello Eric,
The lobbing of the DML is expected by the theory.
There is a trace of it in the Tectonic papers. Those measurements are from an anechoic chamber.
When we get a measurement in a room with REW with a standard FFT, the observation time is defined by a window. If the window it "too long", some reflections will enter into it which will mask the CF. If the window is set to reject the reflection, the frequency resolution is then reduced like by a smoothing.
The principle of wavelets is a bit different. The IR is analyzed thanks to a specific signal. For all the frequencies, this shape of this signal is the same. It is the duration which changes. The general shape is defined by a so called "mother wavelet" which is scaled (compressed in time or dilated).
The consequence of that is observation time decreases when the frequency increases. For a wavelet of 1/6 of octave (a wavelet is like a bandpass filter), the observation window is maybe 5 or 6 periods (to be checked). For a 1/3 of octave, it will be less. For a 1/9, more.
So by nature, the wavelet is a good way to reduce the observation time when the frequency increases.
As the CF is expected at some kHz, my hypothesis is it is high enough for the reflections to be rejected.
In the the time to frequency transformation, it is known that it is not possible to be precise in time and in frequency. The wavelets offer an excellent performance in this time/frequency compromise.
Christian
Thickness 0.025, Young's 30 MPa, Poisson's 0.3 and density 25
Perhaps I'm doing the displacement in a bad way, but since I cannot have that many nodes in the free version, I have only fixed the edge nodes and not an area. It is a very rough approximation, but due to the low resolution, if I would select a couple of complete quads the area would be too big instead:
@Veleric :
Hello Eric
I made a test on measurements yesterday... I was not able to find the CF... If the long window FR of a panel is not too bad, the short time FR seem messy. Let me know from your tests.
Christian
Just stumbled across this paper on DML and bending wave, I'm not sure if it's been linked here already. https://publications.lib.chalmers.se/records/fulltext/154618.pdf
Wood veneer is available in 1/28 if an inch thickness you could veneer the front and back side of a foamcore art board or the gatorfoam board. You could use a dense hardwood veneer or try Douglas fir or northern grown spruce as they are used in instruments but my guess (and it is just my guess) is that hard and dens is the goal here. forgive me for entering into this so late in the day. I have begun to red from post number one and this is my first comment.
would using adhesive back foam on both side of a panels edges to interface with a frame offer and benefit to using just a single layer do you think?
just a suggestion. PVA is not very hard and it is flexible, why not use a high gloss Acrylic spray paint? The higher the gloss the higher the solids content, or you could choose some other hard/harder spray paint?
On the subject of Wood as a material, it is also worthwhile looking at Delignified Translucent Boards.
Even though being produced at a 1200Kg m/3, the boards are generally between 1mm - 3mm for optimal optical transmission of light.
The weights of such a thickness for a board might be usable.
The new and unusual make up of the board is quite different to a board typically used.
The new properties within the Board might add an attractive property to the sonic able to be produced.
Even though being produced at a 1200Kg m/3, the boards are generally between 1mm - 3mm for optimal optical transmission of light.
The weights of such a thickness for a board might be usable.
The new and unusual make up of the board is quite different to a board typically used.
The new properties within the Board might add an attractive property to the sonic able to be produced.
Hi mate
Some of these quotes are from a long time ago
May I suggest you read through the whole thread before raising old items which may have been covered many times
Cheers
Eucy
the melior range came later the company was Highwood Audio in Calgary Alberta Canada Paul Burton and I started the business. We designed and manufactured and distributed through Sumo Audio in California USA. Due to unfortunate circumstances at Sumo we had to part business ways. After that Highwood Audio's investors merged us with Meitner in Montreal and they (Ed and his rt. hand man Zanni ) moved to Calgary. Ed still lives and has a business (EMM Labs) in Calgary. Just a little bit of history.
could yo please elaborate on how you determine what constitutes a good panel and where a good exciter location are? thank you.
Hi Mr James. Welcome to the DML thread. I gather you have extensive experience in designing planar speakers, but hope you could bring (and draw) some inspiration here too. I know this is a bit off topic but saw this new planar development that enables more bass. The presenter, Aaron, claims the planar achieves more bass by getting the mylar sheet to move more air. This implies pistonic movement, more like a conventional cone speaker. Now I am not sure if this is how planars work, since they are also dipoles in nature like dml panels. Just thought it is very interesting since dml panels also struggle in producing bass.
hello twocents, I did not watch the whole video but they are using is a dual drive motor with magnets on both the front and back side of the diaphragm in addition they are using stronger magnets to allow for a greater spacing and so greater available diaphragm displacement. This is much the same as the Eminent Technologies planar magnetic loudspeaker. If they play very low it probably means they are using wire voice coils likely copper for the added weight but I did not watch too much of the video so I cannot be sure. Planar magnetic speakers which make bass most often depend upon the VC having enough mass to lower the FS of the panel. Such panels will most often have more mas per unit are than a conventional cone woofer does. Its a matter of making resonance your friend and getting it to do useful work for you.
IIRC Diptyque uses coil traces on both sides of their film. On one side the run the long way and on the other side they run the short way, so they're offset by 90 degrees, which adds stability to the film. The magnets are also aligned with this crosshatch somehow, but I never saw pictures, just heard convos in youtube videos. Two-sided traces increase the weight of the film compared to others and idk if this is desired or not. I'd guess not, but it's the cost of the increased stability.
has anybody tried wicker it i rater stiff and on the hard side but the weave would introduce lots of loss at structural resonant points (that could be counter productive or no depending on just on much loss there is)?Chdsl.
I have already stated my interest in the embroidery ring, for testing different materials?
Whether the ring would be better depends on testing and comparing performance.
The main thing is that the card and paper in a frame works well
The card was already my second favourite panel material,having the panel going down to 40hz is a bonus.
Obviously more tests and comparisons need to be made for best sound.
Such a large sound from such a small panel is a plus too.
At some time I'm going to want to test the bigger panel and see what happens.
I do have some thin cotton sheets from an old duvet I intended to stretch,when I can get to the local art and craft store,covid allowing!
Canvas is too heavy for my liking,paper is even better,cotton?
We shall see
Steve