Hi Steve
When ready I will create a new thread which I will link to this one so people who are interested can find the new one. I have two directions that look promising in theory. One has a conventional geometry, the second does explore flat coils. I want to test them out first before setting up the thread. Could a be a while though.
Burnt
homeswinghome this is what I meant by laser velocity https://mtiinstruments.com/products...-laser/microtrak-4-laser-displacement-sensor/ its nice to have access to a university lab equipment.
Also Eric and homeswinghome I would suggest using a linear solenoid has a tapper for your experiments since it can give a known energy and contact area that everyone can reproduce. Like Burnt Coil suggested, I will not post any more on my Omi-directional transducer as it is a distraction of this thread I will post on separate thread.
Also Eric and homeswinghome I would suggest using a linear solenoid has a tapper for your experiments since it can give a known energy and contact area that everyone can reproduce. Like Burnt Coil suggested, I will not post any more on my Omi-directional transducer as it is a distraction of this thread I will post on separate thread.
aagas,
On your DML sub for a large area transducer # 7381 all rubber speaker this is what I would laminate these :
Electrically Conductive Carbon-Filled Slippery UHMW Polyethylene Film https://www.mcmaster.com/8327K11
UHMW Polyethylene Film https://www.mcmaster.com/85655K12
Electrically Conductive Carbon-Filled Slippery UHMW Polyethylene Film https://www.mcmaster.com/8327K11
One would then excite the two other films with an audio signal with an output of 500-600VAC. This could be done either with a HV audio transformer or with amplifier using current SiC or GaN FETs as the HV output stage. I would not think this falls in the DML category since it is applying a uniform electrostatic field across the outer surfaces.
On your DML sub for a large area transducer # 7381 all rubber speaker this is what I would laminate these :
Electrically Conductive Carbon-Filled Slippery UHMW Polyethylene Film https://www.mcmaster.com/8327K11
UHMW Polyethylene Film https://www.mcmaster.com/85655K12
Electrically Conductive Carbon-Filled Slippery UHMW Polyethylene Film https://www.mcmaster.com/8327K11
One would then excite the two other films with an audio signal with an output of 500-600VAC. This could be done either with a HV audio transformer or with amplifier using current SiC or GaN FETs as the HV output stage. I would not think this falls in the DML category since it is applying a uniform electrostatic field across the outer surfaces.
I assume you mean the Chladni plate experiment? Who is the we you are talking about? Do you mean "we" as in humans? Chladni did his experiments in the late 1700's, so even more than a few decades ago. I certainly didn't mean to imply that I was discovering something new!
I was only really doing the Chladni plate experiment for fun, as I think it's a cool way to demonstrate the patterns of the nodal lines in resonating plates. But after I got going with the glass plate, and playing with my finite element model of it, I noticed that according to the model, the nodal pattern of that one particular resonance at 554 Hz was quite sensitive to the value of the poisson's ratio. So seeing the pattern formed by the rice in this plate actually provided some nice additional evidence for what the poisson's ratio actually is for my plate (about 0.20 it turns out).
The patterns formed by plates of other materials will be largely similar, but the exact patterns will depend on the particular material's elastic properties (elastic moduli and poisson's ratio(s) , density, and size (length, width, thickness).
Few here would dispute that, I expect. The more surprising thing about glass is that it actually has more liquid character than most would imagine. Since glass does not crystallize like many solids, it's still able to "flow" like a liquid over very, very long times scales. But for the purposes of this discussion, I think it's safe to consider glass to be a typical elastic solid!
Glass absolutely can and does bend in it's solid (like) state. As does steel, aluminum, polystyrene foam, wood, etc, etc. In the context of a flat panel speaker made of glass (or any of these other materials), the bending it undergoes is not permanent bending, but rather elastic deformation. That is, a deformation that is only temporary. Once the force applied to the glass is removed, the glass returns to its original un-deformed state. When glass cracks due to resonance, it does so because the elastic bending deformation becomes so large the the bending stress in the glass exceeds the strength of the glass. The fact that glass can break due to resonance is more evidence (if it was needed!) that glass bends.
Eric
Haha, I just checked my exciter. To my surprise, like yours, it actually works. Based on the plume of smoke that came from it, I assumed it was gone. I ran a frequency sweep on my latest favorite plywood panel, but alas, there was much more distortion than usual around 2 kHz. So indeed, it'll never be the same. I may keep it though for later Chladni plate experiments and the like. Biggest problem though, is that is actually stinks horribly!
Eric
So I spent the morning testing these new exciters side by side, on the same panels, modified, different materials, etc.
DAEX32Q-8 DAEX25FHE-4
First test: Simple apple to apple swap out on the same panels (small 6"x10"x3/4" high density EPS). The 32Q's were first and I could tell a huge difference was to come just from hearing my current 25FHE's for over a year on my existing setup with closed cell foam panels, and yep, huge difference compared on the small EPS panels. The 32Q's sound muted big time compared to the "in your face" 25FHE's. Night and day! -- Eric Clapton: If I Could Change The World..... Adele : Hello --
I ran a few more tests on some of the foam panels and it was exactly the same. (These test's remind me just how much I prefer the closed cell foam over EPS, though not as efficient, it sounds more "calm", no harshness or "tunnelly" stuff going on.)
I can see where the 32Q's would be an excellent choice for hard substrates such as glass, plexiglass,acrylic,aluminum,etc. where highs are harder to tame. Hard to imagine a 25FHE's high end on such material ever being bearable.
Pictured below are the springs bent away to let the 32Q be tested to see just how much they come into play. I couldn't tell much difference, seems there was some more high end, nothing crisp (not sure how much of all that plastic crap has to do with this as well). The springs are also used to keep the voice coil centered so going without them is a no go, had to hold everything just right to test. I did verify that the plastic is glued to the voice coil with some black glue.
With all this talk about using glass objects, maybe these 32Q's could be used stuck to the bottoms of a couple of vases while being hidden below in their fancy little vase stands. That'd be a trip watching people trying to figure out where the sound is coming from. Probably would work for some low background music. Something like porcelain vases would be cool. Hmmmmmmmm
I'm thinking my next purchase is going to be some DAEX30HESF's. Seems like the best of 3 worlds- medium size voice coil, no plastic crap, and 40w. I don't even recall seeing these when I ordered last. Seems they don't make 40w - 8 Ohm exciters?
I'm sticking with the new 25's for my rear surrounds.
DAEX32Q-8 DAEX25FHE-4
First test: Simple apple to apple swap out on the same panels (small 6"x10"x3/4" high density EPS). The 32Q's were first and I could tell a huge difference was to come just from hearing my current 25FHE's for over a year on my existing setup with closed cell foam panels, and yep, huge difference compared on the small EPS panels. The 32Q's sound muted big time compared to the "in your face" 25FHE's. Night and day! -- Eric Clapton: If I Could Change The World..... Adele : Hello --
I ran a few more tests on some of the foam panels and it was exactly the same. (These test's remind me just how much I prefer the closed cell foam over EPS, though not as efficient, it sounds more "calm", no harshness or "tunnelly" stuff going on.)
I can see where the 32Q's would be an excellent choice for hard substrates such as glass, plexiglass,acrylic,aluminum,etc. where highs are harder to tame. Hard to imagine a 25FHE's high end on such material ever being bearable.
Pictured below are the springs bent away to let the 32Q be tested to see just how much they come into play. I couldn't tell much difference, seems there was some more high end, nothing crisp (not sure how much of all that plastic crap has to do with this as well). The springs are also used to keep the voice coil centered so going without them is a no go, had to hold everything just right to test. I did verify that the plastic is glued to the voice coil with some black glue.
With all this talk about using glass objects, maybe these 32Q's could be used stuck to the bottoms of a couple of vases while being hidden below in their fancy little vase stands. That'd be a trip watching people trying to figure out where the sound is coming from. Probably would work for some low background music. Something like porcelain vases would be cool. Hmmmmmmmm
I'm thinking my next purchase is going to be some DAEX30HESF's. Seems like the best of 3 worlds- medium size voice coil, no plastic crap, and 40w. I don't even recall seeing these when I ordered last. Seems they don't make 40w - 8 Ohm exciters?
I'm sticking with the new 25's for my rear surrounds.
Attachments
I am sure that with the right exciters , stud walls can sound very good, giving a full frequency response .
I was not expecting the good sounding results from my wall.
Steve.
32Q's lack the higher frequencies. The DAEX30's are better then the 32Q's. The problem is they dont make an 8ohm version of the DAEX30s.
Sorry to hear about your eye problems, as well as your ears.
Hope you manage to get your audio sorted out for the next year.
Steve.
The little spiked glass candle holder. Height 8cm, bottom diameter 6cm, top distance from spike to spike 9cm. Sound quite nice and full at 30% - 80% volume control. Didn't try more. Have two of them.
3mm thick glass candle holder, candle practically finished, about 2cm still left. 1cm thick glass bottom, diameter 10cm. Total height 13cm. Lovely sound coming out of it, bass and all. Most probably the 1cm thick bottom and the 2cm thick candle wax must be adding to the sound quality. Got two of them, that is, wife buys them.
Ikea glass side table, glass panel diameter 47.5cm, glass thickness ~4mm, height from floor 61cm. Nice sound, gets better, when the Ikea mats were placed over the glass. The porcelain X'mas tree must be adding some value too. At the moment, glass is lying free over the steel bracket. It must be isolated and fixed permanently to the round metal groove. Something heavy (and nice) has to be placed on the shelf below. The steel legs are isolated from the floor, but have to be given better isolation. Got two of those side tables.
By the way, the best sound came from the practically empty thick glass bottom candle holder.
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Glass thickness: 3mm,
Exact total height: 13cm
Glass bottom thickness: 1cm,
Glass bottom diameter: 10cm
Open top diameter: 13cm
Candle wax left: ~2cm
Not bought from Ikea.