Hi Christian
I'm still trying to progress on what will I think be my final panel as too many competing activities impact on my time, ...however, part of these tests involved adding a second smaller exciter in the top corner of my Blackwood panel, and testing does show a flatter response in the the mid and higher frequencies, so it may be something you should try also.
Eucy
The head of the 'standard' exciter that makes contact with the flat panel remains stationary. The rigid spiders are limiting its movement. Once the music or sound is connected to the exciter, the vibrations are transmitted to the panel. The panel is quite substantial, whereas the exciter is relatively diminutive in comparison. Similarly, when the flattened voice coil is affixed to the flat panel, the panel itself effectively becomes the stiff spider (as well as the top) of the exciter.
Next, secure the heavy magnet(s) just behind the panel on a frame, and connect the flattened panel to the music or sound source. The constrained flattened voice coil will transfer vibrations to the panel, initiating bending waves across its surface and propagating sound waves into the surrounding air. It’s essential that the flat panel has a somewhat stiffer surround, perhaps made of rubber or silicone, to properly secure it within the frame.
For clarity, let’s designate A as the flattened voice coil and B as the magnet(s) fixed slightly away from the panel on a frame. The flattened voice coil is virtually weightless. You might also consider using compliant suspension for the panel edges, much like in traditional speakers.
Henry Azima, the creator of exciter transducers, had to devise a solution, leading to the invention of the exciter itself. The concept of a voice coil adhered to a flat panel transferring vibrations to create bending waves would not have become commercially viable, but the necessity for a functional device prompted the emergence of the exciter. Ultimately, it is the voice coil that plays a crucial role in transferring vibrations to the surface of the flat panel, enabling the desired sound production.
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Eucy,
Final panel? I don't understand the concept! There is always, at least, one more.
Eric
Thank you Eucy
I made some tests in this way with no real success... Which exciters have you tested?
Christian
Generally in my tests, I have some distortion above the noise floor below 500Hz. I don't know if the distortion values below the noise floor are relevant. Some algorithm are able to find information below the noise level... is it true for REW? Better to be cautious with that.
Which SPL have you for your measurements?
I have no direct evidences. It is an assumption. The H2 distortion have been often reported here. A cause of H2 is non symmetry somewhere (the transfer curve is different for positive and negative input values) like in a single ended amp. Some design efforts are needed to correct the possible non symmetry of a magnetic circuit, as it is claimed by XCite, I thought it would be visible. In an other hand, what would be the other possibles causes of non symmetry? The panel stiffness? the fact the panel is driven from one of its face not from its center?
I love "outside the box" ideas as much as anyone, but I'm thinking the same thing as Eucy regarding the flat coil concept. can anybody explain to me what there is to gain?
Sure, with a flat coil directly on the panel, you would eliminate (most) of the weight of the coil former, but those weigh what, about 1-2 grams? You would also eliminate the need for a spider, as the plate itself would perform the same function, at least in the case of a panel fixed to a frame by a suspension.
Would elimination of the spider and one or two grams of coil former provide any significant benefit? Or are there other benefits that I'm missing?
Burnt's design concepts like the one below seem to me like they would work. But at the very least would require spines to support both magnets, which is one (or two) more spine(s) than you need for a conventional exciter. Does such an arrangement provide a more linear magnetic force? Or increased power handling? (That one seems possible to me). What else am I missing?
Again, I'm definitely not dissing the concept, I'd just like to better understand what is to be gained.
Eric
Christian,
Typically 75 to 80 dB.
I don't think the panel stiffness. Most panels are symmetrical so would flex the same in either direction. In the case of a softer panel, I can imagine the latter reason to be a possibility. Another could be if the exciter is mounted to a spine that pushes the voice coil off-center on the magnetic field of the magnet.
Eric
In the advantage side, it works as a push pull so maybe in a more linear way?
In the drawback side, the excursion and the air gap are linked. The more excursion, the larger air gap, so a lower efficiency or to compensate more magnet. It is already a characteristic of the exciter to have a "large" air gap to allow a possible misalignment of the voice coil.
It opens the question of what is needed for the membrane : to be driven on a large diameter or to come at the opposite to a as small as possible driving point?
With a standard exciter, we already know the area of the membrane inside the voice coil diameter has its own life (drum effect). In such a design, this area would probably be larger so with a resonance lower in frequency with a possible mask in front due to the magnets...
Many questions!
Christian
I think I am in the same SPL range. I will check in my next tests.
It is interesting to introduce the misalignment due to external constraints on a voice coil as distortion source. With a spine, it can be an offset in the voice coil axis; without, it can be a small angle due to the magnet weight. Most of my tests are without any support... To be considered too!
As I said, I'm not sure I like the Zenker exciter design , but I have no experience with this exciter.
I have previously had negative results from using plastic encased drive units.
The plastic cases usually produce too much noise for my liking.
I believe the exciter also has two fairly stiff spiders?
If it does, is this a good idea?
For certain conditions this would be a bonus, but maybe not for all ?
I purchased the 25 fhe exciter and as far as i can tell, it is pretty much identical to my 10watt exciters performance?
The 25fhe is a good exciter but was a waste of time and money for me, as I gained nothing.
Will a 40watt exciter make make that much difference, or is it still under powered for heavier panels?
Steve.
Hddz.
Thank you for clearing that up for me.
The exciter looks to be black plastic , as I have said I have no experience of this exciter.
This must make it quite heavy?
Steve.
Thank you for clearing that up for me.
The exciter looks to be black plastic , as I have said I have no experience of this exciter.
This must make it quite heavy?
Steve.
Hi Steve, I was mistaken - it is plastic. It's quite hard plastic. To test it I melted it with a soldering iron, and it smelled a lot like PVC (?)
Sorry for the caused confusion. Greetings, Hans
Sorry for the caused confusion. Greetings, Hans
Nope, as far as I can tell, just a single aramid spider. Feels about as stiff as other typical exciters.
The plastic casing is quite hard and stiff, much more so than the plastic casings on any of the Dayton plastic casings I've seen. It's no surprise that HvdZ thought it was metal, as hard and stiff as it is. The casing makes no noise that I can detect. I'm far from convinced that it's worth the price, but otherwise I see nothing wrong with it.
Why would plastic make it heavy? No doubt it is heavier than the 25FHE, about 135g vs. 103g in my measurements. Presumably due to the double magnet.
Is that a question or a statement? Which is the 10 watt exciter you like? Is is still available? I can get a 25FHE (24 watt) for about $13, and the similar 25VT (20 watt) for $9. The 25CT-4 (10 watt), which I have not tried is indeed cheaper at $7.50, but not by much. Is that the 10 watt one you like or is it another?
Eric
Same for me, for sure. I can't attach a spine support for every test I do. Now, I usually only add a support once I'm sure of a design. To me, the support is a necessary evil for long term durability. As long as you ignore the flapping/noise at the magnet resonance (usually around 20-50 Hz for the high power exciters), I think that testing sans support is fine, and similar to what you will get with a well constructed support.
Eric
Thanks Hans.
No problem 😊.
I did think it would be a little heavy if it was cast metal of some sort.
https://www.xcite-audio.com/technology/
There still seems to be a lot of unnecessary plastic in its casing.
And yes it has only a single spider.
This must be a fairly stiff spider to support the heavier weight over time.
They make it sound like they use the spider to prevent excessive coil travel for safety?
Thanks again.
Steve.
https://uk.rs-online.com/web/p/spea...zl8ewoDpbSmDX-P0VP4aAt5ZEALw_wcB&gclsrc=aw.ds
This is about the closest exciter to my exciter on the market today.
It might even be the same?
The Xcite seems to be about the same price as most of the other 40watt exciters on sound imports site and cheaper than some.
https://www.soundimports.eu/en/dayt...t":40},"y_pos":{"product":4694.66650390625}}}
It was a statement and a question.
I mentioned this some time back that the 24watt exciter heats up to exactly the same temperature as my 10watt exciters, under the Same conditions.
I was wondering if others had had the Same issues?
And inviting comments, maybe.
I never said the plastic would be heavier than metal?
Read previous posts to Hans.
Steve.
Continuation...
Here’s a video featuring a Japanese inventor who has employed the concept of keeping the voice coil and the magnets separate. His speakers were known as FAL. As you may observe, his flat panel is quite compact, perhaps reflecting the nature of Japanese music. He utilised a standard reflex box to produce bass from the system. The rectangular coil is affixed vertically to that panel. This video is 12 years old, which suggests that the idea itself is even older. If that coil were to be flattened and adhered to the panel, one might not require such an elaborate magnet system; perhaps just two rectangular neodymium magnets would suffice, positioned to cover the longer sides of the flattened voice coil. Naturally, his approach of using a standard reflex box for bass is rather commendable.
Here's 2 screenshots from that video.
You can observe that the vertically placed voice coil is secured by a sort of plastic structure, which prevents it from moving at all.
You might notice that the shorter sides of the voice coil are not covered by the magnets. The rest is left to one’s imagination.
Here’s a video featuring a Japanese inventor who has employed the concept of keeping the voice coil and the magnets separate. His speakers were known as FAL. As you may observe, his flat panel is quite compact, perhaps reflecting the nature of Japanese music. He utilised a standard reflex box to produce bass from the system. The rectangular coil is affixed vertically to that panel. This video is 12 years old, which suggests that the idea itself is even older. If that coil were to be flattened and adhered to the panel, one might not require such an elaborate magnet system; perhaps just two rectangular neodymium magnets would suffice, positioned to cover the longer sides of the flattened voice coil. Naturally, his approach of using a standard reflex box for bass is rather commendable.
Here's 2 screenshots from that video.
You can observe that the vertically placed voice coil is secured by a sort of plastic structure, which prevents it from moving at all.
You might notice that the shorter sides of the voice coil are not covered by the magnets. The rest is left to one’s imagination.
I believe that to be a plastic diaphragm, with a coil stiffener formed within it. The stiffener doesn't prevent the coil from moving, it provides stability for the coil within the magnet air gaps, as rectangular coils lack the geometric strength of cylindrical ones, and the stiffening also braces the central area of the diaphragm.
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