Hello lorso.
Yes walls do , surprisingly, make good panel speakers .
40hz to about 10k, that I have tested so far and probably dependant on the exciter.
The monacor exciter is similar to the exciter I have just bought, except monacor is plastic instead of metal.
It could be a good alternative if your other half does not like the look of speakers.
I know a few who do not , even the most beautiful looking ones (speakers, that is 😳)
Walls should not be overlooked as an alternative.
Steve.
Yes walls do , surprisingly, make good panel speakers .
40hz to about 10k, that I have tested so far and probably dependant on the exciter.
The monacor exciter is similar to the exciter I have just bought, except monacor is plastic instead of metal.
It could be a good alternative if your other half does not like the look of speakers.
I know a few who do not , even the most beautiful looking ones (speakers, that is 😳)
Walls should not be overlooked as an alternative.
Steve.
When one is interested in obtaining the full spectrum of sound from a single flat panel using just one exciter (or two), without the ability to utilise the "rear wave," one might consider the late Stig Larsson's ortho-acoustic idea. In this case, the panel cannot simply be suspended with a string. Instead, it should be supported by a semi-elastic surround, such as silicone, or even placed on a semi-elastic base. The flat panel needs to be positioned at an angle to the vertical and turned 45° towards (or away from) the back wall. If, by chance, the panel with the exciter can be placed in a cut-off type of box, with the bottom and side plates somewhat lined with damping material, this would enhance the sound. With the entire box covered, it would also be WAF friendly!
Thank you Steve,
I know those, last spring I performed right before an Argentinian artist that uses the same exciters together with drums. Indeed they look really neat, I might get one for new experiments!
Lorenzo
Nice tidy environment!
The uncluttered timber wall would provide a pleasingly resonant output. I have tried the same type of exciters, the Aiyima ones mentioned in this post and the one below, on a hollow brick wall and on a gypsum board wall. The sound was much more pleasant on the brick wall, but somewhat hollow on the gypsum wall. These exciters are designed to be placed horizontally, as they are essentially a party gadget. Aiyima refers to the aluminium plate as a shock rod. You’ll notice how it bounces here. If you want to use the Aiyima exciters, you'll need a solid support for the driver part of it.
I hope you achieve great results with the timber wall speaker! 🙂
Lorso.
The aiyima exciters are very cheep compared to ordinary exciters even with all the metal involved.
Does the sound from the exciters not travel down through the whole house ?
It is early days for me to come to a conclusion on the sound of these exciters but the main drawback is having to use fairly rigid panel materials for good sound transfer.
Over Fifteen years ago when I started playing around with exciters , they were all regarded as toys, but that did not stop me making the best speakers I had ever heard, by using them .
It all depends on how much you want to get involved in the sound they produce.
If modern producers of exciters were seriously interested in producing hifi grade exciters, they should give an idea of the best materials and designs for the best possible sound, with measurements.
Everyone has to start from scratch not knowing what to do.
You end up doing the same old things trying to find the best materials for a certain exciter and wasting time and money doing their job.
This is where NXT went wrong, I believe.
They should have produced a fully working panel and promoted that first, showing how good the sound could be.
DML's ended up as a joke only good for toys.
They are just distortion as far as the audio scene are concerned.
DML is still a dirty word even today, unless you have actually heard good sounding exciter panels.
Most people have never heard of them.
Steve.
The aiyima exciters are very cheep compared to ordinary exciters even with all the metal involved.
Does the sound from the exciters not travel down through the whole house ?
It is early days for me to come to a conclusion on the sound of these exciters but the main drawback is having to use fairly rigid panel materials for good sound transfer.
Over Fifteen years ago when I started playing around with exciters , they were all regarded as toys, but that did not stop me making the best speakers I had ever heard, by using them .
It all depends on how much you want to get involved in the sound they produce.
If modern producers of exciters were seriously interested in producing hifi grade exciters, they should give an idea of the best materials and designs for the best possible sound, with measurements.
Everyone has to start from scratch not knowing what to do.
You end up doing the same old things trying to find the best materials for a certain exciter and wasting time and money doing their job.
This is where NXT went wrong, I believe.
They should have produced a fully working panel and promoted that first, showing how good the sound could be.
DML's ended up as a joke only good for toys.
They are just distortion as far as the audio scene are concerned.
DML is still a dirty word even today, unless you have actually heard good sounding exciter panels.
Most people have never heard of them.
Steve.
The exciter is not exactly a toy, but it has become a party gadget due to the production of these kinds of resonance speakers with Bluetooth. Everyone has a mobile phone, so a pocket resonance speaker can bring some joy to a gathering. However, nowadays, children no longer play with such toys. In any case, the exciter is a speaker driver without the cone, suspension, and basket. Its voice coil is restricted in movement by a stiff spider. Thus, when that spider, or anything fixed or glued to it, touches a surface, it transfers vibrations so that the surface produces sound. The neodymium magnet system helps to make the exciter compact while still being powerful enough to make a wall resonate. It also demonstrates that the voice coil does not need to have a pistonic motion to create sound; a voice coil that is restricted from movement can also produce sound. In other words, a wire or coil connected to an amplifier will generate music if placed in a magnetic field. All you need is a coil connected to a sound amplifier, a magnetic field, and a surface for the coil to rest upon. Music ensues.
Sure, if you attach a coil to a moveable surface, and apply an appropriate magnetic field, you will get music. But I don't understand what you mean when you say that a voice coil that is restricted from movement can produce sound. If the surface on which the coil rests is truly restricted, and therefore can't move at all, it can't produce sound waves. Do you think otherwise? Or do you mean something different?
Eric
Ah, I see, you didn't mean totally restricted from movement, you just meant restricted by a spring.
Concerning the Ayima exciter specifically, when you say it's more of a "party gadget" are you saying that it's more of a party gadget than the more common exciters (say DAEX25FHE-4), or that they are all party gadgets? While I have not tried one of the Ayima's yet myself, they don't really appear to be much different, and the specs seem similar.
Eric
It is not the surface that is restricted, but rather the voice coil, as illustrated in the second image. The spider is secured at four points, in addition to the four screws. This is similar to all other exciters. The voice coil is not permitted to move, and there should be no pistonic motion whatsoever. Additionally, one of the reasons why the entire driver section begins to jump about. It is not the voice coil that produces the sound, but rather the surface it contacts.
A wire does not have sufficient surface area to displace the air and generate sound. It must make contact with a surface, which then vibrates and moves the air. (Gilbert Briggs - creator of Wharfedale speakers)
Everything you wrote seems correct, except this part. While the spring resists the movement of the coil, it does not prevent it. If it did, the panel to which it was attached wouldn't move either, and wouldn't make a sound.
I'm not sure why you are making such a point about the driver moving about. To me, it's the same as all the common exciters in that regard. Do you think it is different?
Eric
Not that much. The resonance frequency of the voice coil of an exciter is some hundred hertz. With the low mass of the voice coil it is not that high. The main function of the spider of an exciter is not its stiffness in the the voice coil axis (the panel itself insure the return) but to keep the voice coil centered in the gap.
More precisely, it is a force like in any loudspeaker. The force moves the panel (or the cone). The speed of the panel or of the cone change the air pressure locally creating a sound.
??? no displacement, no speed, no sound. It was in old posts that "pistonic" refer to a model of acoustic source for which all the points of the emitting surface move together, with the same displacement. A kind of simplification that allows a theoretical approach
Without the requested SPL and neither the desired bandwidth. A bit like a guitar or a violin or a piano or a harp string without the instrument body or the sound board.
Christian
Steve,
Can you clarify for me, what you mean when you say "cheap"? Do you mean "inexpensive" or "poorly built"? Having not purchase any, I can say anything about the quality, but for me, they border on the slightly expensive side. At Parts Express, perhaps the biggest exciter dealer for us in the US, they are $25, compared to about $13 for a DAEX25FHE, which seem to be about as good performing as anything else I have tried. Is your pricing different?
Thank,
Eric
lehka,
There seem to be a lot of concepts bunched together here: Transmission lines, foam cores panel, back wave, wobble and so on. So, as usual, I'm a little unclear on your point.
But, you do raise one interesting point regarding the back wave. That is, is there any reason that we couldn't combine the concepts of DML and bass reflex? For example, why not enclose the back of a DML with a volume of air, combined with a port of the right dimensions, to extend the bass range of a DML, the same way you might for a conventional speaker?
I did a quick search and shockingly, did not find any clear attempts. Is it just a bad idea? The closest example I know of was this paper by Ben Zenker, which seems related, if not exactly the same . It feels like there must have been other examples, perhaps even in this very thread!
https://www.researchgate.net/public...oudspeakers_Using_the_Local_Air_Spring_Effect
What do you all think, recall?
Eric
bd,
Thanks. I see your point (I think) about the curved panel concept. I assume what you are thinking is that by curving the panel, the coincidence "spike" might be spread out over a range of angles, due to the curvature of the panel, rather than concentrated at a single angle. Is that what you had in mind? It make sense to me. At the same time, I think Christian could be correct, that in the opposite plane (90 degrees) the stiffening due to the curvature, could have the effect of reducing the coincidence frequency and exacerbating the coincidence effect. I suspect that whether or not it helps or hurts would depend on the panel and curvature.
Eric
Steve,
I was thinking that this exciter might provide an opportunity to examine the "oil can" effect, if I am using the right term. With its solid foot, the effect should be mitigated, right? What do you think?
Eric
Hi Eric,
The ODA speaker (Zenker was involved in this project) uses a passive back membrane. Does that count? Seem to trade quasi omni directivity for extra bass.
https://patents.google.com/patent/WO2020118065A1/en
The ODA project has fallen quiet - the fate of all DML companies?
The ODA speaker (Zenker was involved in this project) uses a passive back membrane. Does that count? Seem to trade quasi omni directivity for extra bass.
https://patents.google.com/patent/WO2020118065A1/en
The ODA project has fallen quiet - the fate of all DML companies?
+ @Veleric
Thank you HvdZ.
The directivity measurements I am doing with open back DML show important SPL out of axis. One reason is most probably the coincidence frequency (generaly above 5kHz). For the others lower in frequency (say in the 1 to 4kHz range), I am currently in the hypothesis of an effect of the combination of the front and the rear waves as in any open baffle. I am doing some tests on that direction.
The tendancy of the tests already done being to confirm this hypothesis, it is the right time to collect the type of rear load of the DML we could know. I was just starting a list when I read your post and ODA was not in my list, neither their patent.
I have in mind : Podium, Tectonic, Teftra, Jazz man, Yamaha, Katz layer sound, Bertagni, Cohen biphonic, Goebel.
Some of them have the back side partially open with several openings so a certain percentage of the surface is closed with some mesh or absorbant which plays the role of an acoustic resistance which reduce by a few dB the rear wave.
In my current understanding, the main role of the rear load is to help to get a better directivity plot. The second may be to extend the frequency range.
Christian
There are hundreds, if not thousands, of changes in electric current within a minute in a "voice coil." The pistonic movement is unidirectional, moving to and fro. When the air is pushed (or pulled) by a cone in that single direction, how does it create so many different "movements" in the air adjacent to the cone's surface? The vibrations generated by the "voice coil" are transferred to the cone surface, which produces bending waves across its surface, subsequently transferring that energy to the air nearby. If you take a "normal" speaker and remove the suspension, you will notice a significant change in sound quality. The suspension at the top of a speaker cone is not particularly elastic, as it is designed to maintain the cone in a specific position.
The component we refer to as a voice coil is primarily designed to minimise the amount of wire required to produce sound. The late Gilbert Briggs elaborated on this in his writings. By winding the wire around a cylindrical core, we can reduce its size. However, it is also possible to wind it around a square, rectangular, or other shapes of core. The key objective is to transfer the vibrations from the wire to the surface in front of (or behind) it. This vibrating surface is what ultimately generates the music.
You can place a "voice coil" core vertically on a table and place a weight on top of it to prevent it from moving. When you connect the amplifier to the coil, the surface of the table will begin to vibrate, effectively producing sound. This demonstrates how the vibrations generated by the voice coil can be transferred to a solid surface, causing it to resonate and create audible sound waves.
---------------
By the way, sound is heavily influenced by its surroundings. Since very few people live in an anechoic environment, sound measurements taken in one room can differ significantly from those in another. Some rooms are organised with minimal furniture, which can lead to clearer sound reflections, while others may be cluttered with various items, creating a more chaotic acoustic environment. The presence of furniture and other objects can absorb, reflect, or diffuse sound waves, thereby affecting the overall sound quality and perception within the space.
Last edited:
Hello Eric.
The problem is that most of the oil can problems show up above 9 or 10 k depending on exciter coil size.
If the exciter does not reach 10k then that will prevent the problem showing up.
I am hoping that a single bolt from the exciter to the panel will improve things , if only to improve the panel mounting.
The exciter mounting is also positioned in the centre of the coil area , would this suffer from oil can distortions?
Also, I was not suggesting that the exciter was cheaply made, quite the opposite.
This one cost me about £5 from aiyima.
This exciter seems to operate more like a shaker , if that makes sense.
I'm sure there is a use for this type of exciter, but can it match the audio quality of the coil , actually on the panel.
Steve.