Yes, me too, especially in combination with the sensitivity figures. You can get some piston action of the plate for sub response with a stiff plate and loose suspension, but for the response to become balanced the mids and highs then need to be low. The exciter simply cannot displace enough to keep up at 50Hz otherwise.
Indeed. Some designs seem to to use uncontrolled 3rd mode resonance (with the concomitant weight and compliance) to "lever" a small driver movement into a large panel movement. But if the edges are not terminated correctly, it leads to unrestricted edge movement and this increases distortion.
The 1st, 2nd and 3rd modes need some semblance of carefully-controlled edge termination while still allowing sufficient excursion to allow good response.
For interest, I recently measured the throw of a Dayton DAEX25FHE-4 exciter at 1.1mm in and 1.4mm out.
A Dayton 3.5" TEBM65C20F BMR driver measured 2.5mm in, 2.9mm out.
So if it could be controlled, and the panel be able to bend sufficiently, the BMR driver should provide more base than the standard exciter...Yet to be tried
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I've been wondering about gluing a neodymium magnet to a panel with a coil mounted on a brace on the frame so that there is no suspension. I don't think there's any way to get the flux density nearly as high without the steel, but can it be high enough?
Would it perform better or worse without springy suspension returning the panel to the neutral position?
I've found that distortion measures much lower when the exciter is not braced, which seems counterintuitive to me. But if un-bracing the exciter improves distortion, would un-suspension-ing it improve it more?
Would it perform better or worse without springy suspension returning the panel to the neutral position?
I've found that distortion measures much lower when the exciter is not braced, which seems counterintuitive to me. But if un-bracing the exciter improves distortion, would un-suspension-ing it improve it more?
To me it seems like it should be the other way around. If making it more rigid with bracing increases distortion, why would making it more rigid by removing suspension reduce distortion?
I don't have issues with distortion with my current bracing, but it is compliant and more of a suspension of the exciter.
I think in my most recent brace tests the distortion must have come from the entire (solid and heavy) brace vibrating. It makes sense to me now why any bracing has to be compliant. Holding an exciter against a 2x4 or any solid wood furniture does make quite a bit of sound, so making a big and heavy brace is not going to solve that problem like I thought it would.
Regarding suspension, I noticed some product material talking about Xcite XT32-4 having suspension that is tuned differently for better FR. If that really is effective, can it be made even better? I saw a comment from BurntCoil (sp?) that the best suspension is no suspension. Idk if that's true, but it seems like it probably is.
Regarding suspension, I noticed some product material talking about Xcite XT32-4 having suspension that is tuned differently for better FR. If that really is effective, can it be made even better? I saw a comment from BurntCoil (sp?) that the best suspension is no suspension. Idk if that's true, but it seems like it probably is.
It does make sense. The point of suspension in a driver is to suspend the cone. With magnet attached to the plate, and coil to a stiff bracing, the plate itself would suspend the magnet.
Your typical Dayton and Xcite are intended to be used without bracing, or at least to be easy to integrate in most designs. If doing a complete design with frame, plate and driver, I don't see why it would not work to fix the magnet directly.
At least in theory, but I do think it is quite hard and perhaps next to impossible to make such a design though. You need extreme precision to align magnet and voice coil. With the plate holding the magnet and being suspended in the frame, you need to be able to mount it very precisely and make sure it cannot move at all, even if the mounting should be compliant. Say you use a boundary around the plate like the spider in a driver/exciter. Even if you have same material and precision, it is now many times bigger, but the gap in the voice coil have not changed, so you will have less precise alignment and hence need a larger gap, so will get less sensitivity.
Your typical Dayton and Xcite are intended to be used without bracing, or at least to be easy to integrate in most designs. If doing a complete design with frame, plate and driver, I don't see why it would not work to fix the magnet directly.
At least in theory, but I do think it is quite hard and perhaps next to impossible to make such a design though. You need extreme precision to align magnet and voice coil. With the plate holding the magnet and being suspended in the frame, you need to be able to mount it very precisely and make sure it cannot move at all, even if the mounting should be compliant. Say you use a boundary around the plate like the spider in a driver/exciter. Even if you have same material and precision, it is now many times bigger, but the gap in the voice coil have not changed, so you will have less precise alignment and hence need a larger gap, so will get less sensitivity.
I think you're referring to the plate as the vibrating membrane itself. In such a case, you don't mount the magnet to the (membrane) plate. You mount it to a back-brace which is attached to the frame. The reason one would support the magnet is such a way is to prevent it sagging and eventually causing the voice coil to rub against the magnet in the pole gap.
The only thing mounted to the membrane is the voice coil. Nothing else.
Hello Andre, I think I mix up things because it is mentioned to mount the coil on the a brace/frame? So the magnet is on the suspended vibrating panel?
BTW Listening to my panels I liked the unbraced exciter better (I know, not scientific, just comparing side by side), but I decided to just go for a workable and reliable solution and stop trying to get the "best"results.
In the attached clips, the brown wooden bits are the braces. The stucco white is the vibrating panel.
It is more or less the kind of braces I use. The right concept is in my plywood panel in a 3 part variant to avoid misalignment at the exciter.
Andre,
Cool drawings. But I think what HvdZ was referring to was Sapphire Sloth's idea (below) for a suspension-less exciter, rather than a mounting a conventional exciter.
I think HvdZ might be right, in that the better option might be to mount the (lighter) coil and former to the panel, rather than the (heavier) magnet. But I also suspect Leob is also correct that getting good enough alignment of the magnet and the coil would be difficult in practice. It's an interesting idea, however.
Eric