A Study of DMLs as a Full Range Speaker

@Andre Bellwood
You have any good ideas how to mount the motor magnet to the back plate?

The back of the Xite is not even, and seems very easy to get some slight misalignment, especially when trying to mount a cluster of 4 exciters.

One can make it more forgiving by using a softer more compliant material to hold up the exciter, but how much does it help in that case? Then there will be room for sagging eventually as well. And you also need to make sure it doesn't push or pull on the exciter at all, which will reduce sensitivity and possibly cause distortion as well. So you really need a very precise solution that is rigid enough to be very stable over time with a lot of playing and handling.

And due to the shape of the back of the exciter, I would get very limited adhesion surface, so I think it will be some risk that it will not stick over time, which would also cause distortion. I could cover the whole exciter to improve adhesion, but that would result in bad ventilation.

Have you discussed sagging and bracing with Xcite? I did reach out to them on Facebook but never got a reply there, so I should probably mail them instead.
 
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I could print out
Hi Leob
1/You could use epoxy putty to level out the back, or 3d print a mounting plate to compensate.
2/ Can you post the mounting pattern you use please?
Eucy
I can pint out a holder that fits in the pattern on the back of the Xcite to keep the exciter in place with very good precision, or use some kind of putty as you suggest. But it is not that easy to ensure that there is no stress in any direction, especially if you want to keep as much as possible of the back of the exciter open to avoid overheating. The screw holes on the Daytons makes it easier, but even then it was a bit tricky. With the Xcite it is even harder.

For the plate I'm testing with Xcites, I'm using the same brace construction as I used before, but only to help with cable management and to offer som protection against bumping the exciters. You cannot really see in the picture, but there is around 10mm space between the brace and exciters.

I could easily add some printed TPU spacers that holds up the exciters, but I'm still not really convinced it would be a good idea. It seems logical, and is what I did with my Daytons, but they still developed issues and makes things much more complicated and sensitive to the tiniest misalignments.

Probably what I should do is run a low frequency sine for extended time, same as when preconditioning woofers. That should soften up the suspension and make them sag...if there is an issue with the Xcites as well.
 

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You have any good ideas how to mount the motor magnet to the back plate?

The back of the Xite is not even, and seems very easy to get some slight misalignment, especially when trying to mount a cluster of 4 exciters.
Hi Leob,
This is how I mounted the 30HESF-4 to my back plates. I strip the adhesive tape off the front of the driver and mount it to the front panel with epoxy, The motor magnet is not a tight fit in the hole in the backplate, and I run a bead of silicon all around it to keep it snug. This means that I can centre everything perfectly without alignment problems while the adhesives cure overnight.
Yes, the sticker is removed off the magnet.
1706590373132.png

I'm using the back plate as a damper/attenuator for the rear wave on stage (so it's not so loud for the musos), and also just to improve the looks for an installation. The other smaller drivers (25FHE's) are mounted via their threaded holes on the inside of the back plate, and you can see only their mounting screws. The 25FHE's are about 6mm shallower than the 30HESF's, and that's another reason that I use adhesives that will cure relatively slowly: The HESF is free to find its own level relative to the height of the 25FHE's which determine the distance from the backplate to the front panel.
Using this method it should be easy to mount the Xciters irrespective the shape of their plastic shrouds. I suspect that epoxy might not adhere to those shrouds (I don't know what material it is) and it might be difficult to mount them directly to a flat brace given their uneven shape.
Have you discussed sagging and bracing with Xcite? I did reach out to them on Facebook but never got a reply there, so I should probably mail them instead.
No I did not address this. When I get my Xciters I'll assess them properly. But I think the above method is a universal solution irrespective the shape and adhesion characteristics of the device.
 
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I could easily add some printed TPU spacers that holds up the exciters, but I'm still not really convinced it would be a good idea. It seems logical, and is what I did with my Daytons, but they still developed issues and makes things much more complicated and sensitive to the tiniest misalignments.
Hmmm... A cluster like that makes individual hangers impractical...Personally, I'd try and opt for a printed support plate that encompassed all 4 exciters, and fitted over them so the plane of the plate lies on the centre of gravity of the exciter. That plate could in turn be supported from your bracing arrangement. A tad complicated but worth a try. Similar concept to Andre's but without a full backing plate
 
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https://www.parts-express.com/Tectonic-TEAX32C20-8-32mm-Self-Supported-Exciter-8-297-2114?quantity=1

This is the only self supporting exciter that I would use on a rigid panel, but I would have to change how it is mounted to the panel.
Thinking about it, you could probably do something similar to an ordinary exciter ? For testing purposes.
For using multiple exciters on pro gear, I would still use a back brace (probably).
Further back on this thread I posted a short video of two exciters on a panel, they were both reacting different to the panel at low frequencies.
At high power, even with a 100hz cross over this could still be a problem ?
This could be a reason for odd exciter failures on the same panel.
I have still not seen an answer to this problem .
I seem to remember tectonic (i think)discussing this problem and their partial remedy?
These problems (i think)are mainly for high power pro audio gear.
Unless you are using a very inefficient heavy panel , a single exciter with an XO of 100hz should be enough for most peoples audio rooms.
Steve.
 
Although it is of very little difference for pro use, it would be interesting to know how noisy the plastic casing is, compared to a ordinary exciter?
The hdn8 has a very noisy plastic casing , shall we call it self-noise 😀
Ordinary exciters produce noise even when they are not attached to anything, does the casing on the Xcite exciter produce noise or reduce noise?
Everything about the Xcite seems pretty standard to me, except the magnet?
I would still expect sagging to be a problem.
Steve.
 
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Although it is of very little difference for pro use, it would be interesting to know how noisy the plastic casing is, compared to a ordinary exciter?
The hdn8 has a very noisy plastic casing , shall we call it self-noise 😀
Ordinary exciters produce noise even when they are not attached to anything, does the casing on the Xcite exciter produce noise or reduce noise?
Everything about the Xcite seems pretty standard to me, except the magnet?
I would still expect sagging to be a problem.
Steve.
I cannot comment on the reliability claims yet, but the difference in sound quality between the DAEX30HESF-4 and X32-4 is astonishing really. I thought the description sounded like a lot of hype when I read it, but it really seems to be a big improvement over the other exciters I have tested.
No noise from the casing what I have noticed.
 
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Leob said:
I could easily add some printed TPU spacers that holds up the exciters, but I'm still not really convinced it would be a good idea. It seems logical, and is what I did with my Daytons, but they still developed issues and makes things much more complicated and sensitive to the tiniest misalignments.
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Just for my info. & memory, could you please tell me the model number of the Daytons that developed issues/problems ?
 
I am starting to wonder if I have wasted my money on these new exciters?
Apart from the metal casing on the new exciter, they look pretty similar.
I checked the temperature of the old 10watt and new 24watt and they seem to be exactly the same .
I expected the new one to take more power without overheating when driving heavier panels.
I am wondering whether this is a 10watt exciter with short term 24watts? they also sound the same.
The only difference is that the new exciter has an early roll off above 10k, I presume this is because of the 3M sticky tape supplied with the exciter?
Maybe it is just me being sceptical?
Steve.
 
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@spedge
Not following exactly which two exciters you are comparing, and their thermal management might differ, so that they seem to be the same temp at same power level doesn't mean that max power they can handle is the same. And if they are from different manufacturers the power ratings might be calculated in different ways.

Also I find it can be hard to grasp the logarithmic nature of power handling and dB.
We like to try to make sense of it as linear, but doubling the power results in a barely noticeable difference. So the difference between 10w and 24w is actually quite small. You basically have to double twice to get what is perceived as a clear significant difference, so 40w. Double that again, to 80w, and you get almost double perceived volume compared to 10w.
 
Just a little bit of technical stuff >

So long as a speaker isn't going into dynamic compression/overload,
every time you double the drive-watts you get a 3dB volume increase.
Let's say you were getting 93dB SPL for 10 watts and take it from there >
20 watts would give you 96 dB SPL.
40 watts would give you 99 dB SPL.
80 watts would give you 102 dB SPL.
Going back to 'vintage times' it was considered that 3dB was the basic minimum change that ALL people could notice.
The dB change for what is considered to be double the volume is debated to be between 6 and 10 dB.

You can see why I have chosen to use twin 40 watt exciters per panel. I want to have some 'dynamic SPL capacity'.
 
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I was just hoping the 24watt 25fhe-4 would run cooler than my 10watt exciter at my normal listening levels.
I am still a little suspicious that they are basically the same exciter?
But because of the 4 mounting holes, I might try some different mounting techniques , at some point in time?
Steve.
 
I was just hoping the 24watt 25fhe-4 would run cooler than my 10watt exciter at my normal listening levels.
I am still a little suspicious that they are basically the same exciter?
But because of the 4 mounting holes, I might try some different mounting techniques , at some point in time?
Steve.
These are easy to mount. The four holes can be tapped and appropriate length bolts simply applied from the rear through whatever you want to mount them on. Just one example below. Soft rubber washers could be used along with foam around the rear perimeter of exciter if desired for a somewhat giving mount. I generally just hard mount.
 

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