Christian,
The length of panel is 48" and supported around the perimeter (except the corners) on 3M 411 double sided foam mounting tape, approximatedly 3/4" wide. The image below is of the actual frame (sans brace) that I used for the tests described. I have since removed the 14"x 48"plywood sheet and remounted that to a new frame using Poron foam around the perimeter instead of the 3M 411. Currently, the original (adjustable width) frame has a pink XPS sheet mounted, shown in the image below. But you can still see the gray residue of the 3M 411 tape on the face of the frame. It was difficult to peel it off of the frame so I just mounted the XPS sheet on the opposite side of the frame rather than trying to remove the residue of the tape. You can also see the horizontal cuts in the vertical frame members from the circular saw that I used to trim the panel. The saw blade depth was just a bit deep and sliced into the frame slightly each time I trimmed the panel. I was pleased when I realized that I could do this experiment without completely removing the panel from the frame an remounting it each time. I only had to trim the panel (still mounted), then move the top horizonal frame member to coincide with the new panel width.
Eric
One example I know of is the Armstrong "i-ceilings" speaker. These were made under the NXT license, and had the exciters (two) mounted between the panel and a support. Unfortunately, it's hard to see the details in these pictures. But I took one of these apart and there is a piece of very soft foam glued to the back of the exciter on one side and to the support spine on the other side.
Eric
Leob,
Pretty commonly I see correlation between the peaks in the SPL and the first few odd,odd panel resonance frequencies, in this case the (1,1), (1,3) and (1,5) modes. Beyond that, not so much. In the image below, the lower (dashed) curve is the measurement of a "tap test" with the tap/mic at the center of the panel, which creates clear peaks at the odd, odd modes.
Eric
Andre,
Wow, I didn't know about that. That looks like it would be worth investigating.....
Thanks,
Eric
Cardboard is mentioned in the chat that goes with the second link (in Russian, Deepl will do the job!).
The cardboard seems to be black painted (with no warping!!!!) and from this sort having 2 paper sheets and 2 thin flute layers. If I remember, this material was pointed before for its performance
Christian.
@Andre Bellwood
I had a quick look to those producys. Akabak offers a free license for DIYer. What about Comsol? Akabak runs under Windows when Comsol is multiplateform (I replaced my laptop... not the OS... still under Linux even if the previous was Manjaro and now it is Ubuntu. Dell delivers laptop with Ubuntu).
Very smart analogy @toddincabo!
Actually honestly I think it is too dumb to warrant a reply.
Personally I don't have endless funds, so I actually care about warranty, and hence manufacturer instructions, since I cannot buy new equipment all the time.
Actually honestly I think it is too dumb to warrant a reply.
Personally I don't have endless funds, so I actually care about warranty, and hence manufacturer instructions, since I cannot buy new equipment all the time.
There may be another mounting method that could make sense. The extra options could be used to mount the exciter on the panel. This includes any screw hole. A Dayton comment on the small exciter with a square mounting plate.
Ideal for commercial or residential sound applications, the Dayton Audio DAEX58FP Flat Pack exciter easily mounts to most any surface using adhesives (3M tape or gel glue recommended) or screw mounted. A 2-1/4" square plate can be attached to virtually any flat surface to produce amazing sound, creating a speaker from most any surface area.
https://www.daytonaudio.com/product/1150/daex58fp-flat-pack-58mm-exciter-25w-8-ohm
The fact that the exciter may finish up with 3m adhesive film pointing away from the panel wont alter the exciter's functionality. Some other exciters are clearly intended to be stuck on but may still have a hole. The holes don't make much sense other than maybe to jig things when they are being assembled. In a machining sense they may be used when two surfaces need to me machined 😉 sort of thing I do at times on my manual lathe at home as the part can't be mounted any other way to achieve the objective. A disc of something or the other etc. No one is likely to mass produce anything using techniques like this.
If I remember correctly I posted a link to a wide field thesis where they used pallet cardboard to keep the panel weight down. This is two sheets either side of a lattice. Sort of honey comb. Bending rates should be very similar in all directions. It's intended to have high compressive strength.
Christian,
Yes I saw the note in the comments saying that the matertial is cardboard. But I'm still skeptical. It doesn't look at all like cardboard to me. You can see some kind of porosity in the edges, but flutes would have a very regular appearance, which I just don't see. It could be an illusion, but it just looks a lot more like XPS than cardboard to me.
Eric
jmproject,
Yes. I did play around with 2 exciters. I found it worked pretty well to place both about 5" from the centerline across the 48" dimension (on the same side), and about 2" on either side of the centerline in the other (short) direction.
But, as you said, the 25FHE-4's are pretty cheap. So my best suggestion is to buy a couple of extras as test exciters and try them at different places for yourself just using double sided tape to hold them in place for testing. Move them around and see what actually works best (ideally using REW to measure). Once you find the places you like, permanently mount "virgin" exciters using the VHB to the selected locations and save the used test exciters for future trials with other panels, sizes, mountings, etc.
Eric
Yes I'm well aware of a few drivers that come with faceplates designed to screw on to a panel. Monacor and Visaton do them as well.
They are not good. Many users strip off that faceplate and rather glue the voice coils directly to the panel.
Keep in mind that the framed drivers, with mounting tabs on the basket assembly, are made to screw to a back brace, and not onto the vibrating front panel.
From : https://wigstonpaper.com/2022/05/25/the-complete-guide-to-fluted-cardboard-corrugated/
Extract below. I think the Conundrum is "double wall" type (3 paper sheets - sorry I wrote 2 previously - with 2 "spacers")
Having a closer look, I have doubt also for cardboard; with in addition the warping problem with painting. The membranes are really flat, the edges not regular. I have doubt for XPS... or if it is with some skin?
It could be similar to my epoxy coated XPS panels?
Thank you Christian for showing this video.
This is the first time I have seen the full reverse side of one of his panel's.
He always hides the exciters, so I think he is not very happy with the person filming.
I was very surprised to see frogs legs( nothing personal 🤣) attached to the exciters.
Not something I would recommend.
Steven.
Thank you Christian for showing this video.
This is the first time I have seen the full reverse side of one of his panel's.
He always hides the exciters, so I think he is not very happy with the person filming.
I was very surprised to see frogs legs( nothing personal 🤣) attached to the exciters.
Not something I would recommend.
Steven.
Looking at the Flutes, I can't help but think that for the purposes of the DML, a lighter Panel is achievable if the Corrugated Infill was to be perforated, the stiffness of the panel should be maintained.
As for the Fluted Panels I have given to @spedge, I was wondering if sanding down one Face might increase the flexion of the panel and further enhance the experience that has already been enjoyed.
I will also reintroduce the idea of using a Panzerholz for its notable Damping and Dissipation Properties.
A Panzerholz Disc / Rosette may prove valuable if produced to a Sandwich Layer between Panels and Exciter or other placement to help manage energy being transferred.
All recommendations are specific to being experimentalist only and are on the table following Five Mugs of Coffee 😎 .
As for the Fluted Panels I have given to @spedge, I was wondering if sanding down one Face might increase the flexion of the panel and further enhance the experience that has already been enjoyed.
I will also reintroduce the idea of using a Panzerholz for its notable Damping and Dissipation Properties.
A Panzerholz Disc / Rosette may prove valuable if produced to a Sandwich Layer between Panels and Exciter or other placement to help manage energy being transferred.
All recommendations are specific to being experimentalist only and are on the table following Five Mugs of Coffee 😎 .