pjpoes, the patent was filed by Fuchs, Hunecke and Zha (http://v3.espacenet.com/publicationDetails/biblio?CC=DE&NR=19506511&KC=&FT=E)
Fraunhofer licenses the design. RPG even uses the diagrams from the Fraunhofer website.
Best, Markus
Fraunhofer licenses the design. RPG even uses the diagrams from the Fraunhofer website.
Best, Markus
where does RPG list using that patent? I also don't see the same images? I'm confused on the relationship between RPG's device and this patented device? I mean, I don't see a patent for RPG's device at all, so I'm assuming it's not their own design, or at least, is not a patentable design, but I don't see mention of this patent or image. Can you clarify a bit?
Thanks for that patent link though, I couldn't find it, and it's images are useful for those of us who want to try and DIY our own versions.
Thanks for that patent link though, I couldn't find it, and it's images are useful for those of us who want to try and DIY our own versions.
Why not just send an email to RPG??
Meanwhile read http://www.rpginc.com/products/modexplate/index.htm and compare to http://www.ibp.fhg.de/akustik/ra/vpr/index_e.html
Meanwhile read http://www.rpginc.com/products/modexplate/index.htm and compare to http://www.ibp.fhg.de/akustik/ra/vpr/index_e.html
I was in the process of asking about any patents attached to the Modex device, including asking specifically about the German patent. I'll let you know what they say, I'm assuming you know the answer, or are you simply guessing based on superficial similarities?
I don't personally see the designs as being identical, nor do I see identical graphs. Everything I see simply show the commonly accepted aspects of panel trap design, it's the same thing that published in acoustics handbooks on the topic, such as the British one I posted over on AVS once. When I had talked with Peter before, it was my understanding that the metal resonating panel was clamped at the edges, and that no dampening touched the panel. This would indicate a difference between the patented device and Modex, no?
Now, as to the real matter of discussion here, I thought you were claiming that this patented device had multiple resonant modes it dampened at. however, my reading of the patent and graphs indicates that, as I understood things before, there is only one, and the dampening simply lowers the Q. I don't think anything is wrong in my understanding of how these work, this patent hasn't changed that.
I think that, as RPG claims the relatively narrow bandwidth of these devices would still require multiple devices at different tuned center frequencies to have broad lf absorption.
I don't personally see the designs as being identical, nor do I see identical graphs. Everything I see simply show the commonly accepted aspects of panel trap design, it's the same thing that published in acoustics handbooks on the topic, such as the British one I posted over on AVS once. When I had talked with Peter before, it was my understanding that the metal resonating panel was clamped at the edges, and that no dampening touched the panel. This would indicate a difference between the patented device and Modex, no?
Now, as to the real matter of discussion here, I thought you were claiming that this patented device had multiple resonant modes it dampened at. however, my reading of the patent and graphs indicates that, as I understood things before, there is only one, and the dampening simply lowers the Q. I don't think anything is wrong in my understanding of how these work, this patent hasn't changed that.
I think that, as RPG claims the relatively narrow bandwidth of these devices would still require multiple devices at different tuned center frequencies to have broad lf absorption.
pjpoes said:
http://www.rpginc.com/products/modexplate/index.htm
Just to make sure you are looking at the right device, there is "modex" and then there is "modexplate"
I think the patent was implied here
"The patented damped metal
plate construction offers absorption via pistonic vibration, damped bending modes and porous absorption."
And the description is the same as if it was the other, namely, # 2 & 3:
Sound (1) strikes the steel plate (2) which pistonically vibrates (3) against the porous absorption spring (4), mounted on a rigid backing (8). The porous absorption also damps plate bending modes (5) and absorbs higher frequencies which diffract around the plate (6) through a perforated (7) metal frame.
And since this was tested in the Fraunhofer Institute:
"Therefore, additional testing has been carried out at the Fraunhofer Institute in large scale impedance tubes..."
case closed!
Dr. Geddes I believe you are correct. I do now see that the German patented device, which I believe is different, uses multiple plates, presumably to have multiple tuning frequencies. However, I don't speak German, the English translation is terrible for such a technical document, and I can't make heads or tails of the images. If the graphs of absorption that show only one peak are in fact supposed to be what the patented device absorbs, then it too has only one resonant peak. However, if those crazy looking zig zag graphs are supposed to be the device, and the other graphs are just for reference to traditional devices, then this patent is for something a bit different. It's still conceptually the same, but uses multiple tunings (I assume akin to a Helmholtz box with multiple port tunings?). However, those graphs show very un-smooth absorption, so I'm assuming that's now what it is, as I wouldn't imagine that to be a good thing.
Markus, I'm assuming you speak German here. What does the image labeled Bild 3 depict, as well as Bild 11? Is the absorption coefficients of Bild 10 supposed to be of their device, or for reference purposes? What do the two lines indicate, different dampening materials? One indicates standard, the other I can't read.
As for the CBA device, that too only shows one peak for it's resonate frequency, no? I don't get how this is a broad band LF absorber. It appears to work just like all others, with claims that it's some how unique. I don't see how, functionally this is any different than any other device out there.
Markus, I'm assuming you speak German here. What does the image labeled Bild 3 depict, as well as Bild 11? Is the absorption coefficients of Bild 10 supposed to be of their device, or for reference purposes? What do the two lines indicate, different dampening materials? One indicates standard, the other I can't read.
As for the CBA device, that too only shows one peak for it's resonate frequency, no? I don't get how this is a broad band LF absorber. It appears to work just like all others, with claims that it's some how unique. I don't see how, functionally this is any different than any other device out there.
TRADERXFAN said:
http://www.rpginc.com/products/modexplate/index.htm
Just to make sure you are looking at the right device, there is "modex" and then there is "modexplate"
I think the patent was implied here
"The patented damped metal
plate construction offers absorption via pistonic vibration, damped bending modes and porous absorption."
And the description is the same as if it was the other, namely, # 2 & 3:
Sound (1) strikes the steel plate (2) which pistonically vibrates (3) against the porous absorption spring (4), mounted on a rigid backing (8). The porous absorption also damps plate bending modes (5) and absorbs higher frequencies which diffract around the plate (6) through a perforated (7) metal frame.
And since this was tested in the Fraunhofer Institute:
"Therefore, additional testing has been carried out at the Fraunhofer Institute in large scale impedance tubes..."
case closed!
I was reading the wrong Modex description and missed that. I now see the common graphs they show. However, look at the Modex corner, same description, different picture. From the Modex corner, it seems to me that the metal plate isn't directly dampened by the absorption. It's not clear to me that they do this, and I don't believe that it works as described in the Patent or in the Huneck web page. I don't think a metal plate is adhered to a piece of foam which acts as a spring suspending it. I believe it's suspended at the edges with dampening in the chamber, but not touching the metal plate. We will see what RPG says though. None the less, given the testing location, I will concede that there must be some common work on the design, or some sort of collaboration.
as I said, I did. I'm waiting a response. However, given the proprietary nature of these devices, I am guessing they won't tell me. They have "shut me down" before when I asked about how it works. The Modex plate seems disturbingly similar, the corner does not. I was most interested in the corner type application for myself, and had been paying most attention to that device and the device generically referred to as Modex. These two devices appear to be different from the Modex plate, but I could be wrong.
"Modex Plate" is foam + steel plate. "Modex Broadband" is foam + steel plate + foam. It all comes from Fraunhofer. Just read the docs on the RPG site.
"The Modex™ Broadband was developed by the Institute for Building Pyhsics at the Fraunhofer
Institute, and consists of a metal plate, embedded between two layers of damping material, surrounded by a
perforated metal frame."
(http://www.rpginc.com/products/modexbroadband/Modex-Broadband.pdf)
"The Modex™ Broadband was developed by the Institute for Building Pyhsics at the Fraunhofer
Institute, and consists of a metal plate, embedded between two layers of damping material, surrounded by a
perforated metal frame."
(http://www.rpginc.com/products/modexbroadband/Modex-Broadband.pdf)
yes I see all that now, as I said, I was looking at different Modex products. I didn't realize they were different.
It's the Modex and Modex corner that I was looking at, and those are the ones I thought were different. They are listed under residential products.
RPG got back to me and said that the MODEX and MODEX corner are their implementation of a more traditional resonant trap, with the panel suspended at the edges (in a proprietary way so they claim) and dampening inside the chamber, but not attached to the plate. The MODEX Plate is Fraunhofer's design, as you point out. They claim only the MODEX corner and Modex are designed for absorption at these very low frequencies (below 150hz).
It's the Modex and Modex corner that I was looking at, and those are the ones I thought were different. They are listed under residential products.
RPG got back to me and said that the MODEX and MODEX corner are their implementation of a more traditional resonant trap, with the panel suspended at the edges (in a proprietary way so they claim) and dampening inside the chamber, but not attached to the plate. The MODEX Plate is Fraunhofer's design, as you point out. They claim only the MODEX corner and Modex are designed for absorption at these very low frequencies (below 150hz).
you know what, the last part of what they told me doesnt make sense, they indicate on their website and in their graphs that the MODEX plate Type 2 is for below 100hz, and clearly show peaking at 40hz. Maybe he was referring to only the Type 1, I dont know, but clearly the Type 2 is also not their own design, and not like the MODEX or Corner.
I think what he was trying to say was that the MODEX and MODEX corner can be custom built for specific applications, and is designed to have greater absorption at even lower frequencies, so yes. However, it's very peaky, as you can see in their graphs.
I also realized that he wasn't talking about the MODEX and MODEX corner as being the only ones for LF absorption, he said home lf absorption, I missed that word, so I'm guessing he meant, the only ones they designed to be sold for home use. It's a size issue I'm guessing, as they are typically smaller but deeper. In the email he indicated that if I needed it, they can make me a corner MODEX with a 12" depth which they have shown to have around a 1.2 absorption coefficient at 35hz. Also, they have a absorption coefficient of 1 at 50hz on the standard corner, which is inline with the German units, but in smaller but deeper package. Again though, it's clearly peakier yet (both seem peaky compared to what you see with a velocity absorber at higher frequencies).
I also realized that he wasn't talking about the MODEX and MODEX corner as being the only ones for LF absorption, he said home lf absorption, I missed that word, so I'm guessing he meant, the only ones they designed to be sold for home use. It's a size issue I'm guessing, as they are typically smaller but deeper. In the email he indicated that if I needed it, they can make me a corner MODEX with a 12" depth which they have shown to have around a 1.2 absorption coefficient at 35hz. Also, they have a absorption coefficient of 1 at 50hz on the standard corner, which is inline with the German units, but in smaller but deeper package. Again though, it's clearly peakier yet (both seem peaky compared to what you see with a velocity absorber at higher frequencies).
Ok, anyway, I think this issue is settled. I think a device like this could be DIYed easily enough, and additional corner traps like the Modex Corner could probably also be made. Software called AcousticCalculator can be used to model what a standard panel trap will resonate at, then just add the dampening. Unfortunately, there is no software I know of that can model the dampening or the German design, but I'm going to guess that if you model the panels mass correctly, it would be very similar.
Dr. Geddes, I emailed you a while back about building me a bandpass box for my drivers. I'm wondering if that is still a possibility, as it would be a nice summer project, now that I'm probably going to be working less. Let me know, and I will try and get you some data for the driver. All I need is the design and panels cut.
markus76 said:TRADERXFAN, thanks for reading my links. Looks like this is something not many people do
Markus
I read them all. You just don;t want to hear about it.
Putting the panel between two pieces of foam would be broadband and *maybe* new. But I'll stand by my statement that only the lowest mode of the plate has any significant effect.