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My Experiment with a Metal Panel Absorber
Old 13th September 2018
  #1441
2 vpr (2,5mm) + 2 bka 1 are ca. 2100€ without shipping
Old 13th September 2018
  #1442
Renz is only glueing the plate on a few spots as you can see kn the pictures
Attached Thumbnails
My Experiment with a Metal Panel Absorber-ff647713-2e01-4ae2-8deb-a86698e750d2.jpg   My Experiment with a Metal Panel Absorber-3ad1d556-c254-44a4-bf0f-d572739c4609.jpg   My Experiment with a Metal Panel Absorber-9b0e70b1-85aa-4489-9d27-1a5af86ec1b3.jpg  
Old 19th October 2018
  #1443
Gear Maniac
 

new rpg modex!?

hi all long time...
did you notice the new rpg modex 15cm?
what you think about the new dimensions?


http://rpgacoustic.com/documents/201...-brochure.pdf/
Old 9th November 2018
  #1444
Oh and the 2,5mm steel plate version definitely uses some different material compared to the isobond 1mm version....will try to take some pictures, maybe someone here can identify the material.

I searched the web intensively the last days to find a suitable replacement material which is cheaper than the 33€/qm of isobond as i have to cover 60qm in the project im currently working on....will try to do some tests with different glasswool and rockwool panels as the panels will be mounted on a solid wall behind 50cm of sonorock and 50cm air gap
Attached Thumbnails
My Experiment with a Metal Panel Absorber-62dd1dd0-5d14-4d8b-9d79-036834b618b0.jpg   My Experiment with a Metal Panel Absorber-2464eb51-b084-41a8-9f95-2ab01b9d4414.jpg   My Experiment with a Metal Panel Absorber-e7f7c0f2-268c-4301-8d49-3a7c52ac1f01.jpg  
Old 19th November 2018
  #1445
Quote:
Originally Posted by RhOdEz View Post
from older VPR thread :

"What materials can be used as an alternative for the steel plate and serve Isobond Basotect or Caruso? What to watch for the selection? PUR foam is equally suitable?

Foam: Actually, all materials which have a similar stiffness. Including foam or mineral wool. It must stop leaving only clog. However, one should pay attention to airborne fibers and odors. (Gerd, PUR's) In principle, the entire construct of VPR to handle very good natured. "

So ,there's possibility of using common and cheap mineral wool glued onto steel plate ?
That could bring down overall price per piece ,it's worth trying ?

will post it to trapping traps thread too
has anyone tried different types of pur foam? basotect has a density of 9kg/m3 and a shore hardness of 60...i can get pur in 18/20, 20/35, 25/40, 35/50 and 40/60....any recommendations?
Old 19th November 2018
  #1446
Gear Maniac
 

Quote:
Originally Posted by housegezeichnet View Post
Oh and the 2,5mm steel plate version definitely uses some different material compared to the isobond 1mm version....will try to take some pictures, maybe someone here can identify the material.
Thank you, just had a quick question: Is the steel plate in the vpr smaller than the cage so the foam acts as a buffer in order to guard the plate from touching the cage?

I was wondering this because how else do they make sure the steel plate stays 'floating'...

Cheers!
Old 22nd November 2018
  #1447
Here for the gear
 
Galaxy Wizard's Avatar
Hey!
Just ordered 3 galvanized steel plates 1,25x2,2 m, 2 mm thick. Since CIB, Basotect and similar products are VERY expensive here (or may be I just earn so little) I am going to experiment with mineral wool and fiberglass of various densities which are very affordable. My primary goal is to test if I can eliminate SBIR with VPRs instead of much thicker layer of just porous absorber. I will post results of my findings.
Old 31st December 2018
  #1448
Quote:
Originally Posted by Vank View Post
Thank you, just had a quick question: Is the steel plate in the vpr smaller than the cage so the foam acts as a buffer in order to guard the plate from touching the cage?

I was wondering this because how else do they make sure the steel plate stays 'floating'...

Cheers!
yes it is smaller
Old 31st December 2018
  #1449
Quote:
Originally Posted by Galaxy Wizard View Post
Hey!
Just ordered 3 galvanized steel plates 1,25x2,2 m, 2 mm thick. Since CIB, Basotect and similar products are VERY expensive here (or may be I just earn so little) I am going to experiment with mineral wool and fiberglass of various densities which are very affordable. My primary goal is to test if I can eliminate SBIR with VPRs instead of much thicker layer of just porous absorber. I will post results of my findings.
SBIR is normally in the 80-200 Hz Range

2mm steel is already quite stiff (stiffness is increasing by the power of 3 so 2mm is 8 times stiffer than 1mm) so i would recommend to use 1mm plates for this frequency range
Old 31st December 2018
  #1450
Lives for gear
hello,


With 1 mm you cover the area 80-200 Hz?
Old 31st December 2018
  #1451
Quote:
Originally Posted by dinococcus View Post
hello,


With 1 mm you cover the area 80-200 Hz?
attached you find the difference shown between 1mm and 2mm plate with the dimensions 1,25x2,2m
Attached Thumbnails
My Experiment with a Metal Panel Absorber-1mm.png   My Experiment with a Metal Panel Absorber-2mm.png  
Old 31st December 2018
  #1452
Lives for gear
thanks
Old 9th January 2019
  #1453
Gear Nut
 

Quote:
Originally Posted by housegezeichnet View Post
Renz is only glueing the plate on a few spots as you can see kn the pictures
These are like the RPG Modex Broaband traps RPG Modex Broadband - Acoustic Products. Is it possible to remove isobond to see how exactly the trap is inside?
Have you also bought modex plate RPG Modex Plate - Acoustic Products ? Can you provide pictures?

Have you made measurements before and after modex traps? Are you happy?
Old 2 weeks ago
  #1454
Here for the gear
 

I am new here and following this thread for a while (as quest) and we know the VPR of RPG with 2,5mm steel / 100mm isobond has a almost 100% absorption on 42Hz, but can somebody tell me when the VPR is threated with let's say 150mm isobond (or some material equal to isobond) and 2,5mm steal it lowers the frequency?
My room is fully treated and reasonably under control at approx 45Hz but I have one room mode left at 35Hz, I want to give it a try the solve this with VPR's aqainst the wall.
The placement of the VPR temporary leave out of acount, I want to know if it is possible to make a VPR who can reach 35Hz with a good absorption value.

Grtz Marcel
Old 2 weeks ago
  #1455
Lives for gear
Quote:
Originally Posted by MarcelvT77 View Post
I am new here and following this thread for a while (as quest) and we know the VPR of RPG with 2,5mm steel / 100mm isobond has a almost 100% absorption on 42Hz, but can somebody tell me when the VPR is threated with let's say 150mm isobond (or some material equal to isobond) and 2,5mm steal it lowers the frequency?
My room is fully treated and reasonably under control at approx 45Hz but I have one room mode left at 35Hz, I want to give it a try the solve this with VPR's aqainst the wall.
The placement of the VPR temporary leave out of acount, I want to know if it is possible to make a VPR who can reach 35Hz with a good absorption value.

Grtz Marcel
The mass surface of the sheet metal determines the frequency resonance not the isobond.
The isobond is used to damp and create the mass string effect.
Old 2 weeks ago
  #1456
Here for the gear
 

Quote:
Originally Posted by dinococcus View Post
The mass surface of the sheet metal determines the frequency resonance not the isobond.
The isobond is used to damp and create the mass string effect.
I have room for 1.0x1.5m, has the thickness of the metal plate let's say 3mm influence on the reduction of the frequency?
Old 2 weeks ago
  #1457
Quote:
Originally Posted by dinococcus View Post
The mass surface of the sheet metal determines the frequency resonance not the isobond.
The isobond is used to damp and create the mass string effect.
Wrong....the steel AND the isobond create a spring-mass-system and its resonance frequency is a result of both the properties of the mass and the spring....the heavier the mass or the thicker the spring the lower the frequency
Old 2 weeks ago
  #1458
Quote:
Originally Posted by MarcelvT77 View Post
I have room for 1.0x1.5m, has the thickness of the metal plate let's say 3mm influence on the reduction of the frequency?
I would recommend to go with an as thick as possible spring aka isobond/basotect and a steel plate as thick as needed for the depth of the damper....always remember that the broadband nature of vpr results from the bending modes of the plate and not the resonance frequency of the spring-mass-system....the thicker the plate the higher the resistance to bending (to the power of 3, so 3mm is 3x3x3=81 times stiffer than 1mm) so if you can use depth you should always go for a thinner plate)
Old 2 weeks ago
  #1459
Here for the gear
 

Quote:
Originally Posted by housegezeichnet View Post
I would recommend to go with an as thick as possible spring aka isobond/basotect and a steel plate as thick as needed for the depth of the damper....always remember that the broadband nature of vpr results from the bending modes of the plate and not the resonance frequency of the spring-mass-system....the thicker the plate the higher the resistance to bending (to the power of 3, so 3mm is 3x3x3=81 times stiffer than 1mm) so if you can use depth you should always go for a thinner plate)
Thanks I thought so.
The max thickness of the absorbent I can manage is 150mm, so I was thinking of using 2,5mm metal plate. Is it safe enough for trying?
Or is it better the use thinner plates such as 2mm/1,5mm to start with.
Old 2 weeks ago
  #1460
Lives for gear
Quote:
Originally Posted by MarcelvT77 View Post
I have room for 1.0x1.5m, has the thickness of the metal plate let's say 3mm influence on the reduction of the frequency?
http://www.rpgeurope.com/products/pr...odexplate.html

My Experiment with a Metal Panel Absorber

Read the pdf in the end of this post.
Old 2 weeks ago
  #1461
resonant frequency of 2,5mm plate on 150mm isobond: 34,96 Hz
bending mode frequencies of a 2,5mm plate below 100 Hz:

15,92 Hz
25,48 Hz
28,66 Hz
33,12 Hz
45,86 Hz
46,50 Hz
54,14 Hz
61,78 Hz
63,70 Hz
69,43 Hz
74,52 Hz
86,63 Hz
92,36 Hz
94,27 Hz
97,45 Hz

resonant frequency of 1mm plate on 150mm isobond: 55,27 Hz
bending mode frequencies of a 1mm plate below 100 Hz:

18,60 Hz
21,66 Hz
24,71 Hz
25,48 Hz
27,77 Hz
29,81 Hz
34,65 Hz
36,94 Hz
37,71 Hz
38,98 Hz
40,76 Hz
45,86 Hz
45,86 Hz
46,12 Hz
52,23 Hz
52,99 Hz
57,33 Hz
58,34 Hz
59,11 Hz
61,40 Hz
62,17 Hz
66,50 Hz
70,57 Hz
73,38 Hz
73,63 Hz
82,80 Hz
83,57 Hz
86,63 Hz
86,63 Hz
91,72 Hz
94,01 Hz
98,85 Hz

resonant frequency of 2mm plate on 150mm isobond: 39,08 Hz
frequencies of a 2mm plate below 100 Hz:

20,38 Hz
22,93 Hz
26,50 Hz
36,69 Hz
37,20 Hz
43,31 Hz
49,43 Hz
50,96 Hz
55,54 Hz
59,62 Hz
69,30 Hz
73,89 Hz
75,42 Hz
77,96 Hz
81,53 Hz
91,72 Hz
91,72 Hz
92,23 Hz
Old 2 weeks ago
  #1462
Here for the gear
 

Quote:
Originally Posted by housegezeichnet View Post
resonant frequency of 2,5mm plate on 150mm isobond: 34,96 Hz
bending mode frequencies of a 2,5mm plate below 100 Hz:

15,92 Hz
25,48 Hz
28,66 Hz
33,12 Hz
45,86 Hz
46,50 Hz
54,14 Hz
61,78 Hz
63,70 Hz
69,43 Hz
74,52 Hz
86,63 Hz
92,36 Hz
94,27 Hz
97,45 Hz
I see what you mean, the 1mm metal plate has more bending modes, so assuming this plate has a wider frequency range it will work as the 2.5mm does have.
But I am a little unsure about what is the most important thing to hold on, is it the more bending modes the better it is or stick to highest absorbtion rate of the resonant frequency adjusted to the room mode. In my case I am still tend to stick to the 2,5mm plate because of the highest absorbtion rate of resonant frequency.
Old 2 weeks ago
  #1463
Is there no room for helmholtz-resonators in the room? They can do wonders to the lowest axial modes if tuned properly
Old 2 weeks ago
  #1464
Here for the gear
 

Quote:
Originally Posted by housegezeichnet View Post
Is there no room for helmholtz-resonators in the room? They can do wonders to the lowest axial modes if tuned properly
Where I intended to place the vpr's (2) with the same size and depth. I can reach the low end room mode but the frequency range will be narrow. The suggested location is near by corner but with these dimensions I have also my thoughts. This is why I started to investigate of the vpr's because of their wider frequency range. From your experience, what would you suggest about the vpr's?
Old 3 days ago
  #1465
Here for the gear
 

Marcel, do you by any chance live in The Netherlands?

For quite a while I am looking at some huge bass nulls in our dedicated room and I hope to somewhat relieve these issues with a couple of vpr's.

Maybe we could make a joint effort in thinking what to build exactly and eventually purchase the isobond or whatever material is to be used. This because it seems quite hard to purchase it outside of the "acoustic treatment" circuit and which has a price tag. If that's what it is, no problem, but I refuse to believe that something which is in basis an insulation material, cannot be purchased at a better price...
Old 1 day ago
  #1466
zui
Here for the gear
 

Quote:
Originally Posted by Deleted 4adc64a View Post
Attached are some pics of Isobond/Fauxobond for comparison, and a movie of me squeezing the Isobond to show the compression/bounceback. I'm applying a moderate to firm squeeze here (about the same strength I'd use to barre on the guitar, if that means anything to you).

https://www.dropbox.com/s/ye7vefe5yx...ueeze.MOV?dl=0
Hi,what density do you use
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