RPG Diffusor's "BAD Panel", what do you DIYers think?

dmattis

Member
2002-09-12 12:42 pm
Sweden
Hello all!

I'm very curious about the BAD Panel, an acoustical product made by RPG Diffusor Systems.

http://www.rpginc.com/products/badpanel/

Has anybody out there seen/heard/tried the originals - or built clones of these? It should be very simple and cheap! Much simpler and cheaper than any other diffusor I've ever seen. And frankly - this is the only one I'd let into my living room, I can tell you. ;)

The design is IMHO very smart, with a binary _amplitude_ grating rather than the usual _phase_ grating. There should be no practical or economical problem covering large wall areas with these.

The BAD Panels both diffuse and absorb sound, in amounts depending on how you mount them, how big holes they have, and how thich they are. But what materials should one use?

I've searched the web but haven't found any info on DIY BAD Panels. I even asked acoustic guru Jon Risch if he had any ideas, but didn't get any answer that time.

What's your opinion?

Best wishes
Mattias, Gothenburg, Sweden
 
sam9

Haven't used them but did look at the absorption curves on the web site. Is this what you want? The most common frequency range where absorption is needed is mid-upper bass where these don't do much. Instead their absrption is at higher frequencies.

These are more than just diffusors so I suggest you note the absorption characteristics too to decide if that's what you want/need.
 

dmattis

Member
2002-09-12 12:42 pm
Sweden
Re: sam9

sam9 said:
Haven't used them but did look at the absorption curves on the web site. Is this what you want? The most common frequency range where absorption is needed is mid-upper bass where these don't do much. Instead their absrption is at higher frequencies.
Hi Sam,
have you really seen all the absorption curves? Take a look at http://www.rpginc.com/products/badpanel/bad_ac_comparison.htm where 1", 2", 3" and 4" BAD Panel absorption is shown. The latter ones have quite a lot of absorption also around 150-200 Hz.
These are more than just diffusors so I suggest you note the absorption characteristics too to decide if that's what you want/need.
Well, that's true, but I think that most rooms have too little absorption anyway, so I don't see that as a very big problem. What I was aiming at here was mainly the DIFFUSION provided by this construction.

If one doesn't like the absorption peak at 800 Hz when using BAD Panels with 1/2" holes, it should be a good idea to mix them with some panels with holes of other diameters, causing the absorption to end up in other frequencies. See http://www.rpginc.com/products/badpanel/bad_ac.htm with curves for 1/2" and 5/8" holes.

If HF absorption is still too dominant, I guess it would make sense to use a quite stiff and dense absorber in the panels?
This would probably reflect more of the higher frequencies and still soak up some of the lows, right?

/mr
 
Right you are

I didn't notice the grey curve for the 4", just more bightly colored ones. That gives you the choice of selecting which one addresses your particular problem. It's not only the amount of absorbtion but the amount relative to other frequencies. I had seen (heard) an example where someone failed to take this into account and got a result different than intended.

BTW, I use diffuser/absorber pannels ("Double Busters") from Echobusters on the wall behind my Magnepans. They are absorbant in the mid-upper bass which helps me quite a bit in that regard, and in the mid-trebble range the diffuse the backwaves which seems to improve imaging.

The panels you mention could have been used in the same way and the look a tad more attractive than the Echobusters. Wish I had known about them a year ago.
 
All,

i am not too much into absoption, i care not to destroy the acousotc energy my tiny amps and my high efficiency dipole speakers just generated.

May i recommend the Skyline diffusor from RPG? I have heard theireffct on romm sonics ... just gorgeous! Everything so much more clear!

I plan to buy some and maybe make a copy in wood as i do not like styrofoam in my living room.
 
my current home acoustic "wish/project"

Here is what I would like to come up with:
http://www.cnc-holz.com/01akustikplatten.htm

If you look close, some of these acoustic panels are rather simple to make- using a circular saw

You can!! even do that on one side and write your name with the proper machines inthe other side, all being visible through the cuts- I like this a lot. E.g. cut close lines, and then cut something like Jimi Hendrix´s face from the other side
:cool:

Maybe you get my idea when you look closely at the spartanic pictures I linked

Have fun!!

Philipp

BtW: Use real wood "alloy":)
 

jpmatheny

Member
2009-02-18 5:21 am
check this book out

I see that this thread is quite old. However this might be helpful to someone somewhere. The book "Acoustic Absorbers and Diffusers, Theory, design and application" by T. J. Cox and P. D'Antonio is an amazing book containing detailed explanations of both the theory and design of acoustic treatments involving absorbtion and diffusion. I just finished reading the section on BAD panels. I would highly recommend it if you are planning on building any yourself. Turns out, you can't use just any sequence of random holes to get optimal performance. it's interesting reading to me.
 
The thread is old, but sound still works the same. Thanks for the recommendation! Since D'Antonio is the man behind RPG, I expect it to be very interesting reading. $140 at Amazon, yeeehaaa... ;)

True, random shapes are not good enough. Randomness can end up in anything from the worst shape to the optimal shape. The optimum looks random, but that doesn't mean that random is optimal. :)