The Studiotips SuperChunk is an evolved design derived from the idea of stuffing the cavity of a Studiotips Corner Absorber. With key input from Eric Desart.
The SuperChunk is accomplished by cutting up mineral fiber panels into triangles and then stacking them so as to fill the entire corner from floor to ceiling. Panel thickness is immaterial, but the thicker they are the fewer you have to cut, and thicker ones may be cheaper per volume.
Owens Corning 703 is a material which has been used with success, but provided you use some sort of medium to low density mineral fiber insulation board you should get satisfactory results. There is no need to pay more for material handling properties such as one gains with fiberglass panel versus rockwool and higher density versus lower density versions of similar boards is not worth the extra cost, and may actually reduce performance. Thus, even fairly floppy flavors of rockwool are viable choices if you are making a Superchunk of 24" face size or bigger... and floppy rockwool panels are often quite cheap. See the SCA article for more details on choosing a mineral fiber board.
StudioTips Corner Absorber
A light frame covered in cloth and mounted in the corner to cover the panels is then installed to finish off the look of the appliance. Or a series of face panels could be cloth covered and mounted over the stacked triangles to enlarge the volume of the device and provide the finished face.
This design was introduced by forum member Harder aka FarmerBrown in the context of how to optimize the stuffing of the cavity of a Studiotips Corner Absorber. Basically the idea is to cut up mineral fiber panels and make a stack in the corner to build a giant wedge of absorbent.
The wedge can be built vertically in the corner, or laid across the floor horizontally to fill a floor/wall corner, or a frame can be made to hold it in a ceiling/wall corner.
Cover with a breathable fabric and you have a broadband absorber of superlative performance and a very nice "built-in" look.
Comparison test of the SuperChunk can be viewed here.
Corner Absorber Comparison
The tested model is a 24” face unit [a stack of 17x17x24” triangles] made of Owens Corning 703 [3 lbs. pcf semi-rigid fiberglass boards]. We know this model works great... so go that route if you want a proven performer [there are many brands of fiberglass boards of this density (3 lbs. pcf) and all would perform about the same as the Owens Corning product mentioned], but it is rational to expect similar performance with other mineral fibers types in this class [such as 6 lbs. rockwool like Roxul's RHT80], and it has been credibly suggested that slightly less density in such a large appliance might actually work better.
As a guess - I suggest you use rockwool at least in the 4 to 5 lbs. range and fiberglass of at least 2 lbs. per cubic foot., but please feel free to experiment and report results [with pics -dammit!]. Also, 24” face units are by no means a strict requirement as to size, but if you build them smaller the performance will drop off at the bottom of the band. Building them bigger is a reasonable consideration if you have plenty of floor space to spare - but consider using a material with lower gas flow resistance [lower in the density ranges discussed above]. Also, before building smaller units ["BabyChunks" ] you might do well to consider the StudioTips Corner Absorber instead as it is a more efficient design with an amazing return of performance per material/labor cost.
A cut pattern for standard 24x48" boards is shown in the cut pattern attached below, but of course bigger is better - provided you make reasonable choice as to core material gas flow resistance / density] - so use whatever fits your room dimensions / budget. This cut pattern also shows an optional covering panel that can be added to increase depth and width.
Mineral Fiber Cutting video:
http://video.google.com/videoplay?docid ... 8802658704