And ....a better explanation I just found:
The Radial Bridge design was created by inventor Steven Volpp and, until 2002, was manufactured and distributed through Peavey Electronics. The Radial Bridge drums are currently out of production and, with the exception of a few lingering kits here or there, unavailable.
What makes the premier lines of Peavey drums unique is the patented Radial Bridge System. The idea behind the Radial Bridge System is to create head tension without weighing down the shell with lugs and bolts that interfere with its resonance. The head tension is taken by heavy wooden hoops that support the heads with no mounting hardware attached to the shells. This allows the shells to perpetuate a louder and longer sustaining sound.
Peavey tom-toms were made with thin 1/10 of an inch thick, three-ply shells, and the bass drums with five ply shells. Conversely, Peavey's snare drums are made with heavy 1 3/4 inch thick shells that bring out the high overtones in the snare sound.
Peavey drums featuring the Radial Bridge System came in three levels: the Radial Pro 501, 751, and 1000. Peavey now only offers a conventional budget drum set line, the International Series II.
Peavey Electronics also incorporated its patented Radial Bridge technology into two other series of drum kits, each offered professional features at a price . Radial Pro 501 and 751 series drums featured round and flat bearing edges and thin shells with no tuning or mounting hardware attached. Seven inch deep wood snare drums, eighteen inch deep bass drums, (10 lugs per head) and pro style even-sized toms are all standard features. The Radial Bridges on the 500, 501, 750 and 751 are produced from a composite material that has been chosen to have resonant properties close to that of maple. This helps to keep the tone of the drums consistent throughout the range.
The 501 series featured six ply cross-laminated hardwood shells wrapped in black, white or metallic wine red PVC. Hardware for the 501 series is strong and double-braced for easy transportation and storage. Included are two boom cymbal stands, hi hat stand with rotating legs and a chain drive bass drum pedal with plastic/felt beater.
The 751 series tom shells are of four ply maple construction, while the snare and bass drums are six ply, available in high gloss ruby red, sapphire blue, emerald green and black onyx lacquer finishes. Double braced hardware for the 751 series includes two boom cymbal arms, hi hat stand with rotating legs, socket tom arms, tom platform stands and bass drum pedal.s an added bonus, both the 501 and 751 series are completely outfitted with isolation tom mounts, floor tom mount brackets, isolation drum spurs, stainless steel lug inserts and built-in microphone mounts.
The Radial Pro 1000's were originally called RBS-1's. RBS-1 started out life with a Radial Bridge constructed completely from maple ply. The ply was chosen to provide absolute stability and to produce a drum so round as to have other manufacturers weeping as they tried to produce perfectly round shells. This bridge was turned on a lathe to create the bearing edge and produced a lot of waste. Later when the RBS 1 became the Radial Pro 1000 the Bridge was assembled with a block construction.
You can tell just how old these kits are by looking at the badge. The early kits have a black badge that says "pat applied for" and bolts into the shell. The kits in the middle of the production life have a badge that is glued onto the shell and has the American patent number listed on it. The last kits also had a glued on badge and the american patent number and strangely they have the Australian patent number too.
On January 21, 2001 The Hardware for the 501 series was upgraded from single-braced to double-braced for increased stability, including both boom cymbal stands, the hi-hat stand with rotating legs and the snare drum stand.
This upgrade is in addition to features that only the Radial Bridge System® can provide. The 501 series features perfectly round and flat bearing edges and ultra thin shells with absolutely no tuning or mounting hardware attached. Seven-inch, deep wood snare drums; eighteen-inch, deep bass drums (10 lugs per head); and pro style, even-sized toms are all standard features in this series.
The 501 drums feature five-ply, cross-laminated hardwood shells wrapped in black, white or metallic wine red PVC.
The original RBS-1 series with laminated bridges which shipped from 1994 had badges that are screwed on. The RP 1000's which shipped in 1997 have stick on badges ( adhesive backed ).
The original RBS-1 was offered in a rubbed oil finish ( alcohol based toners w/ stain added and topped with Lemon Oil )of Transparent Black, Red, Blue and White. By 1996 there was also Clear White, Clear Violet, and Light Maple. With the natural color of the Maple wood showing through the stain then they can take on a browner or yellower look. In other words the T. Black sometimes looked a bit brown and the T Blue looked a bit aqua or with a slight greenish tint. The original T. Red may have looked a bit pink.
Then there was a natural Maple ( Or, Clear Oil ) finish on the RP 1000 which have a painted Urethane finish.
Followed by Clear Maple Gloss, Clear Blue Gloss, Clear Violet Gloss ( sort of a wine or burgundy color ). Clear Green Gloss. Clear Red Gloss. Black Gloss. The last colors introduced in 1996 were the: Gloss Pearl White, Gloss Yellow , Clear Purple Gloss, Cashmere, Amber ( yellow stain ), Tangerine, Charcoal Violet and Natural Oil.
Don Brewer of Grand Funk ( Railroad ) had a set painted in a HoloFlake finish. There were some 5th Anniversary models sold at NAMM that had multiple colors.
These have a wrapped PVC finish.
