plate construction

J C C & A S S O C I A T E SJ C C & A S S O C I A T E S2082 CEDAR CREST DRIVEHIGHLAND PARK, IL 60035

847 831 5628

REVERBERATION PLATE CONSTRUCTION DRAWINGS

fugalx@att.net

The following drawings were copied from the original sketches of theprototype ECOPLATE™ I. The engineering blueprints that were madefrom these were too large to fit in any available scanner so they (the originalsketches) were corrected per the engineering blueprints. The scans of thedrawings are low resolution to save space but they will print fine.

The only details that are not revealed here are the voice coil-magnetcombination and the pickups. There are still sold on the open market andare available from JCC & Assoc.

The miniboxes shown in Fig. 2 have two grommeted holes, one in eachend of the box. Inside is a terminal strip where leads from the pickups joinwith the cable to the amplifier. The latter can be any good single conductormicrophone cable. The pickup leads should be any small diameter singleconductor cable that is flexible. A twisted pair of #28 wire will suffice if itis under 8” in length. All wire should be kept from touching the plate withtyraps, where possible.

The steel plate can be purchased from most steel companies precut tosize. Stainless steel has more high frequency decay time (suitable for rockmusic) whereas cold rolled steel is more like a concert hall (suitable forclassical music). The EMT 140 was cold rolled. Most of the other parts areavailable from local hardware stores, lumber yards, and electronic supplierssuch as Mouser, Newark and Allied. Somewhat special items (such as thespade bolts and links) can be had at large hardware supplier such asMcMaster-Carr.

The amplifier schematics can be used as a guide or built as is. PC boardlayouts are available. Basically they are flat amps except for the Drive ampEQ noted in Fig. 11. Therefore it is possible to use any good power ampcapable of the required EQ and at least 20 watts. The preamp stage needs to

have a high impedance input.The damping plate is one of the critical parts of any plate system. In

order to adequately control the reverberation time, it must have what theinventors called ”flow resistance”, This is supplied by using typical 2’ x 4’ceiling tiles that have a plastic back with “pin perfs”, that is a large numberof small holes in the plastic backing. DO NOT USE A PLYWOODBACKING TO MOUNT THIS MATERIAL Mount as shown in the drawing.We would urge any builder to get the EMT patents from the www.uspto.gov/Pat. No. 2923369. Also a story on the development of the ECOPLATE™is available by email from fugalx@att.net.

An optional box that provides some isolation can be constructed ofparticle board, but the unit should still be placed in a closet, attic or eventhe studio, because reverb is often added during mix downs. It can be hungfrom chains, if structure borne noise is a problem.

Once constructed the plate must be properly tensioned so the reverbdecay is smooth and even. This is accomplished by achieving even tensionon all four sides of the steel plate. Tension affects, inversely, the lowfrequency reverb time. The more tension the less low frequency reverbtime. Tensioning is usually a long, time consuming procedure and shouldbe done several times a year. Also there is the risk of over tightening theplate and stretching it. If this happens it will not be possible to properlytension the plate again. To avoid this and to make tuning simple, a tuninggauge is also available from JCC & Assoc. for $50. A torque wrench doesnot measure plate tension due to the friction component in the threads.

A somewhat smaller and simpler version of the ECOPLATE™ I wasthe ECOPlATE™ II. Drawings of this plate can be made available in thefuture is there is sufficient interest.

cunningham1986@sbcglobal.net

The most important part in a Plate Reverb system is the damping plate. There are several requirements necessary to ensure that the sound of the reverb decay is realistic. The damping material must have "flow resustance". Armstrong Shasta Fiberglass ceiling tiles 2'x4' and about 5/8 inch thick, with a thin plastic backing that contains many tiny holes are ideal. Available at Home Depot. Mount as shown in the drawing. This is all explained in the EMT Patent, available from our website: platereverb.com Also a story on the developement of the ECOPLATE is available there as well as many other details concerning Plate Reverb. That address is platereverb.com An optional box to provide isolation will be posted there. Many studios, however, often put the reverb in the studio because it is often added during mixdowns. Oterwise the unit can be hung from chains if structure born noise is a problem.

1.5”

3 holes for rivets

Corner reinforcement 1/16”stainless steelone piece each side

39.5” Stainless Steel or cold rolled plate- .024“ thickness

79”

5/8“

Fig. 1

STEEL PLATECONSTRUCTION

3/8”

3/8”

3/16” HOLES

.

..

..

..

.

DriverMountingPlate

Miniboxfor junctionof pickup leads

6”

4- 10/32 Tapped holesin angle ironsfor mounting plate(see detail)

6”

3”

11 3

/8”

10 1/8”

44 1/4”

Steel tubing 1.5”Angle Iron 1.5”

ALL

DRIVER SIDE OF FRAMECONSTRUCTION

Fig. 2

2.5 “

15 1/4”

1.5”

1/2

Detail

Using 1.5” steel tubing1.5” Angle iron

80”

46.5”

MountingPlate rails 10-32 Tapped Holes

16.5”

1/8” Holefor Voice Coil

18”

4 1/8”

10”

4 1/8”

49 1/8”

1.5” Angle Iron (43.5” in lenghth) welded inside frame: 4 Req.

6-1.5“ tubing (4- 6” Pieces, 2- 3” Pieces) welded to frame as shown

PLATE SIDE OF FRAMECONSTRUCTION

1” x 1” x 1/4 Steel tabswelded to frame with 1/4”hole in center. 8 Req.

2”

2”

Fig. 3

Optional1/4-20 tapped holesfor external box

Corner ”L” brackets, riveted in place, 4 Req.

fastened to channel with2 6-32 x 1 1/2” screws

40 3/4”

76 3/4“

13”

7 3/8”

3/4” Aluminum Channel

Shasta (or any OwensCorning pinperf) ceilingtile, 4 pieces cut to size.Insert edges in channels.Tape seams with cloth tape.

Fig. 4

1/2” Steel rod 42”long, 10/32 x 3/4”studs go into a tappedhole at each end then

DAMPING PLATE DETAILS

3/8” Threaded Rod, 48” length. Trim to fit.

5” x 1” Steel Channel 4 Req. (see Detail Fig. 6)

FRAME SHOWING DAMPINGPLATE MECHANISM

Fig. 5

3/8” Thin nuts

1/2”Holes

3/8” Nylon Shoulder washers

3/8” Threaded Rod

3/8” Thin nuts

3/8” Thin nut

Locknut

Locknuts

Reverbtime Pointer

Damping Plate Arm 5“ x 1” x 1/2”Steel Channel

3/8” Hole

5/16” Ho;e

7/8”

3/8”

3 3/8”

Fig. 6

FABRICATION DETAILS, ARM

1.5”

3/8” 3/8”

3/4”

2.5” 4”

DRIVER MOUNTING PLATE

8”

1/8” Aluminum

41 3/4””

1/2” 9/64 hole

7”1”

PIVOT ROD

POINTER

Fig. 7

3/8” Holes

Dia. 1/2”

3/8” Hole

3 21/32”

10-32 TappedHoles

Spade BoltLink

Frame

Plate

DETAIL OFTENSIONINGSETUP

Fig. 8

1/4-20

(I.D. 1.25”)

Hi Boost

Lo Cut

Fig. 9

To PowerAmp

Fig. 10

Fig. 11

Calibrated Tuning Gauge for proper plate tension

Magnet (showing wide gap) on user supplied mounting plate and Voice Coil.

Price $50 USD

Voice coil $75 USDMagnet $85 USD

Special High Resonant Unimorph PickupStereo Pair with special conductive adhesive $50 USD