HERSHEY THEATRE

Technical Specification
Mailing Address: P.O. Box 395 Hershey, PA 17033 Main Telephone: (717) 534-3411 Box Office: (717) 534-3405 Main Fax: (717) 533-2882 Owner The M.S. Hershey Foundation
Executive Director Marketing & PR Community Relations Volunteers Education Tours Don Papson Jill Manley Diane Paul Debbie DiNunzio Mariella Trosko Lisa Balanda (717) 298-2202 (717) 298-2203 (717) 534-3415 (717) 534-3411 (717) 520-5589 (717) 533-6299 DPapson@mshersheyfoundation.org jmanley@mshersheyfoundation.org diane.paul@hersheytheatre.com debbie@hersheytheatre.com mtrosko@hersheymuseum.org lbalanda@hersheytheatre.com
Building (Shipping) Address: 15 East Caracas Avenue Hershey, PA 17033
Building Management Hershey Entertainment & Resorts
Booking Box Office Guest Services Marketing & PR Events and Operations Events Events Events Events Vikki Hultquist Dennis Norton Millie Morris Melissa Stradnick Jay Robertson Sarah Measley Patrick Long Patrick Seeley Rick Weimer (717) 534-8966 (717) 534-3412 (717) 534-3405 (717) 534-8945 (717) 534-3368 (717) 534-3414 (717)-508-1710 (717) 534-3418 (717) 534-3348 vhultquist@hersheypa.com dnorton@hersheypa.com mmorris@hersheypa.com mstradnick@hersheypa.com jrobertson@hersheypa.com smeasley@hersheypa.com pelong@hersheypa.com pseeley@hersheypa.com rweimer@hersheypa.com

House Crew

Head Carpenter Master Electrician Audio Engineer Head Flyman Mike McNally Peter C. DiBacco Bill Hartmann John Skworch (610) 223-6673 (717) 329-9682 (717) 269-6282 skippy045@hotmail.com pdibacco@ppslighting.com soundadv@comcast.net skworchman@verizon.net

Unions

IATSE Local #98 Chester Ross, Business Agent (717) 991-4411 Home (717) 469-2354 Cell (717) 979-3075 ialocal98@yahoo.com
American Federation of Musicians (AFofM)
John Lemke, Musical Contractor

jslemke@comcast.net

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Seating Capacity Orchestra 1144 Loge 122 Balcony 638 Total Capacity 1904 Note: House will open 45 minutes prior to curtain unless otherwise agreed to in writing Box Office Automated Ticket Program Outside Ticket Agency
Hershey Entertainment AS400 Ticketmaster
On Site Display Boards and Spaces Marquee Display Cases 24w x 53-1/4h Lobby A-Frames Display Case 39-3/4w x 78h Cocoa Avenue Banner Space 12-9w x 27-1/2h Chocolate Avenue Banner Space 13-0w x 27-1/2h House Policies Hershey Theatre and all public building are now required to comply with the Pennsylvanias Indoor Clean Air Act passed in 2008, as a result the building and adjacent areas are non-smoking. Smoking is allowed on the ground in designated outside areas. Lobby doors open 90 minutes prior to curtain. Auditorium doors open 45 minutes prior to curtain. No cameras allowed in Auditorium. No alcoholic beverages are allowed into the seating area. Outside food or drink is not allowed.
STAGE INFORMATION Dimensions Proscenium Width Soft Opening using house main Proscenium Height Full Stage Depth Upstage Smoke Pocket to US pilaster Full Stage Width Stage between Columns Distance between Fly Floors Distance between DS obstructions Clear Height under Fly Floor Clear Height under Upstage Catwalk Clear Height under SL Catwalk Stage Center to SL Columns Stage Center to SR Columns Gridiron Height Height under Stage Apron Depth Available Line Sets Batten out trim Distance between 1st and last sets Sound Points SR and SL over apron Sound Point on Center FOH Electrical Points -
48-10 38-6 Arch 26-10 off stage, 31-9 on center 42-6 (From Proscenium to Back wall) 41-0 74-8 72-11 62-11 56-3 25-5 30-0 29-0 38-6 34-5 68-6 8-11 5-0 (9-0 with extension) 47 61-0 34-4 22- 11 None None
NOTE: THE STAGE FLOOR HAS TWO OBSTRUCTIONS LOCATED OFF STAGE AND DOWN STAGE Main Drape and Valance Cage SL This cage is approx 32 x 32 square. The upstage, on stage corner is located 3-0 upstage of plaster and 27-5 1/2 from the centerline of the stage. Support Columns for elevated Fly Floor SR This pair of columns is parallel to plaster and approximately 9 deep and 55 wide. The upstage, on stage corner is located 3- 2 upstage of plaster and 28-91/2 from centerline of the stage. There is a second set of columns located upstage. The clear distance between the columns is 35-7. Deck Extension / Platforms: Hershey Theatre is equipped to extend its stage 4 beyond the apron when the orchestra pit and organ are not in use. The 8- 4 x 8 aluminum framed platforms used to create the extension maybe used independently when the extension is not in use.
Rigging System Type # Sets First Available Set Spacing Last Available Set Dist between #3 & # 49 Arbors Fly Rail Locking Rail Batten Length In Trim Batten Travel Out Trim Counterweight Grid Rating Spot Rigging

Double Purchase 49 Sets--47 available for production (#3-#49) # 3 is 3-3 from plaster line 8 centers typical # 49 is 37-7 from plaster line 34-4 9-0 x 12 with a capacity of 2000 lbs. of weight Stage Right Sets 1& 2 Stage level, Stage Left Sets 3-47 - Fly Floor, Stage Right 26-11 above stage 52-6 Typical with optional SL extension of 50 4-0 Typical 57-4 Minimum / 61-6 Maximum 61-4 Minimum / 64-10 Maximum 40,000 # available counterweight Live 30# / sq. ft Total 42# /sq. ft

House Curtain

Soft Goods
30 single line spot blocks inch (4) x 3-0 Schedule 80 pipes for motor spotting 50 1-0 Box Truss 2 - Inverted 1-ton chain motors 1 Inverted ton chain motor Curved Valance (lineset #1) Burgundy with gold piping Main Drape (lineset #2) - Burgundy with gold fringe Set speed travel open / close Variable speed guillotine 5 Sets of Legs each 10 wide x 24 high with 50% fullness 1 Set of Legs each 10 wide x 30 high (For use with CYC) 4 Borders each 50 wide x 10 high 2 Panels 25 wide x 24 high, used as mid stage black 1 Perforated Front Projection Movie Screen with Frame Screen frame 50w x 226h Distance to bottom screen at out trim 40-10 Screen size 446w x 183h Image size 436w x 173h 1 Perforated Front Projection Screen Approx. Size 40w x 18H Screen Masking 10 wide x 22-6 high

Movie Screens

Man Lifts:
Hershey Theatre has two (2) single man lifts. 1. Genie PLC-24 Battery Operated 2. JLG 30AM Electric
Note: The use of man lifts requires qualified operators and the bypassing of lift safety features will not be allowed in the Hershey Theatre by its staff or that of the visiting productions.
TRUCK ACCESS AND LOADING Landlord requires that no more than two trucks at a time be in the vicinity of the building during regular business hours (Monday -Friday, 8:00am 6:00pm). A theatre representative will advise Production of recommended procedure to comply with this requirement. In addition, due to the building air intakes and the location of a daycare playground adjacent to the theatres loading alley, trucks are not allowed to be kept running during landlords business hours. Use of the parking lot directly adjacent to the theatres loading alley is not to be assumed even outside business hours because it is not the Hershey Theatres lot. The Day Care requires permission be acquired in advance for each use through contact with the Day Care manager. Trucks are not to be moving while our audience is arriving to (one hour prior to curtain time) or leaving (20 minutes after) the show. There is room for two trailers or buses to park in the rear alley of the theatre. All other trailer parking is off-site and requires at least a three-day advance notice to be available. LOAD-IN / OUT The theatre does not have a loading dock. Trucks are unloaded in the alley running parallel to rear of stage using ramps. Stage loading door is at street level. Stage level is 4-0 drop from street level. House has a ramp for this transition. The local crew is very familiar with the load-in situation here at the theatre and typically requires no additional personnel be added to load-in / out labor requirements to compensate for the ramps. Forklift: Theatre does not have a forklift; advance arrangements can be made, with two-week notice. Up Stage Left 11-0 High x 9-10 Wide

Loading Door Location: Door Size:
An elevator with access to the stage, basement and all Dressing Room levels is accessible from the alley: Size: Location: Capacity: Door: 5-5 Wide x 53 Deep Off Stage USR 2500 lbs Stage Side: 3-0 Wide x 6-11 High Alley Side 3-10 Wide x 6-11 High
Production Power Lighting/Automation: Distribution: Location Connections: Notes: Distribution Location: Connections: Notes: Distribution: Location: Connections: Notes: Distribution: Location: Connections: Notes:
1200 Amps Disconnect A 400 Amps, Down Stage Right Cam-Locks with Ground and Neutral Reversed Disconnect AAAmp sub of A Up Stage Right Cam-Locks with Ground and Neutral Reversed
Disconnect AAAmp sub of A Up Stage Right Lugs for bare ends Typically used for motor power Disconnect B 400 Amps, Basement Electrical Room Cam-Locks with Ground and Neutral Reversed Cable path to Disconnect is through a rabbit hole located down stage right. Disconnect C 400 Amps, Basement Electrical Room Cam-Locks with Ground and Neutral Reversed Cable path to Disconnect is through a rabbit hole located down stage right.
Distribution: Location: Connections: Notes:
Audio Distribution: Location Connections: Notes:
400 Amps Disconnect D 400 Amps, Basement Crossover Cam-Locks with Ground and Neutral Reversed Cable Path Stage to Disconnects D is through a rabbit hole Down Stage Left. Distribution Disconnect DDAmp sub of D Location: House Right (Stage Left) Cove Connections: Cam-Locks with Ground and Neutral Notes: Cable Path Stage to Disconnects D is through a rabbit hole Down Stage Left. This space is commonly use by visiting companies for location amp racks. 60 Amps Disconnect 60 Amps, Basement Crossover Lugs for bare end tie in Path to outside is through wardrobe area
Shore Distribution: Location: Connection: Notes:
LIGHTING ROAD / RENTAL SYSTEMS: 1) Usual visiting board position is at the rear of the orchestra level on centerline 96 from stage. This area is 8 wide x 5 Deep and elevated 12. 2) Lighting Power Stage Right Alcove 3) DMX Control Inputs: (All one DMX universe) a) Back Stage Right b) Back of House i) Snake path to FOH runs through basement level through rabbit holes in this area ii) 200 Snake needed 4) The theatre does not have a Front of House electric or cove position a) NO RIGGING POINTS IN HOUSE CEILING FOR LIGHTING OR SOUND i) The theatre has a fully suspended plaster lath ceiling from original construction with no high front position. ii) Due to historical landmark status of building one has not been put in. 5) Option to control both Box Boom and Balcony Rail positions HOUSE SYSTEM System: Dimmer: House Lighting Console: DMX Control Inputs: Front Lighting: Projection Booth Circuits: Control: Throw: Fixtures: Lamp: Balcony Rail Circuits: Control: Throw:

Dimmer per Circuit with Patch Panel in Basement 217 2.4 ETC Sensor Dimmers Available for Production Use 1 ETC Expression 3 Back Stage Right or Back of House
None Manual Approx. 134 at 26 degrees 3 Xenon Super Trooper II 2k HMI

Fixtures:

48, House Circuits 1- 48 Starting House Right (Stage Left) Dimmer per Circuit, 2-DMX runs available from down stage right Curved rail 54 Throw at center at 15 degrees 50 to plaster at centerline 14 elevation above stage 24 Altman 30 degree 4 Altman 40 degree
Box Boom Right & Left Circuits: 12 circuits per side House Right Circuits 49-60 House Left Circuits 61-72 Control: Dimmer per Circuit, DMX run available from down stage right Throw: Ladder Position 37 Throw from bottom at 23 degrees 41 Throw from top at 33 degrees 22-6 to plaster line 38 of centerline 15 to 22 elevation above stage Fixtures: 12 Altman 30 degree per side Stage Lighting: Circuits
36 Stage Floor Pockets Stage Left 73-87 Stage Right 88-102 Upstage 103-Loading Rail Sacopex 1-12 Stage Right 115-Basement Sacopex 1-5 Stage Right 187-216 48- Source Four Pars w/ a 575 lamp 18 Altman 360 Q 6 x 12 with super reflector for 575w lamp 18 Altman 360Q 6 x 16 with super reflector for 575w lamp 23 Altman R40 strip lights with 250w lamps 5 Altman Sky-Cyc-3 Cell with 1000w lamps

Fixtures

AUDIO ROAD / RENTAL SYSTEMS: 1) Usual visiting Front of House position is at the rear of the orchestra level on centerline 96 from stage. This area is 11 wide x 10 Deep 2) Usual visiting Amp location is typically a storeroom house right with direct access to the stage. a) Snake path to FOH runs through basement level through rabbit holes in this room b) 200 Snake needed c) The load-in path to this room is through the house not across the stage 3) House Patch Locations a) 4 Channels at FOH Position b) 2 Channels DSL and 16 Channels DSR c) 3 Dry Lines to Spot booth 4) Road PA a) NO RIGGING POINTS IN HOUSE CEILING FOR LIGHTING OR SOUND i) The theatre has a fully suspended plaster lath ceiling from original construction with no high front position. ii) Due to historical landmark status of building additional points have not been put in. b) There are two, 1 ton points located 22-11 right and left of center over the stage apron 5) Audio Levels a) In consideration for its audience the Hershey Theatre has established a maximum decibel level of 85db for performances

HOUSE SYSTEM HOUSE CONTROL CONSOLE: 1. Allen & Heath GL3800 console 2. 24 inputs including 8 stereo inputs, 8 sub groups / 10 aux sends, 4 way matrix L, R, Mono master. 3. Located above back of balcony, house left, adjacent to spot booth EQUALIZATION: 1. 8 Channel Ashley Protea System II 4.24G Digital EQ with delay, compression available for each channel LOWER ORCHESTRA LOUDSPEAKERS Cabinets: 2 - Custom 2-way loudspeakers right & left of proscenium Location: Right & left of proscenium, 5 above stage level Amps: 1 - BGW-SPA3 amp per cabinet Amp Location: Anti-Pro rooms left and right Delay: Ashley Protea System II 4.24G UPPER ORCHESTRA (UNDER BALCONY) LOUDSPEAKERS Cabinets: 30 - Altec #405-8HT loudspeakers/transformers distributed in ceiling Location: Distributed in groups of 3 around under balcony lighting fixtures Amps: QSC ISA 300T AMP Amp Location: Back of House Left Delay: Ashley Protea System II 4.24G BALCONY (MAIN CLUSTER) LOUDSPEAKERS Cabinets: 2-Custom 3-way loudspeakers JBL Low and Mids Altec Highs Horns 40 X 60 Location Amps: Amp Location Built into proscenium behind decorative framework 1 - BGW-SPA3 Amps per cabinet Attic Catwalk on Proscenium Wall
SHOW MONITORS: 1. Follow spots, all dressing rooms, back stage hallway and common areas powered by a TOA-M-900 mk2 amp 2. Talk back from dressing rooms is not possible. 3. Follow spot both is delayed using a channel of an Ashley Protea System II 4.24G
STAGE MONITORS: 1. AMPS a. 1 QSC RMX ch Power Amplifier b. 1 Crown #DC-ch Power Amplifier c. 1 BGW ch Power Amplifier 2. SPEAKERS a. 2 EV #FM12-2 Floor Monitor Loudspeakers. b. 2 EV #FM-12-3 Floor Monitor Loudspeakers. c. 2 Column speakers d. 2 EV SH-1502 Loudspeakers 3. Monitor control room located off stage right (amps, EQ's, and patch panel) 4. PROCESSORS a. 8 ch Ashley Protea System II 4.24G with wired remote. 3. Monitor system is equipped for six channels of mix onstage from rental monitor mix board or 2 channels controlled at main audio board. PAGING SYSTEM: 1. All dressing rooms and common areas are equipped with speakers for program monitor and paging. All speakers have individual volume control. 2. 4 Airphone #TB-6F telephone intercom stations and paging stations. Locations: 1. Stage Manager position off stage right 2. Sound Room 3. Spot/Projection Room 4. Box Office INTERCOM SYSTEM: 1. Intercom: Single channel (Clear-Com compatible) 2. Locations See diagram for locations on stage Orchestra Pit Lower Orchestra Under Seat H-114 Rear of Orchestra Level Sound Room Spot/Projection Room (3) Loading Bridge Panel Room Dimmer Room 3. Headsets PI SMH 310 and Telex PH88 SNAKE SYSTEM: 1. One 20-connector stage box, 4fixed inputs FOH, 2 fixed inputs SL and 3 fixed inputs upstage. 2. See diagram for location of mic inputs on stage. 3. Six Channel snake from Balcony Rail to DSR patch panel 4. 1 Channel under seat H-114 on Orchestra Level to Patch panel DSR 5. 3 Dry Lines to spot booth via stage DSR or USR

MICROPHONES: 1. 1-AT-25 with switch 2. 6-Shure #SM-57 3. 6-Shure #SM-58 4. 2-Crown #PZM-30GP 5. 2-AT 853RX Cardioid Condenser 6. 2-Samson CO2 Condenser STANDS/CABLE: 1. 5 Atlas #MS-12C Stands 2. 1 Atlas DS-7 Desk Stands 3. 4 Atlas GN-13 Goosenecks 4. Ample mic cable available OTHER EQUIPMENT: 1 Sure 4 Channel mixer DS 2 Radial MK3 direct boxes 1 Radial PCDI stereo direct box 1 CD player (Tascam CD-01U) at FOH booth position 1 CD / Cassette player (Tascam) at monitor position 5 Ch DBX Compressor 1 Alesis Nano-verb
STAGE LAYOUT: ______________________________________________________ 0000 US P I N X SR R X A I L X X ______________________________________________________ DS PROC 00 to patch 00 to patch 00 panel 00 panel ______________________________________________________ DS APRON X PIT 0 - Mic Inputs X - Intercom Stations (**Diagram not to scale**)
20 Channel Head Box 50' R STAGE SL

X (23)(24)

Musical Instruments Grand Piano Upright #1 Upright # 2 Percussion
Black 7 Steinway & Sons Piano Bell Bottom B w/ Padded Bench Black Yamaha Model U5 Black Yamaha U-SPE Pro Upright w/ Artist Bench Standing Chimes 19 Cymbal with Stand 20 Cymbal Set with Straps and Pads
Wardrobe Location: Wardrobe 1 Theatre Basement, Stage Left 18w x 10.5d Tables Direct Access to Sink Power amp 1-Phone Jack Additional Dryer Power located in this room 11w x 6d No Sink Tables Power 2-20 amp located in nearby hall L-Shaped Lower section 14 x 14, upper section 9x 9 No Tables Direct Access to Sink Power 4-20 amp Theatre Basement, Stage Left, Through Wardrobe Large Load 2 Large Load 1 each for a washer and dryer

Wardrobe 2

Wardrobe 3
Laundry: Location Washers Dryers Additional Hook ups Dressing Rooms: Location:
ROOM # 1** FLOOR ROOM USE
Dressing rooms are located off stage right on 5 floors
SIZE CAPACITY BATHROOM SINK SHOWER (MIRRORS) PRIVATE PRIVATE PRIVATE PRIVATE PRIVATE PRIVATE COMMON COMMON COMMON COMMON COMMON COMMON COMMON COMMON PRIVATE YES YES YES YES YES YES YES YES YES YES YES YES YES NO YES YES YES YES YES YES YES
COMMON COMMON COMMON COMMON COMMON COMMON COMMON
IT PH FURNITURE JACK JACKS CHAIRS TABLES 3 10
BASEMENT MAIN MAIN SECOND SECOND SECOND THIRD THIRD THIRD FOURTH FOURTH FOURTH FOURTH FIFTH FIFTH
CHORUS GREEN DRESSING DRESSING DRESSING DRESSING DRESSING DRESSING DRESSING DRESSING DRESSING DRESSING OFFICE CHORUS
19W X 13D 7W X 8D 14W X 9D 11W X 13D 8W X 11D 8W X 9D 11W X13D 8W X 13D 8W X 13D 11W X 13D 8W X 13D 8W X 10D 11W X 13D 17W X13D 19W X 13D

NO YES

Phones and Internet: Phone and Internet access is available to visiting productions for an additional fee contact Event Services for rates. There is no wi-fi internet service at the theatre. For the number of phone lines possible per dressing see dressing room schedule Internet jacks are located in dressing rooms 11,21,31,41,and 51 as well as the green room Line 1 Line 2 Line 3 Line 4 Line 5 Line 6 Line 7 Company Main Line Company Fax Company Modem As Assigned As Assigned As Assigned As Assigned (717) 534-1998 (717) 534-9876 (717) 534-2529 (717) 534-2979 (717) 534-0639 (717) 534-0545 (717) 534-9959

Hospitality and Catering The Hershey Theatre has no on-site catering facilities we will be happy to work with your caterer or suggest one for you to use. There is no readily available supply of ice at the Hershey Theatre
Elevator and Lifts Dressing Room Elevator: Size: 5-5 Wide x 53 Deep Location: Off Stage USR Capacity: 2500 lbs Speed: NA Service: Basement Service Corridors through 5th floor dressing rooms Door: Stage Side: 3-0 Wide x 6-11 High Street Side 3-10 Wide x 6-11 High Orchestra Pit Lift: Size: Approx. D shaped 40 wide x 10@ Center Location: Approx. 7-4 Down Stage of plaster line Capacity: 7000 lbs Speed: 141ft. / sec. Full travel 60 sec. Service: Lift can travel 8-4 between house orchestra level and trap room. Cannot come to stage level Note Lift is operated from a push button DSR Note: Four Access Doors at Basement Level 3 DS (SL/C/SR 1 USC) Film Sound Lift: Size: 6-3 deep x 15-0 wide Location: 7-4 from plaster line on centerline Capacity: 2000 lbs Speed:.56 ft / sec Full travel 24 sec. Service: Trap Room to Stage Level / Elevated Stage Platform + 13-6 Note: Lift is operated from a push button DSR Note: Lift is not available to visiting Productions Down Stage Lifts 1-SL, 2-CS, & 3-SR Size: 9-0 deep x 36-0 wide Location: 13-7 from plaster on centerline, Service: Lift range of motion is stage level to + 7-1 above stage. Capacity: 9,000 lbs each lift. Speed:.134 ft / sec Full travel 52 sec. Notes: Each Lift 9-0 deep x 12-0 wide Lifts are operated from push buttons DSR Must be run individually Lifts are referenced 1,2,3 starting on SL
Up Stage Lift: Size: Location: Service: Capacity: Speed: Notes:
Lift(s) Cannot Go Below Stage Level
9-0 deep x 36-0 wide 22-7 from plaster on centerline, Lift range of motion is from 6-3 below stage to 7-1 above stage 25,000 lbs.134ft. / sec Full up travel 52 sec. Lifts are operated from push buttons DSR

BI-AMPLIFICATION

To bi or not to bi by John F. Allen In recent years the technique known as bi-amplification has received quite a bit of attention. Conventional two-way speakers are two wire speaker systems fed by one amplifier. The two wires are connected from the amplifier to a crossover circuit or frequency splitter, that sends the low frequencies to the bass drivers and the high frequencies to the tweeters. These conventional crossovers are passive. In other words, they operate without the need for external power. Since the electrical signals that pass through passive crossovers are at amplifier output (or speaker) level, the components used are rather hefty, though not too expensive. In a bi-amplified system, an active crossover requiring external power and operating at amplifier input or line level, is placed before the amplifiers. This means that a two-way speaker system now needs two amplifiers; one for the woofer and one for the tweeter. There is a misunderstanding spreading around some in this industry that there is one truth in audio and it is that there is a clear and irrefutable benefit in bi-amping every loudspeaker in every sound system. However, the issue isnt quite that simple. Why, for instance, should one spend the extra money and incur the added complexity of a biamplified system if, because of other design choices, there results no audible improvement in the sound quality? Basically, there are two valid reasons for bi-amplification. If the sound system designer is in a situation where it is the most efficient way to deal with multiple speaker sections and to overcome an audible weakness of some part of the reproducing chain (speakers, amplifiers, passive crossovers etc.). You bi-amplify if it really helps. Otherwise, one should avoid it if possible because its more expensive and more likely to drift. To design and build a loudspeaker cluster that will cover a stadium from a point high above the center of the building, one uses a multitude of woofer sections and high frequency horns. There are often several high frequency horns of progressively longer throw coverage patterns stacked one above the other designed to evenly cover a large area. In installations such as these, it is far more convenient to use separate amplifiers for not only the woofers and tweeters, but for the different tweeter horns as well. Sometimes bi-
2 amping is the easiest way to match the impedances presented to the amplifiers by a large number of drivers. In addition, it can aid the installers by allowing individual level adjustments for the different horns to be done with the simple input level controls on the amplifiers. The horns that are covering the most distant seats may very well need to play louder than those covering the nearer seats. Should there be additional high frequency horns underneath a grandstand or balcony, fed by delayed signals, a bi-amplified approach is the easiest way to go. Expensive yes, but much less tedious to set up. If a designer wished to use passive crossovers in such systems, the level adjustments for the various speakers would need to be done with transformers. Once set, of course, such a system would presumably maintain its calibration for years without drifting. But a technician would have a more difficult task should he be required to later change the level of a particular speaker section by just 2 dB. Other situations that benefit from bi-amplification are cases of mismatched speaker systems, poor performance from the available passive crossover, portable road systems or custom speaker assemblies for which no passive network is available. A mismatched speaker system is one where there is a significant difference in sensitivity between the low frequency sections and the high frequency sections. Such a difference is typical of speaker systems that use a direct radiator woofer and a large horn loaded tweeter, for instance. Systems such as these can exhibit as much as an 11 dB (12 1/2 times power) difference in sensitivity between the two sections. Using a single amplifier with these speaker systems means that not only do you need a much more powerful amplifier to drive the relatively insensitive woofer, but the amplifier may produce greater intermodulation distortion of the high frequencies when asked to push the bass so hard. Bi-amplification would avoid this problem. There is another factor in favor of bi-amping speakers with horn tweeters and direct radiator woofers. The woofer drivers in such systems are usually mounted in vented boxes. This is to say that the air behind the drivers inside the cabinet, is vented to the outside through one or more holes or ports. Also, the less sensitive a speaker, the greater the driver excursion required to deliver a given sound level in the room. With diaphragms needing to move so much farther and the use of vented boxes, the electrical damping factor of the amplifier becomes more important for controlling the drivers motion and minimizing overshoot. The insertion of anything into the speaker line that adds resistance, such as a passive crossover, reduces the damping factor. Therefore, I recommend that anyone considering the use of a passive crossover should determine its insertion loss. Some crossover designs are reputed to lose as much as 3 dB or more. A 3 dB loss means that 1/2 of the amplifier power is wasted (heating the crossover). An ideal

3 crossover will have no more than a 1/2 to 1 dB loss which is acceptable in many situations. If one is especially upset about a 1 dB loss in a theatre sound system, locating the amplifiers at the speakers would be as effective in reducing this loss as bi-amplification and less costly. However, its better to design sound systems with enough headroom so that a 1 dB loss doesnt matter. Headroom, or more precisely the lack of it, is one of the most common excuses that sales people use to sell bi-amping. The story goes that if an amplifier runs out of power and clips because of a large bass signal, the more fragile high frequency drivers may be damaged. All this is absolutely true until one asks why there isnt enough amplifier power and speaker sensitivity to avoid clipping in the first place. Several people have asked why I do not bi-amplify our HPS-4000 sound systems. The answer is that I have designed the systems using loudspeaker systems that are an order of magnitude more efficient than the direct radiator / horn combinations. The woofers, midranges and tweeters of these efficient systems all have the same sensitivity, as opposed to the 11 dB difference encountered with direct radiator / horn combinations. The passive crossovers I use have an insertion loss of about 1/2 dB and a 1000 Watt capacity. In addition, they are designed specifically for the speakers they are used with, which means they can have less circuitry. The design of these loudspeakers employs sealed back air chambers and no vents. This approach provides a high mechanical damping factor not available with vented boxes. This, and the lower driver excursion obtained with the more sensitive design, results in the electrical damping factor provided by the amplifier becoming less important. In other words, the normally valid reasons for bi-amplification dont usually exist with the speaker designs I like to use. This is one of the many reasons I chose efficient loudspeakers. One last reason I dont bi-amp our sound systems is that, so far at least, I havent been able to hear the difference between the systems where I have used multiple amplification and those where I have not. A test was conducted by a designer of an electronic crossover. Using a 3-way fully horn loaded loudspeaker, a 12 pole switch was installed so that the system could be used with its own passive crossover or the electronic crossover and tri-amplification. After the levels were properly matched, none of the participants, including the designer of the electronic crossover, could tell which was which. The question remaining in this case is why one should go to the trouble and expense of three amplifiers per speaker when no

4 improvement is heard? The only reason to bi-amp or tri-amp in these situations would be the need for two to three times more amplifier power than is available from a (reliable) single amplifier. This can happen in very large theatres. (See BOXOFFICE October, 1982 page 32). Recently a new development may add a new factor to the issue. BGW Systems, Inc. has introduced a signal Processing Amplifier called the SPA-3. Depending on the configuration ordered, the unit can be used to either bi or tri-amplify 2 or 3 way speaker systems. These SPAs contain their own electronic crossovers, independent high quality power amplifiers, time alignment delays, a parametric equalizer for the woofer to take care of any room peaks and an adjustable treble boost for the tweeters. This kind of device can be especially useful for theatre systems that use cinema processors that do not have 1/3rd octave equalization. One particularly nice feature is that BGW will supply these SPAs with crossover filters designed for the speaker systems you are using. Theatre sound system designers who are currently using stage speakers with the inefficient direct radiator type woofers and horn loaded tweeters, should investigate these new signal processing amplifiers. We have seen that the issue of multiple amplification of loudspeakers is not always clear. Like many other things in audio, if we can cut through the religious fervor, we can see biamping as a tool that can be helpful in some circumstances, or unnecessary and wasteful in others. Copyright 1986, John F. Allen. All Rights Reserved. John F. Allen is the founder and president of High Performance Stereo in Newton, Mass. He is also the inventor of the HPS-4000 cinema sound system and in 1984 was the first to bring digital sound to the cinema. John Allen can be reached by E-mail at JohnFAllen@aol.com.