{{< MultiGalleryComponent galleries="carl-dunn-led-zeppelin-1973, 1973-led-zeppelin, 15a-zeppelin-may-1973" >}} The first leg of the 1973 Led Zeppelin US tour was scheduled for May 4 to June 3, 1973 and the second leg was scheduled for July 6 to July 27,1973. Peter Grant wanted a larger lighting rig for the tour, so Kirby Wyatt designed the largest Showco lighting system to date using eight of the new pneumatic light trees, three onstage follow spots mounted on three scaffolding towers and a reflective mirrored backdrop behind the band. The photo below shows the stage setup with the house lights turned on:

{{< StoryImage id="showco-1973-led-zeppelin-002-zep-73" title="1973 Stage Setup" caption="Led Zeppelin 1973 US tour stage setup. Kirby Wyatt’s lighting design included eight of the new Showco lighting towers and three onstage follow spots mounted on scaffolding towers that were erected downstage left and right and upstage center. Kirby also designed mirrored panels behind the band and a round reflective effects panel mounted on the scaffolding at rear center stage. Extremely bright arc welders were sometimes employed behind the guitar amp line and drums to produce dramatic special effects reflected by the mirrored panels. " credit="© Rusty Brutsche Archive" size="large" >}} {{< StoryImage id="showco-010-zep-tampa-1973" caption="1973 Led Zeppelin tour stage setup and audience in Dallas Memorial Auditorium, May 18, 1973. The Showco sound system consisted of two of the new three-way speaker systems." credit="Photo Carl Dunn" size="large" >}} {{< StoryImage id="showco-zep-15a-001" caption="Led Zeppelin 1973 tour outdoor show with 3-way sound systems and the Big Outdoor Bass Horns." credit="© Jim Bornhorst Archive" size="large" >}} {{< StoryImage id="showco-1973-led-zeppelin-009-zep-73" caption="Led Zeppelin 1973 US Tour using Showco Lighting." credit="© Rusty Brutsche Archive" size="responsive" >}}

## Showco 3-way sound system 1973 {{< GalleryComponent id="1973-led-zeppelin-outdoor" >}} The 1973 Led Zeppelin world tour began with a tour of the UK starting in January followed by a tour of Europe in March. The US leg started with two outdoor stadium shows in Atlanta on May 4 and Tampa on May 5. We had made another big improvement to the Showco sound system in 1973 by going to a three-way speaker system. We replaced the four 2470 drivers on the mid-range horns with two JBL 2480 two inch drivers and we designed a new high frequency horn cabinet that housed two JBL 2390 horns (without the lenses) each with a JBL 2470 one inch driver. Jim Bornhorst in 1973 designed a new three-way master crossover drive panel with crossover points of 800 Hz between the bass and the mid-range horns and 4,000 Hz between the mid-range horns and the new high frequency horns. We continued mounting the power amplifiers inside the bass and horn cabinets. We used the new dual front loaded bass cabinet design in all Showco systems and retired the four speaker bass reflex cabinets. We used four of the new three-way indoor sound systems for the Led Zeppelin show at Tampa stadium on May 5, 1973 for a crowd of 56,000 people. {{< StoryImage id="showco-1973-zep-outdoor-010-zep-outdoor-73" caption="Four of the new Showco three-way sound system for Led Zeppelin show in Tampa Stadium on May 5, 1973." credit="© Rusty Brutsche Archive" size="large" >}} ## Showco Drive Line Design Upgrade 1973 Another major improvement that we made to the sound systems in 1973 was in the design of the drive lines from the master crossover drive panel in the mixing console to the stage to drive the power amplifiers for the horns and bass cabinets. The first-generation design used a 27 pair snake cable from the mixing console to the stage where 20 lines were for microphones, two for the low and high frequency drives, three lines for the stage monitor mixes and two lines for the intercom system. The stage end of the snake was connected to a stage mic box which was a metal box with XLR 3 pin connectors for the 20 microphone lines on the top surface of the box. The connectors for the drive lines, monitor mixes and intercom were mounted on each end of the box. The stage mic box was placed at the center rear of the stage usually behind the drum kit to minimize the length required for the cables from the microphones. We then used a Belden multicable, usually with 6 shielded pairs, to connect the drive lines, monitor mixes and intercom from the mic box to the speaker stacks on each side of the stage. Figuring out how to route these small Belden multicables to be out of the way and avoid damaging them was often difficult and awkward. {{< StoryImage id="showco-6-73-sound-gear" title="Legacy Stage Box" caption="First generation stage mic box with connectors on the sides connected to Belden 6 pair multicable 1972." credit="© Rusty Brutsche Archive" size="medium" >}} We decided to add a second 27 pair “drive line” snake from the mixing console to the stage that was dedicated to drive lines, monitor mixes, intercom lines and spare lines. The drive line snake would go from the mixing console to a Drive Line JBox that was located on the stage left speaker platform behind the speakers. The Drive Line JBox would have a paralleled 27 pair chassis mount snake connector for a second 27 pair snake that would be run either behind or under the stage to a second Drive Line JBox located on the stage right speaker platform behind the speakers. The new JBox design provided separate left and right three-way drive lines, an auxiliary set of three-way drive lines, four monitor mix lines, three intercom lines and 7 spare lines. This design totally separated the mic lines and the mic line stage box from the drive lines, monitor mix and spare lines to the stage. {{< StoryImage id="showco-1973-zep-outdoor-011-zep-outdoor-73" title="New Drive Line JBox" caption="New stereo three-way drive line JBox first used on Led Zeppelin 1973 US tour. Note the 81 pin snake connectors with potted blue silicone strain reliefs. The 27 pair snakes had a male and a female connector on each end so they could be connected together to extend the length. We carried standard lengths of 100 ft and 150 ft. The mixing console to stage run was typically 300 feet and the cross-stage run was typically 100 feet. " credit="© Rusty Brutsche Archive" size="medium" >}} ## Big Outdoor Bass Horns 1973 {{< GalleryComponent id="1973-leon-russell-ontario-outdoor-pa" >}} In 1973 we decided to build some Really Big Outdoor Bass Horns to improve the sound coverage for large outdoor venues. Keny Whitright and Ron Fox worked on the project. Keny designed a large fiberglass horn that would attach to a separate plywood speaker cabinet with two JBL 15” speakers and a Showco 200 watt amp module. The horn would have a 6 ft wide X 4 ft high mouth that would taper down to a vertical throat that was about 8 inches wide X 4 ft high. The depth of the horn was about 6 ft. Keny used a compound curve for the horn shape that he had found in an audio textbook that had a conical function at the throat that changed to a hyberbolic function for the remaining distance to the mouth. Ron built a huge mold and made the horns using a fiberglass chopper gun. Ron also built the plywood speaker cabinets that were designed to attach with spring latches to the fiberglass horn. We built twelve of the Big Bass Horns, and one of the first shows we did with them was a Leon Russell show on July 29,1973 at the Ontario Motor Speedway in Ontario California. The new bass horns performed well but not well enough to justify their large size. We used them for outdoor shows for several years, but we did not build anymore and later sold them to another company.

{{< StoryImage id="showco-leon-russell-mid-horns-1973" caption="Showco outdoor Big Bass Horns Leon Russell July 29, 1973." credit="© Rusty Brutsche Archive" size="responsive" >}} {{< StoryImage id="showco-1973-leon-russell-ontario-outdoor-pa-leons-pa-21" caption="JBL 2356 mid-range long throw horns with JBL 2480 drivers are stacked on top of the Big Bass Horns. Inside speaker stack and stack onstage is a standard indoor system. This was a three-way system. The JBL 2361 3 cell long throw horns with JBL 2470 drivers positioned under the JBL 2356 horns were used for high frequencies. The inside stacks of the standard indoor system had the new high frequency horn cabinets with the 2390 rectangular horns and 2470 drivers. A forklift driver accidentally dropped one of the fiberglass Big Bass Horns to the ground from about 25’ up. They were so robust that it just bounced 2 or 3 times with no damage whatsoever! " credit="© Rusty Brutsche Archive" size="responsive" >}} {{< StoryImage id="showco-1973-leon-russell-ontario-outdoor-pa-leons-pa-25" caption="Front view of Showco speakers for Leon Russell Ontario Motor Speedway July 29, 1973." credit="© Rusty Brutsche Archive" size="large" >}}

## Quicksilver Messenger Service Show - April 20, 1973 {{< GalleryComponent id="1973-quicksilver" >}} We used the Big Bass Horns for a Quicksilver Messenger Service outdoor show at Memorial Stadium in Daytona Beach, Florida on April 20,1973. Buddy Miles and Boot were also on the show.

{{< StoryImage id="showco-1973-quicksilver-001-quicksilver-73" caption="Fiberglass mouths of the Showco Big Bass Horns used on Quicksilver outdoor show in Memorial Stadium in Daytona Beach, Fl April 20, 1973. " credit="© Rusty Brutsche Archive" size="responsive" >}} {{< StoryImage id="showco-1973-quicksilver-002-quicksilver-73" caption="Speaker cabinet with two JBL 15” speakers for Showco Big Bass Horns used on Quicksilver outdoor show at Memorial Stadium in Daytona Beach, Fl on April 20, 1973. The spring latches attached the horn mouth to the speaker cabinet. " credit="© Rusty Brutsche Archive" size="responsive" >}}

Showco History