The next leg of the Zeppelin tour was scheduled to begin on August 10, 1970, and Three Dog Night also had tour dates booked throughout 1970 - so we had to build a second Showco sound system to cover both acts. Maxson and I wanted to build standardized equipment that was designed for the road. Every piece of equipment would have casters and the size of the individual pieces of sound equipment, especially the bass cabinets, would be small enough to be manageable by the road crews and fit through a 30” doorway. We wanted to build multiple systems so we could do multiple tours simultaneously and the equipment would be interchangeable so multiple systems could be used together to do larger shows. And most importantly we wanted the equipment to be reliable and easily serviceable. All of the cable connections would have connectors and the cables would be color coded for length and application We selected the Shure 548 microphone as the primary mic for our sound system. The 548 was a new model that Shure had just introduced and it used the new Unidyne IV element. It also featured a male XLR 3 pin low impedance balanced microphone connector that was essential for our application. We needed a good strain relief on the cable/connector connection, and we needed the ability to have mic cables with both male and female XLR connectors so the cables could be connected together for extended lengths. The 548 also had a metal dust cover that made it more rugged and more suitable for live portable sound applications. See the [Shure 548 Unidyne IV](https://service.shure.com) documentation at service.shure.com. We purchased Atlas mic stands, and we made our own mic cables using Canon XLR connectors and Belden 8413 shielded two conductor cable, which had a smaller outside diameter than the Belden 8423 cable that was commonly used. {{< StoryImage id="showco-shure-548-unidyne-iv" title="Shure 548" caption="Shure 548 Unidyne IV Microphone with Integral XLR Connector 1970. We used the model without the on/off switch." credit="Photo from service.shure.com" size="medium" >}} Jack Calmes had set the pricing for the rental of the Showco sound system at $750 per show ($6,500 in 2025) which included two crew, trucking and all travel expenses for the crew including food and lodging. The rental fee was payable in cash at every show so although it was a challenge for the crew to collect and wire the cash back to Dallas, we had the advantage of not having to carry any receivables and we did not worry about bad debts-no cash, no show were our financial terms. Since we were now generating revenues, were able to afford to hire some additional employees. We hired Chuck Conrad who was an electronics engineer that we had met while Chuck was working at Taft Broadcasting. Maxson worked with Chuck to develop a second generation Showco Master Crossover Drive Panel with internal line amplifiers that were designed using integrated circuit chips and a Spectra Sonics electronic active crossover card. It was a big improvement over the first generation Maxson passive crossover that used the RC network and the makeshift line amplifiers. The master panel also included a headphone intercom system for communication between FOH and the stage, plus volume controls for the high and low drives with separate mute switches for each drive. Chuck designed a six-channel audio mixer, named the Showco Yellow Mixer because it was painted yellow, that used integrated circuit chips and featured tone controls on each of the six microphone inputs. Chuck said that he used yellow paint because it was highly visible in the dark and readily available from Elliott’s hardware, our local super-duper, stock everything and charge high prices hardware store. (Home Depot put stores like Elliott’s out of business). At the time, that particular yellow paint was popular for repainting refrigerators. Chuck designed the second generation stage monitor mixer that featured three separate monitor mix output channels. Each channel had a volume control for the output of each of the four yellow mixers in the rack, a monitor volume control that fed the monitor mix into the headphone system, a master volume control and bass and treble controls for each mix. Each monitor channel used line amps with a 600 ohm balanced output made with integrated circuit chips to drive the monitor power amps and speakers. For the second generation Showco mixing console, I built a double wide, vertical 19” equipment rack that housed four yellow mixers, the new Master Crossover Drive Panel and the new stage monitor mixer - along with other equipment including a Melcor 7 band equalizer, a UREI 1176LN limiter, a Kenwood oscilloscope, two drawers and a Sony cassette tape recorder. Keny Whitright later added an active combining network for the four yellow mixer outputs that included a 40 Hz high pass filter to remove unwanted low frequencies from being reproduced by our sound systems.

{{< StoryImage id="showco-1970-73-sound-equipment-020-equipment-70-73" caption="Second generation Showco Mixing Console with Chuck Conrad Designed Master Crossover Drive Panel, Four Showco Yellow 6 Channel Mixers and a Three Channel Monitor Mix Drive Panel 1970." credit="© Rusty Brutsche Archive" size="medium" >}} {{< StoryImage id="showco-1970-73-sound-equipment-023-equipment-70-73" caption="Rear View of Second Generation Showco Mixing Console 1970. A 27 pair mic snake connector was mounted in the center of the vertical dividing wall of the double rack." credit="© Rusty Brutsche Archive" size="medium" >}}

## First Showco Studio Style Mixing Console In the latter part of 1970, Chuck Conrad and Maxson also designed and built the first Showco recording studio style mixing console. It used the circuitry and components from the yellow mixers, master crossover panel and the monitor mixer mounted in a recording studio style chassis. The console had twenty mic channels each with input pad, solo, monitor sends and bass and treble equalization. The monitor mixer channels, master crossover panel and stage intercom were built into the console. The console used rotary potentiometers instead of silders to control the volume of each microphone in the audio mix. {{< StoryImage id="showco-1970-73-sound-equipment-017-equipment-70-73" title="Studio Console" caption="First Studio Style Showco Mixing Console Designed By Jack Maxson and Chuck Conrad 1970." credit="© Rusty Brutsche Archive" size="medium" >}} ## Design of Showco Speakers Evolves 1970 Throughout 1970 Maxson and I toured with our two sound systems doing shows not only for Zeppelin and Three Dog but also many other shows. We were learning quickly what worked and what didn’t work with our equipment. The JBL 2470 drivers on the JBL high frequency horns were failing at a high rate. JBL sold replacement diaphragms that were field replaceable but they were expensive and having the drivers fail during a show was unacceptable. JBL made a 2” driver with a higher power rating, the 2480, but the frequency response was only out to 6 kHz compared to the 12kHz of the 2470 and that was not enough for our two-way system. We decided to go to four 2470 drivers on each of the 2350 radial horns (the three cell JBL 2361 long throw horns were not compatible with four drivers). We mounted two 2470 one inch drivers on a JBL 2332 dual 1” entry adaptor that was tapered for 2 inch horn entry. Two 2332 adaptors with four 2470 drivers were then mounted to a JBL 2329 dual entry throat that matched two 2” diameter drivers to a JBL 2350 radial horn throat. This arrangement provided equal path lengths from the four 2470 drivers to the horn throat but increased the throat distortion. By today’s standards of precise phase alignment between sound system transducer components and short direct path lengths from mid range drivers to horns, this seems like a bizarre choice. But in 1970 we were not thinking about throat distortion and phase alignment; we just needed the drivers to keep working and not blow up. When I built the first plywood cabinets for the JBL high frequency horns, I built them too narrow so they were unstable on the casters. I mounted the internal components with hardware that left the bolt heads protruding from the outside surface of the cabinets and for internal access I made one entire side of the cabinet removable which weakened the structure of the cabinet. When the cabinets were loaded in the Ryder truck the vibration and shock forces caused the bolt heads to destroy any surface that had contact with the horn cabinet such as the side of the truck or the fiberboard bass cabinets. I realized that I needed to design all of the equipment packaging to have perfectly smooth sides and the horn cabinet width needed to be increased so the cabinet would be stable on the casters. Additionally, the dimensions of the various cabinets needed to be chosen to accommodate tight truck packs inside a 90” wide truck trailer. I found some hardware made by J. H. Sessions & Son that was designed for steamer trunks but also used by companies that made flight cases for musical instruments. The hardware was designed to be mounted on the outer surface of a trunk but I mounted the hardware on the inside surface of the cabinet so that the handles and latches would be totally flush with the outside surface. I mounted the hardware using aluminum pop rivets that had flush heads. Sessions is no longer in business, but these are photos of handles and latches like I used in 1970:

{{< StoryImage id="showco-27-case-latch" title="Hardware" caption="Recessed Latch and Handle for Showco Cabinets and Cases." credit="Penn-Elcom.com" size="medium" >}} {{< StoryImage id="showco-28-case-handle" title="Hardware" caption="Recessed Latch and Handle for Showco Cabinets and Cases." credit="Penn-Elcom.com" size="medium" >}}

{{< StoryImage id="showco-brutsche-photo-print-scans-rusty-brutsche-1970-3" title="Building Cabinets" caption="Rusty Brutsché building cabinets for the Showco sound systems 1970." credit="© Rusty Brutsche Archive" size="medium" >}}

{{< StoryImage id="showco-1970-73-sound-equipment-031-equipment-70-73" caption="Photo of the final design for the horn cabinets with the four 2470 drivers, the increased width and an access door. The black capacitor mounted on the inside wall of the cabinet filtered out any low frequencies that might accidently be fed from the Marantz amplifier to the 2470 drivers." credit="© Rusty Brutsche Archive" size="medium" >}} {{< StoryImage id="showco-1970-73-sound-equipment-032-equipment-70-73" caption="Final Design Configuration of Showco High Frequency Horn Cabinet with JBL 2350 Radial Horn and Four JBL 2470 Drivers." credit="© Rusty Brutsche Archive" size="medium" >}}

Maxson and I were not happy with the performance of the JBL 4520 dual speaker rear loaded bass cabinets. The fiberboard material was unsuitable for our application because it was extremely heavy and weak. I did a show in Hawaii with Zeppelin and when I went to the airport to pick up the equipment that had been airfreighted to Honolulu, I found that the baffle boards mounting the two 15” woofers had disintegrated and the woofers were laying loose in the bottom of the cabinets in a pile of sawdust. Fortunately, a guy with the local sound company had a woodshop that he let me use to rebuild the baffle boards using plywood. We also did not like the sound of the cabinets and we felt that the rear loaded design was inefficient and not suitable for our application. We decided to remove the rear loaded horn from the cabinets and convert them to a ported reflex cabinet design with four 15” woofers that were powered by two Marantz 16B 100 watt modules mounted inside the cabinets (aptly nicknamed the “Thunderbox”). Here is a photo of the modified four speaker bass cabinet on the 1971 James Taylor Tour.

{{< StoryImage id="showco-jtaylor-1971-9" caption="James Taylor 1971 Road Crew George Wheatley & Kevin McNevins with four speaker bass reflex cabinets." credit="© Rusty Brutsche Archive" size="medium" >}} {{< StoryImage id="showco-carl-dunn-photos-showco0464_nx_bw_" caption="Showco ported reflex bass cabinets with four JBL 2220 15” speakers powered by an internally mounted Marantz 16B power amplifier 1971." credit="Photo Carl Dunn" size="medium" >}}

In 1970 I hired a man named Ron Fox to help me build equipment in Maxson’s garage. Ron lived in the mid-west and had learned about Showco from seeing shows where Showco was providing sound. He and his wife drove to Dallas, and Ron applied for a job. I needed help so I hired him without knowing anything about his abilities; he turned out to be one of the most talented people that I have ever known. He was a master craftsman, and he could build anything out of wood or metal or other materials such as fiberglass. He had an immediate impact on the quality of the cabinets that we were building in the garage and later in our first woodshop on Motor Circle. We developed designs for various cabinets and cases that became standards in Showco and the designs never changed. The photo below is the standard Showco road case. It was about 30” X 30” X 48” made of ¾” plywood and had four Colson casters: {{< StoryImage id="showco-1970-73-sound-equipment-036-equipment-70-73" title="Standard Showco Road Case" caption="The metal box with the XLR connectors is the first generation mic snake stage junction box. It featured 20 mic lines on the top and three monitor mix outputs and the high and low drive line outputs on each end.The sex of the high drive and low drive lines are reversed to prevent the low frequency line from being connected to the high frequency drivers, which would destroy all of the diaphragms in the HF drivers. The compartment in the lid with the foam lined door is for microphone storage. " credit="© Rusty Brutsche Archive" size="medium" >}}

{{< StoryImage id="showco-1973-led-zeppelin-outdoor-018-zep-outdoor-73" caption="Ron Fox at Led Zeppelin show in Atlanta May 4, 1973." credit="© Rusty Brutsche Archive" size="medium" >}} {{< StoryImage id="showco-1970-73-sound-equipment-029-equipment-70-73" caption="Mic stand case for the Atlas stands designed by Ron Fox. Each half of the case had four Colson casters as the case was very heavy. 1971." credit="© Rusty Brutsche Archive" size="medium" >}}

{{< StoryImage id="showco-1970-73-sound-equipment-024-equipment-70-73" caption="Power Amplifier rack with extended bottom for stability and for cable storage. Each rack had drive line and AC pigtails 1971. More on this later." credit="© Rusty Brutsche Archive" size="medium" >}} {{< StoryImage id="showco-027-equipment-70-73" caption="Each amp rack had four cooling fans on the back door. The racks were designed to be operated with the rear door in place and the fan compartment door open 1971." credit="© Rusty Brutsche Archive" size="medium" >}}

## Creating Showco Self Powered Speakers 1970 One of the shows that I did in 1970 was for Barbara Streisand at The Forum arena in Los Angeles. I met John Meyer, later the founder of Meyer Sound. He was using some of his new JM-3 speaker cabinets that were single enclosure full range speakers powered by Crown amplifiers. Meyer was very secretive about the JM-3 cabinets, but I have recently learned from reading an article that the JM-3 featured two 15” Altec 421A woofers, a single Altec 290 compression driver mounted on a mid-range fiberglass exponential horn designed by Meyer and two Electro-Voice T350 Ultra-Sonax tweeters. I thought the cabinets sounded very good. I had the Marantz 16B power amplifiers mounted in plywood equipment racks that I had made in Maxson’s garage. Meyer suggested that I take the 100 watt Marantz 16B modules and mount them in our bass speaker and horn cabinets and thereby eliminate the amp racks and the need for speaker cables. When I returned to Dallas, I discussed the idea with Maxson; we decided to modify our two systems in the manner suggested by Meyer and mount the 16B modules into the cabinets. I modified both the bass cabinets and the horn cabinets to have a small access door on the rear and a storage compartment behind the door. I also cut holes in the rear of the cabinets for a small connector panel. Each cabinet was fitted with a transformer featuring a low impedance balanced line input and a high impedance output for connecting to the input of the Marantz amps. On the connector panel we mounted a 120V female AC connector and a 3-pin chassis mount XLR connector (the sex of the XLR depended on whether it was a bass cabinet or a high frequency horn cabinet). We connected a 6 ft AC cable pigtail and a 6 ft XLR mic cable pigtail to the connector plate and wired the cabinets so they could be daisy chained together with the pigtails permanently attached to the cabinets and stored in the storage compartments. No amp racks or external speaker cables were required. This provided a very quick and easy way to setup the sound system and our systems used this design until we went to amp racks in 1975. As we began to build more sound systems, the powered cabinet design made training the new sound crews much easier. With John Meyer’s inspiration, we were ahead of our time as today many sound systems have the amplifiers mounted inside the speaker cabinets. {{< StoryImage id="showco-meyer-jm3-speaker-1970" title="Meyer JM-3" caption="Meyer JM-3 three-way speaker 1970. This was a very innovative design with the high frequency horn driver in the same plane as the woofers to ensure phase alignment between the HF and LF components." credit="Photo from article by Michael “Bink” Knowles August 3, 2021 on prosoundweb.com" size="medium" >}} ## Showco Mini System We also built our first full range speaker cabinet in 1972 named the Mini System (or M3). It was a three-way system designed by Keny Whitright with a folded “W” style horn loaded bass section that had two 15” speakers, a JBL 2355 60 degree radial horn with a 2480 2-inch compression driver for mid-range and two 2405 ultra high frequency transducers for highs. Keny lived in Wichita, Kansas where he was studying engineering. He also was very interested in audio. He met Maxson at a Three Dog Night show in Wichita and Maxson suggested that he come to Dallas and apply for a job. Keny and his wife came to Dallas, and I hired him on December 10, 1971. Keny proved to be an extremely bright and capable engineer with many talents. He served many roles in Showco including designing the Mini System and several other successful speaker cabinets. To power the Mini System, we hired an electronics engineer named L.A. Krause to design a three-channel power “tri” amplifier with three separate power modules on one chassis that we mounted on the back of the M3 cabinet. We used these cabinets for applications such as stage monitors, small venue shows and front fill. L.A. also designed a 200 watt single channel power amplifier that was mounted on the back of the bass cabinets. Here is a photo of four of the Showco 200 watt amplifier modules rack mounted 1972:

{{< StoryImage id="showco-15-mccas-monitor" caption="Four Showco 200 watt Amplifiers." credit="© Rusty Brutsche Archive" size="medium" >}} {{< StoryImage id="showco-1973-led-zeppelin-outdoor-014-zep-outdoor-73" caption="Keny Whitright at Led Zeppelin outdoor show in Atlanta May 4, 1973." credit="© Rusty Brutsche Archive" size="medium" >}}

## Showco 18 ft Bobtail Trucks 1970-Myrtle and Loretta Maxson and I and our roadies drove the Ryder yellow trucks for the first part of 1970, but they were extremely uncomfortable and they had no sleeper compartment. In the early days of concert touring, we would arrive at a venue about 8:00 AM, unload the equipment and setup the show, do a sound check, then do the show starting at 8:00 PM. After the show, we would load the truck and depart the venue about 1-2:00 AM, then drive all night to make the 8:00 AM stage call the next day. We really needed our own trucks with sleeping compartments. In late 1970, we purchased two GMC 18 ft bobtail trucks with a sleeper, a lift gate and two sixty gallon fuel tanks. Maxson’s truck was named Myrtle and my truck was named Loretta. I hauled all of the sound equipment and all of the band’s equipment in this 18 ft truck for both the James Taylor and Led Zeppelin 1971 tours. There was virtually no lighting equipment or staging used by touring groups until 1972. {{< StoryImage id="showco-myrtle-gmc-truck-1970" title="Myrtle" caption="Myrtle, an 18 foot GMC bobtail truck with power liftgate, sleeper and two 60 gallon fuel tanks 1970." credit="© Rusty Brutsche Archive" size="medium" >}} ## Moved Into First Building-Late 1970 We expanded rapidly and by 1973 we had eight separate sound systems on the road doing tours and shows. In late 1970, we were able to move out of Maxson’s house and set up a shop in a 6,000 square foot building at 1301 Motor Circle in Dallas. Jack Calmes remained at the Showco offices on Routh Street in the Quadrangle. He had been joined by Kevin McNevins, who was doing the accounting for the sound company, and David Alley, who was helping Jack book the sound systems. We setup a larger woodshop and added a metal fabricating shop; Ron Fox purchased a fiberglass chopper gun to make sound equipment and cases out of fiberglass. We also setup a large electronics shop. In 1971 Chuck Conrad left Showco and in January of 1972 I hired Jim Bornhorst. Jim responded to an ad that we had run in the local paper looking for technical people to be trained as road crews for our rapidly expanding sound systems. Jim was very qualified because he had a degree in electrical engineering from Texas A&M. Jim is immensely talented and he was destined to play a critical role in the future of the company. In 1972-1973 I also hired Tom Walsh as an electronics engineer and Greg Bright as an electronic technician. Both Tom and Greg became integral members of the Showco team and stayed with the company for their entire careers. In 1973 we moved to a larger 33,000 square foot building at 9011 Governor’s Row. Jack Calmes and the other office personnel moved into Governor’s Row and the Routh Street offices were closed. The company continued to grow, and in the early 1980’s we moved into a 60,000 square foot building at 201 Regal Row. To accommodate even more growth, Showco sound later moved back into the building at 9011 Governor’s Row. {{< StoryImage id="showco-076-david-alley" caption="David Alley played the trumpet in the Soul Society and worked with Jack Calmes in the Showco Quadrangle office booking bands as well as the Showco sound systems." credit="Showco Recovered Archive" size="medium" >}}

{{< StoryImage id="showco-greg-bright-1980" caption="Greg Bright Electronics Shop Manager 1980." credit="Showco Recovered Archive" size="medium" >}} {{< StoryImage id="showco-tom-walsh-1983" caption="Tom Walsh Electronics Engineer & Creator of the Bee Gees dance floor controller in 1979, the controller for the Vari-Lite VLO prototype in 1980 and the first Vari-Lite VL1 Control System in 1981. Tom designed the digital hardware for every Vari-Lite product until we sold Vari-Lite to Genlyte Thomas in 2002. His formal education was in music from Indiana University as a violinist. His father was an electronics engineer and Tom decided to learn about digital electronics and give up his career in music. His expertise in digital electronics was self-taught. He is an incredibly brilliant electronics engineer-the Steve Wozniak of Showco and Vari-Lite." credit="Showco Recovered Archive" size="medium" >}}

{{< StoryImage id="showco-motor-circle-electronics-shop-1970" caption="1301 Motor Circle Electronics Shop 1970." credit="Showco Recovered Archive" size="medium" >}} {{< StoryImage id="showco-motor-circle-mc-72-2" caption="1301 Motor Circle Woodshop 1970." credit="Showco Recovered Archive" size="medium" >}}

{{< StoryImage id="showco-9011-shop-2" caption="9011 Governor’s Row 1973." credit="Showco Recovered Archive" size="medium" >}}

Showco History