||This article needs additional citations for verification. (April 2011)|
California Jam, also known as Cal Jam, was a rock music festival concert headlining Deep Purple held at the Ontario Motor Speedway in Ontario, California on April 6, 1974. It was produced by ABC Entertainment, Sandy Feldman, and Leonard Stogel. Pacific Presentations, a Los Angeles-based concert company headed by Sepp Donahower and Gary Perkins, coordinated the event, booked all the talent, and ran the advertising. Don Branker worked for Leonard Stogel and was responsible for concert site facilitation, toilets, fencing and medical. It attracted 250,000 fans that paid, which at the time, set the record for the loudest amplification system ever installed, the highest paid attendance, and highest gross in history. It was the last of the original wave of rock festivals, as well as one of the most well-executed and financially successful, and presaged the era of media consolidation and the corporatization of the rock music industry.
Acts that performed at the festival in order of appearance:
- Rare Earth
- Earth, Wind & Fire
- Seals & Crofts
- Black Oak Arkansas
- Black Sabbath
- Deep Purple
- Emerson, Lake & Palmer
Deep Purple headlined the California Jam Festival and would have performed last but exercised the option to start their performance at sunset if the municipal authorities forced the bands to perform earlier. A photo book by Rufus Stone Limited Editions, United Kingdom, scheduled for December 2012 release, documents Deep Purple's California Jam appearance provides the behind the scene details of the festival creation, interviews with organizers and managers, audience memorabilia, their performance, plus letters exercising their option as headliner to select their time slot.
Deep Purple's performance was one of the first to feature their third line-up, which included vocalist David Coverdale and vocalist/bassist Glenn Hughes. Deep Purple were given the choice of when to go on stage, and chose to go on during sunset thus pushing ELP to be the last band. Figuring that as with all festivals, the show would run late anyway, they stalled when the festival was way ahead of schedule. Angry organizers tried to force the band to go on and then threatened to cancel their performance but a quick thinking announcer told the crowds that Deep Purple would be coming on. The band made everyone wait nearly an hour until near dusk before they hit the stage. Regardless of this, the show didn't end up running late. At the end of the show, guitarist Ritchie Blackmore threw multiple guitars, amplifier and speaker cabinets out into the audience and attacked one of the network's video cameras (which had been getting between him and the audience) with a guitar. Later on, a mishap with a pyrotechnic effect caused one of Blackmore's amplifiers to explode which briefly set the stage on fire. The group had to leave the concert via helicopter to avoid a possibly ugly confrontation with furious fire marshals and ABC executives and potential arrest for the pyrotechnics. The damage to the camera was estimated to be $10,000, later settled by the managers.
Deep Purple's California Jam performance along with some of the performances by other bands was TV and radio broadcast nationwide in the US. It was at this festival that the footage of Keith Emerson playing a grand piano spinning end-over-end 50 feet above the ground was taken.
Attendance and technology 
The concert set a record for the largest number of paid attendance at such an event. Although more people attended the festival at Woodstock in New York, only a few had purchased tickets.
Another record established at California Jam was for the largest (most powerful) concert sound system ever assembled particularly from the demands of Deep Purple who were identified as the "loudest band in the world" by the Guinness Book of World Records. Tycobrahe Sound Company combined the touring systems of Deep Purple, Black Oak Arkansas, Black Sabbath, Earth Wind and Fire, and Rare Earth (each manufactured by Tycobrahe), plus 16 feet (4.9 m) bass horns from Phoenix Sound and several folded bass horns from Flag Systems. Total power was 54,000 watts RMS, provided by a number of BFA-2000 amplifiers, manufactured by Tycobrahe.
The Goodyear Blimp hovering overhead was a first for a music festival. Deep Purple also arrived for the concert in their own chartered jet the Starship with their name painted on the plane's sides, the first time time a major band arrived specifically for a music festival in their own plane.
Another first was the setting of the stage sets for each band on rails, allowing rapid changeover to the next band thus eliminating delays and allowing the rock festival to run on time,in fact ahead of time.
Emerson, Lake and Palmer's touring sound system was set up about 0.5 miles (0.80 km) from the stage and timed with a tape delay to coincide with the sound from the stage.
Broadcast, telecast, and record releases 
Unlike other rock festivals such as Woodstock, the concert was not planned for release as a film or sound recording. However, several portions of it were broadcast live on the ABC television network, which was also a sponsor of the show. The audio portion of the show was also broadcast in stereo on FM radio stations, an early example of simulcasting.
Deep Purple's California Jam performance was the very first full length music concert film to be released and sold on video tape in the early 80's.
Several performances from the show were eventually released on CD and video, both in bootleg and authorized form. One of the more notable bootleg recordings was from a fan who tried to pass off his recordings of a recording from the radio broadcast as something he created. His web site was shut down after he tried selling his unauthorized products without creative approval from the artists involved and the producers of the festival.
Authorized releases include:
- California Jamming, CD of Deep Purple's performance (also released under alternate titles)
- Live in California 74, DVD of Deep Purple's performance
- Beyond the Beginning, Emerson, Lake & Palmer DVD including 44 minutes of their California Jam performance
Cultural impact 
A sequel concert, California Jam II, was held in 1978.