10 Interesting features of the Grateful Dead wall of sound
1. The Wall of Sound was perhaps the second-largest non-permanent sound system ever built.
2. They basically invented/implemented what became known as a line array and it projected high-quality sound for over 180 meters, and good quality sound for almost 400 meters.
“The Wall of Sound is the name some people gave to a super powerful, extremely accurate P.A system that I designed and supervised the building of in 1973 for the Grateful Dead. It was a massive wall of speaker arrays set behind the musicians, which they themselves controlled without a front of house mixer. It did not need any delay towers to reach a distance of half a mile from the stage without degradation.”
From Rick Turner:
". We took the technology as far as we could at the time. Now there are a lot more good choices for drivers, amps, and packaging. The basic principles remain the same because they're based in the physics of sound and wave lengths."
3. Designed by Owsley Stanley
Who also happened to be the LSD chemist for many major events in the 1960s.
4. Phil Lesh's Bass strings were each panned to their own sound system (one per string)
5. Because of its unwieldy size and configuration, the Dean only used it for about seven months in 1974.
6. the system acted as its own monitoring system: it was placed behind the band
This is unusual...
7. to eliminate the feedback they used 2 mics out of phase
8. In the late 1960s huge PA systems did not exist yet...
The Dead had to invent a sound system that they could take on tour.
9. Massive specifications for the time
Grateful Dead Wall of Sound Specs
26,400 watts of continuous power via 44 amplifiers
586 JBL loudspeakers (15", 12" and 5")
54 Electrovoice tweeters
75 tons in weight (approximately)
10. The bass amplifier stack was intentionally 32 feet tall so that it could (theoretically) reproduce the fundamental note of the open E
In this thread Rick Turner discusses these design decisions:
"Line array dispersion theory is based on the wavelengths produced, and wavelengths are pretty much an absolute on this planet. A rule of thumb...a convenient one...is to just estimate the speed of sound at sea level at 1,200 feet per second. Yes, I know it's a little bit slower, but for in your head math, 1,200 is a decent figure. That being the case, a 40 Hz tone has a wavelength of 30 feet. Ain't no way you're going to change that. So, sure, you can use shorter arrays, but you won't get the same kind of dispersion control in the critical vertical dimension. That's what pumps the low end into the audience and minimizes the splatter on the ceiling and behind which just muddies everything up. It's just math, not myth. No voodoo involved."