Anyone hear the "wall of sound"?


It was before my time but the Grateful Dead experimented with a system 35 years ago comprised of nearly 650 loudspeakers powered by 89 300-watt Mcintosh MC2300 amplifiers and and three 350-watt McIntosh MC3500 tube amps. Unlike traditional left-right P.A. systems, this behemoth gave each instrument its own vertical array, and vocals emanated mostly from a center honeycomb cluster above the band.

Vocals, lead guitar, rhythm guitar, and piano each had its own channel and speaker array. Phil Lesh's bass guitar was piped through a quadraphonic encoder that sent a separate signal from each of the four strings to its own channel and set of speakers. Another channel amplified the bass drum, and two more channels carried the snares, tom-toms, and cymbals. Because each speaker carried just one instrument or vocalist, the sound was reportedly exceptionally clear and free of intermodulation distortion.

It projected high quality playback at six hundred feet with acceptable sound & projected for a quarter of a mile without degradation or delay speakers. Speakers sat behind the band so it was the monitors. It filled 4 semi trailers.

I find modern computerized eq and pa systems, for the most part, blow away the mostly muddy sound I remember from the late 70's and 80's (except for really good halls). I am too young to have heard the wall. Any A-goners remember the sound?
stearnsn

Showing 2 responses by richz

Hi, I heard this system many, many times. It really was special and had a unique sound unlike anything else I have heard. It sounded more like a huge stereo than a PA. I have worked my whole life in the pro audio world and that one system still stands out among people who work with live sound. An interesting thing was how they were able to use microphones in front of all of those speakers. Usually, you would not do that as you would get lots of feedback. Eac "mic" was actually two mic's that were right next to each other, just slightly offset, and wired in opposite polarity to each other. By wiring them 180 degrees out of phase, they cancelled each other out. This affected all sound other than a sound that was substantially higher in level in one mic. This required the band members to practically put their mouths on the mic when they sang. They sang only into one of the two mics. It was a great idea that really worked well! Of course the requirment to be on the mic was impractical for most bands. When Phil Lesh hit those low notes, this system was something to be remembered. During the following decades, now and then you would come across pieces of that old "wall of sound"
I just read back in this thread, and since I work in the pro audio market and also enjoy high end home gear I figured I would put in my thoughts. I have worked in the studio world as a designer and engineer, in live touring sound, as a consultant on large fixed installs and as a creator of audio products. I currently am the President of a consutling firm and a VP at a major pro audio manufacturer, where I define DSP based products. Each pro audio market has it's own unique requirments. In general, pros want the same end result as do home listeners, good sound. In the studio, we strive for accuracy. Live sound system operators look for light weight, lots of power, and the ability to stand up to constant abuse. In fixed sound systems, the focus is on reliability, sound quality, and intelligbility. Cinema focuses on sound quality per dollar.

The only place where pros desire distortion is in music creation, not reinforcement. Musicians use distorion and other effects. A guitar amp will intentionally introduce distortion, but not a PA amp. I have noticed that people seem to like distortion in China, but that is just an observation of mine.

So, why not use pro equipment in home settings? The answer is that you can, but you want to choose the correct equipment. Most pro equipment uses the same AC plug as home equipment. I have a few different systems at home. I have one that is based upon B&W Nautilus 801's, Ayre K1 and V1, along with their CD and a Logitech transporter. Another system uses Ayre and Thiel My surround system, which someday if I ever have the time will be a home theater integrates both home and pro audio equipment. I have five "old" B&W 801's, a QSC dual 18" very large cinema sub (it is used in lots of cinemas througout the world), three Crown Macro Reference (also known as Studio Reference I) power amps, and a QSC cinema power amp on the sub. It uses an Anthem D2 as the processor. So, I have home, cinema, and studio equipment in one system and it all works very well together. It has a different character from my my more "refined" systems, but they are all fun to listen to.

I have done side by side comparisons between my Ayre power amp and a QSC pro amp that is targeted to the touring and fixed install markets and has a huge amount of power. I used various high end speakers in doing so. My conclusion is that both amps sounded great. For home listening I had a slight preference for the Ayre, but the differences were not that huge. The QSC is a fraction of the cost of the Ayre. One thing to be very careful of is fan noise. In pro applications, other than studios, we just don't get too concerened about fan noise. Amps and other products are expected to operate normally at 50 degrees C day after day, year after year. A noisy fan in a home system can be annoying.

If anyone has any questions regarding the pro side, please reply. I think I am somewhat unusual in that I enjoy both sides of the audio industry.

Rich