Dec 23, 2012

1974: Wall of Sound Technical Specs


Recently there have been major changes made in the Dead's sound system, bringing it a big step closer to the ancient ideal of the perfect sound system*. This is a technical report; from the standpoint of the ideas on sound reproduction incorporated into its design, and with a description of its sub-systems.

The system is unusual in that all the speakers are arrayed behind the musicians. Conventionally, vocal systems occupy the front corners of the stage. There are two disadvantages to this. It creates a blind spot for people sitting in potentially good seats, and the musicians themselves don't really know how they sound. They have monitors, but these are not very effective, nor are the echoes which ricochet around the hall. With the speakers behind them, in integral array with the instrument speakers, the band is in a much better position to hear what the audience hears, and to adjust accordingly.

With the new set-up there is no need for a mixing console to adjust the various sound levels. Each microphone has a volume control on it, enabling the band to mix the vocal sound from the stage. Each musician has control of his own local sound environment, being able to adjust his stage monitors of other instruments as well as his own instrument.

The sound system is actually a combination of six individual systems, each being electronically separate and having a specific purpose and function. No two musical 'voices' go through the same system. Thus the vocals, piano, drums, lead guitar, rhythm guitar and bass each have their own channel(s) of amplification. This separation is designed to produce an undistorted sound, a clean sound in which qualities like 'transparency', 'brilliance', 'presence', and 'clarity' are substantial musical dimensions.

The whole system operates on 26,400 Watts of continuous (RMS) power, producing in the open air quite an acceptable sound at a quarter of a mile and a fine sound up to five or six hundred feet, where it begins to be distorted by wind. A sound system could get the same volume from half as much power, but it wouldn't have the quality.

THE VOCAL SYSTEM - The signals from each of the vocal microphones are brought together by a Differential Summing Amp, where phase purity can be regulated and hence the transparency of the sound maintained. From there the combined signal goes to a Crossover which divides the frequency range into four band (High, Upper Mid, Lower Mid, Low). The signal in each band is then separately amplified by MacIntosh 2300 amps fed to JBL 15 inch, 12 inch or 5 inch speakers or Electrovoice tweeters.

The center cluster of the vocal system, consisting of high and midrange speakers, is curved so as to disperse sound cylindrically; there is not much vertical dispersion, and horizontal dispersion is ideally between 140 and 180 degrees. The vocal low range speakers are arranged in a column. Each type of speaker is designed to have the same horizontal and vertical angle of dispersion so that all frequencies are heard equally well.

The speaker cones are arranged together as close as possible so that the whole surface of the cluster acts as one working surface. In this way a large mass of air is moved at once which doesn't require very high pressures from any individual speaker.

A major improvement in the quality of the vocal sound is due to the use of differential microphones. Each singer has a perfectly matched pair of Bruel and Kjaer microphones hooked up out of phase, only one of which he sings into. Any sound which goes equally into both microphones is cancelled out when the two signals are added together. Therefore leakage of instruments and background noise into the vocal channel is minimized.

THE PIANO SYSTEM - This is a small version of the vocal system. In this case a crossover divides the frequency range into three parts. The Highs and Mids go through a cluster of 5 inch and 12 inch speakers built in the same fashion as the vocal's center cluster. The Lows go through a column of 15 inch speakers. There is a separate volume control for each of the five Countryman custom pickups (one for each division of the frame) so that Godchaux can balance the sound. Garcia and Kreutzmann both have piano monitors or fills in their areas of the stage, which can be independently adjusted by them.

THE DRUM SYSTEM - The drum system has two independent parts. The bass drum uses one amplification channel and sixteen 15 inch speakers in a column. The other drums and cymbals are miked through a three-way crossover which separates the signal into Highs, Upper Mids and Lower Mids and feeds them to Tweeters, 5 inch and 12 inch speakers. This second part of the drum system uses two channels as it is stereo with identical speaker columns on both sides.

THE GUITARS - Both guitars use columns of twenty 12 inch speakers. Jerry's guitar has extensions beside Keith and behind Bill.

Jerry is using a Doug Irwin/Alembic custom guitar. It has a Gibson/Les Paul type body with a Fender Stratocaster pickup.

Bob currently plays a Gibson 335 guitar. He uses such special instruments as an Eventide Clockwork Digital Delay unit for repeating notes and creating an echo-like delay of different sound colorations and textures. Another accessory is an Alembic Parametric Equalizer (a flexible tone circuit) which gives him complete control of frequency response by enabling boost or cut adjustments at any or all of three band-widths. The sharpness of the boost or cut can also be controlled.

THE ELECTRIC BASS - Phil is using a new quadrophonic bass, the electronics of which were designed and built by George Mundy and the body and pickups by Rick Turner. The new bass has the same versatile qualities as the old bass: three pickups (bass and treble low-impedance pickups covering all the srings, and a quad pickup which has a separate signal for each sring); on each of the bass and treble pickups there are controls which enable him to select 1) the band width of the filter, 2) the center frequency of the filter, 3) the kind of filter being used, and 4) mix unequalized unfiltered direct sound with the filtered sound. The variety of sounds which can be achieved on the bass is the result of the many different combinations of these variables which can be used. The new bass has a frequency response with a crisper tone, and two quad pickups instead of one, the new one being a frequency-detector pickup. The main addition to the new bass is a Digital Decoding Circuit such that ten push buttons on the bass allow Phil to select any one of sixteen quad spatial arrangements of his speakers, and eight in the stereo mode.

DESIGNERS AND WORKSHOPS - The Grateful Dead's sound system has evolved over the last eight years as a technical and group enterprise, a sort of logical accumulation of speakers and people. Changes have been made continuously in all directions which aid in improving the quality of the sound, both which the audience hears and which the band has to work with on stage. The concept and design of the current system/level was worked out by Bear, Dan Healy and Mark Raizene of the Dead's sound and equipment crew, and by Ron Wickersham and Rick Turner of the Alembic sound company. The construction and regular maintenance is done at the Dead's technical workshops by the people responsible for managing and transporting the system on the road. The design and construction of some special electronic components was done at Alembic, where John Curl is a consultant to the project.

The number of people going on the road to handle all the sound equipment, lights, scaffolding and staging varies, but a typical configuration is: band - 6, sound - 10, lights - 4, staging and trucking - 7, road management - 3. The sound system travels in a 40 foot semi, and staging and scaffolding on two flatbed semis and the lights in a 24 foot van. All of this weighs about 75 tons.

We have been trying something new at some concerts on recent tours. Ned Lagin and Phil have been playing electronic cybernetic biomusic, "music as metaphor for thought." Phil's instrument includes a console which contains all the classical electronic-music studio techniques for processing the signals from his quadrophonic bass. It gives Phil the advantages of electronic processing of each string individually. Ned plays a digital-polyphonic keyboard instrument built by Scott Wedge and EM Systems, incorporating the same processing techniques, but he controls his own processing through an "organic artificial musical intelligence" - a digital computer (Interdata 7/16). This enables Ned to "change any or all of the parameters of sound or form in the music at microscopic, atomic musical levels as well as macroscopic formal levels with almost relativistic speeds."

* 'Gandharvas,' world of, wherein sound, as in song and music, is the prevailing quality of existence. (Tibetan.)

(from Dead Heads Newsletter #19, December 1974)

[Numerical table & vocal-system diagram omitted.]


  1. Mind-numbing stuff. Man, I hope this is useful for somebody!

    This is a followup to the Alembic article from the previous year, which I posted a couple days ago - you can see how some of the technical trends developed:

    (This was also an opportunity to surprise people with an actual image! A rare thing on my text-driven blogs...)

    This was taken from the Dead's final 1974 newsletter (though illustrating the sound setup as of July) - by the time it was issued, it was actually out of date since the Dead were no longer on tour & the Wall of Sound was history!
    The 'farewell note' from that newsletter I'll include in a separate post, to keep things chronological.
    (As you'll notice, right now I also have a dearth of articles from 1974...)

    Just a couple comments to make:
    One, it wasn't quite true that "no two musical 'voices' go through the same system." Ned Lagin has stated that when he played during the Dead's sets, his keyboard went through the vocal PA: "I wouldn't have been heard during the singing because of the PA switching to vocals."
    (This makes some sense, since he was only an occasional guest and they had a superfluity of speakers as it was, so there was little need to set up a separate system for him.)

    Lagin also felt that in '74 the Dead were too focused on expanding & adding technology, and this article definitely reflects that. "There was too much emphasis on electronic instruments and technology, rather than on collective intuition and expression. There was...what I call 'technosis,' an obsession with the tools rather than the expression. People wanted to talk to me not about 'Seastones'...[but] about new hardware and computers." (Conversations with the Dead p.373)

    [Small correction - Lagin's instrument was built by E-mu Systems, not EM. See Conversations p. 359-60.]

    It's ironic that although this article boasts of "a major improvement in the quality of the vocal sound," many listeners of '74 tapes have complained about the poor vocal sound, since they often sound pretty tinny on recordings!

    Note that the bandmembers could adjust their own monitors so that "each musician has control of his own local sound environment" - this seems to be a predecessor of their '90s in-ear monitors, where they only listened to their own personal mixes.

    It's also notable that of the three guitarists, Garcia's by far the most conservative - Weir & Lesh have all sorts of techno gizmos & gadgets, but not a word is said about Garcia's.
    There's a pertinent quote from the Grateful Dead Gear book about him sticking to his traditional sound - when Garcia played his first Irwin guitar, he said, "Wow man, if I could get this with a Stratocaster pickup, maybe I could play this shit." (p.128 - the previous Alembic article also noted this!)

    Of course there are many more details about the Wall in that book, as well.

  2. I attended the " The Summers End Concert" at Englishtown Raceway in New Jersey back in 1977 on Labor Day Weekend. The show was a triple bill featuring the Grateful Dead, Marshall Tucker Band and The New Riders of the Purple Sage.The sound system was an Alembic product as I distinctly remember printed handbills describing this incredible sound reinforcement system. I don't think it was the wall of sound but it definitely was the best sounding outdoor show I ever attended.Out in the open general admission field was twelve platforms with massive amounts of speakers spread four across and three deep.Each platform had one of the twelve months of the year attached onto them , I would imagine so the attendee's could remember their surroundings if they needed to, and for the sound engineers as well to tweak each particular unit for optimum performance.I will always be impressed by this vision in my mind of that Alembic masterpiece

    1. It definitely was NOT the system that became known as 'The Wall of Sound " .That system by design and the fact it was geared toward each member of the band having a dedicated speaker stack and amplification was not usable for multiple acts , unless an entirely separate PA system was available.

    2. As I stated in MY original comment " I Don't think it was the wall of sound but it definitely was the best sounding outdoor I ever attended" It's a past thought, like I didn't think some people were so anal about things!

    3. I have been studying electronics,started collecting antique radio in elementary school, studied about every type of amplification cuircit, available anywhere know the sond differences not only between solid state or tube audio but the sound differences from a class A, single ended triode 300b tube to, a switching apmlifier/ power supply using class D,E, & F technology. The part of the freat wall of sound that is so amazing is the fact that each and every string utilized a completely seperate amplifier per string each 180 degrees out of phase with each other to cancel noise, and allow not just bass or treble, but have complete control over each string going into a seperate amplifier to a seperate speaker giving the gutarist absolute and complete control over every aspect of the gutars sound, not just the effect of the gutars sound, plus the type of amplifiers used are absolutely, amazing amplifiers, and have become verry sout after as to todays standards.

    4. I realize that you made this comment several years ago, but just fyi, the Englishtown show PA was a hybrid, using the UltraSound PA that the band normally used, and 12 delay towers that Healy subcontracted through 2 different sound reinforcement companies, one of which was Weisberg Sound from NYC. I worked on the Weisberg crew. Those towers were generally either 5 way or 4 way systems. Weisberg was heavy into speaker design, and custom designed a variety of horn enclosures for different frequency bands. The bass horn cabinets used 4 jbl speakers in a conventional cabinet, but with a custom built horn that used butterfly clamps to attach to the front, forming a giant bass horn but coming apart for easy transport and setup. I believe we used 6 of these, stacked 2x3. Crossovers were custom designed. Amps were Phase Linear. We had some very nice rack enclosures that were built for the Hall and Oates tour that we used for that show. I do remember that at one point in the show, I needed to climb one of the towers and plant myself inside one of the bass horns to check for a blown speaker... fun. Healy fed all the towers with a digitally delayed signal, based on how many feet they were from the stage stacks, with some compensation for temperature and humidity, if I remember correctly. System sounded awesome.

  3. There's a detailed technical article on the Wall of Sound from early 1976, written by Don Davis & Ron Wickersham: (p.24-31)

    Note that the term "Wall of Sound" never appears! (At one point they call it a "sound wall.") Another researcher has pointed out to me that "Wall of Sound" was never used at the time to describe the Dead's sound system, either by the Dead or by the newspaper articles that made special mention of it.
    For instance, BAM asked Garcia in '77 about the Wall of Sound - only, they called it "your gargantuan sound system," and he called it "a model of sound." Looks like the name hadn't yet come to mind! One paper in April '78 mentions "the imposing wall of sound the band used to carry with them," but it's not quite being used as a proper noun.
    My guess is the Dead's '74 sound system started being called the "Wall of Sound" in the late '70s - or even early '80s, as the label spread among fans. (The comparison with Phil Spector's "wall of sound" was presumably coincidental.) The hunt is on for its first Dead appearance.
    (Mickey Hart had described the band's "wall of sound" in a 1968 interview, but he was using it in a different context.)

  4. A somewhat different version of this article (with more technical detail, added in '75 I think) appears here:

    A modern article on the Wall (based mostly on interviews) is here:

  5. In the end they wanted to build something that could not be destroyed the band played their soul AOS3 funded beautiful crystal...even if it was flawed it was a Goliath of sound

  6. As someone who has been in the audio industry for 25 years, I wish bands today took the interest in their instruments the likes of the Grateful Dead . These guys started Alembic Gtrs.and sound processing, basically designed the line array, helped redesign pickup technologies, and still playing together today. Rush is one of the only other bands I can think of that cares this much about their sound and show performance....

  7. Kevinonwheels , You are spot on with the comment about sound quality ! So many bands just crank up the volume and use distortion as a sound effect ! Given the type of superior sound reinforcement equipment available , why would bands sacrifice the audience,s eardrums ?

  8. The Audio Engineers Handbook had a chapter on this system for quite a few years. It both demonstrated different approaches to overcome problems with live concert sound and the principles of sonic physics that were used and demonstrated to develop those alternate approaches. The whole system and concept was a noble endeavor that apparently was at least somewhat successful, especially given the environment it was used in. This was at a time when both musicians and audience were regularly using hallucinogens and other mind altering substances, as well as a "maximum freedom and creativity" direction that was being striven for. I'm sure it made some truly life altering experiences for some concertgoers. As someone that has many years experience as both on-stage musician and Front-of-House sound engineer, it seems to me that the system had a few shortcomings that kept it from becoming the standard for live sound everywhere after that.
    1> Giving each microphone pair it's own volume control at the mic makes no sense. The problem with giving the musicians complete control of their level in the mix is that they are too close. They have no idea if their amp or voice is twice as loud as the keyboard or is being drowned out by another guitar. Add some egocentricity to that, plus being "in the moment" and all mic volumes will end up on ten. There HAS to be someone back from the stage, hearing everything like the crowd does that decides relative level and eq-ing to compensate for timbre changes that naturally occur when you mic an acoustic instrument and put it through a 35 foot stack of speakers. The musicians mixing themselves is fine if you are in an "immersive" experience tripping on LSD and dancing naked in the crowd while crying at how close that #3 Tom-tom sounds to you, it is quite another if you are a young fan who has only heard the album recording of the song and only attended other live shows mixed on a conventional sound system and enhanced with "backing tracks" to more closely match the recorded version. The wall of sound system would only have confused and repulsed them and they would have said the sound sucked.
    2> Did the wall of sound give the drummer a volume knob? Acoustic drums are truly acoustic. Volume control is in the drummer's technique and size of his forearms. Both hands are usually busy and holding drum sticks, which makes twiddling a volume control pretty hard to find time for, plus they are not used to adjusting a knob to fit in; the rest of the band adjusts their volume to blend with them when they are rehearsing or not playing on stage. When they are on stage, the guitar and bass amps are usually beside and forward of the drummer. Were it not for monitor speakers, most drummers on stage wouldn't even be able to tell which song the band was playing. If all instruments and mics went into a snake and then out and back through a recording type console that had a direct out for each channel, post-fader,(normally goes to the recorder in a studio) which would be routed to the amps and speakers for the instrument on that channel, the separation of instruments would be preserved. The engineer could then also provide a summed mix for monitors, recording, in-ear monitors, sound for video recording, live broadcasts, etc. I think that would have gotten it accepted and loved by all who heard.
    Brian D. Smith, Bradenton, FL.

    1. You bring up some interesting mysteries of the Wall of Sound!

      First off, I think that the Wall of Sound was more than "somewhat successful" in its endeavor (aside from the ridiculous size, expense, labor & transportation needed, which is really what doomed it). I don't agree with the notion that the system was designed for people on mind-altering substances, or that the average listener would have thought "the sound sucked."

      Reports are that the sound was loud and clear and spacious, even at quite a distance (the main problem being the crummy-sounding vocals due to the mics used), and audience tapes show that the band was consistently mixed well, without individuals getting drowned out. (Where you sat did make a difference, though - if you were in front of Keith's speakers for instance, you'd get louder piano.)

      But the question you bring up still remains important and vaguely answered. As one article puts it, "[Instead of] front-of-house mixers...each of the Wall's vocal microphones had a volume control function, so the band was able to mix vocal sounds on-stage as they played. Each individual band member also [was] able to tweak the levels of not only his stage monitors...but also of his own instrument."
      As you ask -- how exactly did they do this? Did they really keep tweaking volume levels throughout the show as they played? Were Bill or Keith or Donna able to keep turning themselves up in the PA if they wanted to?
      Personally I think all this was worked out in the soundchecks before the shows, using the sound crew out in the hall as the band's "ears," and other than guitar volume changes, the mix was pretty much "set" once the show started. Maybe there is an interview I haven't seen that addresses this, because the technical articles written at the time don't explain it at all. But the tapes themselves show that there was never a volume free-for-all during the Dead's Wall of Sound shows.

  9. I went to a Hollywood Bowl Dead concert with the wall of sound; before seeing this I would have guessed it was 1973, but it probably was the July 1974 date.

    I was interested in audio as a teen, and remember trying to count all the JBL drivers. Did not realize that the tweeters were EV. All those Mac amps were impressive----basically ranked among the best hi-end HiFi amps of the day. Other things I remember were the UCLA football players used for security (or so we were told) and Jerry being a little late to the mic after instrumental breaks---not sure what was going on there, but I had my suspicions. One really amazing sensation were the effect of Phil's super clean bass notes on my body-like they were just flowing through me. I have not ever experienced that before or since that concert. I am not sure, but again I have my suspicions---about MY state of mind at the time! I would have sworn that those bass notes were way lower in pitch than the lowest a 4 string bass is capable of---which I believe is somewhere in the vicinity of 40hz. These seemed maybe half of that to me---felt more than heard.

    The H-Bowl is a great musical venue, but not much room to boogie. I think the only other concert I attended there was Louis Armstrong, about 10 years earlier.

    1. Very cool summery and recollection. For the low end subsonics of Phils bass, his lowest note (E) is 41.2hz. The size of a 41.2hz wavelength in the air is 27.4ft. Guess how tall Phils bass stack was? 27-1/2 ft. There is a difference between a speaker that can produce the sound of 41hz and an array that moves the entire waveform of 41.2hz. So I think that is why it left such an impression. Frankly, Im jealous. Cheers.

    2. I don’t think you understand waveforms…