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The Grateful Dead's Wall of Sound (2019)

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Re: The Grateful Dead's Wall of Sound (2019)

#31

Post by dekhn »

TylerE wrote: post #28
scrumper wrote: post #4

Article doesn't mention one of the more interesting (to me) aspects which was how feedback was avoided. The solution is elegant: each vocal microphone is doubled, meaning there are two at each position. The phase is inverted on one of them, the singer sings into only one, and both are sent to the speakers via their channel's amp. The effect of that setup is that only the difference between the two microphones is ampl…

While it's true that they did that and why, I'd ultimately chalk it up as more of a flaw than a feature. Vocals never sounded great on wall of sound shows because they could never sing perfectly into one mic. This can be confirmed by listentng to soundboard tapes of the shows, and comparing them with ones a year or two either side - the full on Wall was only used for about a year. While the WoS laid much of the groun…

(I assume you're aware, but for the larger audience)... the grateful released an album "Two From the Vault" which was a soundboard recording... but the original soundboard had huge phase cancellation errors due to microphone placement. To recover it, some 20+ years later, with digital tech, the sound engineers could recover the original signal using some clever FFT and phasing very similar to what you describe modern secondary arrays use to self-tune.

Re: The Grateful Dead's Wall of Sound (2019)

#32

Post by insaneirish »

plussed_reader wrote: post #14
scrumper wrote: post #4

Article doesn't mention one of the more interesting (to me) aspects which was how feedback was avoided. The solution is elegant: each vocal microphone is doubled, meaning there are two at each position. The phase is inverted on one of them, the singer sings into only one, and both are sent to the speakers via their channel's amp. The effect of that setup is that only the difference between the two microphones is ampl…

Since balanced cables predate the GD, this strikes me as an acoustic implementation of an EE concept. Neat!

Here's a fun one. I'm involved in maintaining the audio system for an auditorium used by a non-profit. After a flood and remodel, including replacing some audio components (like microphones), it was observed that the microphone on the main podium always had a 60 Hz hum. The hum depended on where the microphone was facing. Sometimes it was there, sometimes it was not.

Being a non-profit facility, there are no fancy DSPs to notch out the hum or anything like that, so more creative solutions were investigated. It was determined through dumb experimentation that orienting an identical microphone 180 degrees to the one with the hum and setting the gain similarly would nearly eliminate the hum.

Eventually, the working theory became that a relatively new large pad transformer installed across the street was being picked up by the microphones. Orienting one microphone 180 degrees from the other caused the hum to be picked up out of phase from the main, and thus could be mixed in to cancel out the main mic hum.

Ultimately the real solution was simply buying better microphones, but there was a period of some months while a microphone sat off stage, pointed backwards.

Re: The Grateful Dead's Wall of Sound (2019)

#33

Post by dekhn »

buildsjets wrote: post #24
stevehiehn wrote: post #2

I remember chatting with a sound technician at a concert once and he told me that putting amplification in front of the performers only started happening in the late 60's (ish). Before that musicians were actually subjected to insane DB's by standing only a few meters in front of the amplification. (Don't take this is as fact, but this diagram suggests that he was correct)

Some techniques require this. Ted Nugent wouldn't have gotten the crazy howling feedback out of his semi-hollowbody Gibson Byrdland had he not been standing directly in front a pair of Fender Super Twins pushing 4 15" drivers. If it doesn't make your pants flap in the breeze, turn it up!

I believe most musicians these days achieve this using a nearby monitor speaker, for example Trey Anastasio from Phish, although I believe he may have adopted newer technology (see https://treysguitarrig.com/2023/08/31/2023-summer/ for more details). He could sustain notes for a long time with his custom hollowbody (like, minutes at a time).

Re: The Grateful Dead's Wall of Sound (2019)

#34

Post by upheaval7276 »

scrumper wrote: post #4

Article doesn't mention one of the more interesting (to me) aspects which was how feedback was avoided. The solution is elegant: each vocal microphone is doubled, meaning there are two at each position. The phase is inverted on one of them, the singer sings into only one, and both are sent to the speakers via their channel's amp. The effect of that setup is that only the difference between the two microphones is ampl…

Here is a much more detailed article that covers the mics and so much more: https://www.vice.com/en/article/wnnayb/the-wall-of-sound

Re: The Grateful Dead's Wall of Sound (2019)

#35

Post by ChainOfFools »

insaneirish wrote: post #32
plussed_reader wrote: post #14

Earlier quoted context omitted.

Since balanced cables predate the GD, this strikes me as an acoustic implementation of an EE concept. Neat!

Here's a fun one. I'm involved in maintaining the audio system for an auditorium used by a non-profit. After a flood and remodel, including replacing some audio components (like microphones), it was observed that the microphone on the main podium always had a 60 Hz hum. The hum depended on where the microphone was facing. Sometimes it was there, sometimes it was not. Being a non-profit facility, there are no fancy DS…

It's been quite a few years since I last worked in live show production, but on any show at a venue where we couldn't be sure of access to clean power, humbuckers (not the guitar pickups, a nickname for what I believe was just a dumb 60hz notch filter or ground loop isolator inlined on house power taps) were a standard pack out in the road kit.

I would have expected that this decades-old and well established component of power infrastructure would have been commoditized by now and integrated into any dedicated AV performance/production space such as an auditorium.

Re: The Grateful Dead's Wall of Sound (2019)

#36

Post by dylan604 »

llamaimperative wrote: post #8
itishappy wrote: post #7

Earlier quoted context omitted.

> common signal in both (i.e. the sound coming out of the speakers) is nulled out, but the difference signal (the voice) makes it through. What drives this? Singers and speakers are both localized sources, so I'd expect the mics to pick up similar phases for each. I bet it's distance! Falloff depends on distance to source, so there should be a larger difference in volume for closer sources.

Yeah one microphone was behind the other, though I was under the impression it was half a wavelength behind and thus created something quite akin to modern active noise-cancellation? Edit: Apparently this is not the case!

Half wave length in what frequency would be the first thing that would give me pause to this. I'm reading this after your edit, but even before I got to the edit my brain was already heading towards nope

Re: The Grateful Dead's Wall of Sound (2019)

#37

Post by llamaimperative »

dylan604 wrote: post #36
llamaimperative wrote: post #8

Earlier quoted context omitted.

Yeah one microphone was behind the other, though I was under the impression it was half a wavelength behind and thus created something quite akin to modern active noise-cancellation? Edit: Apparently this is not the case!

Half wave length in what frequency would be the first thing that would give me pause to this. I'm reading this after your edit, but even before I got to the edit my brain was already heading towards nope

Yeah that asterisk popping up in my head was why I did some more digging as well :) thought tbf, the Dead never seemed to care much about vocal quality so it wouldn’t have been crazy for this to work well only for a narrow band. I don’t have any intuition for exactly how narrow that band would be and how that’d sound in practice though.

Re: The Grateful Dead's Wall of Sound (2019)

#38

Post by TylerE »

bongodongobob wrote: post #30
TylerE wrote: post #28

Earlier quoted context omitted.

While it's true that they did that and why, I'd ultimately chalk it up as more of a flaw than a feature. Vocals never sounded great on wall of sound shows because they could never sing perfectly into one mic. This can be confirmed by listentng to soundboard tapes of the shows, and comparing them with ones a year or two either side - the full on Wall was only used for about a year. While the WoS laid much of the groun…

Well, yeah, compared to today it's not great but no one had tried anything like that before. They delayed the sound to distant speakers with tape delay . It's cool as shit and was the groundwork for how we do things today. It's like saying relay computers were dumb... Boolean logic was new and no one had ever attempted stuff like that before.

No, the whole point of the WoS was that there were no distant speakers. Everything was single sourced, to the point where each speaker only carried a single instrument.

Re: The Grateful Dead's Wall of Sound (2019)

#39

Post by dekhn »

bongodongobob wrote: post #30
TylerE wrote: post #28

Earlier quoted context omitted.

While it's true that they did that and why, I'd ultimately chalk it up as more of a flaw than a feature. Vocals never sounded great on wall of sound shows because they could never sing perfectly into one mic. This can be confirmed by listentng to soundboard tapes of the shows, and comparing them with ones a year or two either side - the full on Wall was only used for about a year. While the WoS laid much of the groun…

Well, yeah, compared to today it's not great but no one had tried anything like that before. They delayed the sound to distant speakers with tape delay . It's cool as shit and was the groundwork for how we do things today. It's like saying relay computers were dumb... Boolean logic was new and no one had ever attempted stuff like that before.

Not exactly: the wall of sound was only set up on stage. However, you could hear the music extremely clearly 1/4 mile away, due to the coherence. The delay towers were used before the WoS.

Re: The Grateful Dead's Wall of Sound (2019)

#40

Post by Liquix »

zer00eyz wrote: post #18
jMyles wrote: post #5

Earlier quoted context omitted.

I'd love to hear more about your experience and observations of taping at the shows. Not only did GD (and particularly Jerry Garcia and John Perry Barlow) eschew the 'intellectual property' model of music, their thought-leadership has lived on to become much of what we today consider fundamental internet technology and methodology. Early decentralized crypto-economics, peer-to-peer file sharing, and the founding of t…

It's almost impossible to talk about The Dead and not talk about LSD. Owsley (wall of sound engineer) was one of the original major LSD manufactures... and a dead show was always where you went to score ACID if you lived on the east coast. This remained true well into the 90's. I'm going to guess that all of those early internet pioneers that you mentioned also have fond stories of LSD. The Dead, Bill graham, hells a…

> I'm going to guess that all of those early internet pioneers that you mentioned also have fond stories of LSD.

What the Dormouse Said by John Markoff is exactly that. A dive into how psychedelic counterculture made its mark on folks at Stanford, folks at XEROX PARC, Doug Engelbart, Jim Fadiman, Steve Jobs, etc. Not the most cohesive narrative but fascinating stories

https://www.amazon.com/What-Dormouse-Said-Counterculture-Per...

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