Hacker News Board Hacker News, browsed like a classic message board
Live data from Hacker News

The Grateful Dead's Wall of Sound (2019)

audioacademy.in

Post reply on HN
Print view View original

51–60 of 130 posts

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

#51

Post by JohnBooty »

jtriangle wrote: post #13

Dave Rat, of Rat Sound/RHCP/Bassnectar/etc fame, has some very interesting takes on the wall of sound idea using modern equipment. The core of it is that speakers are bad at polyphony, so if you can avoid it, you can produce something that sounds more natural to human ears, and do so in a larger area. The way to avoid it is more speakers, more stacks/arrays/etc. You don't necessarily need an array per instrument, bec…

    The core of it is that speakers are bad at polyphony
You can look at intermodulation measurements for some popular and affordable home speakers here. The TL;DR is yeah, you're going to go from something like -60dB distortion to -40dB when doing synthetic multitone tests, but I would not remotely characterize this as being "bad" at polyphony nor the primary reason for the Wall of Sounds primordial "one vertical speaker array per instrument" design.

https://www.erinsaudiocorner.com/loudspeakers/kef_r5_meta/

https://www.erinsaudiocorner.com/loudspeakers/sony_sscs3_tow...

more: https://www.erinsaudiocorner.com/loudspeakers/

    The way to avoid it is more speakers, more stacks/arrays/etc.
If we're talking about his remarks here I'd characterize his take as "more vertical arrays" and not just "more speakers." I realize it's a bit pedantic of me, but some people think that simply adding more speakers equals more betterer sound and it's quite far from the case. In general, multiple loudspeakers arrayed horizontally (this includes MTM center channels in home theater setups) lead to comb filtering.

I'm sure you know that, just clarifying for others.

If he has written about this elsewhere I'd love to read more!

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

#52

Post by switz »

block_dagger wrote: post #43

For those wanting to listen to free legal taped audio of Dead shows, head over to https://relisten.net/grateful-dead or install Relisten app for iOS. All fan supported and open source.

Hey! I created this website and have been maintaining it along with my friend Alec for the last decade. Fun seeing it pop up here on HN. Thanks for sharing!

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

#53

Post by neckro23 »

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…

This is very similar to how noise cancellation works on cell phones. The secondary mic is typically on the back of the phone and picks up the ambient noise to be subtracted from the primary mic’s signal.

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

#54

Post by amlib »

JohnBooty wrote: post #44
amlib wrote: post #22

Earlier quoted context omitted.

I wonder how do they deal with the phasing over so many speakers? Wouldn't an array of speakers require you to do something about that? Specially so if you are stuck with 70s tech.

deal with the phasing over so many speakers? Each performer had their own vertical stack of speakers. So, no phase issues / comb filtering on the horizontal axis. https://www.soundonsound.com/techniques/line-arrays-explaine...

I was thinking more in terms of the Wall of Sound as shown in the article. Were they also doing vertical stacks per channel/instrument or were they doing arrays of speakers arranged in a grid per channel/instrument? From what I take it was the later as line arrays weren't a thing at that point, right?

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

#55

Post by TacticalCoder »

JohnBooty wrote: post #6

You can see a partial legacy of the "Wall of Sound" at most concerts today - vertical line array speakers. https://www.soundonsound.com/techniques/line-arrays-explaine... For the most part, each performer plugged into the "Wall of Sound" had their own vertical 1xN stack of drivers. 3 drivers in a vertical line away will have less distortion than 3 drivers in a horizontal array; the horizontal drivers will suffer from…

> modern tower speakers have a vertical array of 2 or more drivers whose centers are aligned in a vertical line

But you cannot say that on HN. HN is the place where people believe soundbars are as good as high-end audiophile speakers!

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

#56

Post by TylerE »

dekhn wrote: post #31
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…

(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…

Ironically i haven't really listened to most of the official live albums much. I tend to just go straight to the board tapes, which often sound better due to having a few decades of technological advancement - many were transferred in the 90s or 2000s. Of course they didn't have then what we have now, but even consumers by then had access to software for things like mastering that would have made any 70's engineer drool - certain kinds of repairs are much more easily done digitally - back in the day cutting out a spot of stactic or a mic pop involved literal tape and razor blades.

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

#57

Post by jtriangle »

JohnBooty wrote: post #51
jtriangle wrote: post #13

Dave Rat, of Rat Sound/RHCP/Bassnectar/etc fame, has some very interesting takes on the wall of sound idea using modern equipment. The core of it is that speakers are bad at polyphony, so if you can avoid it, you can produce something that sounds more natural to human ears, and do so in a larger area. The way to avoid it is more speakers, more stacks/arrays/etc. You don't necessarily need an array per instrument, bec…

The core of it is that speakers are bad at polyphony You can look at intermodulation measurements for some popular and affordable home speakers here. The TL;DR is yeah, you're going to go from something like -60dB distortion to -40dB when doing synthetic multitone tests, but I would not remotely characterize this as being "bad" at polyphony nor the primary reason for the Wall of Sounds primordial "one vertical speake…

I'm simplifying things significantly because I don't expect most HN'ers to know the ins and outs of pro sound.

Dave Rat has a good youtube channel, he also has some sort of insider subscription thing that I've never bothered with. I wouldn't say his ideas necessarily translate to every situation, but, he really presents these ideas as tools to use in a toolbox, not as gospel.

One interesting thing is that, we generally view comb filtering as universally 'bad', when, in reality, our ears do an excellent job of sorting out comb filtering when it comes to natural sounds. In fact, comb filtering is how we can locate a sound in 3d space with only two reference points (and, if you try, only one reference point moved around a little). That's remarkable, and points back to how speakers comb filter instead of mere comb filtering itself.

In practice, say you have a rock band, and your sound system has two arrays with subs spaced 40ft apart. Now, you're going to get a less than ideal pattern from that in the ranges where the bass guitar and kick drum live. How do you fix it? The answer is fairly simple, you simply run bass/kick in stereo, then, you delay the bass on one side by a little, kick on the opposite side just a little, then add some kind of EQ difference to the delayed side of each, then play with the delays until it sounds right.

Why does that work? Or does it really work? It's odd, because the math says "no no, it'll sound bad", the reality is, it can tighten up that comb to the point you don't really hear it and you can get good bass coverage out of a fairly poor system design.

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

#58

Post by plussed_reader »

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…

That is my kind of tickler/teaser. Thanks for the share.

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

#59

Post by dekhn »

TylerE wrote: post #56
dekhn wrote: post #31

Earlier quoted context omitted.

(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…

Ironically i haven't really listened to most of the official live albums much. I tend to just go straight to the board tapes, which often sound better due to having a few decades of technological advancement - many were transferred in the 90s or 2000s. Of course they didn't have then what we have now, but even consumers by then had access to software for things like mastering that would have made any 70's engineer dr…

Two From The Vault isn't a "official live album", it's a soundboard that was shelved for decades due to the quality of the recording. I got this album on CD when I was in college (early 90s) and didn't have access to high quality taping equipment, and soundboards from the late 60s were very rare. The audio quality is absolutely excellent (I am just relistening to it now, there's only tiny background hiss, excellent clarity on all the instruments, decent vocals, and only a bit of high-volume distortion on the guitar and bass). It's also a nice counterpoint to the original of the "From The Vault" series, One From The Vault, which was recorded years later under ideal conditions and the band had been practicing extensively.

Much has changed from the days when we had to implement balanced binary trees of tapes (analog tape copies were lossy, so you wanted to minimize the total depth of copies).

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

#60

Post by owenmarshall »

gjmacd wrote: post #19

The most incredible sound system to hear a band play out of tune and out of key for 90 minutes.

90 minutes? At a _Dead_ concert?!

That’s enough to cover a typical Playing>Uncle John’s>Drums>Space, and probably not get all the way through the reprises. You’ve easily got another two hours of jam.

Post reply on HN