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Topic: Why is real pro audio gear so small and light? (Read 7923 times) previous topic - next topic
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Why is real pro audio gear so small and light?

Anyone here work in big scale audio installations?

Sorry if this is a little off topic but I'd be intrigued to discover what the technical innovation was that made sound re-inforcement gear so small and light.

Time was you went to a gig and there was an army of sweaty roadies lugging a mountain of speaker cabs. and amps. in and out of the venue. You could hardly see the band sometimes.

Nowadays you have to look hard to see it. You can apparently fill the Albert Hall with the contents of a Transit. Except the mixing desk(s) lol.

What brought that about exactly?

Why is real pro audio gear so small and light?

Reply #1 –
Many years ago I worked for a small sound & lighting company, but I haven't been involved "backstage" for many years...

For small acts, there are now more-portable plactic/fibreglass speakers as well as lightweight "powered" speakers and all-in-one systems with the mixer & amp built-into the speakers.

For the big acts, I dunno...  I think they are using more trucks than ever!  I don't know about the audio, but there are usually multiple huge video screens and massive lighting systems.  Often they bring their own stage-platform and sometimes there are two complete set-ups so they can "leapfrog" and set-up the next concert while tearing-down or transporting the previous one.  ...I don't know if there are fewer sweaty roadies, but I think there are more cranes & forklifts.

I'm not sure about the sound reinforcement systems, but there is less on-stage monitoring equipment because the musicians are using in-ear monitors.  And, the stages have become bigger and less crowded, and they have become more of a "set", and they are hiding some of the equipment behind the set pieces.  I have a sneaky feeling that the stacks of Marshall amps you sometimes see are a prop (and an advertisement).  Most of the sound should be coming from the sound reinforcement PA system where the sound guy can control it, not from the on stage amps...  I've noticed that there are often spotlights on each amp lighting-up the "Marshall" name...  Hmmmm...

Overall, I'd say the systems have gotten more complicated with wireless mics, wireless guitar transmitters, wireless in-ear monitors with separate mixes for each performer, etc.  Plus all of the computerized video & lighting equipment.

Quote
You can apparently fill the Albert Hall with the contents of a Transit.
  The Royal Albert hall probably has good acoustics, and therefore shouldn't require that much audio power! 

Why is real pro audio gear so small and light?

Reply #2 –
The class D amplifiers with switching power supplies are a huge weight (and power) savings.

The digital mixing desks would be smaller if they didn't have so many new features. There isn't a physical knob for every control parameter but there's a lot more control parameters than there used to be.

Lighter digital networking instead of bulky multichannel analog cabling are used in many systems.

Advanced materials such as neodymium Magnets, fiberglass and carbon fiber make the speakers smaller and lighter.

Line array speaker systems focus the sound on the audience. Primarily that makes things sound better by eliminating extra sound bouncing off things but also it reduces how much power is required.

In ear monitors remove "wedge" style monitors from the stage.

Why is real pro audio gear so small and light?

Reply #3 –
Quote from: DVDdoug on
I have a sneaky feeling that the stacks of Marshall amps you sometimes see are a prop (and an advertisement).


From what I have seen, each guitar has only one working amp on stage despite there being a stack of 2000.  I have taken a behind-the-scenes tour of Ozzfest every year from 2004 to 2007.  Each and every time, there is at least one band with a wall of amps.  Slayer was like that in 2004.  The person who gave the tour (I think it was Big Mike) pointed out that only one set of thick wires were running into three of the amps and that the rest didn't have wired running into them.  Lamb Of God was like that in 2007 and again, Mike pointed out how only a three of the amps were actually working while the rest were just for show.  There is even some behind-the-scenes footage of a Korn concert where Munky (the guitarist) stated that he only uses one amp while the rest are just for show.

I imagine that speaker sizes have decreased drastically due to increasing technology.  There is an older system in my living room.  It is a Sony home theater system (from 1993) with two floor standing speakers, one huge subwoofer, a 5 disc CD changer, a controlled amplifier, a dual cassette tape deck, and a rather large AM/FM controller.  This whole setup is huge and the system has 150 watts of total power.  Fast forward to 2001 where I have a 5.1 surround sound system with a 5 disc CD changer, dual cassette tape deck, and subwoofer.  The whole system can fit in the same space as the two speakers of the old Sony one yet it has a total of 600 watts power.  Go into 2004 and my Logitech system fits in the same space as the subwoofer for the 2001 system and had 550 watts of RMS power (1000 watts of max power).  I know that watts are not a good measurement for sound quality but it gives you an idea regarding the power of each system while the sizes are drastically increased.

I remember my Dad telling me about seeing AC/DC in El Paso, TX with their original singer.  He actually sat inside one of the speakers, they were that huge.  He then saw Marilyn Manson with me in 2004 and was disappointed to see that his speakers were much smaller.  However, at the end of the show, he said that was the loudest concert he had ever been to.

I am sure many older concert goers miss seeing the old speakers that are as big as a Volkswagen Bug.  However, these newer systems allow for bands/artists to have a larger light set and stage without adding more trucks (unless you are KISS).

Why is real pro audio gear so small and light?

Reply #4 –
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(unless you are KISS).
  Or Spinal Tap!    In The Return Of Spinal Tap (filmed live at The Royal Albert Hall, coincidently) there is a HUGE Marshall amp, obviously a joke/prop.  I don't remember exactly how big it is, but it's probably 4x the size of a real amp.

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There is an older system in my living room. It is a Sony home theater system (from 1993) with two floor standing speakers, one huge subwoofer.
  I actually have a  pair of ridiculously huge speaker stacks in my living room...  Just short of the 8-foot ceiling!  They are not props, but of course I don't take "full advantage" of them either...  I don't want to blow-out all of the windows on my block!  (Actually, I don't want to annoy my neighbors, and maybe I'm getting too old for really-loud music.)  My rear-surround speakers are "floor standing" speakers with 15" woofers hanging by chains above my couch!

Why is real pro audio gear so small and light?

Reply #5 –
Thx for replies. Particularly Notat who has pretty much nailed it in 6 sort paragraphs. 

I have one outstanding question.

In 'ye olden dayes' main PA speaker cabs. had like 1 or 2 actual drivers inside a huge and heavy enclosure. They were even shaped like horns and had vents and baffles and all that stuff found in hi-fi speakers. Only bigger.

Now they seem to have simply bolted 4 speakers onto the front of a long box about the size of a small coffin. Each box has it's own amp(s) depending on the freq. range it has been assigned.  Doesn't seem to be any acoustic treatment of the audio waves at all.

Why doesn't that matter any more? Or is the fuss made over hi-fi speaker cabinet design completely overrated?

Why is real pro audio gear so small and light?

Reply #6 –
Quote from: RonaldDumsfeld on
In 'ye olden dayes' main PA speaker cabs. had like 1 or 2 actual drivers inside a huge and heavy enclosure. They were even shaped like horns and had vents and baffles and all that stuff found in hi-fi speakers. Only bigger.

Now they seem to have simply bolted 4 speakers onto the front of a long box about the size of a small coffin. Each box has it's own amp(s) depending on the freq. range it has been assigned.  Doesn't seem to be any acoustic treatment of the audio waves at all.

Why doesn't that matter any more? Or is the fuss made over hi-fi speaker cabinet design completely overrated?


Mostly these days the amplifiers are more powerful and they're just using speakers which are not so extreme in their design for efficiency.  When I started going to shows it was unusual for a PA or instrument amp to have as much as 100 watts available, so big efficient horn-type speaker cabinets were used to make up for the lack of power.  Also, the PA wasn't used to carry the entire band's sound, usually just the vocals and sometimes keyboards/brass/drums.  Back then, guitars usually provided their own backline, hence the origination of many big cabinets lined up.

The only reason there are still active speakers for the guitars these days at big shows is that many musicians prefer the sound they get when capturing the sound of their instrument amp via a mic; this is then routed through the PA.  There are some electronics that can mimic the sound of a mic'ed cab, but not everyone likes to use them.

Also, even small combo amps can now provide as much as 200-500 watts of real power due to advances such as Class D, so the PA rigs can be much smaller and use less efficient speakers in turn.  Some of the modern cabs are still ported, but you almost never see horns any more because they're so huge and bands are willing to spend more power to get a smaller speaker.

Why is real pro audio gear so small and light?

Reply #7 –
Quote from: kornchild2002 on
There is an older system in my living room.  It is a Sony home theater system (from 1993) with two floor standing speakers, one huge subwoofer, a 5 disc CD changer, a controlled amplifier, a dual cassette tape deck, and a rather large AM/FM controller.  This whole setup is huge and the system has 150 watts of total power [...] Go into 2004 and my Logitech system fits in the same space as the subwoofer for the 2001 system and had 550 watts of RMS power (1000 watts of max power).  I know that watts are not a good measurement for sound quality but it gives you an idea regarding the power of each system while the sizes are drastically increased.

I can pretty much guarantee you that your big Sony speakers were dramatically more efficient than the Logitechs, and therefore required far less power to achieve the same acoustic output, particularly in the low frequencies (all considerations of differences in sound quality/accuracy/dispersion/etc. aside).

The two main reasons for this are 1) the overall lower efficiency of smaller low-frequency drivers, and 2) baffle step diffraction (Google).  While it's true that Computer-Aided Modeling and advanced acoustic research facilities such as the NRC in Canada have made smaller but still "good-sounding" speakers possible, you can only bend the laws of physics so far, and this is especially true when it comes to low-frequency reproduction.

Yes, there are a plethora of compact "subwoofers" out there, and they may be capable of "loud bass," but the *accuracy* of that bass - as well as freedom from cabinet/port resonances (which will never be shown in a simple frequency-response graph) - is often lacking.
"Not sure what the question is, but the answer is probably no."

Why is real pro audio gear so small and light?

Reply #8 –
Quote from: GregDunn on
[...] but you almost never see horns any more because they're so huge and bands are willing to spend more power to get a smaller speaker.

Actually, there are arguably more "horns" than ever being used in sound reinforcement systems, they just don't *look* like horns - they're called line arrays.
"Not sure what the question is, but the answer is probably no."

Why is real pro audio gear so small and light?

Reply #9 –
Line Array + Google = Eureka + 

Why is real pro audio gear so small and light?

Reply #10 –
Quote from: RonaldDumsfeld on
In 'ye olden dayes' main PA speaker cabs. had like 1 or 2 actual drivers inside a huge and heavy enclosure. They were even shaped like horns and had vents and baffles and all that stuff found in hi-fi speakers. Only bigger.

It still takes a big box to reproduce the low frequencies. All modern rock-n-roll PAs use sub woofers. Since low frequencies are not directional, they can hide these large speakers under the stage or elsewhere. In the vintage systems, all sound came from the main speakers - nothing was hidden. Subwoofers are a bit smaller than they once were and they are less efficient. Much of the tuning that had previously been done mechanically with bulky baffles, enormous horns and and enclosed volume is now done electronically.

Why is real pro audio gear so small and light?

Reply #11 –
Quote from: GregDunn on
The only reason there are still active speakers for the guitars these days at big shows is that many musicians prefer the sound they get when capturing the sound of their instrument amp via a mic; this is then routed through the PA.  There are some electronics that can mimic the sound of a mic'ed cab, but not everyone likes to use them.


And for the feedback effects, I guess; bringing the guitars to the cabinet has an effect still. Besides they are "monitors" too.

(Not a "big show", but U.D.O. has for the last couple of tours offered a live recording of the show on USB for sale in the merch boot a few minutes after they go off stage -- and one can notice there are no microphones in front of the instrument speakers. But they were wired and producing sound, yes.)


As for Slayer: when the stage has 2x 11 Marshalls rigged up as two inverted crosses, then of course it is a prop. (Wonder if all those are actually for real or some are merely display boxes like on IKEA.)

Why is real pro audio gear so small and light?

Reply #12 –
Quote from: RonaldDumsfeld on
Anyone here work in big scale audio installations?


What you're talking about affects even relatively small operations.


Quote
Sorry if this is a little off topic but I'd be intrigued to discover what the technical innovation was that made sound re-inforcement gear so small and light.


Speakers really haven't shrunk that much, but when they shrink they typically shrink by trading off efficiency for size given the bandpass.  Arrays and phased arrays are used to simulate large waveguides. This is essentially trading off many small speakers for just a few very large ones. Phased arrays can do things that were never done with traditional technology.

The big technological change has been in power amplifiers.  Between switchmode power supplies and output stages with multiple power supplies that are switched in and out so that the power dissipated across the output transistors is minimized, power amps have lost up to 3/4  or more of their size and weight. Surprizingly enough, there is not all that much going on with switchmode output stages.  As 18 pound SS amplifier might put out about 50 wpc, max in the early 1980s. Today, up to 2 KW. A conventional technology power amp that weighs 18 pounds would put out maybe 150 wpc x2  today.

One other thing - the need for huge mixing consoles has been vastly reduced by digital consoles. I mix on a Yamaha 02R96 which packs 56 input channels of mixing into the space required for 24 channels or less. This is accomplished by virtualizing the controls. The faders are virtualized so that each one controls 3 channels, and the rest of the controls are virtualized so that they control at least 66 channels (56 in, the rest are outs).

Why is real pro audio gear so small and light?

Reply #13 –
Quote from: Notat on
It still takes a big box to reproduce the low frequencies.


The good news is that this is totally false.

The laws of physics allow a multi-way trade off:

(1) Physical size
(2) Bass extension

<now you think I agree with you, but you're wrong! ;-)>

(3) Efficiency


The efficiency of a speaker can vary over an approximate 20 dB range. For a given amount of bass extension, efficiency can be traded off for smaller enclosure volume.

I've seen subwoofers with bandpass down to 10 Hz that were like 8 cubic feet OD. There were 230 volt power lines running to the power amps placed in the basement to deal with the cooling fan noise.

Yes, this means that speakers with deep bass and good efficiency are large.  But high efficiency is no longer absolutely needed.

So, since power amps are cheap, and we can build speaker drivers with great power handling capacity, and trade off efficiency!

Hoffman's Iron Law:

where n0 = reference efficiency (% based)
Fs = the resonant frequency of the driver (measured in Hz)
Vas = Volume of air which, when acted upon by a piston of area Sd, has the same compliance as the driver's suspension (measured in m^3)
Qes = electrical "Q" of the driver at Fs (unitless)

n0 = (9.614 * 10^-7 * Fs^3 * Vas)/Qes * 100



Why is real pro audio gear so small and light?

Reply #14 –
Quote from: Notat on
The class D amplifiers with switching power supplies are a huge weight (and power) savings.


While there are a few power amps with Class D outputs, the vast majority of high-powered pro amps combine switchmode power supplies with stepped power supply linear output stages. There are two or three pairs of power supply voltages that are applied to the output stage through swtiching transistors. The voltage applied to the output stage roughly follows the audio signal, with the linear output stage taking out the roughness of the switching. Variously called class G or H.

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The digital mixing desks would be smaller if they didn't have so many new features. There isn't a physical knob for every control parameter but there's a lot more control parameters than there used to be.


What actually happened is that there was a lot of market resistance to highly virtualized digital mixing consoles such as my 02R96 with 3 layers. A layer is a mapping of the physical faders and a few associated other controls. You push a button to remap the faders to the various layers to control up to 3 inputs with one physical fader. I know of experienced sound guys who just couldn't adapt to layers, even after years. Newer small and medium digital consoles minimize the use of layering (2 max) and some mid-sized digital consoles have no layers at all. They still use virtual controls for many peripheral functions like equalization, reverb, EFX, patching, and monitor mixing. People adapted to this more readily, probably because they are used far less frequently.

The actual feature sets of digital consoles haven't changed that much, since the previous generation digital consoles already did so much. A mid-sized digital console of the previous or this genration includes EQ and EFX units that would fill several full-height racks and cost $10,000s if implemented traditionally. Just the wiring would probably cost more than the console.

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Lighter digital networking instead of bulky multichannel analog cabling are used in many systems.


Good point. At least one console (Roland) is pretty much based on digital cabling. 64 channels of high quality audio can be easily routed over one piece of twinaxial or CAT 5 network cable. The equivalent in analog would be well over an inch in diameter. 100 feet or more is required by most shows.  We're talking wooden spools of wire that you could turn on the side and use for a small picnic table. It takes muscle to route and remove this stuff.

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Advanced materials such as neodymium Magnets, fiberglass and carbon fiber make the speakers smaller and lighter.


Another good point. Neo magnets and high-tech composites shave weight dramatically, which is especially critical if the speaker is flown which is generally the best way to do it.

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Line array speaker systems focus the sound on the audience. Primarily that makes things sound better by eliminating extra sound bouncing off things but also it reduces how much power is required.


In a real-world setting the distance from the speaker to the listener can vary dramatically. The old rule of thumb was to fly the speaker so that this stayed within a 2:1 range, but modern arenas with balconies can make this an impossible dream. The individual speaker modules in a line array can be tweaked to optimize the relatively small amount of seating that they cover.

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In ear monitors remove "wedge" style monitors from the stage.


Digital mixing and cabling systems make it entirely feasible for each musican to manage his own monitor mix. Instead of running 16 pairs of signal wires to each musican't mixer, a single piece of CAT5 can be daisy-chained. The individual musician's mixer doesn't need to have 16 sets of controls for 16 channels, because digital logic enables one set of knobs to control all 16 channels.

Why is real pro audio gear so small and light?

Reply #15 –
Quote from: Arnold B. Krueger on
While there are a few power amps with Class D outputs


It's going class D quite quickly at the high end though for example QSC PowerLight 3, Crown iTech, some Lab.gruppen stuff and quite a lot of stuff that's integrated into active line array elements. Given it's only happened in the last few years I suspect it'll be a decade at least before the majority is class D unfortunately :/

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What actually happened is that there was a lot of market resistance to highly virtualized digital mixing consoles such as my 02R96 with 3 layers.


Hence designs like the M7CL, don't underestimate the amount of intertia in the industry. On the other hand I think that layers and very highly virtualised desks do present a barrier. I work in student theatre a lot where we get a large number of people who aren't experienced engineers through and some who've never seen a mixing desk before. Almost universally they can grok (a suitably set up) M7CL in minutes where I've had to give up on getting some people to understand an 01V96.

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Good point. At least one console (Roland) is pretty much based on digital cabling.


And other systems put all the AD/DA and DSP at the stage end and all the engineer has is a control surface on the end of a bit of ethernet, that still tends to be at the high end of the market though.

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Digital mixing and cabling systems make it entirely feasible for each musican to manage his own monitor mix.


...in turn this has allowed 'silent' stage and other techniques to become feasible. In this case though you do end up putting more kit in as you need bass cancellation and steering techniques which increases the number of subs, amps and processing channels needed.

Why is real pro audio gear so small and light?

Reply #16 –
Quote from: mixminus1 on
Quote from: GregDunn on
[...] but you almost never see horns any more because they're so huge and bands are willing to spend more power to get a smaller speaker.

Actually, there are arguably more "horns" than ever being used in sound reinforcement systems, they just don't *look* like horns - they're called line arrays.


Sorry for not being clear - I was referring to the bass cabinets not the mid/high frequency drivers.