Tag Archives: Mixing

Building A Small System

A guide to building a simple live-sound rig, from input to output.

Please Remember:

The opinions expressed are mine only. These opinions do not necessarily reflect anybody else’s opinions. I do not own, operate, manage, or represent any band, venue, or company that I talk about, unless explicitly noted.

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Every once in a while, I get a request for information on how to create or add-on to a system for live audio. I like to personalize this information, because rigs for show and event production are best built for specific applications. However, there is a point where insisting that everything be approached in a customized way becomes inefficient – a lot of the same ground gets covered repeatedly.

So…

If you’re wondering what I think is required for a “small, basic, but still worthwhile” audio rig, read on. I’ll be including lots of links to vendor pages where you can buy various products.

(We’re going to go in order of signal flow, by the way.)

Input Transducers and Interfaces

For the smallest possible rig, take a distributed approach: With anything other than vocals, have the musician supply their own, personalized sound. Further, seek to avoid the whole issue of putting the output of that sound through the PA. Let a guitar amp make the guitar sound, let the drums just make their own noise in the room, and so on.

Having the ability to put more in the PA increases your potential control over the sound of the show, but outside factors can prevent that potential control from becoming actual control. Also, more inputs means more complexity, and thus more difficulty in system operation. There’s no hard and fast rule of what to be ready to reinforce, but I generally encourage folks – especially folks new to this whole thing – to ease themselves into the maelstrom that is live audio.

Wired Microphones

A decent mic will basically sound like the thing it’s being pointed at. For this reason, don’t agonize about getting specialized mics for everything right off the bat. A good “vocal” mic will be fine for many, many instrument applications. I recommend buying mics with tighter patterns (super or hypercardioid), as they can make the handling of high-gain situations much easier. Tight-pattern mics do require that the musicians – especially the vocalists – be able to use them appropriately. This issue should be considered as something for the musicians to figure out, because no system can fix everything (and a basic rig can fix even less of everything, if you take my meaning).

My current favorite mic is the EV ND767a. You might also consider the Audix OM2. Here’s a comparison of the two at Sweetwater.

Microphone Accessories

Each mic you buy will require an appropriate stand and XLR-Female to XLR-male cable.

Budget stands (like these from OnStage Stands) are just fine… if you can put in the effort to be nice to them. Gator Frameworks also has some promising offerings.

When it comes to cable, don’t overspend and don’t oversave. For a 20+ foot mic cable, paying more than $1.00 per foot is a huge premium for no benefit that I’ve been able to clearly observe. There are perfectly decent cables that can be had for as low as $0.40 per foot when purchased in a bundle. Going much below that, though, is likely to lead to problems.

I’ve been quite happy with cables I’ve gotten from Audiopile and Orange County Speaker. I’ve gotten some REALLY inexpensive cables from Unique Squared that were okay for a good while, but started having problems after a number of uses.

Wireless Mics

One word: Don’t.

Wireless is a pain in the donkey, with the FCC selling off all kinds of UHF spectrum to cellphone and computing companies, and the frequencies used for digital wireless becoming ever more crowded and hostile. Functionally, wireless transmission of audio is far more “fragile” than signal running on a cable, with all kinds of weird things that can happen outside your control.

But no matter what I say, you’re going to buy at least one wireless mic anyway, so…

Buy a digital system that operates in the 2.4 Ghz band if you want a chance at retaining your sanity in the short term. Specifically, look at the XD-V55 systems by Line 6. They’re very reasonably priced, have nice features like remote monitoring of mute status and battery level, and are the best wireless experience I’ve personally had to date.

You can, of course, go up from there.

Wireless Mic Accessories

Handheld wireless mics benefit greatly from having a stand available for every transmitter. Further, each receiver will need a cable to interface with the rest of the system.

Direct Boxes

A direct box is what I class as an “interface,” because it doesn’t convert acoustical events into electrical signals. A DI makes signals that are already electrical play nicely with pro-audio equipment when they might not otherwise. An aspect of this is also isolation, in that the DI creates what you might call an indirect connection between a console and a device. This can be very handy if the sending device (a guitar, keyboard, sampler, whatever) can’t tolerate phantom power, and the console has phantom applied to the signal line in question.

Direct boxes come in two main flavors, passive and active. Active DI boxes require external power of some kind, be that power from the wall, batteries, or phantom from the console. If you’re going to buy DI boxes, buy ACTIVE models. An active DI will work with almost anything, whereas some instrument pickups pair quite badly with passive boxes. You might as well buy units that work everywhere, and thus simplify your life. Expensive models from BSS, Radial, and Countryman are certainly nice, but there’s great value to be had in units from ART and Behringer, especially the “multiple modules in one box” offerings.

DI Box Accessories

Just like a microphone, each DI box will require an XLR-Female to XLR-Male cable. Remember that multi-module DI boxes require a cable for each individual module.

You don’t have to actually mount a rackable DI system, but you might want to. Sweetwater and Audiopile both sell quality rack cases in a huge variety of configurations.

Snakes/ Multicore Connections

Depending upon how you implement the mix and signal processing part of the rig, you may or may not require multicore cabling. If you want to send and receive a bunch of audio signals at a remote location, a snake really is a must. If you merely want to control the processing of signals from a remote location, you might be able to use your console in the same way you would use a traditional snakehead or stagebox.

If you do use a multicore, I suggest getting one that’s a little “overkill” in terms of the number of lines it contains. If a line fails, you’ll have a spare to patch to. “Headless or “fan-to-fan” snakes are a bit cheaper, but less convenient than multicores that terminate one end at a box. (You will always have to hunt for the specific line you want to connect to. It’s like a law of nature, or something.)

Audiopile would be my first choice for buying a snake I was really serious about. I have had good results with Seismic Audio fantail-to-fantail snakes, but my experience with their stagebox offerings has been mixed.

Mixing Consoles and Output Processing

This is where things get REALLY interesting.

Essentially, you have three major choices:

1) Use a relatively simple console where output processing is handled externally, and place all that at a “remote” location.

2) Use a more sophisticated console that encapsulates the output processing, and place the console at a “remote” location.

3) Use a more sophisticated console that encapsulates the output processing, leave the console close to the stage, and control the console from a remote location.

Option one takes up more space and requires more complicated physical patching, but the interface can be easier to understand at an intuitive level. Option two is compact and easy to physically patch, but the whole thing can be less intuitive for an inexperienced operator. Option three is like option two, with the added issue that control can depend entirely on an external device and network connection. If those fail, you may be in big trouble.

In every case, a console with some room to grow in terms of both inputs and outputs is a good idea. Don’t go overboard, though. You’ll end up spending a lot of money to no functional end. Especially if you’re new to all this, keep your monitor sends down to a maximum of four.

Option 1

The Console

Whatever you do, buy a console where the EQ has sweepable mids on the EQ and pre-fader auxiliary sends for each unique monitor mix you want to handle. A Soundcraft EPM8 is probably the minimum you should look for. I’ve been quite pleased with Yamaha’s mid-basic offerings, which have been revamped since I’ve bought one.

Simple, analog consoles “race” in a VERY tight pack, which means that there are lots of little permutations and many viable choices. Mackie, A&H, and Peavey are all worth looking at, and Behringer, while not having the shiniest reputation, has a knack for cramming lots of features into small cost. An XL2400 has what I would consider to be pretty darn flexible routing for a $650 mixer.

Console Accessories

Some consoles can be easily cased up or rackmounted, and some can’t.

You will need patch cables and/ or adapters with appropriate ends to get from your console outputs to your processing, one cable for each channel. As with other cables, high-dollar options really aren’t necessary. Stay somewhere in the $2/ foot range, and you’ll have patch connections that are long enough for some wiggle room and cheap enough that you won’t cry about ’em.

Also, get yourself a decent set of headphones for listening to the console’s solo bus. I have a pair of very-well-loved HD280s, and lots of other options exist. You want to look for closed-back, durable, “un-hyped” phones if you’re doing your own hunting.

The Processing

What you choose for output processing depends greatly on your own personal taste and comfort level. At the minimum, you should have an independent EQ for each mix. A really basic setup might be three mixes – one for the audience, and two monitor mixes for the stage. Things go up from there, of course.

Graphic equalizers, while not my personal favorite, are straightforward for most folks to operate. I generally recommend 31-band models over 15-band units, because you can focus in on a problem area without sledgehammering material that’s not making trouble. Peavey and dBX are good overall bets, but affordable graphics are similar to affordable consoles: All the players are very similar. I do like the features of the Behringer FBQ3102, but I also had one die after a year of use and a bumpy ride in the back of a truck.

If I’m going for an EQ-only solution, I can tell you that I vastly prefer a flexible parametric EQ over a graphic. In that realm, I have been extremely impressed by Behringer’s Feedback Destroyers. To be clear, my experience is that their automated feedback management is mediocre at best – but they are WICKED HANDY when you run them manually. You get a huge number of fully parametric filters at a very low price point. I’ve never had a major problem with any Feedback Destroyer I’ve owned. (Be aware that parametric EQ is more involved than graphic EQ. It’s not quite as “grab-n-go.” There are more choices that you have to make deliberately.)

If you want your processing to include dynamics, and also to let you have a graphic EQ combined with a parametric EQ, then a Behringer DEQ2496 is another killer device. Again, I haven’t found anything else exactly like it “in the wild,” although a Driverack PA2 is actually very close. DEQ2496 units do sometimes have problems with one of the internal connectors getting loose, but it’s an easy fix once you get the cover pulled off the device…and the connector freed from being glued down. (You will very definitely void your warranty if it’s still in effect, but hey, live a little.)

Processing Accessories

You may or may not be able to patch your snake returns (or other output cables) directly to your processing, so some adapters or patch cables might be necessary.

Also, you should definitely rack up any outboard processors you have for your system. It really does help to keep things neat and tidy.

Option 2

The Console

Digital consoles are a great route to take if you want to keep everything in one box. The downside, of course, is that the one box becomes a single point of failure. Then again, in any case, losing the console pretty much ends your day if you don’t have a spare.

Another factor to consider is that the processing available in digital consoles tends to be more fully featured while also being somewhat abstracted. This can make them overwhelming for new users, who simply don’t know what to make of all the options available.

If you’re going to be physically present at the console, you may as well get one that has a control-surface integrated in some way. An X32 Producer is a pretty natural choice, along with offerings from Presonus, Allen & Heath, and QSC.

Console Accessories

As was said earlier, rackmounting or casing the console might be possible. You can decide if you want to go to the expense or not.

The need to buy patch cables or adapters may still be there, depending on the configuration of your snake or other output lines.

And you’ll still want some headphones.

Option 3

The Console

You can leave the console on stage and mix remotely with the consoles detailed above, although the control surface might be a bit of a waste. Affordable digi-mixers that lack a surface are an interesting new product on the scene – just remember to factor in the cost of a remote-control laptop or tablet. Also, be aware that remote control is inherently a bit more “shaky” than being physically present at the mixer. It’s not horribly problematic, of course, but you have to have a contingency plan.

Surfaceless consoles at lower price points are available from Behringer, Soundcraft, and A&H. More expensive units also exist, of course.

Console Accessories

Surfaceless consoles are definitely rackable, and definitely should be.

Remember to buy the necessary patch cables or adapters for the outputs.

…but you can probably skip the headphones, because the consoles don’t currently stream the solo bus to a remote location (that I know of). That’s another downside of the number three option – to access the solo bus, you still have to be physically present at the console’s location.

Output Transducers (Speakers, That Is)

You’ll notice that I didn’t include an option for amps and passive speakers, and there’s a reason for that: This is supposed to be a simple system, and powered speakers are really the way to go to achieve simple.

Also in the service of simple is to keep your monitor wedges and FOH speakers interchangeable. Unless it’s completely inappropriate for your application, having loudspeakers that are all of the same model means that you can expect similar behavior from each box. If a failure occurs, you can swap one box for another and not have to think about it too much.

When buying powered loudspeakers, accept nothing less than an honest-to-goodness, biamped, fully processed unit. There are plenty of powered speakers that are single amped, with no processing outside of a passive crossover that is placed between the amplifier and the drivers. You want something more – something with an active crossover, basic corrective EQ applied at the factory, and an internal limiter. A peak SPL rating of greater than 120 dB @ 1 meter is also a good thing to look for, even with all the “fudging” that marketing departments apply to output numbers.

In terms of specific recommendations, I can say that PVXP12s have done very well for me. I can do “rock and roll” monitors with them in a small space, and I’m confident that they would perform equally well as an FOH unit. There are lots of other possibilities of course, provided by JBL, Mackie, Yamaha, and Behringer (just to name a few).

Loudspeaker Add-Ons

First, make sure you have the necessary cables to get from the console or snake outputs to the loudspeakers. Because speakers tend to be deployed in a rather spread-out fashion, it’s advisable to buy a bit more cable than you think you need. A 50 footer for each loudspeaker is probably a good start.

When it comes to stands for your FOH speakers, it’s good to get something a little nicer. Stands with locking collars and/ or piston assists can be a big help. I’ve used crank stands in the past, and they’re okay, but given a chance I’d make the upgrade to a more technologically advanced support.

The Biggest Accessories Of All

In the end, none of the fancy gear will mean much without power. You don’t have to buy really fancy power-conditioning equipment, but some rackmountable power units help reduce the need to fish around for a bunch of “free range” power taps. Of course, you should still keep a few freely-positionable power taps handy, along with several extension cords that use 14-gauge conductors (or something beefier, like 12-gauge). Powered speakers spread out all over creation have an alarming tendency to need those extension cords.

While there are other sundries and gadgets you can add on, going through the above should get you a working rig. As I said, this is a basic system. It won’t do everything for everybody all the time, but it should provide you with a decent start.

Regarding Arrangements and Audio Humans – A Letter

A guest-post for Schwilly Family Musicians.

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Yes, that’s me in the picture up there.

Anyway…

‘It has come to my attention that some of you have, often by accident, placed more responsibility in my hands than might be prudent. This may have come from many things: A misunderstanding of how our roles intersect, an overestimation of what physics will allow me to get away with, misplaced hero-worship, or other such thoughts.

What I am referring to specifically is the idea that your song arrangements are best managed by way of a sound person wielding a tremendous chain of signal transduction and processing equipment. You’ve seen and heard concert setups that have impressed you, and you’ve thought, “This gear, in the hands of a competent tech, will make us sound good.”

My dear Bands, I don’t wish to be combative or contradictory, but I cannot agree with you on that concept.’

Read the rest (for free!) at Schwilly Family Musicians.

Does It Have To Be This Loud?

A love-letter to patrons of live music.

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Dear Live-Music Patron,

Occasionally, you have a question to ask an audio human. That question isn’t often posed to me personally, although, in aggregate, the query is probably made multiple times in every city on every night. The question isn’t always direct, and it can morph into different forms – some of which are statements:

“I can’t hear anything except the drums.”

“The guitar on the right is hurting my ears.”

“It’s hard to talk to my girlfriend/ boyfriend in here.”

“Can you keep everything the same, but turn the mains down?”

“Can you make it so the mic doesn’t make that screech again?”

And so on.

Whenever the conversation goes this way, there’s a singular question lying at the heart of the matter:

“Does it have to be this loud?”

There are a number of things I want to say to you regarding that question, but the most important bit has to come first. It’s the one thing that I want you to realize above everything else.

You’re asking a question that is 100% legitimate.

You may have asked it in one way or another, only to be brushed off. You may have had an exasperated expression pointed your way. You may have been given a brusque “Yes” in response. You may have encountered shrugging, swearing, eye-rolling, sneering, or any number of other responses that were rude, unhelpful, or downright mean.

But that doesn’t mean that your question is wrong or stupid. You’re right to ask it. It’s one of the minor tragedies in this business that production people and music players talk amongst themselves so much, and yet almost never have a real conversation with you. Another minor tragedy is that us folks who run the shows are usually not in a position to have a nuanced discussion with you when it would actually be helpful.

It’s hard to explain why it’s so loud when it’s so loud that you have to ask if “it has to be this loud.”

So, I want to try to answer your question. I can’t speak to every individual circumstance, but I can talk about some general cases.

Sometimes No

I am convinced that, at some time in their career, every audio tech has made a show unnecessarily loud. I’ve certainly done it.

As “music people,” we get excited about sonic experiences as an end in themselves. We’re known for endlessly chasing after tiny improvements in some miniscule slice of the audible spectrum. We can spend hours debating the best way to make the bass (“kick”) drum sound like a device capable of extinguishing all multicellular life on the planet. The sheer number of words dedicated to the construction of “massive” rock and roll guitar noises is stunning. The amount of equipment and trickery that can be dedicated to, say, getting a bass guitar to sound “just so” might boggle your mind.

It’s entirely possible for us to become so enraptured in making a show – or even just a small portion of a show – sound a certain way that we don’t realize how much level we’re shoveling into the equation. We get the drums cookin’, and then we realize that the guitars are a little low, and then the bass comes up to balance that out, and then the vocals are buried, so we crank up the vocals and WHAT? I CAN’T HEAR YOU!

It does happen. Sometimes it’s accidental, and sometimes it’s deliberate. Some techs just don’t feel like a rock show is a rock show until they “feel” a certain amount of sound pressure level.

In these cases, when the audio human’s mix choices are the overwhelming factor in a show being too loud, the PA really should be pulled back. It doesn’t have to be that loud. The problem and the solution are simple creatures.

But Sometimes Yes

The thing with live audio is that the problems and the solutions are often not so simple as what I just got into. It’s very possible, especially in a small room, for the sound craftsperson’s decisions to NOT be the overwhelming factor in determining the volume of a gig. I – and others like me – have spent lots of time in situations where we’ve had to deal with an unfortunate consequence of the laws of physics:

The loudest thing in the room is as quiet as we can possibly be, and quite often, a balanced mix requires something else to be much louder than that thing.

If the instrumentalists (drums, bass, guitars, etc) are blasting away at 110 dB without any help from the sound system, then the vocals will have to be in that same neighborhood in order to compete. It’s a conundrum of either being too loud with a flat-out awful mix, or too loud with a mix that’s basically okay. In a case like that, an audio human just has to get on the gas and wait to go home. Someone’s going to be mad at us, and it might as well not be the folks who are into the music.

There’s another overarching situation, though, and that’s the toughest one to talk about. It’s a difficult subject because it has to do with subjectivity and incompatible expectations. What I’m getting at is when some folks want background music, and the show is not…can not be presented as such.

There ARE bands that specialize in playing “dinner” music. They’re great at performing inoffensive selections that provide a bed for conversation at a comfortable volume. What I hope can be understood is that this is indeed a specialization. It’s a carefully cultivated, specific skill that is not universally pursued by musicians. It’s not universally pursued because it’s not universally applicable.

Throughout human history, a great many musical events, musical instruments, and musical artisans have had a singular purpose: To be noticed, front and center. For thousands of years, humans have used instruments like drums and horns as acoustic “force multipliers” – sonic levers, if you will. We have used them to call to each other over long distances, or send signals in the midst of battle. Fanfares have been sounded at the arrivals of kings. On a parallel track, most musicians that I know do not simply play to be involved in the activity of playing. They play so as to be listened to.

Put all that together, and what you have is a presentation of art that simply is not meant to be talked over. In the cases where it’s meant to coexist with a rambunctious audience, it’s even more meant to not be talked over. From the mindset of the players to the technology in use, the experience is designed specifically to stand out from the background. It can’t be reduced to a low rumble. That isn’t what it is. There’s no reason that it has to be painfully loud, but there are many good reasons why a conversation in close proximity might not be practical.

So.

Does it have to be this loud?

Maybe.

The Priorities List

An enumeration of critical tasks and considerations for making a live show work.

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If you look at any desk that I use, you might not think that I have an ordered mind. It can be a little scary, I admit. I am of the opinion, however, that I’m capable of imposing order on certain parts of my mind – especially when there’s a show to be done. This is important, because I think that really pulling off a show requires some kind of plan. It doesn’t have to be written out in detail, but it has to exist in some form. You can’t just throw things together at random and expect them to work. A clear idea of what’s truly important is a really helpful sort of thing.

It did strike me one day that it might be interesting to attempt putting my basic, mental plan down in writing.

So, here you go.

The Pre-Game

Early Is The New On-Time

My general philosophy is that, if you’re early enough, you remove the need to worry about “the critical path.” The critical path is the shortest sequence of tasks necessary to complete a project successfully. Our project is the show, and the critical path for the show is the minimum necessary to survive the night.

Sometimes, that’s all you can do – but do you really want the bare minimum to be your best practice?

Nah.

The critical path for the show might be two vocal mics and a bit of level in the monitors, but that’s not really “full-service” and this IS a service industry. We have other things we can do…if we have the time. So create the time.

Make The Stage A Place You Want To Be On

Oh my. That stage is a mess, isn’t it? Cables are going everywhere from last night’s chaos, there’s gum stuck to various things, trash is strewn around, there’s a beverage glass jammed in a corner, and there’s a pile of wood fragments from that drummer whose hero is apparently Animal from “The Muppet Show.”

Guess whose responsibility it is to clean that up and make the stage look nice?

That’s right.

YOU have to have comfortable, happy musicians in order to do your job properly, and part of making people comfortable is presenting them with a working space that’s as nice as possible. So, get after it. You’ll be fine if you wash your hands afterwards.

Be Ready To Put Everything Through Some Part Of The Rig

Yes, it might be true that you technically don’t have to mic the amps or the drums to make the FOH mix work. However, just because you don’t need something in FOH doesn’t mean it won’t be wanted in monitor world. If you’ve got the inputs, plug things into them. Have the option available. The musicians will probably appreciate it, and that counts for a lot.

Also, make sure your gear is working during the course of setup. If a mic, cable, lighting instrument, loudspeaker, or whatever else is not cooperating, now is the time to find out. It’s easier to fix a problem before soundcheck rather than during, and much, much easier to fix a problem before the actual show is rolling.

A Tsunami Of Vocal

Vocals are often THE critical thing to get right in monitor world, so take the time to get a baseline sound that’s essentially pleasant, focused on the critical midrange instead of extreme low and high frequency “fru-fru,” and LOUD. You should take your basic cue from this chunk of Iggy Pop’s tour rider. (That’s where I got the “tsunami of vocal” bit.)

Now, yes, not everything will ultimately require “rock show” vocals in the monitors, but you have to be ready. You have to be prepared for situations where the ultimate volume isn’t that high, but the monitor-world loop gain is cranked. Start with the assumption that you need full-blown-rock-show level in the monitors, and make that work as well as you can. Make sure to kill your feedback problems as dead as they can possibly be killed. Test with all your vocal channels unmuted, because the total gain of the entire setup really does matter. A little bit of ringing is NOT acceptable. Do things as correctly as you know how.

If you’re particularly lucky, the musicians will be thoroughly impressed, and then ask you to turn things down. If you’re not particularly lucky, at least you’ll be prepared. (I have nothing against luck, and I acknowledge its ability to trump almost every other factor, but it’s not something you can plan on.)

Everything Else

For mics meant for other sources, you still have to have some idea of how they’ll work in monitor world. You do need to establish some kind of tuning to ward off their major problems regarding mixes for the deck. Your favorite instrument mic may have a tendency to ring at a certain frequency when you’re in a high-gain situation, so you need to get that under control. It’s possible that you’ll only have to take a look at the issue a few times – but you have to take that look.

Just as with vocals, the primary goal is to be able to supply the monitors with sound that’s basically nice to listen to, without a lot of “pre-emphasis” on any particular frequency range, and with plenty of level available. Run up the send level of an instrument mic and talk into it. Does it wound weird? Fix it.

Not On The Fly

Make sure your mixing console and/ or lighting system has “sane” presets applied. You want to be able to push things up in a hurry and have a result that is basically okay. Starting completely from scratch is a fun thing when you have rehearsal time and a single band to invest all your energy in, but that doesn’t happen so often in the small-venue world. (It’s especially rare when the venue signs your paycheck instead of an individual act or tour package.)

From a sonic perspective, if a mic is pointed at something and you push the fader up, the resulting sound should be a believable facsimile of that thing. From a lighting perspective, you should have several basic “looks” or “moods” that you can summon without having to think about it too much.

Don’t worry about your presets not being exactly right for everything. If they’re not helpful, you’ll recognize it and take steps to correct it (or learn to). If your preset works for the average case, it’s a good preset and will save you time. Dealing with something truly crazy has to be done on a case-by-case basis anyway, but the average stuff is what you’ll run across the most. That’s why it’s average.

Get The Band In The Room

I often say that loading the band in “is the job.” If the band isn’t in the room, and their gear isn’t in the room, then there isn’t going to be much of a show, right? So, get your hands dirty. Find some heavy stuff and move it. Not only does this help you actually get the show moving, it is often highly appreciated by the musicians. It’s a great way to actually show them that you’re all on the same team. It’s also a great way to prevent the band from getting fatigued before they’ve even played a note.

Also, to a certain extent, helping with the load in gives you a chance to really see the gear you’re going to be working with. If you see four toms for the drum kit, but you only have mics for three, you can make a note to get out another mic without having to be asked first. Did you run an XLR for the bass amp, but it doesn’t have an XLR direct out? Now you know, and you have a bit of time to get out a DI or set up a microphone.

But the main thing is to be helpful and facilitate the musicians being pleased.

Happy, comfortable musicians. Let that be your mantra.

Downbeat and Beyond

What’s Needed On Deck?

Your first priority is to get the stage sounding the way the musicians need it to sound. If they are comfortable and can play their best, then they will deliver the best show possible. Mixing FOH around what’s required for the musicians to deliver is a perfectly acceptable compromise. Forcing the sound on deck to conform to FOH in such a way that the actual performance is harmed? That is not an acceptable compromise.

This goes for lighting, too. If that super-moody light cue with the lasers prevents the players from seeing something they need to see, that just doesn’t work.

If the musicians are truly “in the zone” and fired up, that will translate to the audience. It will translate even if every production factor isn’t exactly where you might want it. You might not get to call your favorite light cues, or FOH might not be as clean and punchy as you might want, but the crowd is still very likely to be happy.

Vocals/ Melody, Then Everything Else

Anyone who tells you that drums and bass are the foundation of a mix is dead wrong. (There, I said it.) The foundation of the sound is the vocals. If there aren’t any vocals – either generally or just at some particular point – the foundation of the music passes to whatever carries the melodic theme.

I can prove my assertion about the vocals.

“Your head is humming and it won’t go – in case you don´t know
The piper’s calling you to join him
Dear lady can you hear the wind blow and did you know
Your stairway lies on the whispering wind?”

What song is that? That’s right! It’s “Stairway To Heaven” by Led Zeppelin. Amazing that you knew that without any music being played. Maybe it’s because you could understand the vocals?

I’m not saying that “Stairway” (or any other song) isn’t a total package. I’m not saying that the iconic guitar intro doesn’t matter. I’m not saying that the rhythm section is unimportant. The way the song builds to a thundering climax is a great bit of fun, and a major part of the song’s overall success.

What I AM saying is that if the vocals or key melodic elements – like a guitar solo – are lost while you try to dial up a crushing drum-n-bass tone, then you’ve got your priorities wrong.

Adjust For The Sake Of The Show

If you’re going to make a sonic change, that’s great. If you’re going to make a lighting change, that’s great.

But make sure you can easily justify that change in terms of serving the actual show. There’s a piece of advice that was given by Dave Rat which I particularly agree with:

Don’t fiddle.

That is, don’t make changes for the sake of making changes. Your existence at the audio or lighting console is justified by the need for an operator to be present and conscious; no further justification is required. If the EQ on the vocal channel is working, and you can’t supply a reason to change it other than “I have to change something,” then keep your paws off the EQ. If the light cue looks fine, and you’re worried that you should flash some PARs or twirl some movers because, you know, you’ve got all these buttons and knobs… Really. It’s okay. Leave it alone.

Of course, if the light cue looks okay, and changing to another cue will totally punctuate the transition to the song’s bridge, then PUNCH THEM BUTTONS, COWBOY!

Context matters.

I do support the idea of experiments. If you want to try something because you’re curious, then that’s a good thing. However, take the time to figure out how to do the experiment without calling a lot of attention to what you’re attempting. Be as subtle as you can. “Roll” things in and out instead of jumping around, if possible.

By extension, this also means that you don’t have to drive everything all the time. Let the music ebb and flow. The balance amongst all the parts doesn’t have to stay exactly the same all the time. Having that balance change just might be part of the ride. There’s no need to manage all the faders all the time. They will continue to exist even if you don’t touch them.

Breathe.

Try To Keep The Audience Happy

This one’s tricky, because you have to have a certain amount of confidence in your production decisions. You have to know when certain requests aren’t physically possible, or really aren’t in the best interests of the show at large.

Even so, do your best to be aware of the audience’s needs. If the crowd is running for the exits while holding their ears, then ask yourself if you’re being unnecessarily loud. If somebody asks for more bass/ less snare/ a different approach to the top end on the vocals/ whatever, then try to accommodate them if you can. This stuff is subjective, and if you can make one more person happy without wrecking the experience for everyone else, you might as well try it. The worst that can happen is that everybody else will hate the adjustment, and ask you to put things back to where they were.

This goes for lighting folks as well. Watch what happens when you call different cues, especially the ones that put light directly into the audience. If a bunch of people suddenly look unhappy, change to a different cue and don’t call the offender again.

Aftermath

Socialization

Once the show is over, you still need to keep the band happy. Try not to rush them out of the venue. Let them talk to the folks who came out, because that will help them build their audience. It’s also nice for players to just generally depressurize after all the excitement. Don’t run the post-show playback (if any) too loud. Giving everybody some time to unwind is just a courteous thing to do, if it’s feasible.

Load Out

The performers are probably rather tired after all the excitement, so the after-show is another great time to help with the moving of heavy objects. This further cements the idea that you and the band are on the same team, with an emphasis on building a good relationship for the next gig.

Further, this means that you can be on point to ensure that the gear is watched. Gear has a nasty tendency to get stolen in the post-show chaos, so keep an eye on things. If the load-out is a multi-trip affair, and it looks like gear might be left unattended, then stay where everybody else isn’t. You might just prevent something from “walking off.” Then, when somebody else returns, you can make another trip with a heavy object.

Setup Begins At Teardown

If you do nothing else, grab the grilles and pop-filter inserts off the vocal mics and wash them thoroughly. A nice, fresh, non-smelly vocal mic is much more hygienic, and also communicates (in a subtle way) that you care about the performers’ comfort.

If you know that someone else has to use the stage before you come back, then you have to clean up now. Get the cables wrapped and the trash picked up.

It’s ideal, of course, to get cleaned up even if you don’t strictly have to. Something might come up before the next show, meaning that you’ll have less time than you planned for. No matter what happens, leave the stage in a condition that you can manage even if you don’t have all the time you want for the next show’s prep.

Now, loop back to the top and do it all again…

The Puddle Mountain Arc

If you have the space and technical flexibility, a semicircular stage layout can be pretty neat.

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Just last week, my regular gig hosted a show for The Puddle Mountain Ramblers. During the show advance, Amanda proposed an idea.

What if we set up the stage so that the layout was an arc, instead of a straight line?

I thought that was a pretty fine idea, so we went with it. The way it all came together was that fiddle, bass, and banjo were on the stage-right side, the drums were upstage center, and guitar plus another fiddle were on the stage-left side. The setup seemed very effective overall.

Why?

Visibility, Separation, and Such

The main reason for the setup was really to facilitate communication. PMR is a band that derives a good deal of comfort and confidence from the members being able to see what each other player is doing. Also, it’s just generally nice to be able to make eye contact with someone to let them know that it’s their turn for a solo. Setting up in an arc makes this much easier, because you can get essentially unobstructed sightlines from each player to every other player. An added benefit is that all the players are closer together on average, which reduces the difficulty of reading faces, identifying hand movements, and keeping time. (An arc is geometrically more compact than a line. In a linear configuration, the farthest that any two players can be from each other is the entire length of the line. Bend that same line into a circle or circle-segment, and the farthest that any two players can be from each other is the line length divided by pi. That’s a pretty significant “packing.”)

Another benefit of the configuration is (potentially) reduced drum bleed. In a traditional setup, an upstage drumkit is pretty much “firing” into the most sensitive part of all the vocal and instrument mics’ pickup patterns. In an arc layout, with the drums at the center, the direct sound from the kit enters any particular mic at some significant off-axis angle. This bleed reduction can also extend to other vocals and instruments, especially because the mics can easily be at angles greater than 90 degrees relative to other sources.

Of course, it’s important to note that – especially with wide-pattern mics, like SM58s and other cardioids – compacting the band may undo the “off-axis benefit” significantly. This is especially true for bleed from whatever source is commonly at the midpoint of the arc’s circumference, like a drumkit probably would be. For the best chance of bleed reduction, you need tighter-patterned transducers, like an ND767a, or Beta 58, or e845, or OM2, or [insert your favorite, selectively patterned mic here]. Even so, the folks closest to, and at the smallest angle from the drumkit should be the strongest singers in the ensemble, and their miced instruments should be the most able to compete with whatever is loud on deck.

A third “bit of nifty” that comes from an arc setup is that of reduced acoustical crosstalk from monitor wedge to monitor wedge. With all the wedges firing away from each other, instead of in parallel paths, the tendency for any one performer to hear the wedges adjacent to them is reduced. Each monitor mix therefore has more separation than it otherwise might, which can keep things “cleaner” overall. It may also reduce gain-hungry volume wars on the deck.

Downsides

There are some caveats to putting a band on stage in a circle-segment.

The first thing to be aware of is that you tend to lose “down center” as a focal point. It’s not that you can’t put someone in there, but you have to realize that the person you’ve put down-center will no longer get the visibility and communication benefits of the arc. Also, a down-center wedge will probably be very audible to the performers standing up-center from that monitor, so you’ll have to take that into account.

The more isolated that monitor-mix sources become from one another, the more important it becomes that each monitor mix can be customized for individual performers. If you were on in-ears, for instance (the ultimate in isolated monitor feeds), separate mixes for each individual would be almost – if not entirely – mandatory. Increasing the mix-to-mix acoustical isolation pushes you towards that kind of situation. It’s not that shared mixes can’t be done in an arc, it’s just that folks have to be inclined to agree and cooperate.

A corollary to the above is that the show complexity actually tends to go up. More monitor mixes means more to manage, and an arc layout requires more thinking and cable management than a linear setup. You have to have time for a real soundcheck with careful tweaking of mixes. Throw-n-go really isn’t what you want to do when attempting this kind of layout, especially if you haven’t done it before.

Another factor to consider is that “backline” shouldn’t actually be in the back…unless you can afford to waste the space inside the arc. If at all possible, amps and instrument processing setups should utilize the empty space in front of everybody, and “fire” towards the performers (unless it’s absolutely necessary for the amps to combine with or replace the acoustical output of the PA).

If these considerations are factors you can manage, then an arc setup may be a pretty cool thing to try. For some bands, it can help “square the circle” of how to arrange the stage for the best sonic and logistical results, even if pulling it all off isn’t quite as easy as “pi.”

I’ll stop now.

What Just Changed?

If an acoustical environment changes significantly, you may start to have mysterious problems.

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Just recently, I was working a show for Citizen Hypocrisy. I did my usual prep, which includes tamping down the “hotspots” in vocal mics – gain before feedback being important, and all that.

Everything seemed copacetic, even the mic for the drumkit vocal. There was clarity, decent volume, and no ringing. The band got in the room and set up their gear. This time around, an experiment was conducted: A psychedelic background video was set to play in a loop as a backdrop. We eventually did a quick, “just in time” soundcheck, and we were off.

As things kicked into gear, I noticed something. I was getting high frequency feedback from one of the mics, it wasn’t running away by any means, but it was audible and annoying. I thought to myself, “We did just give DJ’s microphone a push in monitor world. I probably need to pull the top-end back a bit.” I did just that…but the feedback continued. I started soloing things into my headphones.

“Huh, guitar-Gary’s mic seems okay. DJ’s mic is picking up the feedback, but it doesn’t seem to be actually part of that loop. That leaves…*unsolos DJ’s mic, solos drum-Gary’s mic* Well, THERE’S the problem.”

The mic for vocals at the drumkit? It was squeaking like a pissed-off mouse. I hammered the offending frequency with a notch filter, and that was it.

But why hadn’t I noticed the problem when I was getting things baselined for the night? Gary hadn’t changed the orientation of the mic so that it was pointing at the drumfill, and neither the input gain nor send gains had changed, so why had the problem cropped up?

The answer: Between my setup and actually getting the show moving in earnest, we had changed the venue’s acoustical characteristics, especially as they concerned the offending microphone. We had deployed the screen behind the drums.

Rolling With The Changes

Citizen Hypocrisy was playing at my regular gig. Under conditions where we are NOT running video, the upstage wall is a mass of acoustical wedge foam. For most purposes, high-mid and high frequency content is soaked up by the treatment, never to be heard again. However, when we are running video, the screen drops in front of the foam. For high frequencies, the screen is basically a giant, relatively efficient reflector. My initial monitor-EQ solution was built for the situation where the upstage wall was an absorber. When the screen came down, that solution was partially invalidated. Luckily, what had to be addressed was merely the effective gain of a very narrow frequency range. We hadn’t run into a “showstopper bug,” but we had still encountered a problem.

The upshot of all this is:

Any change to a show’s acoustical environment, whether by way of surface absorption, diffusion, and reflectance, or by way of changes in atmospheric conditions, can invalidate a mix solution to some degree.

Now, you don’t have to panic. My feeling is that we sometimes overstate the level of vigilance required in regards to acoustical changes at a show. You just have to keep listening, and keep your brain turned on. If the acoustical environment changes, and you hear something you don’t like, then try to do something about it. If you don’t hear anything you don’t like, there’s no reason to find something to do.

For instance, at my regular gig, putting more people into the room is almost always an automatic improvement. I don’t have to change much (if anything at all), because the added absorption makes the mix sound better.

On the reverse side, I once ran a summer show for Puddlestone where I suddenly had a “feedback monster” where one hadn’t existed for a couple of hours. The feedback problem coincided with the air conditioning finally getting a real handle on the temperature in the room. My guess is that some sort of acoustical refraction was occurring, where it was actually hotter near the floor where all the humans were. For the first couple of hours, some amount of sound was bending up and away from us. When the AC really took hold, it might have been that the refraction “flattened out” enough to get a significant amount of energy back into the mics. (My explanation could also be totally incorrect, but it seems plausible.) Obviously, I had to make a modification in accordance with the problem, which I did.

In all cases, if things were working before, and suddenly are no longer working as well, a good question to ask yourself is: “What changed between when the mix solution was correct, and now, when it seems incorrect?” It’s science! You identify the variable(s) that got tweaked, and then manage the variables under your control in order to bring things back into equilibrium. If you have to re-solve your mix equation, then that’s what you do.

And then you go back to enjoying the show.

Until something else changes.

Loud Doesn’t Create Excitement

A guest post for Schwilly Family Musicians.

Please Remember:

The folks in the audience have to be “amped up” about your songs before the privilege of volume is granted.

The full article is here.

Alan Parsons Is Absolutely Correct. And Wrong.

Live sound is not the studio, and it’s dangerous to treat it as such.

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This article is the “closing vertex” of my semi-intentional “Gain, Stability, And The Best Holistic Show” trilogy.

I’m here to agree and disagree with Alan Parsons. Yes, that Parsons. The guy who engineered “Dark Side of the Moon.” A studio engineer with a career that most of us daydream about. An audio craftsperson who truly lives up to the title in the best way.

I am NOT here to trash the guy.

What I am here to do is to talk about a disagreement I have regarding the application of a specific bit of theory. It was a bit of theory that was first presented to me by the late Tim Hollinger (whom I greatly miss). Tim told me about an article he read where Alan Parsons explained why he (Parsons) mics guitar cabinets from a distance. Part of Parsons’ rationale is that nobody listens to guitar amps with their ear right up against the speaker, and also that guitar players are so loud that he doesn’t have a bleed problem.

I don’t know if the Premier Guitar article I found is the same one that Tim read, but it might be. You can read it here. The pertinent section is below the black and white picture of Parsons working in the studio.

Alan Parsons Is Academically Right

I don’t know of any guitar player who listens to their rig with an ear pressed up to the grill cloth. I can also tell you that, in lots of small-venue cases, a LOT of what the audience hears is the entirety of the guitar cab. A close-miced version of that sound might also be present in the PA, but it’s not the totality of the acoustical “solution.”

Also, yes, there are plenty of guitar players who run their rigs “hot.” Move a mic 18 inches from the cab when working with a player like that, and bleed might not be too problematic in a recording context, even if everybody’s in the same (largish) room. Solo the channel into a pair of headphones, and you’ll probably go, “Yup, there’s plenty of guitar in that mic.”

There’s not much to say about the correctness of Alan Parsons’ factual assertions, because they’re…well…correct.

The Problem Is Application

So, if Parsons is accurate about his rationale, how can there be a disagreement?

It’s pretty easy actually, and it comes from a statement that Parsons makes in the article I linked above: “Live sound engineers just don’t seem to get it.”

Parsons is correct about that too. Really! Concert-sound humans, in a live context, DON’T “get” studio recording applications. The disciplines are different. In precisely the same way, I can say that studio engineers don’t “get” live sound applications in the live context. This all comes back to what I’ve said in earlier articles: The live-audio craftsperson’s job is to produce the best holistic show possible at the lowest practicable gain. The studio craftsperson’s job is to capture the best possible sound for later reproduction. These goals are not always fully compatible, especially in a small-venue context.

(And before you write me hate-mail, it’s entirely possible for an audio human to become competent in both studio and live disciplines. What I’m getting at here is that each discipline ultimately has separate priorities.)

Obviously, there are some specifics that need addressing here. The divergent needs of the studio and live disciplines take different roads at a number of junctions.

I Don’t Want To Mic The Room, Thanks

In the studio, getting some great “ambience” is a prized piece of both the recording process and the choosing of a recording space. The very best studios have rooms that enhance the sound of the various sources put into them. Grabbing a bit of this along with the correct dose of the “direct” sound from a source is something to be desired. It enhances the playback of that recording, which takes place at another time in another room – or is delivered directly to a person’s ear canal, in the case of headphones.

But this is not at ALL what I want as a live-audio practitioner.

For me, more often than not, a really beautiful-sounding room is an unlikely thing to encounter. There are such things as venues with tremendously desirable acoustics, but most of the time, a venue is primarily built to satisfy the logistics of getting lots of people into one space in whatever way is practical. In general, I regard any environmental acoustics to be a hostile element. Even a relatively nice room is troublesome, because it still causes me to have to deal with multiple, indirect arrivals which smear and garble the overall sound of the show. Unlike in a recording context, I am guaranteed to hear the ambience of the room.

Lots of it.

Too much, in fact.

I do NOT want any more of it to get captured and shot out of the PA, thanks very much. I don’t need my problems to be compounded. In the very often occurring case that I need to forge a total solution by combining room sound with PA sound, I want the sound in the PA to NOT reinforce the “room tone” at all. I’ve already got the sound of the room. What I need is something else.

Close micing prevents my transducers from capturing “the room” and passing that signal on to the rest of the system.

Specificity Is My Friend

For a recording engineer, a bit of “bleed” from the drumkit (and everything else) is not necessarily a bad thing. For me, though, it’s counterproductive. If I need more guitar because the drums are too strong, I do NOT want any more drums at ALL. I want guitar only, or vice versa.

Especially in small-venue live-sound, you tend to have sources that are very close together (often much closer than they would be in a nice studio), and loud wedges instead of headphones. On a large stage, this problem is mitigated somewhat, but that’s not what I tend to run into. Also, in a studio, it’s very possible to arrange the band such that directional microphone nulls help to minimize the effects of bleed. Small venues and expectations of what a band’s setup is “supposed” to look like often get in the way of doing this live.

In any case, live show bleed tends to be much more severe than what a studio engineer might encounter. This compounds the “I need more this, not that” problem above.

As an example, I recently worked with a band where the drummer specifically asked for his kit to be miced with overheads. I happily obliged, because I wanted to be accommodating. (Part of producing the best holistic show is to have comfortable, happy musicians.) At soundcheck, I took a quick guess at where the overheads should be. I wouldn’t say that we could really hear them, but hey, we had a decent total solution in the room pretty much immediately. I didn’t really think about the overheads much. About halfway through the show, though, I got curious. I soloed the overheads into my headphones.

In order to get the drum monitors where he wanted them, we had so much guitar and bass coming through that they almost swamped the drums in the overheads.(!) The overheads were basically useless as drum reinforcement, because they would pretty much end up reinforcing everything ELSE.

If a mic is going to be useful for live sound reinforcement, specificity is critical. Pulling a mic away from a source is counterproductive to that discrimination, so I prefer not to do it.

Lowest Practicable Gain

In general, higher gain is not a problem for studio folks. Yes, it might result in greater noise, and it can also reduce electronic component bandwidth, but it’s really a very small issue in the grand scheme of things.

In live audio, higher gain is an enemy. Because microphones encounter sounds that they have already picked up and passed along to the rest of the PA, they exist in a feedback loop. As the gain applied to the mic goes up, the more likely it is that the feedback loop will destabilize and ring. If I can have lower gain, I will take it, even if that means a slightly unnatural sound.

Now, you might not think that feedback would be a problem with a source as loud as a guitar amp can be, but you also may not have been in situations that I’ve encountered. I have been in situations where players, even with reasonably loud amplifiers, have asked for a metric ton of level from the monitors. Yes, I’ve gotten feedback from mics on guitar amps. (And yes, we should have just turned up the amplifiers in the first place, but these situations developed in the middle of fluid shows where stopping to talk wasn’t really an option. Look, it’s complicated.)

Even if the chance of feedback is unlikely – as it usually is with louder sources – I do NOT want to do anything that causes me to have to run a signal path at higher gain. Close micing increases the apparent sound pressure level at the transducer capsule, which allows me to run at lower gain for a given signal strength.

The overall point of this is pretty simple: The desires of recording techs and the needs of live-sound humans don’t always intersect in a pretty way. When I disagree with Alan Parsons, it’s not because he doesn’t have his facts straight, and it’s not that I’m somehow more knowledgeable than he is. I disagree because applying his area of discipline to mine simply isn’t appropriate in the specific context of his comments, and the specific live-show contexts I tend to encounter.

It’s Not Actually About The Best Sound

What we really want is the best possible show at the lowest practical gain.

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As it happens, there’s a bit of a trilogy forming around my last article – the one about gain vs. stability. In discussions like this, the opening statement tends to be abstract. The “abstractness” is nice in a way, because it doesn’t restrict the application too much. If the concept is purified sufficiently, it should be usable in any applicable context.

At the same time, it’s nice to be able to make the abstract idea more practical. That is, the next step after stating the concept is to talk about ways in which it applies.

In live audio, gain is both a blessing and a curse. We often need gain to get mic-level signals up to line-level. We sometimes need gain to correct for “ensemble imbalances” that the band hasn’t yet fixed. We sometimes need gain to make a quiet act audible against a noisy background. Of course, the more gain we add, the more we destabilize the PA system, and the louder the show gets. The day-to-day challenge is to find the overall gain which lets us get the job done while maintaining acceptable system stability and sound pressure.

If this is the overall task, then there’s a precept which I think can be derived from it. It might only be derivable indirectly, depending on your point of view. Nevertheless:

Live sound is NOT actually about getting the best sound, insofar as “the best sound” is divorced from other considerations. Rather, the goal of live sound is to get the best possible holistic SHOW, at the lowest practical gain.

Fixing Everything Is A Bad Idea

The issue with a phrase like “the best sound” is that it morphs into different meanings for different people. For instance, at this stage in my career, I have basically taken the label saying “The Best Sound” and stuck it firmly on the metaphorical box containing the sound that gets the best show. For that reason alone, the semantics can be a little difficult. That’s why I made the distinction above – the distinction that “the best sound” or “the coolest sound” or “the best sound quality” is sometimes thought of without regard to the show as a whole.

This kind of compartmentalized thinking can be found both in concert audio veterans and greenhorns. My gut feeling is that the veterans who still section off their thinking are the ones who never had their notions challenged when they were new enough.

…and I think it’s quite common among new audio humans to think that the best sound creates the best show. That is, if we get an awesome drum sound, and a killer guitar tone, and a thundering bass timbre, and a “studio ready” vocal reproduction, we will then have a great show.

The problem with this line of thinking is that it tends to create situations where a tech is trying to “fix” almost everything about the band. The audio rig is used as a tool to change the sound of the group into a processed and massaged version of themselves – a larger than life interpretation. The problem with turning a band into a “bigger than real” version of itself is that doing so can easily require the FOH PA to outrun the acoustical output of the band AND monitor world by 10 dB or more. Especially in a small-venue context, this can mean lots and lots of gain, coupled with a great deal of SPL. The PA system may be perched on the edge of feedback for the duration of the show, and it may even tip over into uncontrolled ringing on occasion. Further, the show can easily be so loud that the audience is chased off.

To be blunt, your “super secret” snare-drum mojo is worthless if nobody wants to be in the same room with it. (If you follow me.)

Removed from other factors, the PA does sound great…but with the other factors being considered, that “great” sound is creating a terrible show.

Granularity

The correction for trying to fix everything is to only reinforce what actually needs help. This approach obeys the “lowest possible gain” rule. PA system gain is applied only to the sources that are being acoustically swamped, and only in enough quantity that those sources stop being swamped.

In a sense, you might say that there’s a certain amount of total gain (and total resultant volume) that you can have that is within an acceptable “window.” When you’ve used up your allotted amount of gain and volume, you need to stop there.

At first, the selectivity of what gets gain applied is not very narrow. For newer operators and/ or simplified PA systems, the choice tends to be “reproduce most of the source or none of it.” You might have, say, one guitar that’s in the PA, plus a vocal that’s cranked up, and some kick drum, and that’s all. Since the broadband content of the source is getting reproduced by the PA, adding any particular source into the equation chews up your total allowable gain in a fairly big hurry. This limits the correction (if actually necessary) that the PA system can apply to the total acoustical solution.

The above, by the way, is a big reason why it’s so very important for bands to actually sound like a band without any help from the PA system. That does NOT mean “so loud that the PA is unnecessary,” but rather that everything is audible in the proper proportions.

Anyway.

As an operator learns more and gains more flexible equipment, they can be more selective about what gets a piece of the gain allotment. For instance, let’s consider a situation where one guitar sound is not complementing another. The overall volumes are basically correct, but the guitar tones mask each other…or are masked by something else on stage. An experienced and well-equipped audio human might throw away everything in one guitar’s sound, except for a relatively narrow area that is “out of the way” of the other guitar. The audio human then introduces just enough of that band-limited sound into the PA to change the acoustical “solution” for the appropriate guitar. The stage volume of that guitar rig is still producing the lion’s share of the SPL in the room. The PA is just using that SPL as a foundation for a limited correction, instead of trying to run right past the total onstage SPL. The operator is using granular control to get a better show (where the guitars each have their own space) while adding as little gain and SPL to the experience as possible.

If soloed up, the guitar sound in the PA is terrible, but the use of minimal gain creates a total acoustical solution that is pleasing.

Of course, the holistic experience still needs to be considered. It’s entirely possible to be in a situation that’s so loud that an “on all the time” addition of even band-limited reinforcement is too much. It might be that the band-limited channel should only be added into the PA during a solo. This keeps the total gain of the show as low as is practicable, again, because of granularity. The positive gain is restricted in the frequency domain AND the time domain – as little as possible is added to the signal, and that addition is made as rarely as possible.

An interesting, and perhaps ironic consequence of granularity is that you can put more sources into the PA and apply more correction without breaking your gain/ volume budget. Selective reproduction of narrow frequency ranges can mean that many more channels end up in the PA. The highly selective reproduction lets you tweak the sound of a source without having to mask all of it. You might not be able to turn a given source into the best sound of that type, but granular control just might let you get the best sound practical for that source at that show. (Again, this is where the semantics can get a little weird.)

Especially for the small-venue audio human, the academic version of “the best sound” might not mean the best show. This also goes for the performers. As much as “holy grail” instrument tones can be appreciated, they often involve so much volume that they wreck the holistic experience. Especially when getting a certain sound requires driving a system hard – or “driving” an audience hard – the best show is probably not being delivered. The amount of signal being thrown around needs to be reduced.

Because we want the best possible show at the lowest practical gain.

The Inverse Relationship

The more gain you apply, the more unstable the system becomes.

Please Remember:

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If you want to louse up the sound of a PA system without actually damaging any components, there’s a really quick way to go:

1) Plug in some microphones.

2) Keep the PA and the microphones in the same room.

3) Apply enough gain to the microphones such that they actually become useful for sound reinforcement.

In other words, just go ahead and use the PA as you would normally expect to use it. As you add more gain to the system, the system’s sound quality will degrade progressively. If you want to avoid this degradation, don’t use the PA for anything except playback – not turntable playback, though! Those tone arms are sensitive to environmental vibration. Use a media player, or a phone with the right software.

Okay, so I’m kinda “winding you up” with this. To be practical, we have to use PA systems in the same room as the microphones they’re amplifying. We do this all the time. We tend not to agonize over the loss of sound reproduction quality, because it just isn’t worth it. The issue is just inherent to the activity.

The reason to present this in such a stark fashion, though, is to get your attention – especially if you’re new to live audio. There are plenty of inescapable facts in this business, but one of the most important bugaboos is this:

In any audio system that involves a closed or partially closed loop from the input to the output, the system’s stability decreases as the applied gain increases. Further, to use such a system means that the assemblage is at least partially destabilized as a matter of necessity.

Gain

We spend a lot of time working with and talking about “gain” in pro-audio, but we don’t usually try to formally define it very often. Gain is a multiplier applied to a signal’s amplitude. Negative gain is a multiplier that is less than one, and positive gain is a multiplier that is greater than one. A gain of exactly one (the multiplicative identity) is “unity,” where the input signal and the output signal amplitudes are the same.

For convenience, we usually express gain as the ratio of the input signal to the output signal in decibels. Unity gain in decibels is zero, because 0 dB relative to a given amplitude is that same amplitude.

Because our systems work in partially closed loops, we can also talk about concepts like “loop gain.” Loop gain is the ratio between the system output and system input, where the output is at least partially connected to the input. A system with a loop gain greater than one is in the classic “hard feedback” scenario, where an unwanted signal aggressively self-reinforces until it can no longer do so – or somebody fixes the problem. A loop gain of exactly one is still a huge problem, because a signal just continues to repeat indefinitely. The sound may not be getting progressively louder, but it’s still tremendously annoying and a grossly incorrect rendition of the original sonic event.

Especially in the context of system stability, it’s important to understand that there is a difference between gain settings and “effective loop gain.” For instance, a microphone with greater sensitivity increases the effective loop gain of a system, because it increases the system output for a given, re-entrant signal from an input…if the downstream gain settings remain fixed.

“We plugged in that condenser, and we got crazy feedback!”

“Of course we did. That condenser is 10 dB more sensitive than the mic it replaced, and you didn’t roll the preamp gain back at all. You would have gotten feedback with the original mic if you had suddenly gunned it +10 dB, that’s for sure.”

In the same vein, any physical change that increases the intensity of re-entrant signal relative to the original input is also an increase in effective loop gain. If somebody insists on having a microphone close to a PA speaker, then the system’s electronic gain structure has to be dropped if you want to compensate. (Sometimes, you don’t want to fully compensate, or you can’t for some reason.)

Stability

Okay, then.

What do I mean by “stability?”

For our purposes, “stability” is a tendency for a system to return to a desired equilibrium after having been disturbed. In an audio system, the “disturbance” is the input signal. If our sound rig was perfectly stable, the removal of the input signal would correspond with an instantaneous stoppage of output signal. The system would immediately come to “rest” at zero output (plus any self noise).

Systems used only for playback tend to have very high stability. When an input stops, the system stops making noise almost immediately.

Yes, there are limitations. Loudspeaker drivers don’t actually come to a stop instantly, for example.

Anyway.

Playback-only systems have such great stability because they tend to be “open loop.” The system’s output is not reintroduced to the system input in any meaningful way. (Record players are an exception to this, as I alluded to in the introduction.)

But PA systems being used for actual bands in an actual room are at least a “semi-closed” loop. Some portion of the output signal makes it back to the input devices, and travels through the system again. This increases the time necessary for the system to settle back to “zero output plus noise” for any given input signal – and, if you REALLY want to split hairs, you have to deal with the reality that the system never actually settles to zero at all. The signal runs through the loop indefinitely, until the loop is broken by way of a mute button, a fader being set to -∞, or the system having its power removed. To be fair, the repeating signal is usually lost completely to the noise floor in a relatively short amount of time. Even so.

Cooking up a “laboratory” example of this is fairly easy. You just take a sample of audio, run it through a delay line, and apply feedback to the delay line. To get a quantitative perspective on things, you can figure out the time required for the total output to decay into an arbitrary noisefloor. You do this by taking the signal loss through each traversal of the loop, dividing the noisefloor dB (a negative number indicating how much signal decay you want) by the “loop traversal loss” dB, and then multiplying that number by the loop traversal time.

For example, let’s say that I have a desired noisefloor of -100 dB, referenced to the original input signal level. The loop time is 10 ms, which I encounter regularly in real-life applications. If the loop traversal loss is -50 dB (meaning that the signal drops 50 decibels each time it exits and re-enters the system), then:

-100 dB/ -50 dB = 2
2 * 10 ms = 20 ms

In 20 ms, the signal has dropped far enough that I can ignore it.

Fifty dB of rejection is REALLY high for a small-venue PA system. That kind of system “instability” is impossible for me to hear. Take a listen yourself:

A traversal loss of 20 dB means that it takes over twice as long to hit the desired noisefloor – 50 ms. I can sorta start to hear some issues if I know what to look for, but it’s nothing that’s really bothersome.

A signal that decays at the rate of only 10 dB per loop traversal is audibly “smeared.” A 100 ms decay time is actually pretty easy to catch, and I’ll bet that if the instability was band-limited (as it usually is), we’d be well inside the area where the mic is starting to get “ringy and weird” in the monitors.

…and then the singer wants nine more dB on deck, which bumps the decay time to a full second. The monitor rig is getting closer and closer to flying out of control.

You get the idea. This simulation is rather abstract, but the connection to real life is that adding gain to a system reduces loop traversal loss. That is, if a signal has a loop traversal loss of -20 dB, and we increase the applied gain by 10 dB, the loop traversal loss is now only -10 dB. It takes longer for the signal to settle into the noisefloor. The system stability has decreased.

And, of course, if we go far enough with our gain we’ll get the total loop gain to be one or greater. FEEEEEEEDBAAAAAACK!

The Upshot

What this all comes down to is pretty simple:

Anything that causes you to increase a system’s effective loop gain is undesirable…but sometimes you have to do undesirable things.

Live sound is not simply an academic exercise. There are all kinds of circumstances that end up pushing us into the increase of total loop gain, and while that’s not our most preferred circumstance, we often have no choice. Even though any increase in gain also increases the instability of our systems, there’s a certain amount of instability which can be tolerated. Also, because there’s always SOME amount of re-entrant signal, there’s no setup which is fully stable – unless we give everybody in the room a set of in-ears. ($$$)

Also, we can get a bit of help in that our systems aren’t linearly unstable. We tend to get instabilities in strongly band-limited areas, which means that surgical EQ can patch certain problems without ruining the whole day. We reduce our loop gain in a very specific area, which hopefully buys us the ability to get more gain across the rest of the audible bandwidth.

Of course, if something comes along which lets us reduce our effective gain, that makes us happy. Because it helps keep us stable.