Too Many Microphones? Part I

We’ve all been there.  Somewhere closer to the beginning of the journey of learning our new recording skills than the end.  We’ve watched tutorial videos, seen photos of famous sessions from the past, and maybe even *gasp* cracked open a book or two on the subject of instrument mic placement.  “Man,” we think, “my stuff just doesn’t sound as good as the stuff in these videos/photos/books.  WHAT’S THEIR SECRET?”  Then it clicks:  They’re using three microphones on that kick drum!  There are two on that snare!  They’ve got 2 microphones on the guitar cabinet, and neither one of them is an SM57!  I HEARD THAT EVERYTHING ON MICHAEL JACKSON’S “THRILLER” WAS RECORDED IN STEREO!!!

“THAT’S the ticket,” we think!  They must be getting all that (insert nebulous descriptive term – punch, edge, etc. – here) from the multiple microphones!

And thus begins a journey down a potentially slippery slope.  But what makes it so slippery, and how can we avoid taking a bad first step into this brave new world?

Learning “The Rules”

There’s an often-quoted phrase:  “You have to learn the rules before you can break them.”

Man I hated that phrase.  “SCREW THE RULES,” I wanted to shout every time I heard it, “I’m doing what I want.  I’m breaking new ground here!  And it’s going to be WAY cooler than your boring-assed rule-following method!”

You know what?  I was wrong.  That awesome inner-monologue was – in my case – wanting to skip learning the stuff everybody knows, so I could introduce the world to my obvious next-level genius.  There were just a few small problems with that plan:

1.) Clients (it turns out) had certain expectations of my skill set when they hired me.  Much to my chagrin, those expectations most often involved understanding the meat-and-potatoes basics of recording.  Or if you’re working on your own material you can translate this as, “You want the best possible result in the shortest amount of time in order to stay creative.”

2.) I (it turns out) had certain expectations of how much food, shelter, and clothing I needed in order to continue…you know…living.  How much of those things I could afford was intrinsically tied to meeting my clients’ needs.  That’s true no matter whose material you’re working on!

3.) My “next-level genius” ideas (it turns out) were often neither.  Most of the time they were interesting experiments that didn’t work out.  Or worst of all they weren’t actually new ideas.  Just new to me.  No matter, because my clients didn’t have time, budget money, or patience for any of it.

Suddenly I found myself running smack into the, “You have to learn the rules before you can break them,” wall.  Which nearly all of us do.  It’s all a part of the process.

The First Phase

The basic problem in any multiple microphone situation is this:  phase cancellation.

I could spend many pages worth of time writing about what phase cancellation is, what causes it, why it can be a bad, or a good thing in regards to audio.  But many very smart people have already committed their fine minds to that cause.  Here’s a solidly written article from Sound On Sound magazine to get you started:


I highly recommend putting the time, and effort into learning about the subject.  It’s a little knowledge that will feel like free money when you apply it.  But if you want to cut a corner for now here’s the TL;DR version:

If you record an instrument with two microphones that are receiving acoustic information at different times, when combined those two signals will cancel out frequency ranges in one another.  And unless you learn to recognize it, you’ll spend endless amounts of time chasing your tail trying to fix it later on.

Story Time I

Some years ago while engineering an album for a successful producer, he asked if I could do him a favor.  He’d been hired to mix a single for an independent artist.  They had a tight deadline, and the producer wanted me to take a quick break from working on the album to prep the indie single for mixing.  He was going to do that on our usual day off.  Our album artist was in town from overseas, and the producer was up to his neck in work.  So I happily agreed.

I don’t remember very much about the song, or the quality of the recording.  Here’s what I DO remember in vivid detail:  48 tracks of the same rhythm guitar part.  12 passes, 4 microphones on the amplifier for every pass.

My very next (and private) thought?  What a phenomenal waste of time.  I had a fair amount of experience mixing professionally at this point, and I knew the tendencies of the producer I was working for.  The fate of at least 44 of those tracks was going to be the mute button.

A few days later I pulled up the mixed Pro Tools session.  Of the original 48 rhythm guitar tracks, 45 had been muted.  Of the three that remained (each from a different pass), every one was recorded with the same microphone.

Stereo Vs. Mono Sources

The first step on our road to understanding is the difference between using multiple microphones on mono vs. stereo sources.

Now I might be getting a little simplistic for some of you.  Please know that I understand we’re about to dive into basic recording 101 here.  But we can all use a little refresher every now and then, right?

Most things we record in the studio can at their simplest level be described as mono (or point) sound sources.  Individual drums, guitar amplifiers, bass amplifiers, acoustic guitars, and many mechanical keyboards.  Some synthesizers have only a single mono output.  Many stereo synthesizers have patches that are mono as well, even if they have stereo outputs (exactly the same information is being sent to both left and right outputs).  These instruments can be captured, and faithfully represented by a single microphone (or DI box) on a single track.  Under certain circumstances an engineer may choose to capture them with multiple microphones for creative reasons, but it isn’t a necessity.

A few things are inherently stereo audio sources, which means they require two microphones (or DI boxes) on two tracks (or in DAW world a stereo audio track) to be correctly represented.  Drum overheads, room microphones, stereo keyboard.  Though again, the engineer may choose to record these things in mono under some circumstances.

Then there are a few things that over time have come to be accepted when recorded either as mono, or stereo.  Acoustic piano is a great example.  Rhodes electric piano, and Leslie speakers (with B3 organ or guitar as their source) are others.

It’s important to understand what category the sound source you’re recording falls into.

Back To Basics

The first guideline you should keep in mind before trying to throw three microphones on something that really only requires one is:  Can you make it sound great with just one microphone?  If the answer to that question is no, then you’ve got a whole host of options at your disposal before adding a mic.

Let’s look at the idea of a mic-ing a guitar amp.  As mentioned above it is nearly always a mono sound source.  Play the guitar in the room with the amp.  Does it sound good in the room?  Does it sound good at the spot where you’ve placed the microphone?  (Yes get right down on the floor and listen close up…with flat-filtering earplugs in if the amp is cranked.  ALWAYS PROTECT YOUR HEARING!)  If it doesn’t, try adjusting the settings on the guitar, the amp, or both.

If that doesn’t get you where you need to be then you can try a different guitar.  A different amp.  If you’ve got a session guitar player, and don’t have a tight deadline you can even try another guitarist!

Once you’re happy with the sound in the live room, go back and listen in the control room.  If it’s not working there, the work you’ve already put in allows you to be certain your problem isn’t the guitar tone.  It’s in the recording chain.  So move the microphone, try a different microphone, or a different pre-amp.  Chances are you’ll have it sounding great long before you’ve exhausted all of those options.  And every time you do this exercise, you’ll learn something new about a certain guitar, amp, microphone, gear setting, etc.  Each one of those things is another tool you’ve added to your belt that will make you better/faster next time.  And the same concepts apply to any instrument you’re recording.

Adding microphones without understanding why you’re adding them, and how to place them correctly is likely to create more problems than it will solve.  And in a worst-case scenario, you could end up delivering 3 bad sounding microphones worth of information to your client/mixing engineer, instead of one good one.  Which isn’t the end result anybody is after!

Great!  So When SHOULD I Think About More Microphones?

That, my friends, will be the topic of my next post!

Do You Know Your TRACKS From Your STEMS?

Let’s set the scene:  You’ve worked hard to get your recording project this far.  Perhaps you’re the band member who “had a knack” for the sonic side of things, and the willingness to take on that role for your cash-strapped musical project.  You could be a songwriter, or producer just embarking on the road of a new career.  You’ve researched who you want to have mix your creation, and you’re excited because your first choice has agreed to take on your project.  “Great,” you say as the initial conversation winds down, “I’ll send over the stems for the first tune as soon as I can!”

My question to you now is, do you know exactly what you’ve just said?  If you’re like a great many of my clients, the answer is no.  What you really mean is, “I’ll send over the tracks for the first tune as soon as I can!”

These days the term “stem” as it relates to recording/mixing gets thrown around as a synonym for the term “track.”  The difference may seem subtle at first, but in reality they are two very different things.  Using them interchangeably at the wrong time could cost you a lot of time, and money.

So let’s dig in!

How Did We Get Here?

This is a tough one to answer definitively, but I think there are two issues at play:

The first is the usage of the term “stem” in many DAW’s export pop-up windows.  The people writing the code had to settle on a term for the files created during the export process, and the one they chose is “stem.”  Unfortunately, as we’ll soon see, that’s very often incorrect.

That led to the second issue.  A whole lot of people learned to refer to all exported files as “stems,” because that’s what they saw on their computer screens.  A whole lot of other people heard them use it, and we were off to the races.

So What’s A Track?

Tracks are the files created during the recording process.  Even if effects are applied.  Even if multiple instruments have been bussed together.  The correct term for anything created before the mixing process is “track.”

The term has its roots in analog recording.

  • Once we moved past stereo (or 2-TRACK) tape, we were working on multiTRACK machines/tape reels.
  • Two  24-TRACK analog tape machines locked together meant you had 48 TRACKS to record on.
  • If you ran out of TRACKS on tape during the recording of a song because you needed to add more instruments, you might bounce your 10 drum TRACKS down to two to make room.  The result was that you now had a stereo set of drum TRACKS.
  • The Beatles famously bounced performances down again, and again because they were working with only a 4 TRACK recorder during the making of Sgt. Pepper’s Lonely Hearts Club Band.  When they started mixing, they were working from the TRACKS they’d created.
  • If you bus your snare top and bottom microphones together, the result is a single snare TRACK.
  • In most DAW’s you create mono or stereo audio TRACKS.  Even if you mix them together during the tracking process (for instance if you’ve run out of playback voices), they’re bounced to another audio TRACK.

The word “stem” was never, nor as a rule should it be used to refer to the results of the basic, or overdub recording process.  These files are TRACKS.

Then What’s A Stem?

Stems are created during the mixing process.  In the music world, they are essentially sub mixes of instrument groups printed as stereo, or mono files.  Usually when re-combined at unison gain they give you a very close approximation of the master mix.


  • A drum STEM would be a printed stereo sub mix of all of the drum TRACKS as they’ve been treated during the mixing process.
  • A keyboard STEM would be a printed stereo sub mix of all of the keyboard TRACKS as they’ve been treated during the mixing process.
  • A guitar STEM would be a printed stereo sub mix of…you get the idea.
  • A bass STEM might very well be a mono sub mix of all of the bass TRACKS (microphones and DI) as they’ve been treated in the mixing process.  Or it might be a stereo sub mix if the bass is a stereo keyboard patch, or if a stereo effect has been applied.  The same would be true for lead vocals.

The key phrase you’ll have no doubt noticed above is, “…as they’ve been treated during the mixing process.  If you’re not in the final mixing stage of your project, you’re not creating stems, and you shouldn’t be referring to your files as stems.

Stems can be split into smaller, more numerous groups.  You can have one guitar stem that’s only the lead guitars, and another for just the rhythm parts.  One stem for live drums, and another for programmed drums.  One for keyboard pads, a second for leads, and a third if you have a keyboard bass.  A lead vocal stem, and a backing vocals stem.  It all depends on your (or your client’s) needs.

If you’re working in the post-production world, stems will most often be used to refer to the individual audio elements used to create the audio bed for the video.  So there might be a dialog stem, a sound effects stem, a foley stem, a room tone stem, and a music stem.  That music stem will often contain already mixed/mastered stereo music files.  Sometimes the project will require multiple music stems.  And THAT leads us to…

Why Does This Matter?  It’s 2017!  GET OFF MY BACK OLD MAN!

One of the most common ways for music to generate income these days is through placement in movies, television shows, and commercials.  Let’s create another little scenario:

In a huge step forward for your career, a song you worked on has landed a big dollar placement in a new national ad campaign for Mega Mart.  Mega Mart will be making a series of commercials.  For a section of each they want the full version of your song playing.  Underneath the voiceover they just want to hear the instrumental mix.  Then they want just the drums and bass to play while the VO artist delivers their famous tag line, “Mega savings at MEGA MART!”

So the post production mixer for the project calls, and requests the Master MIX*, the Instrumental MIX, the Lead Vocal STEM, the Backing Vocal STEM, the Drum STEM, and the Bass STEM files.

If you’ve been referring to every TRACK you create as a STEM you’re going to badly misunderstand our poor post-production mixer.  They’re expecting two stereo MIXES, a mono STEM (bass), and three stereo STEMS (lead vocals, backing vocals, and drums).  What you deliver instead are the two stereo MIXES, followed by the kick, snare, hat, ride, rack tom, floor tom, overhead left, overhead right, room left, room right, bass amp, bass DI, lead vocal, lead vocal double, and the 12 backing/harmony vocal TRACKS you recorded.

Suddenly our post mixer is downloading 26 unmixed files instead of 6 mixed files.  Mega Mart is pressuring them to deliver because their first ad buy starts airing in 48 hours, and now they’re desperately trying to get a hold of you to sort the situation out.  They say, “We asked for STEMS and you sent us TRACKS.  Could you please send us the STEMS for this song right away?  We’ve got a tight deadline here!”

You get the message at 2am after a night of celebrating your big placement, but you’re not sure what they’re talking about (and you’ve had a few margaritas).  You thought you’d sent exactly what they’d asked for!

Sadly when you get in touch with them it turns out they didn’t have time to wait.  Mega Mart had OK’d another song they’re happy to use in their commercial, and those folks knew exactly what files to deliver.  Now you’re out, and your dreams of being, “The Mega Savings Song,” and collecting the mega paychecks that come with it are over.

Obviously that’s a little extreme!  But it illustrates the point.

Less extreme is needing only an 808 kick drum TRACK to create a playback track for a live show, asking for an 808 STEM, and getting a single stereo file with the 808 kick, snare, hat, and cymbals that were also used on that particular song.  You email the mix engineer to ask them  for just the 808 kick drum.  They email back to let you know that since they delivered exactly what you asked for the first time, there’s going to be an additional fee for giving you what you actually need now.  Time is money, after all!

All it takes is one moment of misunderstanding at the wrong juncture of your project to turn a simple request into a complicated mess.

*BONUS ROUND:  Are Mixes Also Stems?

No.  Though we almost always print multiple versions of a mix, they are always referred to as “mixes.”  Master MIX, Instrumental MIX, Lead Vocal Up MIX, Bass Down MIX, etc.  We often print an A Capella MIX, which means only the vocals and vocal effects in a single stereo file.  While you could easily call this a “Vocal STEM,” (and you’d be correct in saying that they’re the same thing) that is not the common convention.

So there you have it!  The basic difference between stems, and tracks (and mixes if that information helps).  As with everything, there OF COURSE are exceptions to these rules (such as the A Capella MIX/Vocal STEM situation).  What I’ve tried to do is lay out a good foundation from which you can build your knowledge.  If you follow these guidelines, you’ll be in safe territory.  Now go forth, and communicate with confidence!