Friday, November 25, 2011

Engineering Drums Part Six: The Snare Drum

There are so many variables in the recorded sound of a snare drum – so many woods and metals and synthetic materials shells are made from, types of strainer and snare assemblies, diameter and depth, types of rims, heads, tuning, muffling, and then selection of microphone, placement, etc...  Nevertheless, effectively miking a snare drum can can be done with a consistent, and rather simple approach.

Regarding snare drum selection and preparation, here are the bullet points:

  • wood shells are darker and drier sounding than metal shells
  • metal shells provide greater overtones or 'ring' and are brighter than wood shells
  • smaller diameters yield a higher pitch and similarly tensioned larger diameters
  • deeper drums have more body or tone than shallow drums
  • the more strands of snares on the drum (i.e. 42-strand vs. 20 strand), the greater the 'snare' content of the sound
  • tuning the top head of a snare drum below its midrange yields a very deep tone (which can be emphasized by bringing the mics in closer)
  • tuning above the midrange brightens the tone and shortens the decay, with higher tensions beginning to choke the response from the drum.

If you need more info on tuning, please refer back to my tuning entry for some essential guidance and a few tips.

Now let's briefly cover microphone selection. THE most relied upon microphone for snare drums these days (and for the last couple of decades now) is Shure's SM57 dynamic. This mic, used in every studio and live venue across the planet, has a frequency curve featuring a rising response through the midrange peaking in the 'attack' range at around 6kHz and rolling off above 10kHz. Also, the LF response rolls off below 200Hz and is several dB down at 100Hz, making it an excellent choice for the midrange nature and articulation of a snare drum.

There are other mics on the market that work well for snare drum. I have had fantastic results with the Audio-Technica ATM23HE, Audix D2 and i5, Sennheiser MD421, BeyerDynamic M201, and others. But for the sake of this article, I am going to suggest you stick with the SM57. Chances are you will get superb results with 57's, and if you don't, then something else is almost certainly wrong. Using a 57 will remove the mic from the list of factors when troubleshooting a poor sound.

Snare drums are typically miked with two mics: one on top to capture the overall tone and body, and one underneath to capture the response of the snares. The SM57 is a great choice for both positions.

So... the drum sounds great, and you got a couple of SM57's. Let's begin.

Critical question: What is it that we, as engineers, are ultimately trying to capture? The sound or the performance? 

Answer: the performance (with the best possible sound).

Next question: Should we hinder the performers in the quest for the perfect sound? 

Obvious answer: absolutely not.

I'll just say ithindering the very thing you've been hired to capture well is just dumb.  You've not been hired to make it challenging for performers to perform.  You've been hired to capture their performance.  Buckle up, dear readers;  here comes another rant.

I am convinced that as audio engineers it is our responsibility to capture the greatest possible performance with the greatest possible soundin that order.  To this end we must take great care to make players comfortable, so they can play their best.  Sometimes drummers arrange their kits in a way that makes placement of microphones tricky. If an engineer's default approach is to tell a drummer to raise his hi-hat to get it away from the snare, or to move a tom or raise his cymbals, etc, then they're essentially asking him to be uncomfortable when playing for the sake of sound (“... but by all means, don't play like you're uncomfortable..”). 

If this describes you, you need to wise up, or you should be fired.
Nobody has ever hired you for the purpose of making it harder for players to perform, and when they figure out that's what you're doing you likely won't get a second gig.  The performance you've been hired to capture is key – it's number one. If your approach to capturing it actually weakens the performance itself by forcing performers into a state of discomfort, then how is your effort doing anything other than damaging that which is most important? 

Wise up!  Do you seriously contend that the small improvement in sound you may achieve by making a player uncomfortable on his instrument outweighs the negative effect to the performance? 

Or put another way, "do you want to be hired again?" 

Performance comes first. Your sounds come second. Period.

Become a beloved engineer by ensuring the performers are comfortable with their instruments, and what they're hearing. If they aren't, they'll focus their energy on trying to overcome the obstacles thrown in their way rather than just playing, which is what they're really supposed to do.

So... back to miking a snare drum – starting with the top mic, position it with its tip about one inch inside the edge of the top rim, about two inches off the drum, pointed at the center of the head. This is a good place to start as it generally produces a useful balance between attack and tone.

Audition the sound with this placement and decide what changes are needed.

If the sound is to long/ringy, add a bit of moon gel or drum gum (or a loop of duct tape) to dampen the ring and shorten the decay of the drum. If the drum is dead, it probably has too much muffling and needs to lose some to liven the sound up, or perhaps the head is too slack and needs to be brought up a bit.

If you want a bit more body in the sound, then either move the mic a little closer to the drum, or point the mic somewhere between the middle of the head and the rim nearest the mic. As the mic gets closer, the proximity effect will exaggerate the low mids a bit more. Use this effect sparingly, as in most mixes the higher frequency information of the snare can get lost in the blend of other instruments, leaving it darker sounding than you thought when first tracking it.

As you point the mic more toward the edge you will get more harmonic in the sound, and the decay may appear to lengthen.

Leakage from the hi-hat is always a concern when miking the snare drum. Because the hi-hat and snare are usually close together, it isn't practical to expect to get complete isolation, but careful placement can certainly minimize the leakage to manageable levels. Since the SM57 (or most any mic you'd choose for miking a snare) has a cardioid pattern, point it, as much as possible, away from the hi-hat. Generally the top mic will be between the hi-hat and the first rack tom mounted directly on/above the kick drum. If the drummer's hi-hat is particularly high, you might have success placing the mic below the hi-hat, pointed at the snare toward the floor toms. This position usually isn't possible, but can be helpful if there's room.

Remember to work with the drummer on placement. It's fine to ask it he would be comfortable moving something – many times it'll be no big deal. But don't demand he comply. If you need to lower the angle of the top mic to keep it out of his way, then do it. Use your ears and find the best possible sound with just mic placement while keeping the drummer comfortable.

If the placement leaves something to be desired in the sound, see if you can tweak the drum itself to compensate. For example, if you find that to keep the drummer comfortable you have the mic farther away than normal, you may be lacking a little body. See if you can drop the tuning a tad to compensate, or switch to either a deeper drum or a drum with a thicker shell, and, therefore, a stronger fundamental tone.

Or if you're forced to place the mic really close, see if you can switch to a brighter sounding snare drum to compensate for the increased proximity effect.

With regard to the bottom mic, placement is usually easy as it is out of the drummer's way.  With the bottom mic you're trying to capture the articulation of the snares. Start by placing the mic near the center of the drum, 2 to 4 inches off the bottom, pointed directly at the snares. When you listen to this mic it will sound very snarey and flat, with very little tone. The snare response should be clear and defined, not smeared. If the snares have a strong metallic character, try backing the mic off a bit more until you have a clear, almost delicate 'snap' from the snares with a minimum of rattle.

Now audition both mics together and blend the amounts of each to create the complete snare sound. If you hear odd interaction between the mics, alternate muting each one to see which mic has the sound you're hearing and tweak the placement of that mic in an effort to eliminate or minimize it the problems you're hearing.

When miking a drum from both the top and bottom the sound is literally going away from one mic while simultaneously moving toward the other mic. For this reason you will experience significant signal cancellation (particularly at lower frequencies) when the two signals of these out-of-phase mics combine. To solve this, reverse the polarity on one of the mics (often the lower mic). Doing so will put both mics 'in phase' together, preserving all the tone and articulation from both mics.

Even when reversing polarity of one of the mics, it can also be useful to further tweak the distance of the bottom mic to bring the pair more completely into complimentary phase. Simply flipping one mic 180 degrees out of phase doesn't ensure the best result. The layout of a drum kit often limits the amount of room you have to make adjustments to the placement of the top mic, so it is simpler to adjust the bottom mic, where you have more room.

As always, use your ears and take your time. A little time spent at this stage will reduce the amount of processing needed later (which we will get to in future posts) and will absolutely make your final product better.

Thanks for reading.


Tuesday, November 15, 2011

Engineering Drums Part Five: The Kick Drum

Kick drums (bass drums) provide the low frequency, rhythmic foundation in pop music.  We want to capture this well as it is this LF content that provides the exciting 'thump' in the music that we feel in our chests.

Select a dynamic mic that has extended LF response (yes, occasionally you will find an engineer who uses a condenser mic on kick, but this is tremendously rare). Some common choices for kick mics include the AKG D112, Shure Beta 52, BeyerDynamic M88, Audio-Technica ATM25, Sennheiser MD421, and the Audix D4 or D6.

The D6 is an example of what I would call a 'tuned' kick drum mic, that is, its frequency response is not meant to approach linear, but rather has a purposefully manipulated curve designed to produce a pre-equalized, modern kick drum sound. Other tuned kick mic models include Sennheiser's E602 and Electro-Voice's N/D868. These tuned mics can be very cool, and helpful for getting sounds quickly, but be aware that the more tailored a mic's frequency response is, the less flexible it is as well (the more likely it will sound great on one drum, not so much on another). So if you choose a mic with a tailored frequency curve, make sure you really like what it does on your drum, or you may be swimming upstream later trying to undo its impact on the sound.

Kick drums sound quite different from one another depending on variables such as dimensions, shell material and thickness, bearing edges, types of heads used, tuning, and muffling, so unless you're tracking the same drum over and over, I recommend you select a mic with a little less personality, but rather one that yields a solid, complete tone and allows the engineer some freedom to tailor it as needed through the use of placement, EQ and dynamics processing. More often than not, for the kick I use an AKG D112 – it is a proven, well known performer that works well on a variety of kick drums, though there are many other mic options that also work quite well.

For pop/rock music kick mics are generally placed inside the drum. Access to the drum's interior is usually accomplished via a hole cut into the front head, allowing the boom arm of a mic stand to reach into the drum. You can also gain access to the interior of the drum by removing the front head altogether, but doing so will dramatically reduce the drum's ability to resonate compared to having a front head (even a head with a hole in it), and modern drum sounds often benefit from the additional resonance from having a front head.

Begin by placing the mic inside the drum about halfway between front and back heads, off center, pointed at the beater to capture the impact. When placing the mic I'm looking for a good balance of attack (from the beater) and tone (from the shell) – this placement is a usually a decent place to start. In this position it's close enough to the batter head to get some good definition, but the off center placement means that when the mic is pointed at the area of beater impact it is also pointed, somewhat, toward the shell as well, which increases the tonal component of the sound.

Listen critically to the sound with this initial mic placement, and decide what you'd like to change about it. No, don't reach for an EQ to try to make the sound better;  make it the best it can beget out there and move that mic around or tweak the drum to capture the sound you want.

The main components of the overall sound you're listening for are attack, tone (or body) and resonance.

Adjusting attack:

Placing the mic closer to the batter head increases the amount of attack in the sound. Pulling the mic back will reduce the attack.

Also, with directional mics high frequency sensitivity is greatest when the mic is pointed directly at the source. This HF response then rolls off as the sound becomes more off-axis. Therefore, if you like the amount of attack, but would like to lower the frequency of the attack, keep the mic a similar distance from the batter head, but turn it a little, so it's not pointed as much at the beater. Conversely, if you want the attack to consist of higher frequency content, point the mic directly at the beater.

If you find yourself wanting greater attack than mic placement alone can provide you may want to try fitting the batter head with a beater impact pad.  These vinyl/plastic pads are self-adhesive patches that you place at the point where the beater makes contact with the batter head.  These pads enhance attack (and also increase the durability of the head).  If you don't want to buy one of these pads, you can essentially make one by cutting a 3"x3" piece of old drum head and duct taping it in the same spot.  This will give more 'snap' to the attack.  

Alternatively, you can change the beater to a harder type.  For instance, if the bass drum beater is made of felt, switch to one made of wood or hard plastic.  The harder material will create a stronger attack.

"Why not just use EQ?" you may be wondering.  Because even the best EQ will still affect everything the bass drum mic picks up, including the bleed from the bottom of the snare drum that is just on the other side of that batter head.  By altering the drum and/or beater, you affect the captured attack of the sound without affecting any of the leakage that may find its way into your kick drum microphone.  The result will be much more managable when mixing with less need for fiddling to get things to behave.  It requires a touch more discipline when tracking, but eliminates headaches later on and provides the best results in the final product.

Adjusting tone:

To increase the drum's tone simply back the mic away from the batter head, closer to the front head. With this greater distance more of the drum's depth will be captured, creating a fuller, deeper tone. To further emphasize the tonal component, turn the mic away from the beater, and more toward the shell instead. This rounds off the attack content and further features the shell's contribution to the sound.

Sometimes the tuning of the drum may seem right, but it's tone is too bright and can actually approach an almost basketball-like 'ping' in the midrange. This happens when the interior shell of an unmuffled bass drum is hard enough that the sound actually bounces around inside the drum rather than being evenly diffused or absorbed. This is particularly true of acrylic and fiberglass drums, as well as those from a couple of manufacturers who like to seal the interior of their wood drums with a thick coat of hard polyurethane. To solve this annoying resonance place a dish towel, washcloth, hand towel, or similar sized soft cloth along the inside bottom of the shell, not touching either head. Since it doesn't touch the heads it doesn't dampen the resonance of the drum, yet the soft texture of the towel gives the soundwaves a place to go. This works surprisingly well.

For greater absorption use either a thicker towel or a larger one folder into a smaller footprint (still not touching the heads).

If you want to further increase the fundamental low-frequency content of the tone there is an old trick that can help – you must dampen the shell's resonance. To understand why this is so I'll make a slight detour, but one that I promise you will find useful, not only for understanding kick drums, but ALL drums.

For the past 25 years or so it seems that drum manufacturers have been striving to create drums that resonate well. Sounds like a great thing.... who doesn't love resonance? They make thinner shells that resonate easier and design mounting hardware that allows the drum to resonate fully, all in an attempt to create more 'tone.' The funny thing is that this 'tone' everyone is striving for is actually comprised of less fundamental tone, and more overtones or harmonics.

When someone strikes a drumhead the sound goes down the inside column of the drum shell and gets the bottom head moving too. The tuning of these heads, along with the dimensions of the drum, determines the drum's fundamental pitch. When the vibration of the heads is unhindered, the fundamental pitch is strong. But thin shells with mounting hardware designed to let them resonate fully respond easily to the vibration of the heads by doing a little vibrating of their own. The shell's involvement absorbs some of the heads' vibrations which actually dampens the fundamental. What, then, is the product? More harmonic content. This dampened fundamental/increased harmonic results in a brighter overall tone that is common to modern drums. This is why thinner shelled drums have a brighter tone.

Conversely, a thick shell isn't as easily set in motion by the vibration of drum heads, so the fundamental pitch is stronger. This is why thick drums are louder and darker with more fundamental pitch than their thinner-shelled cousins. This is true of other acoustic instruments as well.

For example, Martin's D-35 acoustic guitar is known for its darker tone, compared to, say, their D-28. Both are dreadnoughts of the same size and materials with same level of craftsmanship, but the D-35 has a three-piece back rather than the two-piece back of the D-28. Three pieces of wood, along with the greater amount of glue needed to combine them, create a guitar back that is slower to respond to vibration than a two piece design that uses less glue. Since it can't vibrate so easily, it doesn't hamper the fundamental content as much, and the guitar's tone becomes darker and louder.

Make sense?

So back to kick drums. Since hindering the drum shell's ability to resonate increases the fundamental pitch, then bass drums that have a couple of toms mounted to its top will have a stronger fundamental than that same drum with no toms mounted to it (since the weight of the toms will hamper the shell's ability to resonate freely). 

Some people have 'virgin' kick drum shells that are drilled for nothing other than lugs and spurs. Such free-standing drums, particularly those with thinner shells, allow maximum vibration which dampens the fundamental yielding a more harmonic tone. So... to increase the fundamental pitch you must dampen the shell's tendency to resonate. To do this place a a weighted object(s) inside the drum, resting on the bottom of the shell. I have a few pieces of heavy 4” iron pipe that I place on a towel inside kick drums when I want a stronger fundamental pitch. I know of folks who use a canvas bag with around 25 lbs. of bb's in it. Any weight you add to the inside of the shell will dampen it, bringing out the fundamental pitch.

Be aware , however, that leaving such a weight inside the drum continuously will eventually warp the shell. I have seen kick drums from studio 'house kits' that have become very warped from years of having a heavy weight laying inside. So use the weight as needed, but please use caution, so you don't damage the drum itself.

Adjusting resonance:

If the drum is too resonant, or 'boomy,' apply (or increase) padding, such as a folded towel or blanket or even a small pillow against the batter head. This will tame the duration of the head's vibration, reducing the drum's resonance. The more padding you use, the shorter the resonance will be.

You can also pad the front head some, if needed, though I often find that muffling the batter head of a well-tuned bass drum is enough.  Trust your ears.

Supplemental mics:

It is common practice these days to use a second mic to capture another perspective of the kick sound to be combined with the internal mic for a more complete presentation. The ability to balance these mics in post gives the engineer additional flexibility for shaping the kick drum sound. Usually these mics are placed outside the drum, a few inches off the front head.

Two types of 'mics' are most commonly used for this (one of which isn't really a microphone at all): 1) a large-diaphragm condenser mic and 2) a speaker wired in reverse.

For a more natural sound I use a large diaphragm, cardioid condenser to capture the 'out front' perspective of the bass drum. I place it in close, so the proximity effect of the cardioid pattern works to capture the low frequency energy of the drum. This mic usually sounds a little incomplete by itself, but coupled with the internal mic yields a defined kick with a solid LF component and natural feel. Because of the sensitivity of condensers mic it can be helpful to angle the mic down a bit to help minimize bleed from the rest of the drum kit. If necessary you can use a heavy packing blanket to cover the front of the kick to further isolate this outside mic. In practice this isn't usually required, but you may find it helpful.

For a more exaggerated LF punch wire a 6”-8” speaker to an XLR connector (speaker leads to pins 2 and 3 and speaker metalwork to pin 1) and place it a few inches off the front head, pointed right at it. Yamaha actually makes a subkick mic that is essentially such a device. It's handy to use, but you don't have to spend $300 on it if you have a speaker or two laying around already. A speaker is essentially a very large dynamic microphone in reverse anyway, so wiring it for use as a microphone actually makes more sense than one might think at first.

Trivia time: did you know that the bass guitar sound for the Beatles' “Paperback Writer” was achieved using a reverse-wired Tannoy speaker placed directly in front of Paul McCartney's bass cabinet? (I'm a huge Beatles fan and just had to share).

Back to the speaker wired as a mic – when you audition this 'mic' alone it isn't gonna sound very good. It'll be foggy and muddy with almost no definition, but coupled with the clarity and punch of the internal mic, you will have a HUGE bass drum sound. Use it sparingly as the effect is easy to overdo.

These mics offer lots of options on selection and placement. Just trust your ears and play around with them, and you'll get some excellent results.

And remember that anytime you use two mics on one source always be sure to check your polarity settings. If they are in opposite polarity much the wonderful low end that you're working so hard for will be cancelled, leaving a very nasty, filtered, unsatisfying result.

Next comes the snare drum. Thanks for reading!


Monday, November 14, 2011

Engineering Drums Part Four: Microphones

Microphone selection for drums is a HUGE topic that could easily fill a small book, so to keep this entry from becoming one, and in the interest of keeping things simple and practical, I will give only a very basic explanation for the types of mics typically used when tracking drums and where, on the kit, they typically go.

Dynamic microphones -- Dynamic mics function using a principle called 'electromagnetic induction.' In English this means that a conductive metal vibrating within a fixed magnetic field will generate a small current which is used to provide the mic's output signal. Since magnetic material is used to generate the magnetic field, these microphones require no external power source to function.

The two dynamic designs in use today are ribbon mics (where a thin 'ribbon' of metal is suspended directly within the magnetic field) and moving coil mics, where a plastic diaphragm is attached to a voice coil of wrapped wire which is then suspended within the magnetic field. The movement of the conductive metal (the ribbon or the voice coil) in response to sound waves generates the current, and therefore the output signal.

Because of limitations in commonly used magnetic materials these microphones tend to be less sensitive to softer dynamics as well as high frequencies (compared to higher fidelity microphone designs). The durability of the moving coil design, in particular, coupled with its relatively limited sensitivity make these mics exceptional choices for loud, bombastic signals with limited HF detail, such as kick drums, snare drums, and toms.

The physical design of ribbon microphones (an extremely thin corrugated metal ribbon suspended in an open magnetic field) make them somewhat prone to damage from plosives or other gusts of wind (which fully exert the ribbon, destroying it) as well as higher SPL sources. But the extremely low mass of the ribbon itself, coupled with the smooth character for which ribbon mics are known make them a valid choice for overheads (when you want a smooth sound) and room mics.

Condenser microphones – Condenser mics, also called 'capacitor' mics, work on an electrostatic rather than electromagnetic principle. The capsule of a condenser mic is made from two plates, one of which is fixed (called the 'backplate') and the other being moveable (called the 'diaphragm' or 'film'). Together, these two plates, along with the fixed amount of air in between them, form a capacitor (also called a condenser, hence the name, 'condenser mic'), which can store an electrical charge. A fixed DC polarization voltage is applied across this capsule, and as the air pressure (sound) causes the diaphragm to move, the distance between the two plates of the capacitor varies.  As this distance changes, so does the voltage across this capacitor.  This voltage becomes the output of the microphone.

This is a slight oversimplification of how it works (you can google 'condenser mic' if you want the whole scoop), but the bottom line is that the moveable plate of the diaphragm (most often a gold-sputtered mylar film between 3-6 microns thick) is of such a light weight that it responds well to even the lightest changes in sound pressure, making these mics sensitive to very low level signals as well as much higher frequencies than most dynamic mics. Because of their high frequency response they are great for use as overheads and on hi-hats, and given their sensitivity to low level detail, they make exceptional room / distant mics as well.

Electret condenser mics are condenser mics that have a fixed polarization charge on the capsule rather than needing an externally supplied polarizing voltage.  They still, however, require a power source for the impedance converting amplifier.

Among both externally polarized and electret condensers there are two practical variations: small diaphragm and large diaphram. Because of their even lower mass, small diaphragm condensers tend to possess an even faster response time, yielding a more neutral, lifelike response, while larger diaphragms tend to be less lifelike but a bit more opulent or larger-than-life in their presentation. For the sake of miking drums either type is perfectly appropriate.

Stay tuned, and we'll puts these mics to use...


Friday, November 11, 2011

Engineering Drums Part Three: Drum Kit (Singular)? Or Drums, Etc. (Plural)?

As an audio engineer, how do you perceive the drum set? Is it a single instrument to you, or do you think of it as a collection of several individual instruments over which you want control? I ask this question, because your answer will determine how you approach miking drums, and, IMHO, how much success you will have presenting it to your audience, whether live or on record.

I think of drums as a single instrument. Just as a guitar is made up of a body, a neck, fretboard, frets, strings, bridge, nut, etc. to make the whole, so do the kick, snare, toms, and cymbals combine to become one overall instrument – one person plays a guitar, and one person plays a drum kit. Bands don't have a kick drummer, a snare drummer, a tom-ist(?) and a cymbal player in the band. They have a drummer. One person playing one instrument.

This is critical thinking in my experience. The most natural, and musical results capturing drum sounds that I have heard are those achieved by approaching the kit as a collective whole rather than a bunch of individual pieces. Here's why:

Having the ability to treat each component within a drum kit as a separate item (to be controlled individually) requires you to first isolate each item, otherwise you'll be treating the leakage as well. Drums are close together, along with loud, metal cymbals, and there simply isn't a microphone capable of picking up audio from one while ignoring the others. So the only way you'll get anything resembling isolation from component to component is to hard gate everything, which makes bleed from other components sound awfully strange as those gates open up and slam shut. Such gate 'chatter' quickly makes the drum sound awkward at best, and downright amateurish (or just BAD) at worst.

There will be bleed from mic to mic when recording or broadcasting a drum kit. Period. So unless you embrace this reality and use it to your advantage you may as well look into securing some blood pressure medication.... you'll be needing it.

Now let's start with the basic foundation of your drum sound.... the kick? Nope. The snare? Nope. I'm going with overheads.

Overheads?” you say? Yes, overheads. Not as obvious, or as sexy a choice as kick or snare, but if the kit is one instrument, what other mic other than an overhead hears the whole kit? Overheads are critical to the quality of your drum sound. 

[Yes, any room mics used will hear the whole kit as well, but they're farther away to capture ambience.  They're not part of the close-up 'kit' sound]
Here's the deal. While the drums on the kit will get there own mics, the cymbals generally don't. Overwhelmingly, cymbals are miked with a pair of condensers placed over the top of the kit, a few feet off the cymbals. The hi-hat will often get its own mic (which isn't always needed when mixing), and occasionally I'll stick a mic on the ride to give it more definition as needed, but the overheads are up high capturing the kit -- not just cymbals. The whole kit.

If this makes sense to you and you're okay with it you can pretty much skip the rest of this post. If this doesn't sit well with you, then you're likely from the “overheads are for cymbals only” school of thought, and your engineering will surely benefit from some additional explanation.

The frequency and harmonic content of cymbals goes down well into the low-mid range (these are 16” to 20” or greater diameter hunks of metal vibrating. Loudly). The only chance you have to isolate cymbals from the kit in any practical way is to drastically cut everything from the high mids on down (or, worse yet, boost everything above this range). When you do this you effectively cut the frequency range of the cymbals in half removing the punch and body that cymbals need in pop music. Bad idea. What drum is there whose frequency response you'd be willing to hack in half in the same fashion? Why, then, would it be acceptable to do this with cymbals?

Some engineers, when faced with this reality will opt to individually close-mic each and every cymbal, taking them from the proverbial frying pan and squarely into the fire. Now, not only do they now have increased leakage issues (more mics / more leakage) but they're now listening to the cymbals from a fundamentally unpleasant vantage point. When was the last time you listened to a cymbal with your ear right on it? That's not how we hear cymbals. They don't sound good up close -- they hum.


Yes, HUM. Remember, cymbal harmonics go down into the low-mid range. Take any cymbal, and 'crash' it with your finger and put your head near it as it decays. Hear that hum? Put a mic directly on a single cymbal and you will have a lot more of that to contend with than ever before. For every single cymbal. On. The. Kit.

If your solution to a problem is to create 2 new problems, is it really a solution?

Stay tuned...

Happy Tones!

Thursday, November 10, 2011

Engineering Drums Part Two: Tuning

Tuning drums is as much art as science. Drums vary tremendously from kit to kit with all the various materials (maple, birch, poplar, aluminum, brass, copper...), to various sizes, and ratios of diameter to depth, all of which affect the way you'll tune the drum to get the sound you're after. Rather than try to give anything close to an exhaustive lesson on tuning drums (which would be a book, not a blog post), I will give very basic tips that can be broadly applied, and also try to clear up a few misconceptions shared by both drummers and engineers regarding tuning. Keep in mind I offer these suggestions with the assumption that you are working with good drums with clean, true edges and rims, good heads... you get the idea.

Firstly, when putting heads on drums finger tighten each key rod only, taking care to make sure the head and rim stay centered on the drum (there is a little 'play' in the head when it's totally loose). When it is evenly finger tightened (and the head is snug), use a drum key to begin turning each key rod 1/4-turn at a time criss-crossing the head. Here is a picture showing the lug tuning order for a variety of common lug arrangements.

Sticking with this back-and-forth approach around the drum keeps the head from pulling too much to one side, allowing for more even tuning.

After each set of 1/4-turns tap the head about an inch in from each lug to check the pitch. Thinner heads will have more overtones, which can make hearing the fundamental a little tricky. If this is the case just lightly touch the center of the head with a finger, and the overtones will be well-controlled. Tap near all lugs and determine which are lower, and bring them up with slight turns until each lug shares the same pitch. Then another 1/4-turn for each lug, and another balance. Continue until you reach the pitch you want.

Always tune up, not down. If you find that you need to go lower, loosen the lug more than you intend, and then bring it up to where you want it. Ending with a clockwise turn stabilizes the tuning more than counterclockwise turns.

I generally tune toms near their midrange (which often only takes a full-turn of each key rod past finger tightening). The midrange is where the drum tends to have the most tone and sustain.  Generally, sustain is a good thing in sound reinforcement as it can be controlled with dynamics processing if it's a bit much, but it's very difficult, if not impossible, to add sustain (yes, you could use compression to add sustain, but then you'll be processing all the bleed that the tom mics have, creating an entirely new set of problems.  I recommend getting the most sustain from the drum itself to simplify your life).  

Tuning toms above the midrange shortens the decay, and makes the drum's tone brighter.  Tuning below the midrange shortens the decay and makes the tone darker.  Basically, the midrange with where you have the most sustain.  Go above and you choke it, go below and the head is too slack to achieve full resonance.  

And, for clarity, when I talk about sustain or decay, I mean effective or perceived sustain or decay.  When you're close to the drums you can hear them all resonating easily, but the practical sustain is that which is perceived by the listener who is across the room or by that which projects through the other elements in the mix.  Larger toms can fool you into thinking the decay is too long (larger drums resonate longer!), but in the context of a mix, this is rarely the case.

If you have a kit with lots of toms and want to create a bigger pitch difference between them, you could tune the smallest tom a little above its midrange, and the largest tom below its midrange with a tapered approach between them.  This approach helps define the pitches a little better, and the effect of these alterations create a smooth transition from brighter high toms down to darker low toms.

Tuning batter and resonant heads to the same pitch will make toms punchy with a shorter decay. Tuning one head higher than the other can increase resonance and often emphasize a 'bend' in the tone from attack to sustain. Some folks like to make the top tighter than the bottom, while others prefer the other way around. I've had success with both, depending on the dimensions of the drum, but it requires a little patience and experimentation to figure out what works best for each drum on the kit you're working with.

The snare drum is a rather odd beastie in that its bottom edge has a snare bed cut into it's edges at opposite ends under the snare strainer and butt. This bed, usually 2-3 inches wide at each end, causes uneven pressure on the bottom head that keeps it from resonating the way heads do elsewhere on the kit. For this reason I generally tune the bottom head using thumb pressure, that is, using my thumb I press on the head an inch in from each lug to determine how tight the head is. After much experience I can tell very closely how matched each lug is. Keep in mind that at the lugs immediately adjacent to the snare bed, the head will tend to give a little more. Don't try to match the tension of these lugs to the rest of the head as this variance helps the interaction of the head with the snares.

I recommend making the snare side head rather tight (the equivalent of a few full turns of each key rod). I want it to give a bit with firm pressure, but I want it well above the midrange. With the bottom head loose the snare will lack tone and will sound unpleasantly snarey (is that a word?) and flat. With it nice and tight you will have crisp snare response and plenty of tone.

Now, to clear up some misconceptions:

Firstly, many folks think that snare buzz is bad, and that they must tune the drums to where the snares don't respond sympathetically when any of the other drums are struck. Unless the buzz is extreme this isn't really a practical problem (not to mention that truly getting rid of it is practically impossible to do). The bit of snare buzz that happens with a well tuned kit just makes the kit feel more complete. This isn't the 1980's, where we're using drum machines with samples of individual drums with zero interaction. Modern drum sounds rely heavily on overhead and room mics to give the overall kit a cohesive sound, and the residual snare response is a big factor in that. As a matter of fact Yamaha's top-of-the-line electronic drum kit features a sample of snare buzz that plays (in the output of the snare channel) when each of the other drums on the kit are struck. The purpose of this is to better emulate the response and interaction of an acoustic kit, and the effect is convincing.

Secondly, it seems many folks believe that getting a crisp, fast 'snare' sound requires cranking the tension on the snare strainer so tight that only the strongest hits will actually get the snares moving. This choking of the snares only serves to make your snare drum come across as a tom, not a snare. Snares are the reason the drum sounds like a snare drum! Don't remove them from the equation by tightening them so much that they can't respond to anything but the loudest playing. For the drum to sound natural you need to have excellent snare response at all dynamics. I adjust my snare tension so that a very soft tap with the stick will have crisp, short snare response. I don't want the snares to rattle, just respond articulately with very soft playing. This sometimes results in snares decaying a little past the actual strike, yes, particularly if the drum has very little muffling and greater sustain, but it sounds more natural to the microphones, both near and far.

Thirdly, many people think that you have to muffle drums with moon gel or duct tape to get a rich 'studio' sound. The truth is, microphones don't quite hear drums the way we do. When each drum is miked closely, the mic is usually a couple of inches at most off the edge of the drum, pointed at the head. When was the last time you listened to drums with your ear that close? Likely never. It sounds quite different up close than it does when you're standing a few feet back from the kit. Yes, to some folks the overtones of drums (particularly with unmuffled, single-ply heads) can feel a bit overbearing, but avoid the temptation to pad them down before auditioning the kit through mics. You may be very surprised to hear that your perfectly tuned and muffled drums sound more like a collection of cardboard boxes upon playback through the studio monitors (and no, don't reach for an EQ to boost high mid frequencies trying to put life back in the drums.... GO OUT THERE AND FREAKING REMOVE SOME MUFFLING INSTEAD!!!)

[Wow... okay... deep breath,.... I apologize for that outburst. Where was I?...].

Oh yes... give the drums a chance to breath a bit and muffle only as needed.

On a related note, overtones from drums tend to get lost in the blend of other tracks within a pop mix. There's a lot of midrange information in pop music (vocals, guitars, keys, strings, effects, etc.), and those drums that sound too 'live' when solo'd will sound far more contained in the mix than you may expect. If you tame that life with muffling during tracking you may well find yourself struggling against 'cardboard box' syndrome when mix time rolls around.

Lastly, a big misconception I see people buying into is that to have a bright, poppy snare means to crank the top head up till the drum sounds like a timbale. When you do that you are robbing the drum's ability to resonate (which actually stifles the drum's overtones as well, making its tone.... wait for it..... less bright).  So you wind up with a short, dead pop that more resembles a dull tabletop than a drum. For 'bright' snare sounds choose a metal shell drum, tune the bottom head tight and the top head a little above midrange. Tune it well and use little muffling, so its timbre can project like a good metal drum should. If you want more crack, have the drummer play rimshots instead of hitting the drum dead center.

This works for a wood drum too, but the sound, because of the softer material, will be a bit mellower, but still surprisingly crisp.

The rest of the 'sound' will be the mic you choose, its placement and your processing.

So that's about all I have to say about tuning. The art of tuning drums is extensive, and well beyond the suggestions that I have made here, but armed with this info, a good set of ears and a little patience you should be able to get where you want to go.

Next we pull out the mics....

Happy Tones!

Monday, November 7, 2011

Engineering Drums Part One: An Introduction

Opinions abound about how to mic and mix a drum kit in pop music. Pro audio forums are filled all manner of sage to dang near useless council, from the ever present, and often repeated “whatever sounds good is good," which is true, but offers no direction, to the more eccentric, yet strangely common, “anything more than 3 mics is overkill,” all the way to the entirely un-relatable, “my overheads are C12's, my room mics U47's and everything goes through 1073's.” Yeah, okay. Thanks for that.

While I tend to agree that in art there are no rules, in the world of the recording arts there are most definitely time-honored and well-proven techniques for consistently capturing well the sound of all kinds of instruments, drums included. And while I won't be breaking any new ground with this series of discussions on engineering drums, I will share concepts that, when followed methodically, will produce repeatable, professional results. So let's get rolling.

First things first – how do the drums that you're miking sound? Before you put a mic anywhere near the kit it is critical that the drums sound good. So the set should be of professional quality, well-maintained and well tuned with heads that are appropriate for the type of music you're recording. Let's talk about head selection.

There are a TON of drumhead models out there, from several quality manufacturers, but don't freak out. From a very practical perspective all those models really boil down to essentially two types; single-ply and double-ply. Yes, there are different film thicknesses and texture coatings (or lack of coating), clear, white and colored heads, etc., but pretty much all models you're likely to come into contact with will be mylar and will be either single or double-ply. The choice you make should be based on 1) what kind of sound you want, and 2) how durable do they need to be?

With regard to sonics there are primarily two camps: 1) strong attack with relatively dark and short sustain, and 2) less pronounced attack with a brighter, more complex tone and greater sustain. Heavier styles tend to benefit from the the greater articulation and short punchiness of the former, while lighter, more pop-ish styles often provide more sonic real estate for the latter's longer sustain including greater interaction with room mics. The difference between these tonal profiles lies primarily in the choice of batter head used.

Single ply batter heads have more harmonic content / overtones, producing the brighter tone with greater sustain. The darker tone can be produced by either applying tape or moon gel to single ply heads for by selecting a double ply head instead.

All 'resonant' heads (the bottom of toms and front of kick drums) should be single ply (so they can... well... resonate!).

The bottom of a snare drum requires a special, very lightweight head to allow the interaction of the snares to speak clearly. An Ambassador snare side head or Evan or Aquarian equivalents will do very nicely.

Regarding durability, double ply heads last longer, so if you're working with a heavy hitter you should opt for double ply, or you'll be tuning and even changing heads more often between takes.

This is all, of course, a practical oversimplification of the rather extensive selection of drumhead types available today – I am well aware of this. But from the perspective of an engineer (and/or studio owner who has to replace heads often on a house kit), these tend to be the critical variables in head selection. A good engineer can compensate for most all other performance characteristics through tuning/muffling, microphone selection and placement, and signal processing.

And make sure your heads are of a quality brand. All the major drumhead manufacturers make excellent products, so if you stick with a name brand, you'll be fine.

In the next installment I'll discuss tuning, and then we'll get the mics out!

Happy Tones!

Thursday, November 3, 2011

The Equalizer -- A Tracking Engineer's Friend or Foe?

I love EQ.  I've got lots of equalizers.  Active and passive, graphic and parametric, fixed and sweepable designs, reciprocal and non-reciprocal -- LOTS of EQs.  I LOVE EQ!

Having said that, equalizers are not generally part of my first plan of attack when tracking an instrument.  You see, I also like things to sound natural, not mangled and fake.

I prefer audio to sound good.

Decades ago equalizers were very simple, broad-stroke devices that would perhaps better be termed 'tone controls' rather than an EQ (at least in the sense that we know EQs today).  The practice at the time was for an engineer to choose the proper mic and its placement to best capture the instrument(s) being recorded, and then reach for EQ to broadly correct any overall balance issues.  Back then music was generally recorded with far fewer mics than we use today, usually mixed down to a single track (or mono disc cutter).  Mic selection and placement was key.

Today, we use so many mics (I often use thirteen on a 4-piece drumkit alone), usually dedicating a single track to each one, so when it comes time to mix there is much more frequency interaction and overlap between all these sources, and, therefore, a greater need for filter electronics to sort through it all.  So common is our use of even complex EQ's nowadays that for many folks, particularly young engineers, it has become a primary approach for getting one's tones, and I contend that this should not be the case if you want well presented, natural sounding audio.

I see young engineers all the time placing a mic on an instrument according to the way they've seen it done in pictures in recording industry magazines, and then patch in an eq to fix what they're hearing in the control room -- STOP!!  Don't do that!  If your first mic choice and placement doesn't get you at least 90% of the way to the sound you are hearing in your head, then go back and choose a better mic for the source, or use better placement of the mic you have out.

'Why,' you ask?  Because all audio signals have this little thing called 'phase.'  No, I'm not talking about 'polarity', where we can flip the signal 180-degrees if we want.  Phase refers to the actual timing of frequencies within a given 360-degree audio waveform.  All audio electronics that accept an input and produce an output have a measurable 'phase response' which represents how accurate the timing of an output waveform is relative to the one at the input.  If things are properly in phase it means that the timing of the waveform is unchanged from input to output.

Equalizers not only change the amplitude of a given range of processed frequencies, but actually alter the timing of those frequencies relative to the original input signal.  What does this mean?  In the most practical sense it means that what comes out of an EQ is an unnatural version of the signal that went in, frequency-related amplitude notwithstanding.  The effect of this phase manipulation cannot easily be undone.  If you boost a range of frequencies when tracking a signal only to discover later that you shouldn't have done so, introducing more filter electronics (or virtual filter electronics by way of your DAW's EQ plug-ins) to correct the mistake won't undo the phase distortion of the original processing.  It can tame the amplitude of those frequencies, yes, but the second pass through filters will further distort the signal from its original phase integrity.

And it doesn't take much phase distortion to make a signal sound unnatural.  Most EQ's available to us today have many bands, and each band is screwing with the phase integrity of the input signal.  Pass after pass of filter electronics on all of your tracks will quickly leave an undesirable sonic fingerprint on your entire mix that often makes it sound less professional, or at least, leaves it lacking the authority of tone you want the finished product to have.

So what to do?  Trust your ears.  Go out in the room and listen to the instrument(s) you're about to record.  Walk around and bend down, placing your head in a variety of places to see what perspective best captures the instrument the way you want it captured.  Then decide which mic will fit the bill best, and place it in the spot where your head was.  Go in the control room and listen.  Then go back out and make adjustments as needed.  Then, only when you have gone as far as you can with mic selection and placement, if you feel it absolutely necessary, dial in some minimal EQ to get you the rest of the way there.

Here's a hint:  If you find yourself cutting or boosting more than +/-3dB or so to get a good balance to your recorder, I suggest you still need to mess with the mic and the placement (or choose a better instrument to record!).  The less EQ you use, the more authoritative and natural your tracks will sound.  Period.

(And this goes for live engineers as well, by the way, though other factors such as monitoring and avoiding feedback to come into play as well.)

Happy Tones!

Tuesday, November 1, 2011

Making Records in 1937 (continued)

While I find the process of phonograph record manufacturing in 1937 to be extremely fascinating (“almost 25 million produced in this country alone last year!”), as an engineer I'm even more fascinated by the glimpse this video gives inside the recording studio of that era. In the 1930's (lasting well into the 1960's) making a record was a real-time process, capturing a moment in time rather than the multitrack, overdub by overdub process of making a record that is standard procedure in modern facilities.

Obviously, the limitations of the gear required a different approach then: the extremely basic four channel mixer printing straight to an acetate with no further processing by way of mastering processes.

I love the narration: “Let's look in on the noted band leader, Duke Ellington as he prepares for a recording, working toward that accurate balancing of musical tones required for effective reproduction.” How true. If you examine the video you see that the acoustic guitar and the upright bass are in the front of the band closer to the mics. I see one mic over the piano and another in front center that the sax and later the singer use. Drums and brass back behind (they're louder). Balancing (or you could say 'mixing') was done by placement of the the players and their movements/locations were literally choreographed to create the balanced of the mix (i.e. the solo sax player walks up to the mic for his solo).

I once saw a picture of legendary band leader Spike Jones (father of Skywalker Sound Director of Music Recording and Scoring, Leslie Ann Jones, btw) with his band, the City Slickers, in the studio in the 1940's. I have scoured the internet for this photo, so I could link to it, but cannot find it anywhere (I saw it in print several years ago – if you know a link, please send it to me!).

The photo is fascinating – the floor of the studio is marked out in large, numbered squares with band members scattered among them (most of them standing - mobile). Along the front of the rows of boxes are 3 or 4 mics, and that's it. No doubt the numbered squares were used to choreograph movement of the various musicians.  

If you have never heard Spike Jones and the City Slickers you MUST check out tunes like Der Fuehrer's Face (, Cocktails for Two (, Chloe (, or just about any other tune of his. These are all single performances, committed straight to the recorder, using rather spartan technology with the 'mixing' being done through choreography instead of multiple mics, tracks, takes, and a mix session after the fact.

I am a fan of modern technology, we've got tools that can process and mangle a signal into submission, which is cool, but I believe that all too often these tools promote laziness in our recording technique. Listening to these masterpieces of the past, and knowing just how meager was the equipment used to capture them, I come away reminded and encouraged to not use my tools as a crutch, but to improve my work by relying instead on my ears to select the correct mic and placement for each instrument to minimize the amount of processing required to make it fit in the mix later.

Whenever I've adhered to this philosophy the end result has always been better.

Happy Tones!