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Event 20/20 Near-Field Monitor

Monitoring Basics

Here are the basics of using near-field monitors in the project studio

By Craig Anderton



All the effort you put into recording, overdubbing, and mixing is for naught if your monitoring system isn't honest about the sounds you hear. The issue isn't simply the speakers; the process of monitoring is deceptively complex, as it involves your ears, the acoustics of the room in which you monitor, the amp and cables that drive your monitors, and the speakers themselves. All of these elements work together to determine the accuracy of what you hear.

If you've ever done a mix that sounded great on your system but fell apart when played elsewhere, you've experienced what can go wrong with the monitoring process. Here are some suggestions on getting the most out of your monitors.

HEARING VARIABLES

Ears are the most important components of your monitoring system. Even healthy, young ears aren't perfect, thanks to a phenomenon quantified by the Fletcher-Munson curve. Simply stated, the ear has a midrange peak and does not respond as well to low and high frequencies, particularly at lower volumes. The response comes closest to flat response at relatively high levels. The "loudness" control on hi-fi amps attempts to compensate for this by boosting the highs and lows at lower levels, then flattening out the response as you turn up the volume.

Another limitation is that a variety of factors can damage your ears - not just loud music, but excessive alcohol intake, deep sea diving, and just plain aging. I've noticed that flying temporarily affects high frequency response, so I wait at least 24 hours after getting off a plane before doing anything that involves critical listening. The few times I've broken that rule, mixes that seemed perfectly fine at the time played back too bright the next day.

It's crucial to take care of your hearing so at least your ears aren't the biggest detriment to monitoring accuracy. Always carry the kind of cylindrical foam ear plugs you can buy at sporting good stores so you're ready for concerts, using tools (the impulse noise of a hammer hitting a nail is major!), or being anywhere your ears are going to get more abuse than someone talking at a conversational level. (Don't wear tight-fitting earplugs on planes. A sudden change in cabin pressure could damage your eardrums.) You make your living with your ears; care for them.

ROOM VARIABLES

As sound bounces around off walls, the reflections become part of the overall sound, creating cancellations and additions depending on whether the reflections are in-phase or out-of-phase compared to the source signal reaching your ears. These frequency response anomalies affect how you hear the music.

Also, placing a speaker against a wall seems to increase bass. This is because any sounds emanating from the rear of the speaker, or leaking from the front (bass frequencies are very non-directional), bounce off the wall. Because a bass note's wavelength is so long, the reflection will tend to reinforce the main wave (Fig. 1).


Fig. 1: How speaker placement reinforces bass.

As the walls, floors, and ceilings all interact with speakers, it's important that speakers be placed symmetrically within a room. Otherwise, if (for example) one speaker is 3 feet from a wall and another 10 feet from a wall, any reflections will be wildly different and affect the response.

The subject of acoustically treating a room is beyond the scope of this article. Hiring a professional consultant to "tune" your room with bass traps and similar mechanical devices could be the best investment you ever make in your music. Some studios use graphic equalizers to "tune" rooms, but this is not necessarily a cure-all (see following sidebar).


ROOM TUNING WITH GRAPHIC EQUALIZATION

Equalizer-based room tuning involves placing a mic where you would normally mix, feeding pink noise or test tones through a system, and tuning an equalizer (which patches in as the last device before the power amp) for flat response. Several companies make products to expedite this process, such as RTAs (Real Time Analyzers) that include the noise generator, along with calibrated mic and readout. You then diddle the sliders on a 1/3 octave graphic EQ to compensate for anomalies that show up on the readout. Some devices combine the RTA and EQ for one-stop analysis and equalization.

While this sounds good in theory, there are two problems:

  • If you deviate from the "sweet spot" where the microphone was placed, the frequency response will change.
  • Heavily equalizing a poor acoustical space simply gives you a heavily-equalized, poor acoustical space.

It's better to make the corrections acoustically, using devices (such as bass traps) to minimize standing waves, experimenting with speaker placement, and learning your speaker's frequency response. Also, make sure that phase problems and other gremlins aren't the real culprits.

Like noise reduction, which works best on signals that don't have a lot of noise, room tuning works best on rooms that don't have serious response anomalies.


Fig. 2: The "sweet spot" for near-field monitors.

NEAR FIELD MONITORS

Traditional studios have large monitors mounted at a considerable distance (6 to 10 ft. or so) from the mixer, with the front flush to the wall, and an acoustically-treated control room to minimize response variations. The "sweet spot" - the place where room acoustics are most favorable - is designed to be where the mixing engineer sits at the console.

In smaller studios, near-field monitors have become the standard way to monitor. With this technique, small speakers sit around 3 to 6 feet from the mixer's ears, with the head and speakers forming a triangle (Fig. 2). The speakers should point toward the ears and be at ear level; if slightly above ear level, they should point downward toward the ears.

Near-field monitors minimize the impact of room acoustics on the overall sound, as the speakers' direct sound is far louder than the reflections coming off the room surfaces. They also do not have to produce a lot of power because of their proximity to your ears, which also relaxes the requirements for the amps feeding them.

However, placement in the room is still an issue. If placed too close to the walls, there will be a bass build-up. Although you can compensate with EQ (or possibly controls on the speakers themselves), the build-up will be different at different frequencies. High frequencies are not as affected because they are more directional.

If the speakers are free-standing and placed away from the wall, back reflections from the speakers bouncing off the wall could affect the sound. You're pretty safe if the speakers are more than 6 ft. away from the wall in a fairly large listening space (this places the first frequency null point below the normally audible range), but not everyone has that much room. My crude solution is to mount the speakers a bit away from the wall on the same table holding the mixer, and pad the walls behind the speakers with as much sound-deadening material as possible.

Nor are room reflections the only problem; with speakers placed on top of a console, reflections from the console itself can cause inaccuracies. To get around this problem, I use a relatively small main mixer, so the near-fields fit to the side of the mixer, and are slightly elevated. This makes as direct a path as possible from speaker to eardrum.

ANATOMY OF A NEAR-FIELD MONITOR

Near-field monitors are available in a variety of sizes and at numerous price points. Most are two-way designs, with (typically) a 6" or 8" woofer and smaller tweeter. While a 3-way design that adds a separate midrange driver might seem like a good idea, adding another crossover and speaker can complicate matters. A well-designed two-way system is better than a so-so 3-way system.

There are two main monitor types, active and passive. Passive monitors consist of only the speakers and crossovers, and require outboard amplifiers. Active monitors incorporate any amps needed to drive the speakers from a line level signal.

With powered monitors, the power amp and speaker have hopefully been tweaked into a smooth, efficient team. Issues such as speaker cable resistance become moot, and protection can be built into the amp to prevent blowouts. Powered monitors are often bi-amped (e.g., a separate amp for the woofer and tweeter), which minimizes intermodulation distortion and allows for tailoring the crossover points and frequency response for the speakers being used.

If you hook up passive monitors to your own amps, make sure they have adequate headroom. Any clipping generates gobs of high-frequency harmonics, and sustained clipping can burn out tweeters.

SO WHICH IS BEST?

You'll see endless discussions on the net as to which near-fields are best. In truth, the answer may rest more on which near-field works best with your listening space and imperfect hearing response. How many times have you seen a review of a speaker where the person notes with amazement that some new speaker "revealed sounds not heard before with other speakers"? This is to be expected. The frequency response of even the best speakers is sufficiently uneven that some speakers will indeed emphasize different frequencies compared to other speakers, essentially creating a different mix.

Although it's a cliche that you should audition several speakers and choose the model you like best, you can't choose the perfect speaker, because such an animal doesn't exist. Instead, you choose the one that colors the sound in the way you prefer.

Choosing a speaker is an art. I've been fortunate enough to hear my music over some hugely expensive systems in mastering labs and high-end studios, so my criterion for choosing a speaker is simple: whatever makes my "test" CD sound the most like it did over the big-bucks speakers wins.

If you haven't had the same kind of listening experiences, book 30 minutes or so at some really good studio (you can probably get a price break since you're not asking to use a lot of the facilities) and bring along one of your favorite CDs. Listen to the CD and get to know what it should sound like, then compare any speakers you audition to that standard.

One caution: if you're comparing two sets of speakers and one set is even slightly louder than the other, you'll likely choose the louder one as sounding better. To make a valid comparison, match the speaker levels as closely as possible.

A final point worth mentioning is that speakers have magnets which, if placed close to monitors, can distort the monitor's display. Magnetically-shielded speakers solve this problem.

LEARNING YOUR SPEAKER AND ROOM

Ultimately, because your own listening situation is imperfect, you need to "learn" your system's response. For example, suppose you mix something in your studio that sounds fine, but sounds bass-heavy in a high-end studio with accurate monitoring. That means your monitoring environment is shy on the bass, so you boosted the bass to compensate (this is a common problem in project studios with small rooms). With future mixes, you'll know to mix the bass lighter than normal.

Compare midrange and treble as well. If vocals jump out of your system but lay back in others, then your speakers might be "midrangey." Again, compensate by mixing midrange-heavy parts back a little bit.

You also have to decide on a standardized listening level. Most pros monitor at low levels when mixing, not just to save one's ears, but also because if something sounds good at low volume, it will sound great when you really crank it up. However, this also means that the bass and treble might be mixed up a bit more than they should be to compensate for the Fletcher-Munson curve. So, before signing off on a mix, check the sound at a variety of levels. If at loud levels it sounds just a hair too bright and boomy, and if at low levels it sounds just a bit bass- and treble-light, that's about right.

WHAT ABOUT HEADPHONES?

Musicians on a budget often wonder about mixing over headphones, as $100 will buy a great set of headphones, but not much in the way of speakers. Although mixing exclusively on headphones isn't recommended, keep a good set of headphones around as a reality check (not the open-air type that sits on your ear, but the kind that totally surrounds your ear). Sometimes you can get a more accurate bass reading using headphones than you can with near-fields, and when "proofing" your tracks, phones will show up imperfections you might miss with speakers. Careful, though: it's easy to blast your ears with headphones and not know it.

SATELLITE SYSTEMS

"Satellite" systems use tiny monitors that can't really produce adequate bass in conjunction with a subwoofer, a fairly large speaker that is crossed over at a very low frequency so that it reproduces only the bass region. This speaker usually mounts on the floor, against a wall; placement isn't overly critical because bass frequencies are relatively non-directional.

Although satellite-based systems can make your computer audio sound great or allow a less intrusive hi-fi setup with tight living space, I wouldn't mix a major label project over them. Perhaps you could learn these systems over time as well, but I personally have difficulty with the disembodied bass for critical mixes.

However, using subwoofers with monitors that have decent bass response is another matter. The response of near-field monitors often starts to roll off around 50-100 Hz, which diminishes the strength of sub-bass sounds. Sounds in this region are a big part of a lot of dance music, and it's important to know what's going on down there. In this case, the subwoofer simply gives a more accurate indication of the bass region sound,

STRENGTH IN NUMBERS

Before signing off on a mix, listen through a variety of systems - car stereo speakers, hi-fi bookshelf speakers, big-bucks studio speakers, boom boxes, headphones, etc. This gives an idea of how well the mix will translate over a variety of systems. If the mix works, great - mission accomplished. But if it sounds overly bright on 5 out of 8 systems, pull back the brightness just a bit. The mastering process can compensate for some of this, but mastering works best with mixes that are already good.

Many "pro" studios will have big, expensive speakers, a pair of near-fields for reality testing, and some "junk" speakers sitting around to check what something will sound like over something like a cheap TV. Switching back and forth among the various systems can help "zero in" on the ultimate mix that translates well over any system.

The more you monitor, the more educated your ears will become. Also, the more dependent they will become on the speakers you use (some producers carry their favorite monitor speakers to sessions so they can compare the studio's speakers to speakers they already know well). But even if you can't afford the ultimate monitoring setup, with a bit of practice you can learn your system well enough to produce a good-sounding mix that translates well over a variety of systems - which is what the process is all about.