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electronic MUSICIAN

Master Class – Choosing Studio Monitors

By STEVE LA CERRA | November 20, 2013


QUICK: WHAT is the only component in your studio through which every recorded and mixed sound will pass? Your monitors. The quality and performance of your studio monitors are crucial to your productions, yet it’s amazing how many people will postpone purchasing good monitors while they go ahead and spend money on plug-ins, microphones, or outboard gear. The cold, hard truth is that if you really want to hear what’s going on in your recordings and mixes, you need to choose the right monitors.

Size Matters The first step in picking the right loudspeakers is identifying the application and environment in which you’ll be using them. Bedroom studios don’t call for huge, “mains”-type monitors, and such speakers may actually be counterproductive in small rooms by (a) taking up too much space, (b) overpowering the room and exciting room resonances, and (c) pissing off your neighbors or spouse. A singer-songwriter who is recording acoustic music can prioritize sonic accuracy over high SPL and butt-thumping bottom. On the other hand, if you’re working with clients who like to listen loud and who produce music with a lot of bass, small monitors won’t cut it. Laws of physics still apply: The only way to move a lot of air is with a large driver.

Most small studios are best outfitted with a nearfield monitor—a speaker intended to be heard at relatively close distance. “Nearfield” isn’t defined by a specific distance, but the general idea is that you will be close enough to the speakers (three to six feet) that you hear a large percentage of direct sound from the speakers and a minimum of sound reflected from the room. This configuration is especially ideal when a listening environment is a spare room as opposed to one that has been designed with proper acoustics in mind, because it minimizes the effects of the room on what you are hearing.

But Sometimes Less is More Just because a speaker is made using three drivers (e.g., woofer, midrange driver, and tweeter) does not necessarily make it better than a two-way design. In fact, an argument can be made for the reverse—that given the same price point for a two- or three-way speaker, more money can be allotted per component in the two-way design. Two-ways tend to have simpler crossovers with fewer components, and may therefore be less subject to phase shift in the crossover region.

Passive Aggressive One of the first decisions to make when shopping for monitors is whether you want active or passive loudspeakers. Active speakers feature onboard amplification, while passive speakers require an external power amp. Each type has pros and cons, and good and bad examples exist for both. Don’t underestimate the importance of the power amp you will need to run passive speakers, because the amp will make or break the sound of the monitors. (If you have any doubts, compare the sound of the same monitor powered with different amps.) A quality amp provides more headroom, lower noise, and a higher level of transparency and accuracy over a lesser amp. (Sorry, but Dad’s hi-fi receiver from 1982 ain’t gonna cut it.) When budgeting for passive monitors, allocate about one-third of your budget for the amp. If you’re really tight on cash, start with an inexpensive amp and upgrade later. You’ll also need quality speaker wire; I won’t get into a discussion about spending $500 on a pair of speaker cables here, but I will say that Radio Shack sells 18-gauge, solid-core wire that has a good reputation among audiophiles and costs six bucks for 25 feet.

An active design guarantees proper matching between amplifier and speaker, and you won’t have to deal with speaker cable. Some active monitors employ more than one amplifier— two in the case of a biamped monitor, three in the case of a triamped monitor. This is not a marketing gimmick; it enables a designer to increase efficiency, power handling, and acoustic output. (See “Biamplification” sidebar on page 62 for details.) Found under the “cons” column, active speakers are heavier than passive speakers, and if you blow an amp, the speaker is useless.

The drivers used in active and passive boxes can be constructed from just about every material you can think of, including paper, plastic, titanium, beryllium, Kevlar®, glass fiber, carbon fiber, and resin. The material of construction is not as important as the execution of the design.

Another thing to watch for: Frequency-response contour controls are found more often on active speakers, though they sometimes appear in passive models. A monitor’s bass response changes when the cabinet is placed near a boundary, so the manufacturer may provide an adjustment to compensate for such placement. Some models offer a high-frequency Tilt control that lets you adjust the HF response up or down a few dB to compensate for bright or dead rooms.

Understanding the Specs When researching monitors, you’ll encounter a lot of specifications, some of which are more meaningful than others. One spec that can be taken with a grain of salt is frequency response—one, it doesn’t tell you anything about the way the speaker sounds; and two, it can be subject to change based upon the speaker’s placement in the listening environment (though frequency response does provide a general idea of low-frequency extension). Maximum SPL (sound pressure level), measured in decibels, gives you an idea of the speaker’s peak volume capability, while long-term SPL indicates how loud the speaker can play over a long period of time. Keep in mind that if you are working an eight-hour day, to protect your hearing, you should be listening at SPLs in the mid-80s, and in most cases, these specs are way louder than that.

 
 More monitors give you more options for evaluating your mix.

The Sensitivity spec describes a passive speaker’s efficiency. Speaker sensitivity is defined as the SPL produced by the speaker when driven with one watt of power, measured one meter away. If a speaker has a sensitivity rating of 85dB, this means that one watt of input produces an SPL of 85dB at one meter away. A 3dB increase in SPL requires doubling power, so our example speaker would produce 88dB with two watts, 91dB with four watts, 94dB with eight watts, 97dB with 16 watts, etc.—providing an idea of the type of power amplifier you’ll need.

Another meaningful spec for passive speakers is impedance, or opposition to the flow of electricity. (Impedance is different from resistance, but that’s a topic for another time.) Most passive speakers are rated for an impedance of 4 or 8 ohms; neither rating is considered better or worse. You may find that some power amps have the ability to deliver more power into a 4-ohm “load” (speaker), which is a good thing. If you are considering a speaker rated at an impedance of 2 ohms, be careful: In general, the lower the impedance, the more difficulty the power amp will have driving the load. Of course, exceptions exist: A Lab Gruppen FP10000Q power amp, for example, will have no difficulty driving a 2-ohm load, but at about $6,500, it’s probably well out of the price range for most project-oriented studios. (See “How Much Power Is Enough?” sidebar.)

The Audition More than any other component in your studio, you’re going to live with your monitors on a daily basis (probably for a very long time), so take your time with the audition. Make sure your ears are fresh. No auditions after a 12-hour mix session! Give your dealer the dimensions of your control room, an idea of the type of music you’re working on, and the volume levels you work at. Listen to recordings that are familiar to you, whether they are commercial releases or projects that you have recorded and mixed. You need full-bandwidth, uncompressed files to make accurate judgments about dynamic range, frequency response, and distortion. Have an audition CD ready and narrow your choices to three or four monitors. Spend at least ten minutes listening to one pair of monitors before switching to another pair. Listening to really expensive speakers is a good idea, even if you can’t afford them, because they’ll provide a benchmark against which to judge less expensive speakers.

What should you listen for? Realism, naturalness, and transparency. Recordings of voice and acoustic instruments provide a useful reference against which to judge (especially when it comes to the human voice). If you play an instrument, bring a recording of it. Do you hear details that you’ve never noticed? This is a good thing, an indication of what I call the “ruthlessness factor”—but make sure that this phenomenon does not stem from an exaggerated emphasis on high frequencies, which will eventually cause listening fatigue. If your first instinct is “wow, what bass!” ask yourself whether you’re responding that way because your old monitors lacked bass, or because the new monitors hype the bottom end. The goal is a clear window into the recording, not a rose-colored one. You want a monitor that accurately translates what is coming through the microphone. If there is a low-level hum or buzz on a guitar, or a squeaky kick drum pedal, you want to hear it before it’s recorded and ruins a take.

 

Listen to the monitors at a variety of volume levels, including at the loudest levels you think you’ll ever need. Make sure the monitors maintain clarity at that level without sounding congested. Music with a wide dynamic range should not sound compressed. When you turn the volume down, your monitors should not sound thin and the stereo image should not shift. Active monitors are easier to use when the volume controls are on the front panel (particularly if you don’t have a monitor controller), and some may feature a convenient Link function that enables one knob to control the level of both speakers. Adjusting the volume knob(s) should result in a smooth change in level without any mutes or drastic changes. Note the input connections on active speakers: Are they balanced or unbalanced? XLR, TRS, or RCA? Do they fit in with your current studio wiring scheme or will you need to make changes? For passive speakers, do the connectors securely hold the speaker wire?

Once you’ve narrowed your choices, compare no more than two pairs of speakers at a time. It’s important to set the volume level of both pairs as close as possible, because your brain can fool you into thinking that the louder pair sounds better. For that reason it wouldn’t be a bad idea to have an SPL meter and a test signal (pink noise) with you.

Ask your dealer if an in-studio audition is a possibility. An alternative might be to borrow a pair of monitors from a friend. (This is easier said than done!) Get details on the vendor’s return policy. Can you return the monitors if you don’t like them? How much time do you have to make a decision? If so, who pays for the shipping? (Make sure you unpack them carefully and save the boxes.) What is the manufacturer’s warranty?

Scoping Out a Sub There are two reasons to consider a subwoofer. The obvious reason is to extend the low-frequency response of your system. The not-so-obvious reason is that—when integrated properly—a subwoofer removes the burden of producing the lowest frequencies from the full-range speakers, thus increasing power handling and reducing distortion. Certain systems, such as the Blue Sky ProDesk MKIII are designed as “2.1 systems”—two speakers and a sub intended for use as an integrated system. Other manufacturers offer subs as an option that can be added later; for example, the CMS SUB from Focal Professional is engineered to integrate perfectly with the company’s CMS 40/50/65 monitors, but you can purchase the CMS monitors first and add the sub when finances permit. Don’t take this option lightly; you’ll get far better results adding a subwoofer designed to complement specific full-range speakers than you will trying to “roll your own” 2.1 system. The goals of adding a subwoofer must be met without causing peaks or dips in the overall system response, and manufacturers take great pains to ensure a seamless transition between the sub and the full-range cabs. One last thing to consider is, it’s sometimes counterproductive to use a subwoofer in a small room because the subwoofer may excite room modes, creating resonances that skew frequency response.

Reaping the Rewards A few months ago, a friend of mine was talking about how much trouble he was having getting his mixes “right”—that is, to sound consistent on a variety of systems. When he told me what he was using for monitors, it became obvious where his problem was. I suggested a particular pair of monitors, which he then purchased. A few weeks later, he told me that his life had changed: His mixes were way improved, yet he was spending less time to get better results. That’s exactly the point— you need to spend as much money as you possibly can afford on a pair of studio monitors, as soon as you can. The expense will be offset by the fact that you will save time and produce better work, because you’ll be listening to accurate sound. Your life will change.

Steve La Cerra is an independent audio engineer based in New York. In addition to being an Electronic Musician contributor, he mixes front-of-house for Blue Öyster Cult and teaches audio at Mercy College, Dobbs Ferry campus.

 
 
 
Speaker Placement
Nearfield monitors should be placed on high-quality stands. Placing them on top of a console or desk can cause unwanted reflections (and thus comb-filtering) and resonances, though sound transmission via contact can be reduced through use of an isolation pad such as the Auralex MoPAD. Speaker stands should be rigid and heavy so that the speakers are not allowed to move. Movement in the speaker compromises sound. Every time a woofer produces a kick, the cabinet has a tendency to move back, like the recoil from a gun. Primacoustics Recoil Stabilizers reduce this effect.

When placing your monitors, follow the manufacturer’s guide, but here are some basic suggestions. Most nearfield cabinets should be roughly five or six feet apart, and the same distance from your ears. Each speaker should be the same distance from its respective side wall, or imaging will suffer. Tweeters should be at ear height. Don’t assume that a vertically oriented speaker can be turned on its side and yield accurate results. In some cases, the tweeter must be removed and rotated 90 degrees; in other cases, the manufacturer will warn against alternate positions. Ditto for “toeing in” the speaker. Be aware of whether or not the speakers are intended to be close to a wall or not. Every time you place a speaker near a boundary, the low-frequency response will bump up. Keep the cabinets out of corners for the same reason.

 
Biamplification
A biamped (or triamped) active loudspeaker uses separate amplifiers for each driver, and allocates the power where it is most needed—in the low-frequency region. It doesn’t take much power to make a high-frequency driver (a.k.a. tweeter) loud, because HF drivers tend to be small and their diaphragms produce relatively small movements. On the other hand, a low-frequency driver must push a fair amount of air, and by nature requires more power. For example, a biamped speaker might have a 70-watt amp on the woofer and a 20-watt amp for the tweeter.

Biamping or triamping provides other benefits. The crossover in a passive speaker takes in high levels of electricity from the power amp, and sends high frequencies to the tweeter and low frequencies to the woofer. Since the woofer inevitably requires more power, the power that would otherwise make its way to the tweeter is dissipated as heat (i.e., it’s wasted). As a result, high-level crossover components are more subject to failure. The crossover in an active monitor is typically at line level (prior to amplification), which increases efficiency and increases the longevity of the crossover components. Multi-amp system techniques also reduce a type of distortion known as Intermodulation Distortion (IMD).

 
How Much Power Is Enough?
That’s like asking how much horsepower you want in a car. As much as you can afford. Choose a power amp that delivers sufficient power to produce your desired volume level without pushing the amp hard. You’ll get far better results using a high-powered amp driving small speakers than vice versa. Running a small amp full throttle into expensive speakers is a recipe for disaster: the amp can clip when you drive it hard, and clipping generates harmonics that can burn out your tweeters.
 

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