How to Adjust Monitor Speaker Rear Panel Controls

How to Adjust Monitor Speaker Rear Panel Controls

 When your speaker needs a tweaker, here’s how to do it

by Craig Anderton

Life used to be simple: people pumped your gas, bills included envelopes with return postage, telephones were stationary objects…and speakers had two terminals on the back. Today, many powered monitors have a bewildering forest of controls, options, and switches. So how do you get the most out of them? Well, at least that part is simple: keep reading.

BUT FIRST...

Before you even think about adjusting rear panel controls to compensate for acoustic problems, it's crucial to optimize your setup as much as possible. Just as noise reduction is most effective with audio that doesn't have too much noise in the first place, rear panel adjustment controls are at their best when they don't have to be adjusted too much. 

Because overall system setup is crucial to avoid unnecessary room acoustic interaction, and a room’s natural acoustics may alter the sound level at various frequencies due to abnormal dampening or reflections, follow the checklist below to help set up the right environment for your speakers.

• Set up the system (studio monitors and worktable) within the front third of the room. Doing so will reduce reflection buildup of peak frequencies.
• Center the left and right sides of the system setup an equal distance from the left and right walls. This will produce even mid and low frequency response, and preserve stereo imaging.
• Avoid a listening position (your ears) closer than 3 feet (1 meter) from any wall. Also avoid large objects (such as lamps or decorations) near the studio monitor and listening position.
• Diffusers and absorption material in the corners and back of a room will help remove room interaction by preventing reflections.
• Carpeting will help prevent reflections from hard floor surfaces.
• Studio monitor isolators (foam or rubber pads) will help remove low vibration-inducing frequency coupling between the stands and console or work surface.
• A low noise floor (no outside interference from refrigerators or fans) is important to prevent the masking of low frequency detail. Also remove rattles due to studio monitor playback.

Within the system setup, the studio monitors and listening placement should be positioned in a near field configuration so that the left and right studio monitors are approximately 3 to 5 feet (1 to 1.5 meters) apart, and directed at a 60 degree angle towards the listening location. Measure the distance between the left and right studio monitors to make the listening position is equidistant from both sides; this will form an equilateral triangle.

Most two-way studio monitors incorporate a tweeter (producing high frequencies) and a woofer (producing mid and low frequencies) in one enclosure. In between the tweeter and woofer is the acoustic axis point where the full frequency range comes together. The ideal location for the acoustic axis point is located at ear level in the listening position. It is acceptable to angle the studio monitors so the acoustic axis points in the correct direction. Note that it’s also important to level-match both left and right studio monitors. 

EQUALIZATION OPTIONS

Room acoustics can be the biggest issue in today’s studios because many are in revamped houses or garages that were never designed with acoustic purity in mind. Most manufacturers recognize that their speakers may not live in perfect acoustical environments, and offer equalization options to compensate for acoustics issues. Often these EQs are simple, like high or low frequency boost or cut. Others are more sophisticated.

We’ll describe KRK’s V-Series options because to determine what would be the most useful EQ settings, KRK’s designers modeled and analyzed hundreds of monitor placement and room acoustic situations. If your speaker doesn’t have the same kind of flexibility, you can always try to translate the following settings to an EQ inserted in your DAW’s master bus.

Low Shelf Cut controls compensate for wall coupling. When a speaker is close to a wall, sound emanating from the speaker’s rear bounces off the wall, and reinforces the sound emanating from the speaker’s front. Because low frequency waveforms are more likely to reinforce, the shelf for the V-Series 4 (4” model) starts at about 75 Hz (the 6” and 8” models start at about 60 Hz), with options to cut by -3 dB or -1.5 dB.

Low Shelf Boost is more about adjusting to taste and having more “thump.” Most studios will have sufficient bass with a flat setting. However, the boost is useful when artists want to hear more bass than would be desirable for a mix or master. A low frequency boost lets you mix with the correct amount of bass while giving artists what they want to hear. The V-Series boost complements the cut: +1.5 or +3 dB at around 75 Hz for the 4”, and 60 Hz for the 6” and 8”.

Low Mid Parametric compensates for the lower midrange buildup that can occur if speakers are directing their sound over a large console or other surface. This can produce a somewhat “muddy” sound. The V-Series parametric dips -2 dB at 200 Hz, but another switch position dips ‑2 dB at 200 Hz and adds a low shelf of -2 dB at 75 Hz for the 4” model, and 60 Hz for the 6” and 8” models, in case the speaker rear is also close to the wall.

High frequency controls are about correcting issues too (some mixing environments are “brighter” or “deader” than others), but can also be about adjusting to taste, or compensating for hearing issues.

High Shelf is pretty standard, and if a speaker has only one high frequency control, it will have a similar response—you can boost or cut 2 dB at 10 kHz.

High Mid Parametric Boost is +1 dB at 3.5 kHz. The ear is most sensitive in the 3 to 4 kHz range, and sadly, engineers who’ve mixed a lot at loud volumes often suffer hearing loss in that range. Boosting somewhat will cause engineers to mix these frequencies properly rather than boosting them too much to compensate for the deficiencies in their hearing, which could lead to a harsh sound.

High Mid Parametric Cut is -1 dB at 3.5 kHz. This is useful for a “Jedi mind trick” with artists who aren’t confident about their voices. Reducing the perceived level at 3.5 kHz will make a voice sound less prominent in the mix, but the actual mix will have the voice at the right level.

As with the Low Frequency controls, there are two options that combine parametric and shelving: -1 dB at 10 kHz and -1 dB at 3.5 kHz for rooms that have excessively bright acoustics, as well as +1 dB at 10 kHz and +1 dB at 3.5 kHz for rooms with excessively dull acoustics.

OTHER REAR PANEL GOODIES

There's more to life than equalization, so here's the scoop on the rest of the rear panel.

Inputs. The typical input options are some combination of XLR, 1/4” TRS (tip-ring-sleeve), and RCA phono jacks. XLR and TRS connectors are balanced (and sometimes combined into a single “combi” jack), while RCA phono connectors are unbalanced. Balanced connections are preferable, because they provide more level and lower noise. TRS connectors are balanced if you use a stereo cable (not because they’re stereo per se, but because a balanced line needs three conductors) and unbalanced if you use a standard mono cable. It’s definitely worth using a stereo cable with TRS connectors or an XLR cable.

Input sensitivity. The usual choices are -10 dB (for consumer and prosumer gear) and +4 dB (for pro-level, and often high-end, gear). For example, KRK ships its speakers with a default setting of -10 dB, but note that input sensitivity is not volume. The amplifiers run at full gain, and then you adjust how “hard” you hit it with the input sensitivity control. As a result, you will get better results (more headroom, less noise) when running a system at +4 dB, assuming the device feeding the speaker can generate enough level.

Ground lift. Because monitor speakers have amplifiers and connect to systems, ground loops that result in hum and noise are possible. In ancient times, people cut the ground pin off of 3-conductor AC cables, which was neither safe nor recommended. Enabling the speaker’s ground lift switch has the same effect without compromising safety.

Standby or "sleep" switch. Speakers with a standby option engaged will go into a low-power mode after a certain amount of time. Receiving audio turns it back on again. However, if you mix or master at low levels, the speakers may seem to cut out at inappropriate times, or there may not be enough level to “wake” them up again. If this happens consistently, turn off standby mode.

CAUTION!

It takes a while for the ear to acclimate to changes in EQ and levels. It’s always best to start off with flat settings and get to know your speakers and your room. Listen to music with which you are familiar, and preferably, have heard over quality monitors in a studio with good acoustics so you have a frame of reference.

Try different positions in your room and placement before making EQ adjustments and after finding the optimum position, then adjust the EQ to give you your best listening and monitoring experience.

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 Craig Anderton is Editorial Director of Harmony Central. He has played on, mixed, or produced over 20 major label releases (as well as mastered over a hundred tracks for various musicians), and written over a thousand articles for magazines like Guitar Player, Keyboard, Sound on Sound (UK), and Sound + Recording (Germany). He has also lectured on technology and the arts in 38 states, 10 countries, and three languages.