Speaker setting 2nd part

first part

2nd part

Speaker setting

Finally, we can set our loudspeakers!

Optimal Monitor Placement for Accurate Stereo Imaging

To achieve precise stereo imaging, start by positioning your studio monitors symmetrically (Sz/2) in relation to the center of the shorter wall (Sz) in your room. This means that the distance from each speaker to the nearest side wall (M) should be exactly the same for both the left and right monitor.

Next, measure the distance between the tweeters of your two monitors (A). This measurement should also match the distance from each speaker to your ears, forming an equilateral triangle. In this setup, all three sides—left speaker to right speaker, each speaker to your listening position—are equal. This geometric alignment is essential for producing a balanced and realistic stereo field.

Be sure to angle the monitors inward, directly facing your listening position. When properly aligned, each speaker’s centerline will form a 30-degree angle with the rear wall. You can confirm this angle by using the edges of your mixing desk or table as visual references, as these surfaces should remain parallel to the rear wall.

This triangular monitor configuration minimizes phase cancellation, enhances frequency accuracy, and ensures a consistent listening experience across the mid and high frequency spectrum—a critical factor for both professional mixing and critical listening.

Where should we turn the loudspeaker?

Expert Tips for Studio Monitor Placement

Tony Maserati, a multi–Grammy Award-winning sound engineer, shares a valuable insight about speaker positioning: when seated at the mixing position and turning your head toward either monitor, you should see only the front baffle, not the side of the speaker. He angles his monitors in such a way that the imaginary lines extending from the tweeters cross a few centimeters behind his head, rather than directly at his ears.

This approach contrasts with that of Rod Gervais, who in his book Home Recording Studio: Build It Like the Pros defines the ideal crossing point as approximately 16 inches (about 40 cm) behind the listener. These varying preferences highlight that speaker placement is both science and personal choice.

Tony also offers a practical rule of thumb: the distance between the monitors should equal your arm span. When your arms are stretched out to the sides, your palms should align with the center of each tweeter—a natural way to verify spacing. (Tony often used Tannoy monitors when applying these methods.)

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Avoid Equal and Multiplicative Wall Distances

To reduce phase issues and low-frequency buildup, do not place your monitors at equal distances from surrounding walls. Also avoid placing them at distances that are simple multiples or 1.5x multiples of each other.
For example, if one monitor is 1 meter from a wall, avoid placing it 0.5, 1.5, 2, or 3 meters from other boundaries such as side walls, floors, or ceilings. Such symmetrical spacing can cause harmful standing waves and comb filtering.

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Helpful Tools for Placement

There are tools available to simplify the process. For instance, the online calculator at
👉 http://noaudiophile.com/speakercalc/
lets you input your room dimensions and suggests optimal monitor placement to avoid modal interference and achieve a balanced sound field.

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Speaker Height and Ear-Level Alignment

According to ITU standards, the ideal tweeter height is between 120–140 cm from the floor. Hanson Hsu, founder of ZR Acoustics, observed that in many world-renowned studios, the tweeter center is exactly 1219 mm (48 inches) above floor level.

This aligns with how human hearing perceives direction: our ears are much more sensitive to high-frequency localization than to low-frequency cues. That’s why the tweeters should face directly toward your ears, and both monitors must be placed at equal height and distance from the listening position to preserve the stereo image.

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Tilting the Monitors: When and How

If your monitors are positioned above or below ear level, you may need to tilt them so the tweeters point directly at your ears. A tilt of up to 15 degrees is acceptable, but keep in mind that moving your head forward or backward may still affect how you perceive the high frequencies due to their directional nature.

There’s also an interesting theory: tilting the monitors can place the woofer and tweeter equidistant from your ears (e.g., 105 cm). However, this isn’t commonly implemented with near-field monitors, though main monitors are often installed with a built-in tilt to accommodate this alignment.

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Wall Distance and Bass Control

The distance between your monitors and the room’s walls plays a crucial role in how bass is perceived. Why? Because low frequencies are much more omnidirectional than high frequencies. As frequency decreases—especially below 500 Hz, and fully by 125 Hz—the sound dispersion becomes spherical. This means bass energy radiates in all directions, bouncing off walls, ceilings, and floors, often resulting in boomy or muddy bass.

To control this, carefully experiment with monitor placement and wall distance—or consider using bass traps and acoustic treatment to manage reflections and standing waves.

Thus, the bass sound waves diffuse not only in one

direction –

forward – but they go through the back of the loudspeaker straight to the wall opposite us (towards the back of the loudspeaker) and they bounce from there. When these waves meet the waves coming forth from the loudspeaker an acoustic interference is formed.

If the loudspeaker is at a distance equal to a quarter of the wavelength from the wall behind it the two waves will cancel each other out due to the interference. The cancellation is always at the loudspeaker placed at a distance equal to 1/4 of the wavelength, no matter in which phase the sound wave is.

Why?

Understanding the Boundary Effect (SBIR) and How to Reduce It

One of the most critical acoustic phenomena affecting monitor performance is the Boundary Interference Response (SBIR). This occurs when the reflected sound wave from a nearby boundary (such as a wall or desk) returns to the listener out of phase with the direct sound from the speaker.

Here’s why: if the return path of the reflected sound is 1/4 of the wavelength from the sound source, the total travel path becomes 2 × 1/4 = 1/2 wavelength. A half-wavelength shift results in a 180-degree phase difference between the direct and reflected wave. When these two waves meet, they cancel each other out, because they have equal amplitude but opposite polarity.

This destructive interference is what we call the boundary effect or SBIR. It creates deep dips in the frequency response—particularly in the bass region—and is often more damaging than standing waves in terms of how it affects clarity and punch.

Unfortunately, if your monitors are not flush-mounted (soffit-mounted) into the wall, SBIR cannot be completely eliminated. However, you can significantly reduce its impact through correct speaker placement and targeted acoustic treatment.

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How to Reduce SBIR Effectively

1. Acoustic Panels
   Install broadband absorption panels at the first reflection points behind, beneath, and to the sides of your monitors. These panels help dampen the reflected energy, reducing phase cancellations and improving low-frequency clarity.
2. SBIR Visualization Tools
   You can use an SBIR Calculator, such as an Excel spreadsheet or online tool, to predict cancellation frequencies and find optimal speaker placement. These tools are based on your room’s dimensions and allow you to visualize how moving your monitors impacts boundary-induced nulls.
3. Know the Frequency Width
   The first cancellation peak caused by SBIR is typically about 2/3 of an octave wide, which can result in audible gaps in your frequency response if not addressed.

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Two Monitor Placement Strategies to Minimize Cancellation

There are two main placement strategies to mitigate boundary effect:

Free-Standing with Optimal Spacing and Absorption:
In home or project studios, place monitors at a non-multiplicative distance from all boundaries, and use bass traps and absorbers strategically behind and around them to minimize reflection strength. Avoid placing speakers too close (within 0.5–1.5 meters) to walls without acoustic treatment.

Flush-Mounting the Speakers (Soffit Mounting):

Embedding the speakers directly into a specially designed wall eliminates rear reflections altogether. This is the most effective method but often limited to high-end professional studios.

1. Place Monitors as Close to the Front Wall as Possible

To reduce the SBIR (Speaker Boundary Interference Response) effect, one of the most effective strategies is to position your monitors as close to the wall behind them (the front wall) as possible.

By minimizing the gap between the rear of the speaker and the wall, you shift the cancellation effect to higher frequencies. This is beneficial because high frequencies are more directional and can be easily absorbed using standard acoustic panels or broadband absorbers. As a general rule, aim for a speaker-to-wall distance of 0 to 20 cm. This range often provides a significant reduction in low-frequency cancellation.

⚠️ Important: Always refer to the manufacturer’s placement guidelines. Some smaller monitor models are designed with a built-in acoustic compensation that expects a specific distance from the wall. Placing such monitors too close or too far from the wall can alter the intended frequency response and result in inaccurate sound reproduction.

Even a small amount of targeted acoustic dampening behind the speakers—such as a 10–15 cm thick absorber panel—can make a noticeable difference in tightening bass response and reducing phase-related artifacts.

At very small distances, an acoustic panel of 10 cm behind the loudspeakers can properly dampen the cancellation effect. Broadband bass traps are even better. Of course, it depends on the room as well. The bigger the distance from the wall the less effective the acoustic dampening.

Attention!

If you use very small monitor speakers do not place them too close to the wall! These small monitors are emitting in every direction also in the low-mid frequency range and by placing them close to the wall the cancellation effect is stronger in the low-mid frequency range which produces audible tone coloring. The monitors having their bass reflex hole on the rear side of the box may not be placed closer to the wall than is permitted in the instructions.

A quick tip for the positioning of the loudspeaker:

You don’t have to power the loudspeakers placed close to the wall too much achieving thereby higher volume and lower distortion. But, unfortunately, due to the near field effect, there will be a bass peak (the same when we put our microphone too close to the sound source) but we can easily handle this with an EQ or acoustic panel Even better if we have a calibration software do the EQ setting, e.g. IK Multimedia ARC2, or ROOM EQ WIZARD (REW).

2. Place the loudspeakers at such a distance from the wall that the interference decreases

The more we increase the distance between the wall and the loudspeaker the less the extinguished frequency value will be. If we choose this theoretical distance so that the extinguished frequency is lower than what our loudspeaker can emit, we will not hear the boundary effect. This is a good choice only if we have a room big enough.

We can calculate the canceled-out mid-frequency with the following formula:

Fc=c/4 x D
Fc –> the extinguished mid-frequency

c –> speed of sound (343 m/s)

D –> the distance between the membrane of the loudspeaker and the wall behind it in meters (not the distance between the speaker box and the wall!!! See the picture)

Generally speaking, in the case of a two-way monitor (this is what people call speaker boxes containing 2 loudspeakers) you have to be most careful in the range between 40-80 Hz, and do your best in case of frequencies between 80-200 Hz.

Therefore, the the  in case of a typical studio monitor the recommended wall-loudspeaker distances

Good: Built into the wall or as close to the wall as possible

• Acceptable: 0.1-1 m
• not recommended 1-2,2 m
• Good: above 2.2 m

Of course, we can calculate the optimal wall-loudspeaker distance if we know the frequency of our loudspeaker where the bass starts to die away with 3dB. This is what we call the low cut-off frequency of the loudspeaker.

Dmin=(1,4×343) / 4 x F-3dB
Dmin –> minimum distance between the loudspeaker and the wall behind it in meters

(1,4×343) — > constant=480,2

F-3dB –> the frequency where the low cut-off point of the loudspeaker is, i.e. where the diagram of the sound pressure falls 3dB.

Example:
The low cut-off point of a loudspeaker is 55 Hz. How far it should be placed from the wall?
1st step: 4 x 55=220
2nd step: 480.2 divided by 220 = 2.181818. It should be placed 2.18 m from that order that the bounty effect gets to such a low frequency where the extinction can’t be heard anymore.

In case of large loudspcan can emit very low, frequencies this method leads to very big distances, therefore, not be used in home studios. The other problem is that in case of long distances the side walls and also the floor-ceiling distances will be included in the formula. In this case, the best choice is a monitor built into the wall as we can see in big studios.

Bass cut and the  monitoring distance from the rear wall

In, small rooms the biggest problem is the bass reflected from the rear low-frequency frequency sound pepeaksause peak at frequencies of 1/2, 1, 3/2, etc. which are usually below 6dB and result in rather a high amount of echo. The bigger problem is that the wavelengths and 1/4, 3/4, and 5/4 cause cut, we don’t hear these frequencies.

In small rooms, it usually affects the range below 300Hz which can be quieter even by 30dB. In an ideal case our monitoring position is 3 meters from the rear wall, which shifts the quarter wavelength extinction effect into the frequencies below 30Hz. If you don’t have a such big room for a studio you should certainly place acoustic absorbing panels on that for low-frequency frequency sound waves. This is recommended also in a room that is big enough.

Cancellation effects are caused by waves reflected fthemheom the boundary walls.

The boundary effect is caused not only in the case of sounds reflected from the front wall. The floor, the ceiling, the,e side walls and also the rear wall all have this effect. Therefore, it is advisable to give acoustitoreatment for the whole room. Thus, we need a more general formula to calculate the extinction frequency.

Half wavelength extinction frequency:

Fc=c/4 x D
Fc=c/2 x (D reflex – D direct)
Fc –> the extinguished mid-frequency

c –> speed of sound (343 m/s)

D reflex –> the distance that the sound covers between the loudspeaker and our ears reflected from the walls

D direct –> the distance that the sound covers from the loudspeaker to our ears moving in a straight line.

You can use the same formula to calculate the mid frequencies that are reflected from your studio table or mixing board. and can see on the picture that the sounds are reflected also from the surfaces in front of the monitor, and on certain, frequencies they cause strengthening and extinctions on other frequencies the same way as those reflected from the wall. (E.g. This is why it is not advisable to put the near field monitors on the bridge of the mixing board.) The volume of these reflected sound waves is as much as of those reflected from the front wall thus, they can make much less trouble. You can test this phenomenon if you put a pillow or a folded blanket on the table or mixing board in front of the loudspeakers.

As can sin in the picture this problem is increased if our monitor is close to the reflecting surface, e.g. you put it directly on the table. If you can place the monitors only for a tab for any reason always raise them above the level of the table! By using table stands you can not only raise the tweeter of your monitors at the level of your ears but you can also hear a much “clearer” sound as a result of isolating it from the table.

Monitor Isolation and Avoiding Comb Filtering

Raise Monitors with Stability and Isolation

Always place your monitors on a hard, stable surface or stand. To minimize unwanted vibrations transferring to the stand or desk, insert a vibration isolator between the speaker and the support. Effective materials include:

• Open-cell acoustic foam
• Auralex MoPADs
• Blue-Tac or similar adhesive gel

These solutions help decouple the monitor from the surface and reduce low-frequency smearing, resulting in tighter bass and better stereo imaging.

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Comb Filtering: What It Is and How to Prevent It

Comb filtering occurs when reflected sound waves from nearby surfaces combine with the direct sound from the monitors. The result is a series of phase cancellations and reinforcements across the frequency spectrum, creating a “tubular” or hollow sound—much like a phaser or flanger effect.

How to Avoid Comb Filtering:

• Keep reflective surfaces away from your monitors:
  • Avoid placing them next to walls, rack gear, other speakers, or furniture.
• Always position your computer monitor screen behind the speaker’s front plane and as far back as possible.
• If necessary, tilt the screen downward to direct reflections away from your ears.
• Maintain an open, unobstructed path between each monitor and your ears.

🎧 Pro Tip: You can test for comb filtering by playing familiar music and slowly moving your head or a reflective object around the speaker—any strange, swirling or hollow tonal shifts signal phase interference.