1. Instrument EQ: Beyond “Sounds Good”

🎸 Electric Guitar: The Battle for Spectral Space

The guitar competes directly with vocals in the midrange (1-3 kHz) and with bass in the low-mids (150-300 Hz). A common mistake is overloading these ranges, resulting in a muddy mix.

• Cut at 200-400 Hz: This region often accumulates “boxiness” in guitar amps. A slight reduction lets the bass breathe and vocals cut through.

• Boost 2.5-5 kHz: This is where pick attack and finger articulation live—critical for ensuring the guitar is heard without excessive volume.

• High-pass filter at 80 Hz: Guitars rarely produce useful information below this range, but they can add unnecessary low-end buildup that muddies the subs.

🎸 Bass Guitar: Where Physics Gets Complex

Poor EQ decisions on bass can ruin rhythm perception and pitch definition.

• 40-60 Hz is sacred: These frequencies contain the fundamental notes of the lowest strings (e.g., open E string = 41 Hz). However, many systems struggle to reproduce them cleanly, leading to distortion. The solution? A controlled subharmonic generator (like the DBX 120A) to create audible harmonics in limited systems.

• The “dead zone” at 150-250 Hz: This range builds up energy that creates a “woofy” or “boxy” sound. Cutting 3-6 dB here with a narrow Q (≈2) cleans the mix without sacrificing warmth.

• Attack at 800 Hz-1.2 kHz: This band determines whether the bass is “heard” (clear notes) or just “felt” (muddy vibration).

🥁 Drums: A Nonlinear Acoustic System

Cymbals radiate energy above 10 kHz, while the kick drum dominates 50-80 Hz. The challenge is preventing them from masking each other.

• The “reverse gate trick”: Apply a noise gate to the kick, sidechained from the overheads. When cymbals crash, the gate subtly ducks the kick (1-3 dB), preventing high-end smearing.

• Snare: Transient preservation: A compressor with fast attack (≈5 ms) and medium release (≈100 ms) retains the initial “crack” while controlling sustain.

2. Monitoring Systems: Why Musicians Can’t Hear Themselves

The Wedge vs. In-Ear Dilemma

• Floor monitors (wedges): Provide natural sound but introduce feedback and stage noise. Common feedback frequencies are 250-500 Hz (cabinet resonance) and 2-4 kHz (high-frequency driver beaming).

• In-ear monitors (IEMs): Eliminate feedback but can cause isolation fatigue. Musicians often crank volumes, risking hearing damage. The fix? Incorporate ambient mics with adjustable blend.

Front Fills: The Secret for Front-Row Clarity

Line arrays have limited vertical coverage. Front rows primarily receive sub-bass (omnidirectional at low frequencies), leading to an unbalanced mix. Front fills (e.g., Tecnare IBZA10) correct this:

• Positioned at head height (not on the floor).

• EQ’d with a steep cut below 100 Hz to avoid phase cancellation with subs.

3. Line Arrays: Myths and Realities

Why Line Arrays Deliver Uniform Sound

• Coherent summation: Coupled modules (e.g., Tecnare CLA21PLUS) act as a linear source, minimizing phase cancellation.

• Directional control: At mid/high frequencies (>500 Hz), the curved “J-array” reduces sidewall reflections, improving intelligibility.

Common Setup Mistakes

• Too many top boxes: Overpowers the rear while starving the front rows. The rule of thumb:

  • 1 module per 2 meters of height for short-throw applications (<20 m).

  • Extra modules at the bottom to compensate for natural high-frequency attenuation.

4. Subwoofers: The Physics of Deep Bass

Center Cluster vs. L/R? It Depends on Wavelength

• Sub-bass frequencies (30-100 Hz) have wavelengths of 11 to 3.4 meters. This means:

  • In small venues (<15 m wide), a center cluster prevents phase cancellation between L/R stacks.

  • For wide spaces (festivals), L/R placement ensures even coverage but requires precise time alignment (delay).

Cardioid Sub Arrays: Not Just for DJs

A cardioid setup (3 subs: 2 forward-facing, 1 reversed with inverted phase) reduces stage bass by 6-10 dB. Critical for:

• Preventing drum mics from picking up unwanted low-end.

• Improving monitor clarity.

Conclusion: Sound as a System

Live sound is about managing acoustic energy in space and time. Tools like Tecnare CLA21PLUS (line arrays) or SW218V (subs) are only as effective as the engineer’s understanding of:

• How instrument frequencies interact.

• How room acoustics alter perception (view article: Sound Propagation in Enclosed and Open Spaces )

• How human hearing prioritizes certain spectral ranges (view article: Isoacustic Curves: Human Perception of Sound )

Mastering these principles transforms a competent mix into an unforgettable experience.