🔧 INSTALLER LEVEL: Competition Categories and Judging

Sound Quality Judging Criteria

Sample SQ judging scorecard showing categories, point values, and judge-note fields — Sound-quality judging is usually broken into categories so the evaluation is structured instead of purely subjective. The scorecard keeps stage placement, tonal balance, noise, dynamics, and installation quality visible as separate criteria.

IASCA (International Auto Sound Challenge Association) SQ categories:

1. Imaging and Soundstage (30 points)

Phantom center: Vocalist appears at center, not biased left or right
Stage width: Sound extends at least to dashboard edges, ideally beyond A-pillars
Stage height: Sound appears at dash height or above (not from floor or doors)
Stage depth: Front-to-back layering — front elements forward, reverb trails back
Image stability: Image stays locked as volume changes

How to optimize:

Time alignment precise to 0.1 ms
Level matching between L and R to 0.5 dB
Tweeter placement at ear height or above
Minimal reflections from windshield (damping or absorption)

2. Tonal Accuracy (25 points)

Does the system reproduce spectral balance accurately?
Does the bass have impact without boom?
Are vocals natural and uncolored?
Is treble extended without harshness?

Judges use reference recordings they know deeply. They listen for whether the system sounds like the recording or like "a car stereo."

How to optimize:

Flat frequency response relative to target curve (not boosted bass)
Low distortion at reference listening level
Smooth crossovers with no dip or peak at transition frequency
Subwoofer integrates seamlessly (listener can't localize it)

3. Detail and Resolution (20 points)

Can you hear reverb trails clearly?
Are subtle background elements audible?
Is there a sense of "air" around instruments?

How to optimize:

Low noise floor (no alternator whine, no hiss)
Clean amplification (quality components, proper gain)
High signal-to-noise ratio throughout chain

4. Dynamics (15 points)

Does the system track transients accurately?
Is there contrast between loud and soft passages?
Does bass impact feel physical and controlled?

How to optimize:

Sufficient headroom (no clipping at peaks)
Adequate power for clean transients
Subwoofer with good transient response (sealed preferred)

5. Overall Musicality (10 points)

Subjective catch-all
Does the system draw you into the music?
Is listening fatiguing or pleasurable?

This is where taste meets technical excellence.

SPL Competition Categories

dB Drag Racing classes (example — rules vary by organization):

By vehicle type: - Street class: Must be street-legal, factory-installed glass - Modified: Significant vehicle alterations allowed - Extreme: Dedicated competition vehicles, any modification

By driver type: - Single driver: One subwoofer - Multiple drivers: 2, 4, or more

By test frequency: - Bass race: Competitor chooses frequency (50–65 Hz typical) - Fixed frequency: Organization sets frequency (e.g., 40 Hz, 50 Hz)

Scoring:

Single measurement at specified mic position (usually A-pillar area, or outside vehicle for termlab events). Highest dB wins. Simple.

MECA (Mobile Electronics Competition Association):

Separate SQ and SPL divisions with their own classes. SPL uses a handheld termlab meter. SQ uses live judging.

Building for SQ Competition

Concept diagram of an SQ competition vehicle showing front stage placement, subwoofer position, hidden wiring routes, DSP and amplifier rack, and judge listening position. — An SQ install is built around believable stage placement, symmetry, low visual noise, and repeatable judging. The hidden work matters as much as the visible fabrication because judges are listening for focus, balance, and system discipline, not just flash.

Component selection:

Tweeters: - Silk dome preferred (smooth, natural) - 25–28mm size - Low Fs (< 800 Hz) for low crossover option - Brands: Scan-Speak, Focal, Seas, ScanSpeak

Midrange: - 3–4 inch preferred - Low coloration, flat response - Smooth off-axis response - Brands: Seas, Morel, Peerless

Midbass: - 6.5–7 inch - Well-controlled - Sealed enclosure preferred - Brands: Focal K2, Morel Supremo, SB Acoustics

Subwoofer: - 10–12 inch typically - Fast, accurate — not loud - Sealed enclosure - Low Qts (0.4–0.5) for accuracy

Amplifiers: - Low noise floor is critical - Class AB preferred for SQ (lower residual noise than Class D) - High damping factor (>200) - Brands: Audison, Mosconi, Brax, Hertz

DSP: - Most comprehensive available - FIR linear-phase capability preferred - Full parametric EQ (10+ bands) - Fine time alignment (0.01 ms resolution)

Installation:

SQ judges score installation as part of overall presentation: - All wiring hidden or loomed - No visible RCA cables - Symmetrical placement of components - Professional fabrication of speaker baffles and pods - Clean treatment of all surfaces

Building for SPL Competition

Concept diagram of an SPL competition car interior showing a multi-driver wall behind the front seats, measurement position at the A-pillar, and the short high-pressure path into the cabin. — An SPL wall is about turning the front cabin into the pressure chamber and controlling the shortest path to the meter. The point is not subtlety. It is maximum output at the scoring position with the vehicle built around that single goal.

Driver selection:

The most critical choice in SPL:

High sensitivity (92–96 dB @ 1W/1m)
Large motor, high Bl
Designed for bandpass loading
Multiple drivers — 4, 8, or more

Enclosure:

Bandpass tuned to within 2 Hz of test frequency. Every Hz off costs output.

Sealed rear chamber: 0.7–1.0 × Vas
Ported front chamber: 1.5–2.0 × Vas
Port: Large area, length tuned exactly
Construction: Minimum 1.5" MDF, braced aggressively

Setup for test day:

Measure box resonance with sine sweep
Fine-tune port length if off-target
Set amplifier gains maximally (within thermal limits)
Test with competition meter before official run
Close all windows, doors, vents
Double hearing protection — always