Day 3: Acoustic Measurements

Equipment: - UMIK-1 calibrated measurement microphone ($75) - Laptop with REW (Room EQ Wizard) software - Test tone generator (REW built-in) - Microphone stand positioned at driver's head position

Measurement 1: Full system, no EQ, no time alignment

Result: - Bass peak +8 dB at 60 Hz (cabin gain) - Dip -6 dB at 90 Hz (cancellation between sub and midbass) - Midrange relatively flat 200 Hz-2 kHz - Peak +5 dB at 3.2 kHz (crossover overlap) - Tweeter rolloff -4 dB at 16 kHz (normal)

Measurement 2: Impulse response

Tweeter arrives first (closest to listener), midbass 1.2 ms later, subwoofer 3.8 ms later.

Measurement 3: Individual drivers

Measured each driver in isolation: - Tweeter alone: smooth from 3 kHz up - Midbass alone: shows resonance at 250 Hz (door panel) - Subwoofer alone: smooth from 35 Hz to 100 Hz with cabin gain lift

Analysis:
Primary issues identified: 1. Bass bloat at 60 Hz (cabin mode) 2. Crossover region 3 kHz needs level adjustment (tweeter 3 dB hot) 3. Time alignment required (3.8 ms spread is audible) 4. Door panel resonance at 250 Hz