🔧 INSTALLER LEVEL: Measurement-Based Alignment

Using Impulse Response Measurements

Calculated delays from tape measurements are a first approximation. Acoustic path differences (reflections, diffraction around seats) mean the actual arrival times may differ from physical distances alone.

REW impulse response procedure:

1. Position microphone at listener's ear location (clamped to headrest)
2. Enable one driver at a time in the DSP
3. Play REW's impulse measurement signal
4. Identify the time of the first arrival peak in the impulse response
5. Record the arrival time for each driver
6. Set DSP delays so all drivers have the same arrival time

Reading the impulse response:

The impulse response shows amplitude vs time. The first significant peak (before any reflections) is the direct arrival. Its position on the time axis, relative to time zero, gives the travel time.

At 343 m/s (20°C):

Distance = time × 343 m/s

If left tweeter peaks at 2.1ms and right tweeter at 4.3ms:

Distance_L = 0.0021 × 343 = 0.72m = 28.3 in
Distance_R = 0.0043 × 343 = 1.47m = 58.1 in
Required delay for left tweeter = 4.3ms − 2.1ms = 2.2ms

This measured 2.2ms may differ from your tape-measured estimate due to acoustic path effects — use the measured value.

Fine-Tuning by Ear

After measurement-based alignment, fine-tune listening:

Test track: Solo voice recording, well-centered. Diana Krall, Johnny Cash, or any recording where the vocalist is clearly intended to be centered.

Method: Play and listen. If image pulls left: right channel has slightly too much delay (or left too little). Add 0.05ms delay to left channel, re-listen. Repeat until vocalist appears exactly centered.

Note: This fine-tuning is for the listening position only. Passengers may experience different imaging — the car is fundamentally asymmetric and perfect imaging at all seats is not achievable with standard stereo time alignment.