Target Curve
Canonical Definition
A target curve is a defined reference response used to compare, design, or equalize a measured system under stated conditions such as microphone position, smoothing, seating goal, level, channel, and bandwidth.
Copying a few dB values without the measurement method, seating goal, level, and system limits does not reproduce the original target.
Four Different Traces
| Trace | Meaning |
|---|---|
| Measured response | What the system produced under the stated measurement conditions |
| Base target | The reference response associated with the speaker or channel type and bandwidth |
| House curve | A preference offset added to the base target, often including low-frequency rise or high-frequency fall |
| Filter response | The gain-versus-frequency shape created by the EQ filters themselves |
The filter response should not be mistaken for the final acoustic response, and the measured trace should not be judged without knowing its target and measurement method.
There Is No One Universal Automotive Curve
Many listeners prefer elevated low-frequency energy and a gently falling high-frequency trend at the listening position, but the useful amount and shape depend on:
- vehicle size and cabin gain
- speaker placement and directivity
- measurement position and averaging
- listening level
- single-seat versus multi-seat goal
- program material and personal preference
- system extension, distortion, and available output
A named curve can be a useful starting reference. It should not be presented as the only correct response for every vehicle.
Target Level Matters
If the target is placed too high or too low, automatic EQ may use filters to correct what is actually a channel-level mismatch. Set overall level with gain or trim, then use EQ for response shape.
A practical target level is normally chosen from a stable response region that does not require excessive broad boost or cut. Document how it was selected.
Match Range And Natural Limits
Define the frequency span over which EQ is allowed to chase the target. Avoid forcing filters:
- below the safe low-frequency extension of the driver or enclosure
- above the driver's useful high-frequency or directivity range
- through deep spatial cancellation
- through noisy or low-coherence measurement regions
- through narrow comb-filter details that change with small movement
Broad low-frequency boost can consume amplifier voltage, DSP headroom, excursion, and thermal margin very quickly.
Smoothing And Position
The same raw measurement can look very different under 1/3-octave, 1/12-octave, variable, psychoacoustic, or unsmoothed display. Record the smoothing used for target matching.
Likewise, a single ear-position measurement and a multi-position average answer different questions. A narrow single-seat target may optimize precision at one point; a spatial average sacrifices some local perfection for broader consistency.
Build A Defensible Target
- Define the listening positions and expected playback level.
- Measure each driver and the integrated system after crossover and timing work.
- Choose low- and high-frequency limits from safe capability.
- Set a target level from a stable response region.
- Add a low-frequency rise or high-frequency trend only as a documented preference or system goal.
- Choose smoothing and a match range appropriate to the measurement.
- Limit automatic filters and boost.
- Re-measure and listen at the intended level and positions.
Target-Curve Record
Vehicle / system:
Primary seat or positions:
Measurement method:
Microphone location:
Smoothing:
Target level reference:
LF limit and reason:
HF limit and reason:
Low-frequency rise:
High-frequency trend:
Match range:
Maximum individual boost:
Maximum combined boost:
Listening level:
Date / preset: