
Headrush Dynamics & EQ
Acoustic Pre
Inspired by HeadRush® Original
It is a preamp/EQ dedicated to acoustic instruments, designed to:
- acoustic guitar
- piezo pickup
- amplified string instruments
Main Function: Shape the tone + optimize the signal before mixing
GENERAL FUNCTION
- 3-band equalization
- Phase control to eliminate acoustic problems
Optimized for:
- live (feedback control)
- piezo (harshness correction)
Control Parameters
BassdB
- Typical range: approximately −12 → +12 dB
- Frequencies: ~80–200 Hz
Function:
- controls the low frequencies
Effect:
- negative → less “boom” / cleaner
- positive → more body
Useful for:
- Reduce live rumble
- give depth to subtle sounds
MiddB
- Range: approximately −12 → +12 dB
- Frequencies: ~400 Hz – 1.5 kHz
Function:
- check the averages (most critical area)
Effect:
- negative → less “nasal”
- positive → more presence
Fundamental for:
- make the guitar stand out in the mix
- remove annoying frequencies
TrebledB
- Range: approximately −12 → +12 dB
- Frequencies: ~4kHz – 10kHz
Function:
- controls the high frequencies
Effect:
- negative → hotter / less harsh
- positive → brighter / defined
Useful for:
- add attack and air
- correct piezos that are too sharp
PhaseNorm / Inv
- Norm: normal phase
- Inv: phase inversion (180°)
Function:
- fixes problems with:
- live feedback
- phase cancellations
- interference with monitor/PA
Pro Tips
- Too much Bass → feedback and “mud”
- Too Mid → nasal sound
- Too much Treble → harsh digital
- Phase does not change the direct tone, but interaction with the environment
When to use Phase Inv:
if the sound becomes:
- fuller → leave it like this
- thinner → back to Norm
Rule of thumb:
- choose the option that sounds fuller and more stable
Quick Reference
- Bass (dB): low frequencies
- Mid (dB): medium (presence/nasality)
- Treble (dB): high frequencies
- Phase: phase inversion
Setup Examples
Natural acoustic sound
Bass+2 dB
Mid−2 dB
Treble+2 dB
PhaseNormal
Balanced and open
Eliminate “nasal”
Bass0
Mid−4 / −6 dB
Treble+2 dB
Cleaner sound
Live anti-feedback
Bass−3 / −6 dB
Midslight cut
Phasetry Inv
Greater stability
Piezo harsh correction
Bass+2 dB
Mid−3 dB
Treble−2 / −4 dB
More natural sound

