Free Speaker Parallel Notch Filter Calculator

Calculate precision parallel RLC component values (R, L, C) to tame harsh driver breakup peaks and cabinet baffle step acoustic resonances.

🔊 Acoustic Peak & Driver Specs

Center Resonant Freq f0 (Hz) Frequency of unwanted peak

Driver Impedance Z0 (Ω) At resonant frequency

Peak Attenuation Depth (dB) Amount to lower peak (e.g. 6 dB)

Filter Quality Factor Q Sharpness (1.0 = wide, 3.0 = sharp)

Common Driver Breakup Presets

📊 Parallel RLC Component Values

Notch Resistor (Rp) 0.0 Ω Non-inductive wirewound

Notch Inductor (Lp) 0.00 mH Air core coil recommended

Notch Capacitor (Cp) 0.00 μF Polypropylene film

Bandwidth (-3 dB) 0 Hz 0 Hz to 0 Hz

Circuit Configuration: R || L || C in series with driver (+)

Resistor Minimum Power Rating: 10 Watt non-inductive

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Frequently Asked Questions

Where do I install a parallel notch filter in the speaker wiring?

The parallel RLC network is wired in series on the positive (+) terminal of the driver, placed AFTER the main low-pass or high-pass crossover filter network.

What is the formula for calculating the notch resistor value?

Rp = Z0 × (10^(Atten_dB / 20) - 1). For an 8 Ohm driver needing a 6 dB attenuation notch: Rp = 8 × (10^(6/20) - 1) = 8 × (1.995 - 1) ≈ 8.0 Ohms.

What does Quality Factor (Q) do in a notch filter?

Q controls the bandwidth (width of frequencies affected). High Q (e.g. 2.5) creates a narrow, laser-focused notch to tame a sharp metal cone breakup spike without affecting surrounding musical frequencies. Low Q (e.g. 0.7) creates a wide, gentle dip.

How does driver voice coil impedance affect notch tuning?

Driver impedance fluctuates with frequency due to voice coil inductance (Le). You must use the actual measured impedance of the driver at the resonant peak frequency (from the driver impedance curve) rather than the nominal 4Ω or 8Ω marketing rating.