Qeff + Time Align

Bandwidth Qeff calculator with EMMA guidance, chart, time alignment, and class-aware XO suggestions.

Inputs: Fc, Re (Ω), optional Z@Fc(peak) Qeff = Fc / (F2 − F1) Targets: Re×√2 or Z@Fc/√2 EMMA-oriented guidance (informal)

Inputs

Fc (Hz)

Re (Ω)

Z@Fc (Ω)

On your impedance plot, mark the target ohms, then read F1 and F2 where the curve crosses that level around Fc.

F1 (Hz) — low-side crossing

F2 (Hz) — high-side crossing

Driver class Precision

Target ohms to find F1/F2

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Choose method above.

Qeff

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Interpretation

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EMMA-oriented guidance (informal)

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Note: EMMA does not publish a Qeff spec. This is VX Audio competition-tuning guidance based on listening goals.

Crossover suggestions (derived from Qeff, F1/F2, Fc)

Side	Suggested Fc	Suggested slope	Notes
High-pass (protect below band)	—	—	—
Low-pass (hand off above band)	—	—	—

Visual aid

delay(ms) = distance / speed; speed ≈ 34.3 cm/ms, 13.5 in/ms, 343 mm/ms.

Units

Channel / Driver	Distance	Delay (ms)

Delays are added to nearer channels so all arrivals match the farthest.