Q-factor (in EQ and speakers)

Q-factor (short for “quality factor”) is a dimensionless number describing the sharpness of a resonance or filter band.

In parametric EQ

Q determines how wide or narrow the EQ band is:

• High Q (5-10) – narrow surgical band, useful for cutting a specific room mode
• Medium Q (2-4) – moderate width, good for tone shaping
• Low Q (0.5-1) – wide gentle bell curve, sounds musical

In speaker drivers

Driver Q (Qts, Qms, Qes – Thiele/Small parameters) describes how a woofer damps its own motion. Low Q = tight and damped; high Q = resonant “boomy”.

Rooms and Q

Room modes are high-Q resonances (narrow peaks) that need matching high-Q EQ cuts to correct. Broad tonal balance is corrected with low-Q shelving.