Q (a Theile Small parameter ) - Most commonly refers to the relative damping of a speaker. Also can refer to the ratio of reactance to resistance in a series circuit, or the ratio of resistance to reactance in a parallel circuit.

Qa - The system's Q at Fb due to absorption losses (usually referencing vented enclosures).

Qec - The system's Q at resonance (Fc), due to electrical losses (usually referencing sealed enclosures).

Qes (a Theile Small parameter ) - The Q of a speaker driver at its free air resonance considering only its electrical losses.

Qms (a Theile Small parameter ) - The Q of a speaker driver at its free air resonance considering only its mechanical losses

Qtc - The total Q of a speaker and sealed enclosure working together as one, considering all resistive losses. A Qtc of .7 has smoothest response and the lowest resonant frequency response. A Qtc of above 1.1 yields a "boomy" response.

Qts (a Theile Small parameter ) - The total resistance in a series or parallel circuit. This takes into account all Driver resistances, both electrical and mechanical. One of the three main properties used in Theile/Small Parameter for speaker frequency response calculations.

Quick Release Terminal - A terminal connector that permits easy attachment and removal. These usually provide a way of locking onto what it's attached until it's released, generally by the push of a tab or button.

Quantization - The process of converting, or digitizing, the variable amplitude of an analog waveform to one of a finite series of discrete levels. Generally performed by the A/D converter .

Quantization error - Error resulting from quantizing an analog waveform to a digital format. Can be compensated somewhat by employing oversampling in the conversion process.