Audio Effects, Signal Processors and Mixer Inputs Explained

Audio Effects, Signal Processors and Mixer Inputs

1. Types of general-purpose processors and parameters

Reverberation / Reverb effects: key time and spatial parameters include reverberation time (decay time), pre-delay (initial delay), reverb delay, room dimensions, diffusion, density and liveliness.

Echo effects: main parameters are delay time, feedback (number of repeats), signal level, and intensity.

Modulation effects: parameters include modulation rate (frequency), depth (amount), and whether it is frequency or amplitude modulation.

Level (dynamics) effects: important controls are threshold, attack time and release (recovery) time.

2. Reverb processor adjustable parameters

Parameters used to shape a reverb processor include:

• Reverberation time (decay)
• Initial delay / Pre-delay
• Reverb delay (early reflections timing)
• Room dimensions (virtual size)
• Density (how crowded the reflections are)
• Liveliness (perceived sustain and brightness)
• Diffusion (how scattered / smooth the reflections are)

3. Noise gates: purpose and operation

A noise gate is used to remove very low-level signals (noise) that fall below a user-selected threshold. When the signal level is below that threshold, the gate attenuates or mutes the signal; when the signal is above the threshold, the audio passes through without alteration. Typical gate controls include threshold, attack, hold and release.

4. Four well-known modulation effects

• Flanger
• Tremolo
• Phaser
• Chorus

5. Compressor vs expander: detailed differences

Compressor: reduces dynamic range by attenuating signals that exceed a set threshold. Above the threshold the signal is reduced according to the ratio; below the threshold the signal is typically unaffected. Make-up gain is often applied after compression to restore perceived loudness.

Expander: increases dynamic range by attenuating signals that fall below a set threshold, making quiet passages quieter (this helps reduce noise). There are different types (downward expanders, upward expanders), but the common function is to expand dynamics where needed.

6. Mixing console inputs and characteristics

MIC (microphone input): typically XLR or 1/4" jack, roughly ~1 mV sensitivity (mic level), with high-gain preamplifiers and independent gain/trim control.

LINE (line input): approximately ~50 mV sensitivity (line level), using 1/4" jack or RCA connectors; used for direct instruments, processors and many DJ mixer connections.

PHONO (turntable input): lower-level compared to line and requires an RIAA equalization preamp. Many mixers include a switch to select LINE or PHONO operation for the same physical input.

TAPE (record/playback): RCA connectors, often switched by a flip or button, with sensitivity similar to LINE and used for tape or consumer stereo playback/recording.

7. Why the Talkover function is used in a mixer

The Talkover (or ducking) feature is used in radio stations, clubs and live events to automatically reduce the level of background music or program audio when a microphone is active. This ensures the announcer or presenter is heard clearly over the mix. Talkover typically lowers the background audio by a preset amount while the mic signal is present.

10. Firmware and THX: definitions and roles

Firmware: a fixed program stored in non-volatile memory (ROM, Flash) that provides low-level control and instructions for a specific hardware device. Firmware implements device-specific functions and is often updatable.

THX: a certification and performance standard for audio (and cinema) playback quality. THX denotes that a system or environment meets certain playback fidelity and reproduction criteria for film and high-quality audio.