IEC 60268-3:2018

Overview

IEC 60268-3:2018 - Sound system equipment - Part 3: Amplifiers - is the fifth edition (2018) of the International Electrotechnical Commission standard that defines the characteristics and measurement methods for analogue amplifiers and the analogue sections of analogue/digital amplifiers used in professional and household sound systems. This edition replaces the 2013 edition and introduces technical revisions including specification of the rated condition for digital inputs, updated tolerance for rated power supplies, addition of maximum effective output power to output characteristics, and expanded terms/definitions and rated values. IEC 60268-3 is intended to be used together with IEC 60268-1:1985 and IEC 60268-2:1987.

Key technical topics and requirements

The standard prescribes what amplifier characteristics should be included in specifications and how to measure them. Major topics covered include:

• Power supply characteristics: rated conditions, tolerances for voltage, frequency, harmonics and ripple.
• Input characteristics: input impedance, rated source e.m.f., and rated condition for digital inputs.
• Output characteristics: rated load impedance, output source impedance, distortion-limited output voltage/power, and newly appended maximum effective output power.
• Gain and response: voltage/e.m.f. gain, gain-frequency and phase-frequency response, and effective frequency ranges.
• Distortion and non-linearity: total harmonic distortion (THD), harmonic order analysis, modulation and difference-frequency distortion, and dynamic intermodulation distortion (DIM).
• Noise and hum: standard measurement and reporting methods.
• Protection and limiting: overload characteristics, protection circuits (including d.c. offset protection), sustaining-time and overload restoring time.
• Balanced interfaces and multi-channel: balanced input/output measurements, cross-talk/separation, and channel gain/phase differences.
• Physical attributes: dimensions, mass and environmental/operating conditions.

Practical applications and who uses this standard

IEC 60268-3 is essential for:

• Manufacturer product specifications - to produce consistent, comparable amplifier datasheets for professional and consumer markets.
• Test laboratories and QA teams - for standardized measurement procedures and compliance verification.
• System integrators and audio engineers - to select amplifiers with predictable performance for live sound, studio, broadcast, cinema and residential audio installations.
• Procurement and certification bodies - to assess conformance and ensure interoperability across equipment from different vendors.

Using this standard helps improve interoperability, reduce ambiguity in specs (e.g., rated power and distortion limits), and supports reliable system design and performance benchmarking.

Related standards

• IEC 60268-1:1985 - General.
• IEC 60268-2:1987 - (to be used in conjunction with Part 3).
• Other parts of the IEC 60268 sound system equipment series are relevant when specifying complete audio systems.

Keywords: IEC 60268-3, amplifier standard, audio amplifier measurement, sound system equipment, total harmonic distortion, dynamic intermodulation, power supply tolerance, balanced inputs, multi‑channel amplifiers.