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12 Volt Amplifiers

When comparing audio output ratings of 12-volt amplifiers you want the measurements to be made using the same method. Experts from the consumer technology industry collaborated within CTA’s Audio Systems Committee to produce a standard for this purpose. It describes how to measure the output power of an amplifier in terms of continuous power, dynamic power and maximum dynamic power. It also describes how to measure other amplifier characteristics.

When you see the 12-volt amplifier product mark above on an amplifier’s packaging it indicates the amp has been tested by an independent third party using the CTA standard. Amps tested this way and authorized to use the product mark are listed below.

Authorized Amps

Below is a list of independently tested amps that are authorized to use the CTA 12 Volt Amplifier Power logo.

Manufacturers wanting to get added to this list should contact 12voltamplifier@cta.tech for information about what’s required.

Definitions

  • Continuous Power

    The continuous power output of a sinusoidal signal for at least 15 seconds, expressed in watts, is the square of the RMS voltage measured at the power amplifier’s output terminals when driven to clipping, divided by the resistance of the reference load.

  • Dynamic Power

    A short-term power rating that can be delivered into a reference load with a burst signal representing the amplifier’s music power headroom above its continuous rated power when driven to clipping.

  • Maximum Dynamic Power

    A short-term power rating that can be delivered with a burst signal representing the amplifier’s maximum usable music power headroom above its continuous rated power when driven to 10% THD+N.

  • Signal-to-Noise Ratio (SNR)

    The signal-to-noise ratio (SNR) is the ratio of the measured output noise level to the output reference level, said ratio to be expressed in decibels.

  • Total Harmonic Distortion Plus Noise (THD+N)

    THD+N is defined as the sum of the total harmonic distortion and noise generated by the power amplifier. The percentage of total harmonic distortion of a sine wave of the fundamental frequency, f, is numerically equal to the ratio of 100 times the square root of the sum of the squares of the RMS voltages of each of the individual harmonics to the RMS voltage of the fundamental, expressed as a percentage.

    THD+N is the ratio of a total output signal to the same signal with the fundamental tone removed, leaving only the noise and harmonic distortion components.