Power Amplifier Basics and Theory
Power Amplifier Levels / Wattage – What you Should know and Understand
There is some confusion regarding amplifier power, amplifier loudness, what size amplifier is needed, and amplifier volume controls that we will try and resolve in this section. The diagram below demonstrates the different power levels from Instruments and Microphones to the Amplifier and Speaker. Take a look!
Amplifier level is a term used to designate the strength of an audio signal used to transmit analog sound information between an audio amplifier and speakers. Amplifiers will receive a “line level” signal at its input, which will then be “amplified” through the amplifier’s circuits to the speakers.
Amplifier Level Notes:
- The voltage associated with amplifier levels is usually measured in Wattage (Watts, W).
- Amplifier levels are dependent on the size (wattage) of the amplifier (1 Watt – 4000 Watts or more).
- Amplifier levels are also dependent on the “load” they see. For example: If an amplifier is connected to a 4-ohm speaker – the amplifier is “seeing” a 4-ohm load. As stated earlier: Impedance is measured in ohms, and can be defined as “resistance (opposition to the flow of electrical current representing audio signals).
Warning: If the impedance of the speakers (load) is ever 0 Ohms (zero ohms), this would be considered a “Short.” And there is a good chance the amplifier will “fail or burn up” due to this “short circuit” condition.
A “Best Practice” regarding amplifiers is first to ensure you understand the amplifier’s wattage rating (which is stamped on the back of the amplifier). Second, you will need to know your speaker’s rating (4-ohms? 8-ohms? Wattage?) in order to verify the “Load” that you’re connecting to the amplifier. These two crucial steps will ensure that you are correctly “matching” the amplifier’s “output” wattage to the speaker’s “input” wattage.
What is Bridged Mono Mode?
When you switch an amplifier to “bridged mono mode” (usually via a switch on the amplifier) both amplifier channels are “combined” to drive a single output. As you can see in the example above the power in bridged Mono Mode is extremely high (1800 Watts at 4-ohms for this amplifier). Use caution and read the amplifiers manual prior to using the Bridge Mono Mode. Double check settings, connections, and wattages prior to powering up the amplifier – and always make sure that the speaker you plan to use has a wattage rating high enough to match the amplifiers wattage (or the speaker could be damaged).
