Question 1

Are amplifiers and power amplifiers the same thing?

Accepted Answer

In professional audio terminology, "amplifier" is a broad term that can refer to any device that increases signal level, including preamplifiers, integrated amplifiers and power amplifiers. A power amplifier specifically refers to the final amplification stage that drives loudspeakers, converting line-level signals into high-current output. In event technology, "power amplifier" and "endstufe" are used interchangeably to describe rack-mount units that power passive PA speakers. Integrated amplifiers combine preamplification and power amplification in one unit, while power amplifiers focus solely on delivering maximum output power with minimal distortion.

Question 2

What exactly does a power amplifier do?

Accepted Answer

A power amplifier takes the low-voltage, low-current line-level signal from a mixing desk or DSP processor (typically 1–2 volts) and amplifies it to the high-voltage, high-current levels required to drive passive loudspeakers (often 20–100 volts or more). The amplifier's output stage uses transistors or MOSFETs to control large amounts of electrical power, converting it into the electromagnetic force that moves the loudspeaker's voice coil and cone. Professional power amplifiers also incorporate protection circuits, cooling systems and often DSP processing to ensure reliable, distortion-free performance. Without a power amplifier, passive loudspeakers cannot produce sound.

Question 3

Which power amplifier is the best?

Accepted Answer

The "best" power amplifier depends entirely on your application, loudspeaker system and budget. For mobile PA applications, lightweight Class-D amplifiers from manufacturers such as LD Systems, DAP Audio or Skytec offer excellent power-to-weight ratios and efficiency. For fixed installations, models with DSP integration and network control from RCF, dB Technologies or JBL provide superior system management. For high-end touring, heavy-duty Class-AB or Class-H amplifiers deliver maximum sound quality and reliability. Always match amplifier power to your loudspeaker's RMS rating (aim for 1.5–2× speaker power), verify impedance compatibility and ensure the amplifier's feature set meets your operational requirements.

Question 4

How much power should my amplifier have?

Accepted Answer

Professional power amplifiers should deliver 1.5 to 2 times the continuous (RMS) power rating of your loudspeakers at the specified impedance. For example, if your passive tops are rated at 500 watts RMS at 8 ohms, choose an amplifier that delivers 750–1000 watts per channel at 8 ohms. This headroom ensures clean, dynamic sound without clipping, particularly during transient peaks. Under-powering speakers can actually cause more damage than over-powering, as clipped signals from a struggling amplifier contain high-frequency distortion that can destroy tweeters. Always verify both the amplifier's power output and the loudspeaker's impedance to ensure safe, optimal matching.

Question 5

What's the difference between stereo, parallel and bridged mode?

Accepted Answer

Stereo mode uses both channels of a 2-channel amplifier independently, typically driving left and right loudspeakers or separate tops and monitors. Parallel mode connects both channels to the same input signal, driving two identical loudspeakers with the same mono signal — useful for powering multiple stage monitors from one amplifier. Bridged mode (also called mono mode) combines both channels to drive a single loudspeaker with significantly higher power, typically doubling the output compared to stereo mode. Bridge mode is ideal for subwoofers or high-power tops, but requires a higher minimum impedance (usually 8 ohms) and may reduce damping factor. Always consult the amplifier's manual before using bridge mode.

Question 6

What are good power amplifier brands?

Accepted Answer

Leading professional power amplifier brands include RCF, dB Technologies, JBL, LD Systems, DAP Audio, PSSO, Omnitronic, Monacor and Ram Audio. RCF and dB Technologies are renowned for high-end touring amplifiers with advanced DSP and network control. LD Systems offers excellent value for mobile applications, combining Class-D efficiency with robust construction. DAP Audio and PSSO provide reliable, cost-effective solutions for installations and rental companies. JBL and Omnitronic are trusted names with decades of experience in professional audio. At LTT, we stock amplifiers from all these manufacturers, ensuring you can find the perfect match for your system and budget.

Question 7

Do I need a power amplifier if I have active speakers?

Accepted Answer

No — active speakers (also called powered speakers) have built-in amplifiers and do not require external power amplifiers. Active speakers receive line-level signals directly from a mixing desk and amplify them internally. Passive speakers, on the other hand, require an external power amplifier to function. The choice between active and passive systems depends on your application: active speakers are simpler to set up and ideal for mobile use, while passive systems with external amplifiers offer greater flexibility, easier maintenance and often superior sound quality in large installations. If you already own passive loudspeakers, you will need a dedicated power amplifier to drive them.

Question 8

What cable do I need to connect a power amplifier to loudspeakers?

Accepted Answer

Use professional speaker cable with a minimum cross-sectional area of 2.5 mm² for cable runs up to 10 metres, and 4 mm² or larger for longer distances. The cable should be terminated with Speakon connectors (NL4 or NL2) for professional PA systems, as these provide secure, locking connections rated for high current. Alternatively, use heavy-duty binding posts or banana plugs for installation speakers. Never use standard instrument cables or microphone cables to connect amplifiers to loudspeakers — they are not designed for high current and will cause power loss, overheating and poor damping factor. Always match cable gauge to amplifier power and cable length to ensure optimal performance.

Amplifiers