A buyer’s guide to power amplifiers

An electronic device that increases (i.e. amplifies) the power of the audio signal to levels suitable for driving speakers. We can now make use of the optimum sound quality that power amplifiers offer without necessarily increasing the number of boxes or the complexity of your setup. There’s also the option of bi-amping, which requires at least two stereo power amplifiers (unless you have a multi-channel receiver with spare channels) and some more cables. If you’re looking for the best power amplifiers in the market today be sure to visit poweramplifierreviews.com.

In this class of amplifiers, the active element (the electronic component used for amplifying, which is transistor in this case) is in use all the time even if there is no input signal. Although this class of power amplifiers are superseded by better designs, they are still popular among hobbyists.

This makes their design simple and makes class A amplifiers the most commonly used type of power amplifiers. The most commonly used power amplifiers are the ones that are used in audio amplifier circuits and they come under classes A, B, AB or C. So let’s take a look at them in detail. Power amplifiers designed to amplify Pulse Width Modulated(PWM) digital signals come under D, E, F etc.

Power amplifiers designed to amplify analog signals come under A, B, AB or C category. Here, Radio Frequency Power amplifiers are employed to increase the magnitude of power of modulated waves to a level high enough for reaching required transmission distance. The output of an audio power amplifier ranges from a few milliwatts (like in headphone amplifiers) to thousands of watts (like power amplifiers in Hi-Fi/Home theatre systems).

This type of power amplifiers are used for increasing the magnitude of power of a weaker audio Signal. The power of the input signal is increased to a level high enough to drive loads of output devices like speakers, headphones, RF transmitters etc. A power amplifier is an electronic amplifier designed to increase the magnitude of power of a given input signal.

Use the following formula: Amplifier output noise voltage in dBV + speaker sensitivity at 2.83V – 9 dB. Example: Mono mode driving very high efficiency speakers: (-100 dBV) + (104 dB SPL @ 2.83V 1m) – 9 dB = -5 dB SPL at 1 meter. The protection system monitors output voltage, output current, output distortion, output device SOA (safe operating area), power supply current, power supply voltage, AC line voltage, case temperatures, and power device temperatures. In contrast, all conventional class-AB amplifiers have crossover-distortion artifacts.Traditional class-AB designs attempt to control distortion through the use of feedback.

In contrast, class-A amplifiers eliminate crossover distortion by keeping all output devices turned on at all times. Traditional class-AB amplifiers generate crossover distortion every time the push-pull output stage crosses 0 volts. Unlike power-hungry class-A amplifiers, the AHB2 achieves a power efficiency that rivals that of a Class D (switching) power amplifier.

For example, the noise and distortion produced by the Benchmark DAC3 D/A converter is 20 to 30 dB lower than that produced by most high-quality power amplifiers. The power amplifiers provide wide frequency response, low THD level and high S/N ratio. An optimised power supply, a directly mains-powered power amplifier section and other key design features ensure high performance and reliability.

Unfortunately, the output impedance of the power amplifier along with the load impedance varies as a function of frequency. RF power amplifiers usually have an output impedance of 50 Ω and, in an ideal world, would only be connected to load impedance of 50 Ω. In that case, 100% of the power is absorbed in the load and 0% of the power is reflected back to the power amplifier. Power amplifiers generally have a non-linear amplitude response, where the output power is saturated for large input powers.

Some stereo amps also have two sets of speaker terminals – usually labelled zone ‘A’ and ‘B’ or ‘1′ and ‘2′ – which allow you to run two pairs of speakers at the same time (in different rooms, for example), although this can have a detrimental effect on performance as essentially the amp’s power is being shared multiple ways. The idea is to keep the sensitive preamp circuitry (and the delicate audio signals flowing through it) away from the the electrically noisy high-current power amplifier section. While we like the idea of plug ‘n’ play set-ups as much as anyone, there’s more to getting the best out of stereo amplifiers than simply powering them up on a hi-fi rack, plugging in speakers and going wild with the volume dial.

Advanced zero feedback class A circuitry and cutting edge output transformer design make Ayon triode amplifiers recreate music with irresistible magic and authenticity. Absolute tonal neutrality, outstanding dynamics and a so far unknown level of resolution are trademarks of our amplifiers, complemented by an explosively fast and uncoloured bass and high power triode performance. But in power amplifiers, as large currents are in use, the problem of distortion certainly arises.

Class A Power amplifier − When the collector current flows at all times during the full cycle of signal, the power amplifier is known as class A power amplifier. The Power amplifiers amplify the power level of the signal. One of the main reasons why people decide to add amplifiers to their car audio system is to improve the quality of sound.

The PA8 8 Channel Power Amplifier is a unique single rack-space solution for zoned, distributed loudspeaker systems with eight separate power amplifiers, each with an output power capability of 10W (4 Ohms) or 6W (8 Ohms.) The power supply circuit of an ordinary amp consists of a large-capacity power transformer and a rectifier circuit: after examining ways to achieve ideal voltage and current waveforms, Technics decided to use a choke-input rectification, plus a discrete stabilised power supply circuit. Technics is able to measure an amplifier’s frequency amplitude-phase characteristics with speakers connected, and has developed a speaker impedance adaptive optimisation algorithm using digital signal processing to achieve ideal impulse response.

This enables the construction of a high-power amp using a single push-pull configuration, allowing the length of the large current carrying signal path to be shortened, and resulting in outstanding linearity regardless of the sound level. When it comes to good and quality sounds, power amplifiers are necessities. Footnote 1: Designing Audio Power Amplifiers, Bob Cordell’s encyclopedic book on audio amplifier design, is now available in a second edition from Focal Press:—John Atkinson.

The best-executed class-D amplifiers deliver music with a refined, grainless quality that many audiophiles find appealing. PowerShare amplifiers can be configured to automatically enter standby mode when the audio signal falls below a set threshold, then wake when audio returns. PV amplifiers are designed to operate at line voltages as low as 50% of nominal, employing mammoth toroidal power transformers and offering impressive specifications and features not found on similarly priced competitive units.

^ “Circuit Design Modifications for Minimizing Transient Intermodulation Distortion in Audio Amplifiers”, Matti Otala, Journal of Audio Engineering Society, Vol 20 # 5, June 1972. “Transient distortion in transistorized audio power amplifiers”. For some years following the introduction of solid state amplifiers, their perceived sound did not have the excellent audio quality of the best valve amplifiers (see valve audio amplifier ). This led audiophiles to believe that “tube sound” or valve sound had an intrinsic quality due to the vacuum tube technology itself.

In the 2000s, the Class-D amplifier , which is much more efficient than Class AB amplifiers, is widely used in consumer electronics audio products, bass amplifiers and sound reinforcement system gear, as Class D amplifiers are much lighter in weight and produce much less heat.

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