Home Surround Sound Amplifier

Audio Visual Receiver Amplifiers are the “intelligence” of your Home Cinema. That is why it is important to decide on a quality “AV” Receiver that will provide for all your needs using a 5.1 to 7.1 channel with DTS Surround Sound to systems with separate power amplifiers for added clarity. This means ultimate in clean audio power, precise audio processing, and sufficient connectivity. Clean power is delivered through a massive ”Toroidal” transformer and extra transformers for A/V processing, with the chassis encased in separate panels to reduce vibrations. With this in mind, quality assurance guarantees massive performance when watching Blu-ray and DVD movies and also Live Concerts of Pop artists which I love very much. This can be used in even the largest Home Theater rooms.

Audio Amplifier and its function A simple way to understand how an analogue audio amplifier works is to think of it as a kind of servo-controlled “valve” that regulates stored up energy from the wall outlet and then releases it in measured amounts to your loudspeakers. The amount being discharged is synchronized to the rapid variations of the incoming audio signal.

An analogue amplifier consists of two separate circuits, one of which is the output circuit, which generates a totally new and powerful electrical output signal for your speakers derived from the incoming audio signal. The concluding is an AC signal of about 1 volt that represents the rapidly varying waveforms of sounds, both their frequencies and amplitudes. This low level AC signal is used to modulate the circuit that releases power, voltage and amperage stored up by the big capacitors and transformer in the amplifier’s power supply, power that is discharged in a way that exactly parallels the tiny modulations of the incoming audio signal. This signal in the amplifier’s input stage applies a varying conductivity to the output circuit’s transistors, which release power from the amplifier’s power supply to activate your loudspeaker’s cones and tweeters. It’s almost like you were rapidly turning on the tap, which releases all the stored up water pressure, the water tower or reservoir are the storage in the capacitors.

Different “Classes” of Amplifiers   Class A designs have current constantly flowing through the output transistors even if there is no incoming audio signal, so the output transistors are always on. This type of amplifier has the lowest distortion of any but it’s extremely wasteful and inefficient, dissipating 80% of its power in heat with an efficiency of only 20%.

Class B amplifiers use output transistors that switch on and off, with one device amplifying the positive portion of the waveform, the other device is the negative part. If there is no incoming audio signal, then no current flows through the output transistors. Consequently, Class B amplifiers are much more efficient (about 50% to 70%) than Class A designs, however with different brands there may be non-linear distortions that occur when one set of transistors switch off and the other set switches on.

Class A/B amplifiers combine the virtues of Class A and Class B designs by having one output device stay on a bit longer, while the other device takes over amplifying the other half of the audio waveform. In other words, there is a small current on at all times in the crossover portion of each output device, which eliminates the potential switching distortion of a pure Class B design. Efficiency of a Class A/B amp is still about 50%.

Class D amplifiers, although there are a number of different design variations, these are essentially switching amplifiers or Pulse Width Modulator (PWM) designs. The incoming analogue audio signal is used to modulate a very high frequency PWM carrier that works the output stage either fully on or off. This ultra-high frequency carrier must be removed from the audio output with a reconstruction filter so that no ultra-high frequency switching components remain to corrupt the audio signals. Class D designs are extremely efficient, typically in the range of 85% to more than 90%.

Amplifier Weight and its Robust Amplifier Design: You have to find out if the amplifier is a Class A/B analogue amp or a Class D digital amplifier before you can generalize about weight and amplifier quality. The performance of latest high-quality digital amplifiers such as the Axiom A1400-8 and others has changed the equation. Digital Class D amplifiers are much more efficient (90% & more) than analogue Class A/B amplifiers (about 50% efficient). As such, digital amps tend to run much cooler and therefore do not require the heavy heat sinks associated with high-powered analogue amplifiers, hence the overall weight of a digital amp may not be a reliable indicator of its genuine quality. For instance, Axiom’s eight-channel digital A1400-8 has received superb reviews from audio professionals. And while it’s not exactly light (58 lbs), it still weighs much less than its multi-channel analogue competitors whose output power is often about 200 watts per channel, yet typically weigh from 90 to 120 pounds. Moreover, as an 8-channel power amp, the A1400-8 is much more compact than many analogue rivals, one of the great advantages of high-quality digital designs.

Class A/B amplifiers weight can be of robust design It suggests that the amplifier’s important internal components, the power transformer, heat sinks, and storage capacitors are large, and therefore have plenty of capacity to process and store large amounts of power to handle loud dynamic surround peaks without distortion. By contrast, an analogue amplifier that weighs less may use a smaller transformer with inadequate capacity and fewer or thinner heat sinks, heat sinks look like radiator fins and are used to dissipate output transistor heat generated by high power output and big dynamic swings.

“Digital” amplifiers are different from “Analogue” amplifiers. Digital amplifiers use high-frequency switching circuitry to modulate the output devices. And analogue amplifier works in analogous fashion, regulating the output stage devices (transistors) to release power from the amplifier’s power supply to the loudspeakers in a manner that exactly duplicate the tiny incoming audio waveform.

 Amplifier’s Characteristic. One primary attribute is a ruler-flat smooth frequency response from the deepest audible bass signals at 20 Hz (or lower) to the highest frequencies we can hear, at 20,000 Hz. A smooth, linear frequency response means that the amplifier will treat every incoming audio signal, whether it’s a bass guitar / bass-drum signal at 30 Hz or a rock guitarist / cymbal’s high-frequency harmonics at 10,000 Hz exactly the same way, increasing the electrical strength of each tiny signal by exactly the same amount. Low total harmonic distortion (THD), below 0.5%, is essential so that any distortion artefacts remain inaudible with music.

Can low powered amplifiers put speakers at risk?  The answer is “Yes”. But to begin with it seems contradictory as to how could a low-powered amplifier can burn out speakers, when odds are amplifiers of 200 or 500 watts per channel would seem to put speakers at much greater risk. The philosophy is that a small amplifier of 10 or 50 watts per channel can easily be driven into distortion and “clipping” with even moderately playing loud and with dynamic surround peaks in loudness. It all depends on room size. The clipping cuts off the clean waveform and turns the output signal into an almost pure constant DC signal, which can quickly cause the fine wires in the speaker’s voice coils to overheat and melt.  Advantage of large powered amplifier outputs gives clean power to the speakers, free from AC distortion audio signals, and the speaker voice coils will accept on a momentary basis without damage.

Surround Sound Amplifier “Features” to look out for are: WRAT (wide range amplifier technology) / Three-stage inverted Darlington circuitry / H.C.P.S. (high current power supply) Audio and Video Processing./.Linear optimum gain volume circuitry /.PLL (phase locked loop) Jitter-cleaning circuit technology./ Blu-Ray HDMI support /True HD, DTS-HD Master Audio™, DTS Neo, Audyssey   Dolby® Pro Logic® IIz for expanded surround channels./ DVD-Audio, Super Audio CD, / Built-in Software to correct room acoustics./ Customized 22,000 μf capacitors for effective power supply./ Separate anti-vibration panels./ Playback of Audio Files through Local Network (MP3, WMA, WMA Lossless, FLAC, WAV, AAC, LPCM)./ Internet radio and music streaming connectivity (tuner)./ Bi-Amplification capability./ Gold-plated HDMI./ Terminals (4 Inputs and 2 Output), Gold-Plated, Color-Coded, Banana Plug./ Compatible Speaker Posts / Preprogrammed, and customizable RI Remote control with on-screen setup, / Macro presets for four AV sources and other AV features of your requirements. The feature options are unlimited with high end surround sound amplifiers.

Alphonso Soosay

Home Theatre Consultant

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