Tips For Finding The Best Audio Amplifier

By Brian Fuller

I will take a look at some audio amplifiers as well as mini amplifier models and explain some basic terms to help you pick the ideal amplifier for your speakers

Audio amplifiers come in all different shapes and sizes. They use different technologies and have many technical specs. This makes it difficult to decide which model to pick. You don't have to be an expert. Just follow some simple guidelines and you should be satisfied with your amp.

Amplifiers differ in their size and range from models that will take up a good part of your living room while some of the latest mini amplifier models are as small as a deck of cards. Many amplifiers are rack sized. This allows them to be stacked on top of your other audio equipment.

Most of today's audio amplifiers are based on solid-state technology while a small portion is based on tube technology which has been popular over a decade ago. Unfortunately, tube amplifiers have fairly high audio distortion which describes how much the audio signal is degraded by the amplifier.

Harmonic distortion of tube amplifiers is often as high as 10%. Solid-state amps will have lower audio distortion. However, distortion will depend on the particular audio amplifier technology. Some of the most popular technologies in the past have been "Class-A" and "Class-AB" technologies. These technologies use different arrangements to amplify the audio. Amplifiers based on any of these technologies are also called "analog amplifiers". Audio amplifiers which are based on these technologies typically have low harmonic distortion. Also, this technology is fairly inexpensive. However, the drawback is that the power efficiency is only in the order of 20% to 30%. Power efficiency describes how much of the electrical power is used to amplify the audio as opposed to being wasted as heat. Amplifiers with low power efficiency will require fairly large heat sinks because most of the power is radiated.

In contrast, "Class-D" amplifiers which are also called "digital amplifiers" offer a power efficiency of typically 80 to 90%. This allows the amplifier and power supply to be made much smaller than analog amplifiers. The tradeoff is that digital amplifiers often have higher audio distortion than analog amplifiers. This is mostly a result of the switching distortion of the output power stage. Most recent digital audio amplifiers, however, employ a feedback mechanism and can minimize the audio distortion to below 0.05%.

The amplifier should be able to deliver enough output power to sufficiently drive your speakers which will depend not only on how much power your speakers can handle but also on the size of your listening environment. Speaker power handling is given as peak power which describes the maximum amount of power during short bursts while average power refers to how much power the speakers can handle continuously.

If your listening environment is fairly small then you may not need to drive your speaker to its rated power handling value. You would probably be good having an amplifier that can deliver 20 to 50 Watts even though your speakers may be able to handle 100 Watts of power. Note though that speakers differ in their sensitivity. Typically a low-impedance speaker will be easier to drive to high volume than a high-impedance speaker. Be sure that your amp can drive your speaker impedance. You can easily find the rated speaker impedance range in your amplifier's user manual.

Two other important parameters to look at when picking an amplifier are signal-to-noise ratio and frequency response. Signal-to-noise ratio describes how much noise the amplifier will introduce and should be at least 100 dB for a high-quality amplifier. The frequency response shows which audio frequency range the amplifier covers and should be at least 20 Hz to 20 kHz.

About the Author:

You can find additional information regarding audio amplifier technologies at Amphony's website.

A Glimpse At A Few Of The Hottest Wireless Devices

By Brian Fuller

Lately a large number of wireless audio products have emerged such as latest-generation wireless headphones, iPods, cell phones and wireless amplifier products which promise to cut the cord. I will take a look at some of the newest gadgets and technologies to find out how well they work and in which situations they work best.

Some products come with wireless already built in while others, in particular streaming audio products, often have optional wireless capability. Newest touch-screen iPods and iPhones already have WiFi and Bluetooth built in.

Bluetooth is a fairly low-cost solution but has some drawbacks which are often overlooked.

1) Limited range

Bluetooth devices typically only have a 30-foot range which limits Bluetooth to single-room applications.

2) Audio compression due to limited data rate

Bluetooth will apply audio compression since it does not reliably offer a high-enough data rate for uncompressed audio. Audio compression will degrade the audio quality to some extent. High-quality audio transmission typically does not tolerate this type of degradation. Therefore Bluetooth is normally not used in high-end audio products.

3) Audio latency

Due to audio compression, Bluetooth will introduce a signal delay of at least 10 ms which will cause the audio to be slightly out of sync in case of video and real-time applications. This is again less of a problem for MP3 players.

4) No multiple headphone support

Bluetooth does not support any number of headphones which may be a problem if you have a larger number of people who want to listen to headphones from a single transmitter device.

Another common protocol is WiFi which supports uncompressed audio but also has problems simultaneously streaming to multiple receivers. It is convenient for streaming music from a PC due to the high availability but is normally not used in wireless headphone products due to the relatively high power consumption of WiFi.

Wireless speakers and wireless amplifier products for home theater speakers typically use their own proprietary protocol. Entry-level wireless headphones and speakers typically still use FM transmission which offers low cost but is prone to noise and audio distortion.

More advanced wireless protocols are based on digital formats which eliminate audio degradation and incorporate advanced features such as error correction to cope with interference from competing wireless devices.

Advanced wireless amplifier devices support uncompressed digital audio streaming to preserve the original audio quality. Some of these protocols allow streaming to an unlimited number of wireless amplifiers which is convenient for whole-house audio distribution. The audio latency ranges from below 1 ms to up to 20 ms. A small latency is important for wireless surround sound applications. These wireless audio transmitters typically work at 2.4 GHz. There are also some products such as Amphony's line of wireless audio products which work at 5.8 GHz. Products that operate at 5.8 GHz have less competition from other wireless devices than those using the crowded 2.4 GHz frequency band.

Wireless amplifiers offer different levels of audio quality, output power and standby power. Wireless Class-D amplifiers normally have standby power of 5 Watts or less and a power efficiency of greater than 80% but sometimes high audio distortion. Picking a low-distortion amplifier is key. Good-quality wireless amplifiers have audio distortion of less than 0.05%.

About the Author:

You can get additional information regarding wireless audio products at Amphony's website.