Featured Amplifier Articles

If you've ever glanced at the specifications sheet of an external amplifier, you may have noticed the term "voltage gain". In short, it is the degree to which an amplifier actually amplifies the input from the preamplifier/processor. Often overlooked by those unaware of its importance, this one parameter can have significant implications on actual performance when an amplifier is introduced into an AV system. Understanding the impact that different levels of voltage gain can have in your system can very well be the difference between poor sound and getting the most out of an external amplifier. Read more about amplifier voltage gain to ensure you properly match your amp and preamp to achieve maximum performance.

Whether or not amplifiers sound different is a subject of ongoing controversy. There are sensible, well-informed enthusiasts and magazine reviewers who will swear to their many, obvious differences, differences that are—to them, anyway—almost as obvious and important as the differences between speakers. There are also just as many well-informed enthusiasts and reviewers who say that there are no meaningful differences in the sound of two properly-functioning, properly-performing amplifiers operating within their undistorted performance envelope. And there is a third contingent that opines that the in-situ application of different amplifiers with different speakers and other associated equipment and connectors can produce differences in the sound even though nothing in the system is misbehaving per se. We explore the technical reasons with Rod Elliot of ESP as to why amplifiers can sound different. We’ll open up the discussion, put forward some factual information, relate a few anecdotal experiences and look forward to your responses.

Ever wonder what slew rate was all about? No, it has nothing to do with how a drunk person slurs their speech. When reviewing the spec sheet of an amplifier, one potentially unfamiliar term you may run into is slew rate. There are a lot of gobbledygook explanations floating around the web which seem to misunderstand the basic premise, so we at Audioholics are here to clear the air. In short, slew rate has little to do with how an amplifier produces dynamics so much as its ability to effectively maintain output into higher frequencies. It is the rate of how quickly an amplifier can respond to a rapid change of input level. This is measured as a change in voltage with respect to time as can be seen in the main image of this article. We discuss how to calculate slew rate based on amplifier bandwidth and power and also discuss real world implications of the spec.

We've all seen amplifier companies tout that their amps are "high instantaneous current". Using the very basic principle governing electricity called Ohm's Law (V=I*R), how could it be possible that 100 watt amp has "higher current" than another 100 watt rated amplifier? This very subject has come up on numerous audio forums including the Audioholics forum, and this article explores that topic as well as the history of how the term "high current" became popularized by some manufacturers. We do some basic calculations to illustrate just how nebulous this specification often really is.

There has been much discussion on the major audio forums lately regarding A/V receivers and multi channel amplifier power output capabilities as well as their abilities to drive low impedance loads. Much of the controversy steams around the infamous "All Channels Driven Test" which simulates a best case test load in a worst case environment and by all intents and purposes an unrealistic real world scenario. As a result, we have come up with a standard for measuring amplifier performance that deals with various types of power tests as well as other metrics that directly affect sonic performance and how the amplifier can sound powering various types of speaker loads.

This article explores why the impedance switch exists on some A/V receivers and its intended purpose, including tradeoff’s when following the manufacturers recommended settings. Know the facts when purchasing and setting up home theater equipment. Most importantly, step back and evaluate how you are using your system and make adjustments accordingly to avoid robbing your speakers of power.

Ever wonder how an amplifier works at a very fundamental level? Alan Lofft, Resident Expert of Axiom Audio takes us on a tour of traditional linear amplifiers as well as the newer more sleek Class D designs. Various types of Class D design approaches are discussed including feedback topologies and their implications on audio performance and efficiency. The similarities and differences of traditional Class D amplifiers compared to Axioms new A1400-8 multi channel amplifier is reviewed. Learn what makes these amplifiers tick and why it’s cool in more ways than one to get your hands on the future of high end audio amplification that is powerful, efficient, and lightweight compared to their analog predecessors.

It’s been a few years since our controversial release of “Attack of the Clone Processors” and we felt it was time for a sequel to our blockbuster hit editorial. Engineering a product from the ground up, especially one as complex as a switching amp, takes time and money with the end result often not being as good or cost effective as what can be bought off the shelf like these ICE modules from Bang & Olufsen. I can count the number of manufacturers producing their very own Class D designs and still have a finger left to point at all the copycats. Overall this seems to be a good design approach for manufacturers unwilling or unable to do their own developmental work if cost and full disclosure of performance is kept in check. It’s up to you the consumer to decide if paying a premium price for name brand, exotic accessory parts and cosmetics is worth the investment. Just don’t let anyone tell you that regardless of price, you are buying anything other than a clone amplifier, albeit a reasonably well engineered one.

Ever wonder why the boom box you bought at Best Buy has a higher power rating than your dedicated two-channel power amplifier? Amplifier power ratings are usually honest in Hi-Fi equipment, but become very silly when it comes to the 'mass market' systems and even some of the latest Class D amplifier offerings. Few amps have a dynamic headroom of better than 1 or 2dB, and the greater the headroom, usually the cheaper the power supply for the rated power. This article explores the history of power ratings for consumer audio and also busts the myth about 'RMS' power.