What's in a watt

Wednesday, June 21, 2023

People are often confused about the importance of power, or watts per channel in audiophile amplifier design. Generally and confusingly it is often assumed that more power means better performance. This is often far from the truth. The amount of power you need depends on various factors and the specific requirements of the speakers and your listening preferences. While watts per channel can provide an indication of an amplifier's power output, it is not the sole determinant of an amplifier's performance or sound quality.

In general, higher wattage amplifiers have the potential to deliver more power to speakers, allowing for higher volume levels and the ability to drive demanding speaker loads. If you have large speakers or enjoy listening at high volume levels, having sufficient wattage can be important to avoid distortion and ensure clean, dynamic sound reproduction. 

It’s also worth noting that perceived loudness is not solely determined by the amplifier's power rating. Other factors, such as speaker sensitivity and room acoustics, also play significant roles. For instance, speakers with higher sensitivity require less power to achieve the same volume levels compared to speakers with lower sensitivity. So if you don’t need high volume and your speakers are not difficult to drive then you don’t need high power.

Moreover, the quality of amplifier design, circuitry, and components has a profound impact on the sound quality, regardless of the wattage. Factors like low distortion, low noise, high signal-to-noise ratio, and excellent frequency response are crucial for accurate and faithful audio reproduction. A well-designed amplifier with lower wattage can often provide exceptional sound quality, musicality, and detail retrieval, especially in systems with efficient speakers and moderate listening volumes.

It's worth mentioning that many audiophiles prioritise the overall audio performance and sonic characteristics over sheer power output. They may opt for high-quality amplifiers with lower wattage but superior engineering and build quality to achieve a more transparent and engaging listening experience.

Class A amplifiers are a case in point . They’re known for their high-quality sound reproduction and low distortion. One of the reasons why they can sound fantastic with relatively low power is due to their inherent design characteristics. Many are rated at 20 watts per channel or less.

In a Class A amplifier, the output stage transistors or tubes are biassed in such a way that they conduct current throughout the entire waveform cycle, even when there is no input signal. This means that the output devices are always "on" and ready to amplify the incoming audio signal.

Since the output devices are constantly conducting current, they can respond instantaneously to changes in the input signal, resulting in a highly accurate reproduction of the original audio waveform. This characteristic is beneficial for reproducing subtle details and nuances in the music, which can contribute to a more realistic and pleasing listening experience.

Additionally, Class A amplifiers typically operate in a single-ended configuration, where the output devices amplify the entire audio waveform. This arrangement allows for a simpler circuit design and eliminates the need for complex crossover distortion compensation circuits found in other amplifier classes.

However, it's important to note that Class A amplifiers are generally less efficient than other amplifier classes. The constant current flow through the output devices generates heat, even when there is no input signal, which leads to power dissipation. As a result, Class A amplifiers tend to consume more power and generate more heat compared to other amplifier types.

While Class A amplifiers can deliver exceptional sound quality, their power requirements can be relatively high compared to other amplifier classes. To achieve high-quality sound, they often require robust power supplies and heatsinks to handle the increased power dissipation.

The eagle-eyed will also notice that amplifiers like Naim Audio rarely deliver massive amounts of power. However they deliver their rated power easily and without running into distortion. This means good quality sound across the listening spectrum from low to high. In fact the hallmark of a good amp is that it should sound the same when you turn it down as well as up.

You may recall that in the 80’s more power was always assumed to mean better. But good design very quickly proved that this was not the case.

Leave a comment

© 2022 Moorgate Acoustics Store. All Rights Reserved.