Tag: audio amplifiers

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The same kind of GaN technology that powers these powerful USB chargers is entering another class of electronics

GaN Technology in Audio Power Amplification | audioXpress

500W Heatsinkless Audio Amplifier from Axign and GaN Systems Demonstrates a New World of Extraordinary Audio Performance | GaN Systems

Previous coverage on GaN technology

Belkin joins the GaN bus with two highly-compact USB PD wall chargers

My Comments

Gallium Nitride is a relatively new semiconductor material that is being seen as “today’s silicon”. At the moment, it has been used in various optoelectronics applications like blue, white, green or ultraviolet LEDs and blue and green laser diodes.

As well, it has seen a lot of traction within power electronics use cases like power supplies, inverters and battery chargers. This has been leading to some small powerful USB-C battery chargers and multi-output charging bars. As well, this technology is helping with decarbonisation thanks to its use with solar panels, battery storage systems and electric vehicles. What has driven its use in this field is how powerful the GaN semiconductors are and the fact that there aren’t heat issues with these semiconductors, this allowing for small designs for powerful power-supply circuits.

But over the last two years, some work has taken place with implementing GaN technology within the audio amplifier space. This is similar to power-supply design but is to amplify a variable-frequency signal representing sound in order to drive a loudspeaker. Here it’s about assuring that the sound is amplified in a manner to assure its clarity and intelligibility.

GaN Systems has showcased an audio amplifier design that works at 250 watts per channel for a 4-ohm load with a very low total harmonic distortion of below 0.01% across 20 Hz to 20 kHz. This Class D amplifier circuit has been rated to perform close to a Class A amplifier circuit which represents the pinnacle for hi-fi audio amplification using solid-state technology.

What could this mean for audio equipment design?

This time amplifying sound within audio equipment like amplifiers and active speakers

I see this like how silicon technology impacted audio equipment design through the 1970s.

For example, amplifiers started to acquire power output ratings of at least two figures per channel with specifications that represented an increasingly-clean sound, which led to a requirement to re-engineer loudspeakers for stronger signals. These amplifiers were more tolerant of how the speakers were wired to them thus opening the pathway to multiroom audio or advanced speaker wiring approaches. This was infact a driver for the Receiver Wars of the 1970s with the goal to see who could offer the most powerful stereo receiver that yielded the cleanest sound.

There was also the ability to do away with output transformers which was a boon for a clean hi-fi sound and for mobile and portable use cases. It was also easier to design portable equipment for increased power efficiency which allowed for longer battery runtimes with stronger clearer sound. It also led to a strong effort towards highly-compact hi-fi systems be they integrated systems  with many programme sources on the same chassis or small compact component systems.

Smart speakers and Bluetooth speakers are expected to benefit from GaN audio-amplification technology to assure that clean powerful sound.

Most likely I would see increasingly capable active-speaker designs like smart speakers or Bluetooth speakers appear on the market which are about a clearer stronger sound that what occurred previously. They would also have a neat design even though they have a higher power output due to very little reliance on heatsinks and other thermal-mitigation designs.

As well, manufacturers could get away with designing sophisticated amplifier and speaker setups yet keep the amplifiers in these setups compact. This would benefit multichannel and spatial audio or sophisticated designs with separately-amplified speaker drivers such as “active subwoofer” or “biamplification”.

It would also impact “built-in” audio designs like automotive or marine audio. That also extends to TVs, computer monitors and similar devices  with built-in speakers. This is because there would be powerful high-quality amplifiers that can be integrated in these installations without having to worry about heat buildup.

Like what happened when silicon semiconductors came about, battery-operated devices will gain a performance and efficiency boost. Welcome to longer battery runtimes or significant improvement in sound quality out of those Bluetooth speakers or portable digital radios for example.

GaN semiconductor technology entering the audio-amplification space is demonstrating the fact that this  a significant step towards it becoming the “new silicon” for electronics design.

There has been a consistent range of affordable stereo amplifiers and receivers offered from the 1960s onwards that weren’t about high output levels or audiophile-level sound output quality. Here, they were about playing music from what was fed through them and yielding a decent-enough sound through a set of modestly-priced speakers.

Typically they were sold as something to have as the heart of your first multi-piece hi-fi system whether the system was with source equipment and speakers that you chose or as part of an affordable stereo-system package offered by the manufacturer. In some cases, the circuitry in some of these amplifiers has been integrated in one or more of the premium single-piece or three-piece stereo systems offered by that manufacturer.

Examples of these ranged from the Australian-built valve-based Cosmos stereo integrated amplifier that was sold through the Encel hi-fi store during the late 60s and early 70s, through affordably-priced Realistic stereo receivers sold by Tandy / Radio Shack through the 70s and 80s to the “micro” component systems that most of the Japanese hi-fi names launched through the early 1980s. This class of amplifier or receiver also represented the equipment that was offered at the lower end of a manufacturer’s product range.

In a lot of cases, these amplifiers and receivers were typically used as the heart of an elementary stereo system like one’s first hi-fi setup or a secondary hi-fi setup. Then the user’s needs would change towards using a better amplifier and these amplifiers ended up being used with a pair of cheap speakers to amplify sounds like game sound effects from a multimedia-capable computer.

But lately this practice has shown up again with the likes of Lepai, Topping and others who implement very small stereo integrated amplifiers that work effectively on a single chipset for both channels. Some of these amplifiers may have extra functionality like a phono stage, a digital-analogue converter, or a USB or Bluetooth interface as part of that same chipset or as another chipset that presents a line-level signal. But typically they are sold through different online stores as well as some specialist electronics outlets or hi-fi stores.

Here, these amplifiers are based on a TriPath “Class T” circuit design or a similar design which is based on the Class D switch-mode amplification approach that has allowed for highly-compact audio amplifiers. That is due to the ability to work with low current demands as well as not yielding excess waste heat.

Why are these amplifiers showing up again? Here, the low power output and the small circuit size has allowed for a very small footprint and one could easily connect them to low-powered speakers of which many are in circulation. One of the reasons this has This is brought about through affordable three-piece stereo systems that had given up the ghost and the speakers associated with these systems are seen as of value with a low-power amplifier.

There is also the fact that most, if not all, of the stereo speakers made before the 1970s were engineered for amplifiers which had low power outputs thanks to valve (tube) or early solid-state circuit designs that couldn’t achieve high output power. In this situation, these speakers including the floor-standing types were designed for maximum efficiency and an ideal tonal response while better amplifiers were designed for improved sound clarity.

A common application that these midget amplifiers are being put towards is to become an audio amplifier for your computer’s sound infrastructure. This is seen as being better than a lot of budget-priced active speakers pitched towards computer users which aren’t seen as offering high-quality sound.

Personally I would still value a stereo system based around these amplifiers as another direction towards a cost-effective music system where you don’t want memories of the gaudy 90s.