Studiomaster has published details of its new Class AD Polyphase proprietary amplifier development in a technical reference document on the company’s website.
First announced at this year’s Prolight+Sound exhibition in Frankfurt, the company states that the technology provides improvements in sound quality, efficiency and power density over current Class D designs.
The new topology combines a number of design innovations with a Studiomaster patented “polyphase” output stage, with the goal of providing the equivalent sonic performance of an analog design and greater efficiency than a Class D amplifier, enabling better sounding, more compact devices and power circuit integration.
At the heart of the Class AD polyphase amplifier is a modern take on the “current dumping” design of the 1970s, where a high quality, low efficiency Class A amplifier operates in parallel with a bi-polar output stage.
In the new Class AD design the bi-polar output is replaced with an ultra fast switching Class D stage using MOSFET devices.
To provide even higher apparent switching speeds, the usual parallel operation of the MOSFET devices is replaced by Studiomaster’s patented Polyphase mode, whereby pairs of MOSFETs operate at different times, sequentially. This provides the opportunity to overlap the devices when the load is greater or the signal is bigger.
The net result is a far higher apparent switching speed and a reduction in the required output filtering and switching artefacts, improving sound quality and reducing weight.
Additionally in the Class AD topology, the Class D circuitry becomes inactive at very low signal levels (with only the Class A component operating); thus, at small signal levels the inherent sonic limitations of Class D amplification are eliminated and the system runs as if it were a high quality, purely analog device.
Together, these design innovations significantly reduce noise and provide a consequential power saving and improvement in efficiency.
Studiomaster head of R&D Paul Belcher states, “Innovation has always been at the heart of Studiomaster’s R&D, from the very beginnings of the company and developments like this demonstrate that that is still very much the case. We are already developing new designs that exploit this new amplifier technology across a range of product categories.”
The technical reference document describing the new Studiomaster Class AD Polyphase development can be downloaded at here (pdf).