John
Peachtree Audio has this week announced the GaN400, a new Class D power amplifier. The new model’s name tells us that we expect it to deliver 400wpc into 8 or 4 Ohms via transistors made from Gallium Nitride. The GaN400’s output stage uses GanFETs — a new kind of transistor that might eventually replace MOSFETs as the switching device of choice in Class D amplifiers. To understand why GaNFETs offer so much promise we need to take a step back.
Class D amplifiers aren’t defined by the use of a switch-mode power supply and their signal processing isn’t digital but analogue: a PWM (pulse width modulated) facsimile of the incoming analogue signal is used to switch the output transistors (often pairs of MOSFETs) on and off at very high speeds. Each pulse’s width corresponds to the analogue signal’s amplitude.
According to Peachtree Audio’s Jim Spainhour, a MOSFET’s relatively slow switching speed can cause distortions that only the application of global negative feedback can correct. “And yet on the subjective listening side, you’ll hear people claim that global negative feedback causes an etched smearing of the mids and highs”, he says via email. Spainhour reminds us that celebrated amplifier designers like John Curl, Nelson Pass and the late Charley Hansen often touted the use of zero global negative feedback in their designs.
Now the kicker: GanFETs switch faster than MOSFETs to require far lower levels of global negative feedback.
Spainhour elaborates further: “After more than a year in development the GaN400 is the best sounding amplifier we’ve ever made. It combines some of the midrange and high-frequency qualities you’ll get from tube and low feedback solid-state designs with the speed and bass impact you get with high power Class D. There is no smearing. There is no etched sound. Due to the lack of feedback, it’s not the best measuring amplifier we’ve ever made but the tradeoff is better sonics. Much better sonics.”
The GaN400 is juiced by a 850W RMS regulated power supply, sports both balanced and single-ended inputs and comes wrapped in Peachtree’s super stylish curve-cornered sleeve. It is designed to be paired with the already announced PreDAC (US$2499), which, as the name suggests, is a pre-amplifier with DAC (and MM phono stage).
As such, The GaN400 will ship on its own for US$2999 but when bundled with the PreDAC, the pre-power combo will ring the register at US$4498 — that’s a fully fat $1000 discount. A GaN400 trade-in program is also up and running.
Further information: Peachtree Audio
