Special Features
Stewart Audio’s new “Compact Series” Power Amplifiers utilizes the latest in Digital Au-
dio Technology. The new, all Digital DA Series Power Amplifiers were developed by Stew-
art Audio’s Digital Audio Team and represent the pinnacle of Stewart Audio technology
and design.
Please take a few moments to read through this section of the manual, which provides
an overview of the features that makes this amplifier unique.
How is the DA-70 Amplifier different from other Amplifiers?
The primary difference between the DA-70 Series and other
amplifiers is that it is all digital and it has much higher effi-
ciency. Current digital audio systems use Class A/B amplifiers
to amplify analog signals produced by a DAC. Analog designs
have low efficiencies because of the power consumed in the
active components as a result of the voltage difference be-
tween the amplifier's output and it's power supply. This con-
tinuous control of the supply voltage results in peak efficien-
cies of about 50%. As a result a large power supply and heat
sink are required.
Class D switching amplifiers were developed to overcome this
problem by discretely connecting the load to the power supply.
Higher efficiency is achieved, but Class D is still essentially an
analog solution because it utilizes an analog interface and con-
trol. Stewart’s approach was to develop a new Class D ampli-
fier that utilized digital control. This approach enables lower
cost through digital integration, as well as, eliminating per-
formance degradation due to analog component variations.
5
