Coda Stereo Amplifier 15.5 - Manual (Page 11)

I. Design Philosophy and Approach (continued)
To maintain “Precision Bias” requires an advanced bias circuit that must have a very
high degree of stability under a wide range of temperatures and load conditions.
Most amplifier bias networks are of such high impedance and poor thermal regulation
that at the extremes of operation, bias currents are ineffectively controlled. Advanced
tracking techniques used in the 15.0 result in absolute control of bias currents under all
conditions.
The main power supply of the amplifier consists of two 2000VA toroidal power
transformers (or one 3000VA transformer in the EU) with independent rectifiers to
isolate the channels from one another. 184,000 microfarads of total capacitance
provide effective filtering of all AC ripple.
These attributes result in a amplifier of such extreme linearity and bandwidth that no
overall feedback correction is required or used. One advantage of this is a high
degree of immunity from interactions with loads or cables and a superior transient
response. An extremely low nonreactive output impedance is maintained well beyond
20,000 hz. The resulting uniform damping factor is not commonly found in other
designs.
The chassis of the 15.0 is constructed of machined aluminum milled to very close
tolerances yielding the seamless appearance characteristic of previous products
from Coda. As with all high-power amplifiers, heat dissipation is important. The 15.0
uses six massive aluminum heat sinks without fans for efficient, noiseless, and clean
thermal relief. The thermal coefficient of the 15.0 heat sinks is one of the lowest and
most effective in the audio industry.
DESIGN PHILOSOPHY 10