Coda 02b operation manual Design Philosophy

DESIGN PHILOSOPHY 8

The requirements of a power supply for flawless audio reproduction are straightforward but important. The supplies in the FET PREAMPLIFIER 02b take a very direct approach to high performance. First, a top quality shielded toroid transformer with plenty of reserve current capability is used. About 28,000 uF of capacitance with very low ESR and inductance provides good passive filtering. A reference voltage is developed by delivering a constant current to zener diodes. The resulting voltage is heavily filtered and delivered to each stage through independent class A followers which completely decouples the stages. The resulting non-reactive low impedance over an extremely wide bandwidth yields a perfect power source for the individual circuits. The simplicity and absolute stability of the supplies removes the chance of unpredictable interactions which may occur with the more elaborate, high feedback circuity often used.

Most companies in the upper end of the audio industry use either sheet metal or formed aluminum. By contrast, the FET PREAMPLIFIER 02b has all structural parts made of machined extruded aluminum. The advantage of this over an all stamped chassis is that the machined metal can be worked more precisely allowing us to work on tighter tolerances and use PC mounted parts more easily. Moreover such a design allows easier servicing either for repair or for future upgrading. From the standpoint of appearance, a machined surface can be contoured in a far more precise manner, giving the final product a more seamless appearance.