Coda CSiB Integrated Amplifier

The remote controlled Coda Control Amplifer CSi Balanced is designed with thoroughness reserved only for the finest preamplifier and amplifier gain stages. Analytical design techniques, both objective and subjective, were applied in an open-minded fashion with musical perfection as the goal. The CSiB features a wide range of design topologies and components ported from both broad lineage and the most recent advances in the Coda products and design topologies.

Unlike other integrated amplifiers, the CSiB offers true “separates” performance. The CSiB is, internally, essentially a Stereo Amplifier Ts with a separate preamplifier section based on the circuit topology of the Coda 07x Preamplifier.

On the faceplate, the straightforward controls and display provide comprehensive functionality to the user. All input selections have LEDs to show when they are in use. Buttons control both volume and balance, with an LED display to show which channels are being adjusted. Gain is controlled by a high performance Burr-Brown PGA2310 analog attenuator. This digitally controlled analogue device features an improved output buffer and increased voltage swing for high level input signals. Digitally controlled level tracking allows 1 dB per step attenuation without error. The digitally controlled stepped resistors & zero crossing detection circuit allow for “zipper-free” operation. Total harmonic distortion is less than 0.04% with a signal to noise ratio approaching 130 dB.

The preamplifier section has its own separate power supply with multiple independent transformer taps. A reference voltage is developed by delivering constant current to zener diodes. The resulting voltage is heavily filtered and delivered through class-A followers to provide absolutely stable power to the preamplifier section. A separate power supply is provided for all controls and microprocessor control system.

In the amplifier section of the CSiB, differential voltage gain throughout provides exceptional rejection of external noise and contributes to the inherent stability of the circuit. The front end is designed to provide a slew rate of 50 V/us without entering class B operation as is common in many other designs. This combined with excellent high frequency design insures linear operation at high speed.

The amplifer’s overbuilt power supply take a very direct approach to high performance by utilizing a top quality 3.0 kVA custom toroidal transformer, high current rectifers and a 80,000μF capacitor filter bank with very low ESR and inductance.

This latest generation output stage design is capable of producing peak currents in excess of 100 peak amperes with a degree of linearity and speed unmatched by other designs producing only a fraction of this massive amount of current. This is achieved by the implementation of several distinct circuit features. Each channel uses 20 individual output transistors with a combined power rating of over 4,000 watts and 125 amperes and a bandwidth of 30 MHz. The CSiB V3 operates in Class A up to approximately ~8 watts. At higher output levels, the bias section is designed to produce a precision transition with no abrupt changes in distortion or output impedance. This “Precision Bias” technique yields seamless performance regardless of the complexity of the load. With such linearity and bandwidth, only 6db of feedback is used to maintain damping factor while permitting the minimal value custom emitter resistors to provide current limiting only under extreme conditions that would exceed the output stages high current capabilities. One advantage of this is a high degree of immunity from interactions with complex speaker loads or cables.

Rated Power

V3:

400 watts @ 8Ω

V2:
250 Watts @ 8Ω
500 Watts @ 4Ω
Class A to ~12W @ 8Ω

V1:
150 Watts @ 8Ω
300 Watts @ 4Ω
Class A to ~18W @ 8Ω