Esoteric Master Sound Works C-02 Preamplifier
The C-02 is the latest member of Esoteric’s Master Sound Works line. As I explained in my review of the Master Sound Works A-02 power amplifier for SoundStage! Hi-Fi, this means that the C-02 benefits from what Esoteric has learned from its relationships with recording studios, sound laboratories, and other professional customers.
The C-02’s preeminent feature is undoubtedly its dual-mono design. In some dual-mono preamps, the left and right channels are routed through the opposite sides of a single circuit board, while others employ mirror-imaged boards. In both cases, the mono signals proceed through paths that typically differ in length, direction, and/or location within the case. The C-02 is atypical in having two identical boards, to give the two channels identical signal paths.
As is standard in dual-mono designs, each of the C-02’s channels has its own separate power supply. However, the C-02 is atypical in that each channel’s circuitry contains two transformers. In fact, a total of five transformers is used: one each for the input and output of each channel, and a fifth for the control section. Among other benefits, this is claimed to significantly reduce interchannel crosstalk and noise.
Another important feature of the C-02 is Esoteric’s Quad Volume Control System (QVCS). Changing the volume alters the gain in each of the C-02’s four circuits: a positive and negative for each of the two stereo channels. Many volume controls alter the gain in only two circuits, which, Esoteric says, may cause a gain imbalance between channels of up to 5%. Although such imbalances are rarely severe enough to be audible, the work that has gone into the QVCS illustrates the lengths to which Esoteric will go to create as perfect a product as possible.