Zanden Audio Systems’ top-of-the-tree Model 1200 phono preamplifier has been through several iterations over its long and illustrious career, but arguably none so significant as the move to the new Model 1200 Signature. The two ‘headline’ features are balanced operation (and consequently features twice as many valves as in the single-ended version), and an even greater set of refinements to its equalisation options, as the circuit now includes a provision to adjust the 4th time constant that equates to different cutter-heads used in the making of the record itself!
The ‘problem’ Zanden has long faced with the Model 1200 is there aren’t any problems. From the outset, 17 years ago, the Model 1200 (the first product in the Zanden range) left the designer Kazutoshi Yamada completely satisfied with the performance. As ‘how do I improve on this?’ is a significant motivational force in product design, improving on ‘complete satisfaction’ isn’t easy. Component parts might change with new components improving on old, and old components get discontinued, and these form subtle revisions in the design.
However, the change to the Model 1200 Signature is significant, as the move to a balanced design necessitated the development of a fully balanced LCR-type equalisation circuit. Given a phono cartridge is intrinsically balanced, and both the Model 3000 mk2 line preamplifier and Model 9600 mk2 mono power amplifiers in Zanden’s Classic line are fully balanced circuits as well, a single-ended only phono preamplifier seems a little out of kilter.
However, in reality, the move from single-ended to balanced operation is not without its potential pitfalls, and Yamada-san doesn’t do ‘pitfalls’ when it comes to the Model 1200. In theory, balanced circuits should be able to provide more stable and better-quality performance than single-ended circuits, but audible observations of the sound quality of single-ended circuit (especially a valve-based design) often conclude it has better sound quality than a balanced one.
However, Yamada-san’s skills at producing one of the best sounding amplifier systems (which just happens to use balanced operation). He invented a unique circuit that compensates for a hitherto-overlooked defect of the balanced circuit and installed it first in the Model 9600 series to demonstrate the better sound quality of the balanced circuit without defects. From here, it was a logical step to produce a line preamplifier that exhibits the same benefits. What is that defect? He’s not giving the game away!
Because the Model 1200 phono preamplifier is an LCR design (a passive stage using an inductor in series, instead of a series of resistor/capacitor filters for each shelf in the EQ curve), the move from single-ended to balanced is less straightforward. Initially, this was a research project, as it was not expected that this fully balanced EQ circuit would achieve the sound quality possible from the single-ended circuit. However, not only did this balanced design meet the performance of the single-ended circuit, it ultimately eclipsed it... and the Model 1200 Signature was born!