The Stereophonic Zoom is a document which describes a variable dual microphone system for stereo recording. The system described acts as a spacing unit which can alter the distance between microphones as well as the angle in which they face. The interaction between distance and angle creates a variable stereo width.
Williams argues against the implementation of a singular system for stereo recording because “rather than reduce the choice of systems, an effort must made to increase the number of systems available. Each sound recording engineer must have the largest possible selection of systems to choose from, in order to solve the specific problems presented by a particular recording situation and, to express his own personal interpretation, as freely as possible,”.
He describes the accepted standard listening condition pictured below:
Williams continues by describing the importance of the listening environment in determining the characteristics of the stereo width of a recording. He makes recommendations for treatment following the IEC guidelines for a standard listening room.
Williams goes on to describe how sounds are localized, which I describe throughout my comparison of stereo mic techniques, but include timing differences, varying the intensity between two speakers, or a combination of the two methods.
As per my earlier postings, I opted for an X/Y mic setup, meaning that I’m relying primarily on amplitude variation between the two channels for my stereo.
Williams goes on to describe the specs of the “stereophonic zoom” recording device in great detail, indicating distance v. angle, frequency responses, and the relation between direct in reverberation sound through graphs, and describes the test phases and limitations of the device during testing. This section, while interesting has little to do with my way forward, and can be summarized by saying, on paper this system looks good, though like all things audio, it’s subjective and I’d have to hear results before I’m sold.