Motional Feedback Disk Recording System Design


In 2015, J. I. Agnew started developing a high-end cutting amplifier for disk mastering systems, to be used with motional feedback stereophonic cutter heads. During this process, he investigated the design and implementation problems of such transducers in great detail. As usual, he documented his progress, which evolved into an engineering report, titled "An Investigation of Motional Feedback Disk Recording System Design", which was accepted for publication in the November 2018 issue of the Journal of the Audio Engineering Society, following the customary peer review process.

This is highly recommended reading for anyone developing, restoring, or repairing disk recording equipment or trying to understand how this technology works.

One of the prototype systems described is in regular use at Magnetic Fidelity, having produced several highly successful album masters by now.

Another effect of this investigation is the invention of a unique type of transducer, which forms the basis for the Agnew Analog Stereophonic Cutter Head.

Correspondence with regards to this topic is strongly encouraged. Please feel free to contact us with any thoughts, suggestions, links to your PhD thesis, creative ideas, comments, and so on.

Physical copies of the journal can be obtained directly from the AES Publications Department ( It is also available online:

Citation: J. I. Agnew, "An Investigation of Motional Feedback Disk Recording System Design", J. Audio Eng. Soc., vol.66, no. 11, pp. 966-978, (2018 November).