Thinking beyond 47k: SUT primary loading and its effects on damping

The third white paper from the Clinamen technical library: 'Thinking beyond 47k. SUT primary loading and its effects on damping' is available in PDF format. You can download it here

Topics covered in White Paper No. 3:  "Thinking beyond 47k. SUT primary loading and its effects on damping "

Every Moving Coil cartridge exhibits an ultrasonic resonance whose control is critical for tracking capability and sound quality. While mechanical damping and intrinsic electromagnetic damping are unalterable manufacturing constraints of the phono pickup, External Electromagnetic Damping (EED) represents the sole tuning lever available to the user to balance the response of the moving assembly.

In this context, the 47 kΩ value established as the standard input impedance in MM phono preamplifiers is a historical legacy that limits the true potential of the cartridge-SUT pair, often forcing compromises or incorrect interfacing approaches

In White Paper No. 3, we will examine:

• The role of External Electromagnetic Damping (EED): How much the external dissipative load contributes to fulfilling the cartridge's total damping requirement.

• The limitation of fixed 47 kΩ MM phono inputs: Why changing the step-up ratio to modify the reflected load is a methodological error, and the importance of having a phono input with variable impedance (from 22 kΩ to 270 kΩ).

• SUT self-resonances and resistive/capacitive damping: How the phono load interacts with the intrinsic resonances of the step-up transformer, and why downstream capacitance must be kept to a minimum to prevent shifting resonances down into the audio band.

• Decoupling damping systems: The advantages of leaving a high-quality SUT "unbraked" using light loads (e.g., 270 kΩ), avoiding rigid coupling between the transformer's damping and that of the cartridge.

• The Direct External Electromagnetic Damping method: How to apply a loading resistor in parallel with the SUT primary to provide the cartridge with the exact desired damping without affecting the step-up transformer's behavior.

Optimization notes:

Selecting the SUT ratio "n" for proper voltage management and adjusting the cartridge load (damping) independently are two operations that should be decoupled. This document outlines the physical analysis and practical methodologies to manage the cartridge-SUT-phono triad with maximum rigor.

Each PDF is part of a technical series, currently divided into eight topics, created to be preserved and consulted over time. Together, these white papers form an original library resulting from over fifteen years of research and development in the Clinamenaudio laboratory: an open work synthesizing the principles of audio design according to the 'Natural Way.'

The price of this very special technical white paper is 20 euros. Rather than a simple purchase, your download represents direct support for independent research that addresses high fidelity through objective analysis and instrumental verification, in an industry where myths and trends all too often take the place of physical facts.

You can download the PDF here: "Thinking beyond 47k: SUT primary loading and its effects on damping"