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Output Transformer (OPT) Calculator

First-cut OPT design for single-ended or push-pull stages. · in Transformers

audiomatching

First-cut OPT design for single-ended or push-pull stages. Enter Zp, speaker impedance, output power and lowest frequency. Get turns ratio (Np:Ns), minimum primary inductance, air-gap thickness (SE), and a DC + signal flux check to catch core saturation.

How to use

Two modes — Single-ended / Push-pull.

What it's for

Valve OPT first cut: turns ratio, minimum primary inductance, air gap and the flux check.

You enter

  • Primary impedance (Zp), speaker impedance, output power, lowest frequency, primary DC current (SE), tube plate resistance (rp), and core data (µr, design Bmax, current density).

You get

  • Turns ratio (Np:Ns), primary and secondary turns, effective source resistance, minimum primary inductance for your bass end, air gap and shim thickness for SE.
  • Flux check — DC flux, signal flux at the low end, and the total, flagged if the core saturates.
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