Prima Donnas: 2x56 Guide

Use tube dampers or high-mass isolation platforms to combat microphonics.

Always use a soft-start circuit to protect those precious 1930s filaments. Prima Donnas: 2x56

These tubes are notoriously "microphonic." If you tap the chassis of the amplifier—or even walk too heavily across a hardwood floor—you might hear a "ping" through your speakers. Use tube dampers or high-mass isolation platforms to

In audiophile circles, this specific 2x56 setup (meaning two Type 56 tubes acting as the heart of the preamp or driver stage) is called a Prima Donna for three reasons: In audiophile circles, this specific 2x56 setup (meaning

It features a distinct "shoulder" glass shape (S-12 or ST-12).

For the DIY builders and the spec-heads, the 2x56 setup usually follows a specific architectural philosophy: 2.5 Volts (AC or DC). Amplification Factor (µ): Roughly 13.8. Plate Voltage: Typically run between 180V and 250V.