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Reactenuator - DIY Reactive Variable Tube Amp Attenuator

A variable attenuator (from silent to -6dB) that allows keeping a tube amp's sound and feel at lower volume (within reason). The idea is to send as much of the signal that is NOT going through the speaker into a reactive load. An L-Pad is used just before the speaker to fine tune the output level.

This device will be optimized for live use, where one wants to run an amp at its "sweet spot" while having the option of reducing the volume of said sweet spot.

This project draws inspiration from Randall Aiken's paper on reactive load.

This is an on-going project, make sure to subscribe to my Youtube Channel to get updates.

Schematic


This is v0.1, aka the proof of concept. It only simulates the inductance of a speaker coil, not the resonance. It suffers from limited reactance at higher attenuation levels. But it works!

This is v0.2, which has not been built yet. It adds a bigger inductor in parallel with a big cap to simulate the resonance peak. It also adds 2 extra -6dB stages that allow sending more signal through the reactive circuit compared to the variable L-Pad to allow as much as 18dB of attenuation before the reactive part of the circuit starts to have a reduced effect. Other additions: line output, tuneable reactive circuit and ability to run purely as a dummy load for silent recording