The Portia Street Stomp uses a wonderfully low inductance steel core transformer with quadrifilar windings (four identical windings). This allows for a variety of configurations to get a wide range of tones out of the both the transformer itself and the driving circuit.



The Portia Street Stomp allows you to vary the tone in three ways: 

  • The transformer “Ratio” switch selects between four configurations. Two configurations are effectively 1:1 but use 1 or 2 windings to increase or decrease the total inductance (which will enhance the behavior of the “Primary” knob). In 1:2 and 2:1 mode there will be a 6 dB step up or step down respectively, and the load being presented to the source amplifier will also change.


  • The “Primary” knob allows the source impedance presented to the transformer to be changed continuously, which increases the harmonic distortion of the passive circuit and slightly changes the frequency response.

  • The “Secondary” pot allows the load across the transformer secondary to be varied. This will change the current drive of the source amplifier. A higher load will increase the current demand at a given signal level, which will cause more distortion from the source amplifier. The load pot will also interact with the transformer windings to change the overall tone.


  • Harmonic distortion tone shaping and warmth box.

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