United Studio Technologies - Replay Box

The Replay Box from United Studio Technologies is a direct descendant of the hand-crafted reamplifier boxes designed by Chad Kelly, long regarded as confidential references in high-end studios. This commercially successful version retains the fundamental principle of these historic designs, while adding industrial consistency, increased robustness and ergonomics designed for modern use, both in the studio and on tour.

The central element of the Replay Box is the integration of two totally independent reamplification circuits, each based on a specific transformer. Transparent mode uses a custom 5043 transformer wound in the USA, designed to guarantee maximum signal isolation and extremely faithful reproduction. This circuit accepts a balanced or unbalanced line signal and delivers an unbalanced output perfectly suited to direct drive from an amplifier, pedal or external processor, with an additional passive gain of around +3dB.

Harmonic mode introduces a different approach, using a second, deliberately more colourful transformer. This circuit subtly modifies the bass and upper midrange response, adding slight harmonic distortion and a controlled phase shift in the sub-bass, thickening the signal and producing a denser, more aggressive sound. This mode is particularly appreciated for giving character to guitars, basses or sound textures that require more substance.

The Replay Box has been designed to solve two recurring problems with reamping: noise and lack of gain. Thanks to its entirely passive architecture, its top-of-the-range transformers and its true ground isolation, it allows you to work without hum, without ground loops and without recourse to external boosts or preamps. Its aluminium chassis, recessed design and removable screw-fixed feet make it a reliable tool, equally at home in a studio rack or on stage.