The VHD Pre Module for the popular 500 format modular rack platform makes the uniquely versatile VHD based preamp technology from Duality, SSL's industry leading large format studio console, available for studios of all sizes.
The VHD Pre is an immensely versatile recording and processing device. It can deliver ultra clean SSL SuperAnalogueTM grade recordings but also features a switchable VHD mode. SSL's patented Variable Harmonic Drive (VHD) system uses a 100% analogue signal path to generate rich harmonic distortion. As you increase VHD input gain, the Variable Harmonic Drive process introduces either 2nd or 3rd harmonic distortion or a blend of the two to your source material. At lower gain settings it adds gentle valve-style warmth or a touch of transistor edge. As the gain is increased the more extreme the distortion becomes until at high gain settings it delivers fierce trashy transistoresque grunge. The VHD Pre gives the user ultimate versatility from a studio grade preamp. Whether it's ultra-clean traditional SSL, subtle warming or totally trashy transistor distortion, VHD will change your expectations of what a preamplifier should deliver.
The VHD section of the VHD Pre Module has three rotary controls: a Drive control selects 2nd harmonic or 3rd harmonic distortion or a continuously variable blend of the two. A +20/+75dB gain control sets input level. A -20/+20dB trim control adjusts the output level from the circuit to enable level matching with other devices, because by its nature the VHD circuit can significantly increase signal levels. The VHD Pre Module has a selection of other essential professional preamp features: a signal present LED, a switchable 15Hz to 500Hz LF Filter section, Hi-Z impedance switch for mic impedance matching, +48V phantom power, PAD to enable the VHD system to be used as a line level processing device and a Phase Invert Switch.