(Click on image for larger photo) The All-In-One Tracking Tool for High Resolution Recording The Quartet is a modern class A tube design which includes: The tube Mic/DI Preamp from the MDP-1 The tube Opto-Compressor from the OCL-2 using our proprietary optoelectronic cell A new three band tube EQ with HI and LO shelving and peaking MID band A new de-esser design using opto-inductive filtering and a highly selective detector The Mic/DI, EQ and Compressor/De-Esser can be patched out and used independently. Transformerless or transformer-balanced main output Gold-plated switch contacts, I/O connectors and tube sockets Polypropylene caps and metal film resistors (pairs matched to 0.1%) Fully regulated high voltage (300V) and filament and bipolar power supplies with soft-start warm-up and output muting Custom toroidal power transformer with shield for minimum hum 120V or 240V ac voltage switch on the rear panel.    The Quartet is an all-purpose recording tool designed with the ultimate in sound quality and flexibility in mind. We have combined four elements - Mic/DI preamp, Opto-compressor, EQ, and De-esser -into a fully integrated package that it makes it easy to track any source. In addition, the Mic/DI preamp, EQ and Compressor/De-esser are completely independent entities that can be patched out and used separately - a hand feature that makes it a valuable tool for mixing as well as tracking.    The Mic/DI preamp, borrowed from our acclaimed MDP-1, can handle mics, pickups, keyboards, or line-level signals. It features phantom power, input pad, phase reversal, and a switchable lo-cut filter. Independent gain and output controls permit overdrive of the tube stage to vary the harmonic content of the preamp.    The Opto-Compressor, derived from the popular OCL-2, uses our proprietary optoelectronic cell, and has a sound all its own. It can be used in one of four modes: Fast (for 'invisible' compression), Average (rms responding), a new Vintage mode (with program-dependent response), or full manual operation.    Our new 3 band tube EQ, a modifed Baxandall design, is simple but very effective. The HI and LO bands have up to ±10dB of shelving at 15, 10 and 7 kHz, and 50, 100 and 200 Hz respectively. The MID band has a broad ±10dB peaking response centered at 0.7, 1.6, 2.2, 3.3, 5.0 and 6.5 kHz. The EQ can be placed before or after the compressor with the flip of a switch.    The new De-esser, which is implemented within the opto-compressor, uses an entirely new approach. A highly selective inductor-based detector triggers a very fast opto-inductive notch filter. The user can control the depth of the notch, which in turn controls amount of sibilance to be removed. When not triggered, the de-esser is out of the signal path entirely. (Click on image for larger photo)