Chameleon Labs 7603 Microphone Preamp & EQ

• Selectable 300Ω or 1200Ω Mic Input Impedance

• Custom VU meter (input/output) with calibrated ballistics

• Relay based selection of Line / Mic & DI Inputs

• Overload input and output indicators

• Reverse Phase Switch

• Universal, on-board power supply

Its fundamental design architecture retraces the path of revered, classic pre-amps of the past as well as our popular 7602. Our engineers at Chameleon have worked tirelessly in developing new, pivotal components that allow us to take the next step forward in performance.

These enhancements start with all-new proprietary microphone and line-level input transformers that feature custom-made nickel laminations and bobbin assemblies—all designed in-house. By developing new engineering processes focused on the material science associated with lamination manufacturing, Chameleon was able to develop a lamination “recipe” that delivers optimized audio performance, providing the 7603 with high bandwidth and incredibly low distortion.

Design of our new transformers was based around the need to capture and preserve the delicate audio input signals’ truest form, and so they are enclosed in high permeability MuMetal enclosures, designed to protect sensitive audio signals from radio frequencies, spurious and parasitic noises.

Once your audio exits the input transformer, our circuit boards are carefully crafted to ensure the highest possible signal integrity. As a starting point, we developed a new discrete audio input gain stage based on our vision for a solid topology that provides extremely low noise, high dynamics and extreme bandwidth. All of the 7603’s operational amplifiers used throughout the device are based on this topology.

The 7603 features EQ stages with four different available adjustments—Variable High Pass, Low Frequency Shelving, Mid Frequency and High Frequency Shelving. Our engineers made a conscious decision to stay with the same, desirable, inductor-based topology that made our 7602 so popular, however we implemented our new discrete Op Amp to drive signal through a new set of custom Chameleon designed and manufactured inductors, providing the musicality we all love to use.

The output stage of the 7603 is unique with respect to its design and performance. It can be described as a variable-gain circuit that simultaneously adjusts both the input and output levels in order to generate a lower noise floor and extraordinary audio performance.

The 7603 pre-amplifier provides a desirable set of user selectable functions designed to make the unit flexible and an integral part of the artistic process, incorporating a full portfolio of traditional features as well as some not commonly seen on other pre-amps.

Microphone input impedance can be selected between 300 and 1200 ohms, providing a method by which a microphone can be more ideally matched to the input stage and making it easier to get the best from lower output microphones such as ribbon-based designs.

We added a low impedance Direct Input on the front panel for plugging in instruments such as guitars that can be run through the line input stage, and added a precision VU meter with custom ballistics for visual monitoring of either the input or output levels.