GC Audio Inherit Graham Langley Cartridge

Overview by Graham Langley
“When I first discovered the GC Audio “Inherit” system I was impressed by the innovative concept of interchangeable microphone amplifier cartridges allowing customers the flexibility and freedom of choice to enhance their creativity.

The thought that had gone into the design and the build quality of the product also appealed to me. I was therefore honoured when invited to contribute a “Langley” microphone amplifier cartridge design. I designed a custom preamp to completely match the capabilities of the Inherit System.

The circuit is reminiscent of the topology that I used in Amek console microphone amplifier designs in the 1970s and 80s but with significant improvements, particularly in noise performance.

This cartridge is intended to provide a clean, transparent sound over the full audio frequency
spectrum.

I hope you enjoy using this addition to your “Inherit” cartridge collection.”

The synoptic is a premium differential preamp composed of paired transistors and constant sources. It is digitally controlled in order to isolate the analog signal in the metal cartridge (and therefore separated from the radiation of the linear power supply). Common mode rejection and output balancing are manual for each cartridge manufactured to achieve optimized values. The resistive ratios are composed of low value in order to obtain an optimal EIN.

This preamp is perfect for the user who wants uncompromising sound pickup with a transparent and powerful result.

Input gain ranging from 16dB to 60dB in 4dB steps has been chosen.

Features

• PAD: -20dB
• Input Impedance: 5K Ohms
• EIN (150 Ohms source @ 60dB, 22hz/22Khz) = Better than -127dB
• THD + N: 0.04%
• Commutateur de gain Grayhill à 12 crans 1) 16 dB, 2) 20 dB, 3) 24 dB,  4) 28 dB, 5) 32 dB, 6) 36 dB, 7) 40 dB, 8) 44 dB, 9) 48 dB, 10) 52 dB, 11) 56 dB, 12) 60 dB (+/-1dB)

With the Inherit Rack

• Digital gain command to keep the analog sensitive signal path in the cartridge
• Linear pot for Output Level
• 10 Segments VU meter, factory calibrated 0 dB VU: +4dBu
• Pre/Post toggle of the LED meter for the output level pot to obtain a very high gain without saturating the converter
• Low Cut: 80 Hz - 120 Hz – 12dB / octave slope
• 7 internal DC ultra-low noise linear power supplies
• PAD: -20dB
• +48V Phantom Power
• Phase invese
• DI input impedance: 500K ohms
• Gain command with a 12 Steps Grayhill commutator - 1) 20dB, 2) 28dB, 3) 34dB,  4) 38dB, 5) 41dB, 6) 44dB, 7) 47dB, 8) 50dB, 9) 53dB, 10) 56dB, 11) 62dB, 12) 70dB (+/-1dB)

All measurements were made with Audio Precision Device, 150 ohms Input load and 100 Kohms output load.

Gain Vs Frequency

THD + N Vs Frequency

Phase