GEORGE MASSENBURG LABS 8304 Series II Four-Channel Microphone Preamp

The GML 8300 Series II Microphone Preamps set the industry standard for pristine audio clarity and reference-grade transparency. Now available in 4-channel (8304) versions, these preamps embody GML’s commitment to high-fidelity sound through continuous research and precision engineering. The Series II features a redesigned +48V phantom power supply and phase reverse switches on the front panel, further enhancing the signal purity with exceptionally low noise.

Engineered with an all-discrete, bipolar transistor circuit, the 8300 Series II is completely transformerless, free from FETs, ICs, and electrolytic capacitors in the signal path. Direct-coupled outputs with active servo correction ensure zero DC offset while preserving the natural tonality. Gain control ranges from 10dB to 65dB in exact 5dB steps, and a +24dBv clip indicator provides a safeguard against overloads. Designed to fit seamlessly into a 1U rack, the GML 8302 and 8304 Series II preamps are essential tools for audio professionals seeking uncolored and accurate sound.

Features:

• 4-channel (8304) versions for flexible studio configurations
• Completely transformerless, all-discrete bipolar transistor design for unmatched transparency
• Front-panel phantom power and phase reverse switches for quick adjustments
• Direct-coupled output with active servo correction to eliminate DC offset
• Gain control from 10dB to 65dB in precise 5dB steps with a +24dBv clip indicator
• 1U rack space design, including external power supply (GML Model 8355) with 5-pin XLR power cable

Specifications:

• Input Impedance: 1kΩ balanced XLR, 80 dB common mode rejection at 100Hz & 10kHz
• Max Input: +12.4 dBv (minimum gain setting)
• Throughput: 50 V/μs minimum, symmetrical at 30 dB gain
• Distortion: 0.0015% at 30 dB gain / 0.007% at 70 dB gain
• Effective Input Noise: < -126.5 dBv with 150 ohm / < -129.5 dBv with 0 ohm (400Hz – 30kHz)
• Frequency Response: +0, -0.2dB at 10Hz & 50kHz / +0, -0.3dB at 1.7Hz & 260kHz
• Phase Shift: 22° at 10Hz & 260kHz
• Output Level: +27.4 dBv at clip, unbalanced XLR
• External Power Supply: +28V, separate ground and chassis connections
• Chassis Dimensions: 1.75″ x 19″ rack mount, 10″ deep, satin black anodized finish