Bruel & Kjaer 2807 Two Channel Microphone Power Supply

The Bruel & Kjaer 2807 is a dual-channel microphone power supply that delivers polarization voltage, preamplifier supply power, and impedance transformation for condenser microphone systems. It provides stable 200 V DC polarization with ±0.5% regulation and multiple preamplifier supply outputs, enabling simultaneous multi-channel sound and vibration measurements in laboratory and field environments. Independent attenuation control per channel, external switching capability, and excellent cross-talk performance make it suitable for complex measurement setups requiring flexible signal routing.

## Technical Specifications

**Polarization Voltage:** 200 V DC, stabilized to better than 0.5% across ±10% mains variation.

**Preamplifier Supply Outputs:** +150 V at 2 mA; +12.6 V anode at 100 mA; +6.3 V heater at 200 mA.

**Signal Path:** 2 Hz to 200 kHz (±0.2 dB); extended to 200 kHz (±0.5 dB); flat within ±0.1 dB across 20 Hz to 20 kHz.

**Output:** 28 V RMS (2 Hz to 20 kHz); maximum 8 mA RMS per channel; output impedance 13 Ω in series with 4.7 µF.

**Attenuation:** Adjustable 0 dB to approximately −40 dB per channel via multi-turn potentiometer; insertion loss less than 0.15 dB (2 Hz to 200 kHz).

**Noise & Isolation:** Inherent noise 80 dB to 20 kHz, > 60 dB at 200 kHz.

**Switching:** External control socket for input selection; typical switching time 1 ms; chopper frequency approximately 0.5 Hz.

**Power Requirements:** 100, 115, 127, 220, or 240 V AC (50–400 Hz) at ±10%; 10 VA consumption. Complies with IEC 348 safety class I. Outputs short-circuit protected.

## Key Features

• Two independent channels with separate signal level adjustment potentiometers
• Input impedance 50 kΩ at microphone socket pin 4
• Manual and automatic channel switching via external control socket
• Standard B&K 7-pin microphone input sockets and output sockets
• Compact modular construction (2/12 of 19″ rack module)
• Dimensions: 132.6 mm H × 69.5 mm W × 200 mm D; weight 2.2 kg

## Compatibility & Integration

Designed for Bruel & Kjaer preamplifier types 2615, 2618, 2619, 2627, 2633, 2639, 2645, and 2660. Fits B&K modular rack system for flexible laboratory and field deployment.