Preamplifiers

A condenser microphone must be combined with a preamplifier to provide impedance conversion, some filtering, and the capability to drive relatively long cables without significant signal degradation.

Brüel & Kjær offers a large selection of robust and acoustically optimised preamplifiers that allow operation in a wide range of environmental conditions. The high output current capability of our preamplifiers allows the use of extremely long cables, even with high sound pressure levels present at high frequencies. Preamplifiers are available in both ½" and ¼" dimensions for direct fit with the most used microphone cartridge sizes. For 1" and 1/8", cartridge adaptors are available.

The main types of preamplifier outputs are:

Constant Current Line Drive or CCLD (previously named DeltaTron^®)
Lemo

Type number	Diameter	Optimised	Calibration

2660 - 1-inch microphone preamplifier, very low noise, 20 dB gain, for Type 4179 Designed for very-low-level sound measurements.	1/2 and 1/1 Inch	Low-noise


2660-W-001 - 1-inch microphone preamplifier, very low noise, 20 dB gain, for Type 4179 Designed for very-low-level sound measurements. This is a modified version that can be used with PULSE using extension cable WL-1302.	1/2 and 1/1 Inch	Low-noise


2669-B - ½-inch microphone preamplifier, tapered, including cable AO-0428, B&K connector	1/2 Inch	Acoustical	Charge Injection Calibration


2669-C - ½-inch microphone preamplifier, cylindrical, LEMO 1B connector, no cable	1/2 Inch	Cylindrical	Charge Injection Calibration


2669-L - ½-inch microphone preamplifier, tapered, incl. cable, 7-pin LEMO connector	1/2 Inch	Acoustical	Charge Injection Calibration


2670 - ¼-inch microphone preamplifier, integral 2m cable with 7-pin LEMO plug Designed to operate over a wide range of temperature, humidity and other environmental conditions.	1/4 Inch	Phase	Charge Injection Calibration


2670-WB-1419 - ¼-inch microphone preamplifier, integral 2m cable with 7-pin LEMO plug Designed to operate over a wide range of temperature, humidity and other environmental conditions. Optimised for airbag measurements.	1/4 Inch	Airbag


2671 - CCLD microphone preamplifier for 1/2-inch prepolarized microphones, without cable Designed to be used in a wide range of environmental conditions and in narrow spaces.	1/2 Inch	CCLD


2673 - ½-inch microphone preamplifier with insert voltage facility	1/2 Inch		Insert Voltage Calibration


2695 - ½-inch short CCLD preamplifier Designed for acoustical measurements with a CCLD input module. Prepolarized microphones can be connected to the preamplifier.	1/2 Inch	Short CCLD


2699 - CCLD, A-weighted microphone preamplifier Designed to eliminate low-frequency disturbance caused by body boom and road noise which would otherwise be a source of error during in-car measurements using an A-Weighting filter.	1/2 Inch	A-weighted CCLD