Classic type
The classical preamplifier has an easy to understand concept. It is basically a unity gain amplifier with extremely high input impedance and very low input capacitance.
The classical preamplifier has an easy to understand concept. It is basically a unity gain amplifier with extremely high input impedance and very low input capacitance.
Despite its origin in the vibration transducer world, the Constant Current Line Drive (CCLD) principle is increasing in popularity in the area of sound and measurement applications. Different manufacturers market transducers using the CCLD principle under different names.
Microphone Preamplifiers by HBK are robust and acoustically optimized for a wide range of environmental operating conditions. The high‐output current capability of our preamplifiers is able to drive extremely long cables without signal degradation - even when measuring high sound pressure levels present at high frequencies. The HBK CCLD and classical preamplifier designs fit our range of 1/2" and 1/4" microphone cartridges.
HBK offer 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 HBK preamplifiers allows the use of extremely long cables, even with high sound pressure levels present at high frequencies.
A CCLD input can be connected to both microphones and vibration sensors (and many other sensors with CCLD output). Due to the working principle the signal is superimposed on a DC voltage. This DC bias voltage is typically around 12 V. Bias drift (over temperature or time) will reduce the dynamic range.
Due to the lower DC supply voltage (typically 20 – 28 V DC compliance voltage out of the front-end), there is some limitation in the upper limit for a CCLD solution. Another limitation of CCLD solution is that only prepolarized microphones can be used and that CIC is not available.
This, however, in many practical applications is happily accepted to reap the benefits of CCLD: Ease of use and cheap cables!