Posted to News on 14th May 2007, 13:52
Preamplifier includes high-pass and A-weighted filters
PCB Piezotronics is introducing model 426A11, a 1/2inch preamplifier that operates from ICP sensor power. The preamplifier enables users to select 0 or +20dB of gain and either a 20Hz (-3dB) high pass filter or A-weighted filter output response, in lieu of a flat unfiltered response via two switches located on the external diameter. An overload detector senses both polarity overload signals in front of the filters. The unit comes with TEDS as standard and is programmable upon request.
The Model 426A11 preamplifier includes both A-weighted and selectable high-pass filters for automotive or aerospace cabin testing requirements. The A-weighted filter attenuates signals less responsive to the human ear, normally below 1kHz and above 4kHz. This filter represents how the human ear perceives sound. To make the cabin less noisy, a random incidence microphone (such as PCB Model 377B20), designed to measure sound from different angles of incidence, along with A-weighted filter, is a good choice of test equipment.
When an 'in-cabin' automotive test is performed, manufacturers will sometimes dangle a microphone and preamplifier inside the car's cockpit. Any movement will cause the microphone to sway, generating low frequencies that are not the target of the test and thus adversely affecting results. The high-pass filter eliminates low frequencies, which are not of interest, consume the dynamic range and overload the output signals. This filter, along with the low noise rating of the microphone and preamplifier combination, helps to minimise the noise floor.
The 426A11 is designed to work in a wide range of temperatures (-20degC to +70degC), which makes it an excellent choice for under-hood automotive noise source identification, or brake noise tests, where higher operating temperatures may be required. The product can also be used in standard automotive Pass By Tests, which are conducted to minimise the noise outside the vehicle during operation.
PCB offers the 426A11 with the company's Total Customer Satisfaction policy. This means that if, for any reason, at any time, users are not satisfied with the product, it can be returned for an exchange or refund.
