CCP Pressure Standard Microphone Set GRAS 1/8″ 46DE (6.5-140kHz)

Introduction

• 46DE is a low-sensitivity pressure microphone set for sound measurements at high levels and high frequencies. It consists of a 40DD 1/8″ pressure microphone and a 26CE 1/8″ preamplifier.
• Normally a 1/8″ microphone is used with a 1/4″ preamplifier, but for 46DE GRAS has developed a 1/8″ preamplifier, making the 46DE microphone set the world’s smallest.
• A front-vented version is available, 46DE-FV 1/8” CCP Pressure Standard Microphone Set, Front Vented.

Typical application and use

• As the 46DE is smaller than any other measurement microphone, it can be used in any application where size constraints previously made it impossible to measure, be it separate microphones mounted in very confined spaces or a number of 46DEs mounted closely together for improved resolution. This fact opens the door to more application than we can suggest here.
• 46DE’s low sensitivity and small size makes it ideal for measurements of high levels and high-frequencies, and for measurements of im pulsive noise.
• The low sensitivity and very small form factor makes the 46DE extremely versatile with respect to signal levels, frequency range and applications.
• It can be used for measurements of turbulence and flow in wind tunnels and for engine testing. It is also ideal for measurements of impulsive noise from for example inflating airbags and noise from guns and explosives.
• The very small size makes it possible to measure inside even very small scale models – it can be fitted inside small scale models with minimal disturbance to the sound field. Also, it can measure the higher frequencies used in scale model testing.
• The 46DE is a pressure microphone set and as such optimized for acoustic measurements  of sound pressure at a boundary or wall; in which case the microphone forms part of the wall and measures the sound pressure on the wall itself. However, if used as you would a free-field microphone, it can be used up to at least 20 kHz before you need to apply free field corrections.
• 46DE is also ideal where a large number of microphones on a small area is desired.

Design

• The GRAS 46DE is a high-performance standard microphone set. In our clean-room environment the set is assembled and sealed with a label.

Microphone

• The microphone cartridge is the high-quality GRAS 40DD 1/8″ Prepolarized Pressure Microphone, designed for long-term reliability in multiple environments.

Preamplifier

• The preamplifier is the GRAS 26CE 1/8″ Preamplifier.
• The extremely small preamplifier is divided into three parts, 1) an input section, (3mm in diameter)  that is attached to microphone, 2) a length of cable and 3) the output section located at the other end of the cable in the same housing as the connector. In this way it has been possible to make the part of the preamplifier close to microphone very small, while the more space-demanding electronics in the output stage is located at the other end of the cable where it does not disturb the sound field or poses space-based restrictions on the mounting options.
• The three parts constituting the preamplifier are factory assembled as a complete unit that cannot be disassembled. The cable between the input and output section is 1 meter, longer cable lengths are not available as they would influence the performance negatively.
• This cable is a special multi-screened type spefically developed for 46DE. Despite the extra screening, the 46DE microphone set is a little more sensitive to EMC than microphone sets with conventional preamplifiers.