General Description, Principles of Operation

Battery Indicator: 8-hour battery life, 1 week data retention

Calibrator:	External calibrator
Temperature:	-15° to 50°C operating; -40° to 60°C storage (battery removed).
Humidity:	0 to 95% non-condensing
Magnetic Field Effects:
	Negligible below 50 Oersteds at 50 to 60 Hz
Size:	5 ½ x 2 ¾ x 1 3/8 inches
	(140 x 70 x 40 mm)
Weight:	14 ounces (400 grams)
Construction:	Cast aluminum housing with tamper-, water-, and dust-resistant security cover.

GENERAL DESCRIPTION

The microprocessor based M-27 Noise Logging Dosimeter can be used as a personal noise dosimeter, an area monitor, and as a noise survey instrument. It can be used to check compliance with the requirement of the Occupational Safety and Health Administration (OSHA), or as a community or Department of Defense noise logging dosimeter.

The M-27 simultaneously monitors multiple noise functions for 3 separate dosimeters as well as sound, peak, and maximum levels, and run, pause, upper limit, and real or elapsed times. It also stores, displays, and prints out data for 16 different events.

The readings can be taken at any time without destroying or resetting the data. Even turning the unit off will not destroy the internal memory.

A water- and dust-resistant cover protects the unit from the elements and against tampering.

The unit is small enough to be placed in a shirt pocket or on a belt with the microphone clipped to the shirt collar or on the shoulder. The microphone can be attached to a bracket for use as a sound level meter. Or the unit can be mounted on a tripod for area surveys.

The M-27 is powered by a single 9-volt transistor battery with an 80-hour battery life. A low battery indication is displayed 8 hours before the end of life of an alkaline battery.

PRINCIPLES OF OPERATION

General

The M-27 Noise Logging Dosimeter uses an 8 mm omnidirectional ceramic microphone buffered by a high impedance FET input stage.

The electronics utilizes low power circuitry for long battery life, maximum stability, and high reliability over a wide range of environmental conditions. A block diagram of the M-27 is shown in Figure 3.

Weighting Characteristics

The M-27 has both "A" and "C" weighting characteristics as shown in Figure 4. For OSHA and most noise measurement requirements, the "A" weighting should be used. The "A" weighting has a response similar to the human ear. The "C" weighting is used for measuring noise reduction in hearing protectors and for other scientific purposes.

M-27 specifications

AudioQuest M-27 is a standout speaker designed for audiophiles who demand high performance and exquisite sound quality. As part of AudioQuest's commitment to providing unparalleled audio experiences, the M-27 blends advanced technologies with premium materials to deliver exceptional musical clarity and accuracy.

One of the key features of the M-27 is its innovative driver design, which utilizes a new-generation ceramic cone. This cone is engineered to minimize distortion while enhancing transient response. The result is a speaker that offers a clear, detailed sound across a wide frequency range. The drivers are also matched with an advanced neodymium magnet system, ensuring efficient energy transfer and improved bass response.

The M-27 is equipped with a sophisticated crossover network that has been meticulously designed to maintain the integrity of the audio signal. By employing high-quality components, including precision resistors and capacitors, the crossover effectively divides the audio signal into specific frequency bands, allowing each driver to perform at its best. This attention to detail not only enhances sound quality but also helps to create a more cohesive listening experience.

Another notable characteristic of the M-27 is its sturdy and well-constructed cabinet. Built from high-density MDF, the cabinet is engineered to minimize resonance and vibration, which can color sound. Moreover, AudioQuest has incorporated internal bracing to further enhance structural integrity. The elegantly finished exterior not only adds to the speaker's aesthetic appeal but also serves to complement various home decors.

Connectivity is made simple with the M-27, thanks to its standard speaker terminals that accommodate a wide range of wire gauges. This flexibility allows audiophiles to use their preferred cables for optimal performance. Additionally, the speaker is designed to work seamlessly with a variety of amplifier configurations, making it an adaptable choice for different audio setups.

Incorporating these advanced technologies and design principles, the AudioQuest M-27 is not just a speaker; it's a gateway to an immersive listening experience. With its ability to reproduce sound with remarkable accuracy, it will appeal to discerning listeners looking to elevate their audio playback and enjoy their favorite music in a whole new light. Overall, the M-27 stands as a testament to AudioQuest's dedication to crafting high-quality audio products that meet the needs of serious music enthusiasts.