General Description

The Shure Model 577B SONOBAR® Microphone is a handheld dynamic microphone designed for communications and paging applications that require highly intelligible, low noise output. It can be used in all types of mobile communications, from amateur radio to helicopter news and traffic reports. It is also suitable for public address and paging systems in noisy areas such as factories, airport terminals, and restaurants.

The 577B represents a significant improvement over most microphones with anti-noise features. Shaped frequency response, directionality, and distant sound discrimination contribute to total noise reduction. The microphone operates on the pressure-gradient principle and has two sound entry ports spaced a small distance apart.

The modular design of the 577B greatly facilitates field servicing. The cartridge, switch, and cable can be replaced in a matter of minutes, if necessary.

The 577B is built to withstand mechanical shocks, vibration, high temperatures, and humidity. The exclusive ARMO-DUR® case is impervious to oil, grease, fumes, salt spray, sun, and corrosion. he “Million-Cycle” press-to-talk switch ensures years of reliable service.

A mounting bracket is supplied to provide convenient hang-up when the microphone is not in use.

Features

  • Frequency response tailored for close-talk operation
  • Extremely effective noise cancellation
  • Dynamic microphone cartridge
  • Modular design
  • "Million cycle" leaf-type press-to-talk switch
  • TRIPLE-FLEX® cable provides three to four times the flex life of most coiled cords
  • Rugged ARMO-DUR® case
  • Built-in hang-up button and supplied mounting bracket

Operation

For optimum performance and maximum rejection of background noise, place your upper lip against the lip guard, approximately 25 mm (1 in.) from the grille. Hold down the push-to-talk button while talking normally.

Internal Connections

The 577B is a balanced-line, low-impedance dynamic microphone. It is designed for direct connection to low-impedance microphone inputs and/or installations where long cable lengths are needed. It includes a four-conductor (two conductors shielded) coiled-cord cable and a double-pole, single-throw, leaf-type switch. The WHITE and GREEN leads are the “hot” audio conductors; the shield is connected to microphone circuit ground. The RED and BLACK leads control the switch circuit. The microphone circuit is open when the switch is open, but can be easily modified for normally shorted operation. Refer to Figure 1.

FIGURE 1: INTERNAL CONNECTIONS

INPUT TYPE WIRE COLOR FUNCTION XLR CONNECTOR ¼ IN. PHONE PLUG
BALANCED WHITE AUDIO+ PIN 2 TIP
GREEN AUDIO- PIN 3 RING
SHIELD CHASSIS GROUND PIN 1 SLEEVE
UNBALANCED WHITE AUDIO -- TIP
GREEN AUDIO GROUND -- SLEEVE
SHIELD CHASSIS GROUND -- SLEEVE

Circuit Modification

To modify the microphone circuit for normally shorted operation, proceed as follows:

  1. Remove the three No. 6 Phillips screws from the back of the microphone case.
  2. Separate the front and back sections of the case, and remove the press-to-talk switch button.
  3. Unsolder or clip the GREEN cable lead from the press-to-talk switch solder lug.
  4. Solder the GREEN cable lead to the GREEN cartridge lead on the press-to-talk switch solder lug.
  5. Replace the press-to-talk switch button in the front section of the case, then join the case halves together and install the No.
  6. Phillips screws removed in Step 1 above.

Specifications

Type

Dynamic (moving coil)

Frequency Response

100 to 5,000 Hz

Impedance

at 1kHz

EIA rated at 150 Ω (175 Ω actual)

Output Level

at 1kHz, open circuit voltage

-66.0 dBV/Pa (0.5 mV)[1]

Sensitivity

Equivalent to 32 dB SPL in 1 millioersted field

Operating Temperature Range

-40° to 74° C (-40° to 165° F)

Switch

Double-pole, single-throw, leaf-type, Push-to-Talk

Cable

Non-detachable, 1.8 m (6 ft), neoprene-jacketed coil cord, four-conductor (two conductors shielded)

Housing

Two-tone gray, high impact ARMO-DUR®

Net Weight

330 g (11.6 oz.)

FIGURE 2: TYPICAL FREQUENCY RESPONSE

FIGURE 3: OVERALL DIMENSIONS

Certifications

This product meets the Essential Requirements of all relevant European directives and is eligible for CE marking.

The CE Declaration of Conformity can be obtained from: www.shure.com/europe/compliance

Authorized European representative:

Shure Europe GmbH

Headquarters Europe, Middle East & Africa

Department: EMEA Approval

Jakob-Dieffenbacher-Str. 12

75031 Eppingen, Germany

Phone: +49-7262-92 49 0

Fax: +49-7262-92 49 11 4

Email: info@shure.de

Accessories

Supplied Accessory

Mounting Bracket (3 per kit)

Replacement Parts

Cartridge for 577B R98B
Cable for 577B C117
Switch for 577B RK338S

Service Information

For additional service or parts information, please contact Shure's Service department. Outside the United States, please contact your authorized Shure Service Center.