Shure Models 55 and 55SH Series II Unidyne
dynamic cardioid, including the Stromberg-Carlson MC31
and the Shure 556A and 556B supercardioid microphones

The Stromberg-Carlson MC31 version of the Shure 55 Unidyne.

View another Stromberg-Carlson mic.

Specification sheet for the older Model 55A, B, and C series.

Another more comprehensive Radio’s Master catalog ad.
Microphones seen on this site are not for sale.
Prices are shown for historical purposes.

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The Shure Model 55SH Series II
Unidyne II dynamic microphone

General
The Model 55SH Series II provides the Shure classic UNIDYNE II design coupled with modern acoustic components to meet today’s performance standards. This microphone is excellent for vocal pickup with its characteristic Shure presence peak.

The 55SH Series II has a cardioid (uni-directional) polar pickup pattern that minimizes sound pickup from the rear of the microphone. This allows the Model 55SH Series II to be used in close proximity to loudspeakers without creating feedback problems, and it can perform under adverse acoustic conditions where omni-directional microphones cannot.

The 55SH Series II has a low-impedance balanced output designed for connection to microphone inputs rated at 75 to 300 ohms. The microphone features a cartridge shock mount to reduce stand noise, an ON/OFF switch, and an attached, self-tensioning, ⁵⁄₈"-27 thread swivel mount.

The Shure 55SH Unidyne being supported by a Shure A47 Quick Disconnect.

Features
This microphone is ideal for public address or theater-stage sound systems, as well as for broadcasting, recording, and other sound applications where a stand-mounted microphone with a classic look is desirable.

• Classic appearance, modern performance
  
  
• Frequency response tailored for speech, vocals and instrumental music
  
  
• Cardioid directional pattern for optimum performance in adverse acoustic environments
  
  
• Shock-mounted cartridge minimizes stand-transmitted noise, ensures quiet operation
  
  
• Rugged die cast case and mechanical design for reliability under rigorous conditions
  
  
• Self-tensioning swivel mount, permits tilting through 45° forward and 80° backward
  
  

Specifications

• Type: Dynamic
  
  
• Frequency Response: 50 to 15,000 Hz
  
  
• Polar Pattern: Cardioid (uni-directional), uniform with frequency, symmetrical about axis (see Figure 2)
  
  
• Impedance: Microphone rating impedance is 150 ohms (270 ohms actual) for connection to microphone inputs rated at 75 to 300 ohms
  
  
• Output Level (at 1,000 Hz): Open circuit voltage is −58.0 dBV/Pa (1.3 mV) (1 Pascal = 94 dB SPL). Power level: −58.5 dB (0 dB = 1 milliwatt per 10 microbar)
  
  
• Polarity: Positive pressure on the diaphragm produces a positive voltage on Pin 2 relative to Pin 3 of the output connector
  
  
• Switch: Built-in ON/OFF switch, integral part of swivel mount connector. Three-pin professional type, designed to mate with Cannon XL series, Switchcraft A3 (Q.G.) series, or equivalent
  
  
• Case: Chrome-plated die casting
  
  
• Net Weight: 624 grams (22 ounces)
  

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The Shure Model 556A and 556B
supercardioid dynamic microphones

Hear the sound of the Model 556A

Hear the sound of the Model 556B

Radio’s Master catalog ad. Microphones seen on this site are not for sale. Prices are shown for historical purposes.

Drew Pearson.
Click photo to learn more about Mr. Pearson.

Dwight David Eisenhower.

Download the Data Sheet for the January,
1942 55A, 55B, and 55C Unidynes.

Download the Data Sheet for the January,
1942 556A, 556B, and 556C Unidynes.

Download the Data Sheet for the February,
1951 Unidyne Multi-Impedance Model 55.

Download the Data Sheet for the May, 1951
Small Unidyne Multi-Impedance Model 55.

Download the Data Sheet for the 1967
Unidyne II Models 55S and 55SW.

Download the 2000 User Guide for the 55SH.

Download the Unidyne Story, a 12-page book.

View more photographs of celebrities using RCA and Shure microphones,
as well as a variety of other RCA mic types and Shure remote mixers.