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The Altec 670A
multi-directional ribbon microphone

Altec 670A

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General
The 670 Microphone is a general purpose microphone of broadcast quality having a frequency range that covers the complete audio spectrum. It consists of a ribbon element and a controllable acoustic labyrinth.

Altec 670A
Microphone courtesy of Jeff Rudisill

Directivity
The microphone has three basic directivity patterns as illustrated below.

  •    P   pressure (omni-directional)

  •    C   cardioid

  •    R   ribbon (bi-directional)

These basic patterns may be modified by placing the selector on the back surface of the microphone in intermediate positions. Such placement will result in a compromise between the adjoining patterns.

Polar pattern selector switch

Polar patterns

Impedance
The impedance selecting switch is located underneath the name plate on the front of the microphone. Position 1: 30 to 50 ohms. Position 2: 150 to 250 ohms.

Impedance selector switch

Quoted from the Altec Lansing Corporation Operating Instructions, Part No. 12182

According to Mr. Bill Hayes at MicroMike Laboratories in Anaheim, California, there is a Model 670B that employs a slightly thicker, stiffer ribbon, which modestly improves the frequency response over the A series. Our thanks to Mr. Al Pushkin for contacting Mr. Hayes and tracking down this information.

November, 2006: I have managed to track down a 670A and a 670B, and record them simultaneously, although under rather adverse conditions. Apologies for the ambience. It was this or nothing. References to channels 1 and 2 represent left and right channels of this stereo recording. The 670A is on the left, while the 670B is on the right.

Hear the 670A 670B comparison.

Altec 670 Operating Instructions
Download the Operating Instructions for the 670.
 

 

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