These boxes were obtained from a Corporate TV studio, and most of them show few signs of any use. These KB-112s are in P-Boxes -- "Clear-Com P-Box, a sturdy, lightweight aluminum enclosure with a sloped front, walnut sides, and carry strap. Provides 3-pin input and extension connectors".
Here are some of the features from Clearcom:
The KB-112 is a versatile, single- channel Remote Station that provides two-way (talk/listen) communicating ability. Compatible with all Clear-Com intercoms, the KB-112 is ideal in places where wearing a headset is not feasible: dressing rooms, security entrances, The KB-112 has a push-to-talk electret mic and a built-in speaker with a wide frequency response.
The KB-112 features "control logic" CMOS circuitry for programming the operation of the station. This allows remote or local control (or both) of the speaker and the mic. The station operator pre-sets a bank of dip switches that are located on the electronics module. If pre-set for remote control, the KB-112 speaker and/or mic can be activated by all other Clear-Com stations (on the same channel, using the visual signal circuitry).
The KB-112's operating modes are: NORMAL: Speaker is on. Mic is locally activated by pushbutton on Front Panel. REHOTE PACE: Speaker is off except when turned on by remote control, used to page anyone at that KB- 112's location. Mic is activated locally.
REMOTE LISTEN: Speaker is on. Mic is turned on locally OR by remote control, which allows that KB-112 operator to talk "hands-free."
REMOTE LISTEN-PAGE: Speaker is normally off. Mic remains on for hands-free talking. Another sta- tion can turn off the mic and turn on the speaker for paging that KB- 112's operator.
The KB-112 front panel contains a red LED that lights whenever the mic is active. This is especially helpful when your KB-112 is remote ly controlled; the LED shows that another station operator has turned on your mic. Other KB-112 features are intercom volume control, Visual Call Signal button, and amber Call lamp.
PROGRAM INPUT If desired, you can monitor exter- nal program via the KB-112; its wiring terminal strip includes an access point for input from the auxiliary audio source. The station accepts an unbalanced, line-level singal from audio gear such as mic mixers or portable amps, and mixes it with the intercom output from the speaker
KB-111A & KB-112 SPECIFICATIONS
AMPLIFIER DESIGN Solid-state, integrated-circuit amplifiers which include a mic preamp, headset/speaker power amplifier and signaling circuitry. Current limited with short-circuit and reverse-polarity protection.
MIC PREAMPLIFIER Frequency Response: 200 Hz - 12 kHz with contoured response to enhance voice intelligibility.
KB-111A Mic Input: 200 ½ Mic Preamp Gain: 37 dB KB-112 Mic Type: electret Gain: adjustable 11 dB
HEADPHONE AMPLIFIER Frequency Response: 100 Hz - 18 kHz, ±2 dB Headset Impedance: 8 - 2,000 ½ Output Level: +20 dB @ 600 ½ Amp Gain: 37dB Remote Speaker Stations
SPEAKER AMPLIFIER Speaker Type: 3" square Power Output: 2 watts Frequency Response: 100 Hz - l5 kHz Distortion: 0.5% THD at 1 kHz Speaker Level: 98 dB SPL at 3 feet
GENERAL Signal-to-Noise: 75 dB Line-to-Speaker Gain: 30.5 dB Headset Level: >110 dB SPL with standard ClearCom headsets Line Level: -15 dBv nom*, 0 dBv max Sidetone Adjustment: 35 dB null to full on Signaling Voltage: 11 volts DC on audio line Call Light Sensitivity: 4 volts Station Bridging Impedance: >15 k½ KB-111A & KB-112
PROGRAM INPUT Impedance: 500 k½ Level: .7v for max output
POWER REQUIREMENTS 20 mA quiescent, 60 mA average talk or signaling. 150 mA maximum load. Voltage Range: 12 - 32 volts, 28 volts nominal
CONNECTORS Headset: 4-pin male XLR Line: 5-screw terminal block
DIMENSIONS: 8.6" x 6.5" x 1.43" (218mm x 165mm x 36mm)
WEIGHT: 1.6 lbs. (.73kg) Specifications subject to change without notice *0 dBv is referenced to 0.775 volts rms.