RCA Type BC-5B Audio Consolette
Broadcast Audio Equipment
Model: Type BC-5B Audio Consolette
Part Number: MI-11637-A
Manufacturer: Radio Corporation of America, Commercial Electronic Products, Camden, N. J.
Introduction
The RCA Type BC-5B Audio Consolette is a self-contained unit providing audio amplification, switching control, and monitoring facilities for small radio or TV broadcast stations. It features a compact design, etched wiring for reduced size and weight, and a two-tone umber gray finish. The consolette includes three mixing channels for low-level inputs (microphones, turntables) and one high-level channel for network and remote lines. It offers nine input channel selections, with outputs switchable to either a program or audition bus. A standard four-inch illuminated VU meter is included for monitoring.
Technical Data
| Parameter | Value |
|---|---|
| Power Required | 100-130 V, 50-60 cps, 150 Watt |
| Amplifiers | 6 RCA Preamplifiers 5AR1 thru 5AR6, 1 RCA Program Amplifier 5AR7, 1 RCA Monitor Amplifier 5AR8, 1 RCA Power Supply 5PS1 |
| Inputs | 4 Microphones (37.5/150/600 ohms), 2 Turntables (37.5/150/600 ohms), 1 Network Line (600 ohms), 2 Remote Lines (600 ohms), 1 External Monitor (150 ohms) |
| Output Lines | 1 Program Line (600 ohms, 18 dbm), 2 Remote Line Cue (600 ohms, 18 dbm), 2 Monitor Speakers (16 ohms, 3W each), 1 External Monitor (600 ohms, 6 dbm), 1 Turntable Cue (50,000 ohms, 1 V) |
| VU Meter | One 4-inch illuminated, Type B scale |
| Channels | Program and Audition |
| Signal to Noise Ratio | 68 db below reference at program line output; 66 db below reference at monitor output |
| Gain | Microphone/Turntable to Program: 108 db; Network/Remote to Program: 42 db (includes 30 db pad); Microphone to External Monitor: 84 db; Microphone to Remote Line (Cue): 106 db; Microphone to Speaker (Audition): 124 db; Network to Speaker (Audition): 56 db; Microphone to Speaker (Program): 78 db; Network to Speaker (Program): 78 db |
| Frequency Response | Program Channel: ±1.5 db (30 to 15000 cps); Audition Channel: ±2.0 db (30 to 15000 cps) |
| Harmonic Distortion | Program (18 dbm output): 1% at 30 cps, 0.75% at 50 cps, 0.5% at 100 to 15000 cps; Monitor (6 Watt total): 1.5% at 50 to 15000 cps |
| Tube Complement (MI-11483-A) (Not Supplied) | 1 x 5R4-GY, 2 x 12AU7, 2 x 6V6GT, 2 x 12AX7, 6 x 12AY7, 5 x MI-11299 (selected 12AY7) |
| Dimensions and Weight | Width: 19.5 inches; Height: 11.5 inches; Depth: 21.5 inches; Weight: 66 pounds |
| Finish | Two-tone umber gray |
Description
The Type BC-5B Audio Consolette (MI-11637-A) is designed for audio amplification, switching, and monitoring in small broadcast operations. It integrates the power supply for amplifiers and relays. The unit's housing is compact and styled to match other RCA broadcast equipment. A key feature is the use of etched wiring for amplifiers, significantly reducing size and weight. Input and output connections are made via a terminal block at the rear. Knockout holes are provided for conduit entry. The consolette offers three mixing channels for low-level inputs and one high-level channel for network/remote lines. Nine input channels can be selected, with outputs routed to either a program or audition bus. The VU meter is a standard illuminated four-inch model.
Installation
Location: The consolette can be installed on any flat desk or table, requiring at least a 12-inch clearance at the rear.
Type of Installation: Diagrams illustrate typical single-studio (Figure 17), two-studio (Figures 18, 19), and dual-channel installations.
Removal of Shipping Bolts: Specific nuts, lockwashers, and screws must be removed to allow the preamplifier mounting shelf to float on its vibration mounts.
Tube Installation: Tubes are not supplied and must be ordered separately. They should be inserted into sockets according to stencils, with shields fitted over specific tubes.
WARNING: Do not open the unit or front panel with power on unless thoroughly familiar with the equipment due to high voltages.
Power Supply 5PS1 Connections: The unit is shipped for 110-120V operation. Voltage can be adjusted by repositioning a wire on the power transformer (4T1) for 100-110V or 120-130V ranges. AC power connects to a terminal block (TB1).
External Connections: Audio wiring should be segregated into low-level (microphone/turntable) and high-level (line) cables. Low-level lines should be shielded twisted pairs, grounded at one end only, and kept away from AC power and signal light circuits.
Microphones and Turntables: Connections are made via terminal block 5TB1. All microphones should be phased alike. Input transformers can be configured for 150-ohm or 600-ohm input. Turntables with unbalanced equalizers can be connected without issue if their terminals are not grounded.
Remote Line and Network Inputs: The high-level input can be converted to low-level by modifying jumpers and resistors. Interlock circuits are provided for studio microphone inputs.
Line Equalizer: An equalizer (MI-11752) can be connected to terminals 15 and 16.
Program Line: Output connects to terminals 41 and 42, with a 6 db isolation pad.
Output to External Monitor Amplifier: An external monitor can connect to terminals 43 and 44.
External Input to Monitor Amplifier: An off-air tuner can connect to terminals 31 and 32 for monitoring.
Warning Lights: MI-11706 Series lights can be operated from the speaker muting relay. Control Room and Studio signal lights connect to specific terminals.
Diagrams:
- Figure 14: Type BC-5B Consolette with Panel Open (shows internal components).
- Figure 15: Typical Installation Showing Cable Installation for Consolette (diagram of conduit and cable routing).
- Figure 16: Installation Dimensions (diagram with measurements of the unit).
- Figure 17: Typical Layout for One-Studio Operation (diagram showing console placement and connections).
- Figure 18: Typical Layout for Two-Studio Operation with Control Room and Announce Booth (diagram showing console placement and connections).
- Figure 19: Typical Layout for Two-Studio Operation Control Room (diagram showing console placement and connections).
Operation
Precautions: Preset selector switches before adjusting mixer controls. Select remote inputs first before engaging the REM position. Adjust MON GAIN for desired listening level. Dual channel layouts vary based on station setup.
Routine Procedure: Select input, set mixer switch (Audition/Program), adjust mixer attenuator, adjust MASTER control, check VU meter, monitor selected input via MON INPUT switch, and monitor program via headphone jack (PHONE selector switch).
To put a local program on the air: Select inputs, set mixer switches to P, turn MON INPUT to PGM, adjust MIX controls, and set MASTER gain. Control Room speaker is muted when CR Microphone is in use, and studio speaker is muted when a studio microphone is in use.
To audition a program: Select inputs, set mixer switches to A, turn MON INPUT to AUD, adjust MIX controls. Audition can be heard as when monitoring program.
To put network program on the air: Use key switch 5S4 for NET, set mixer switch 5S8 to P, turn MON INPUT to PGM, adjust MIX 4, and set MASTER gain. Network program can be heard over both loudspeakers.
To audition a network program: Use key switch 5S4 for NET, set mixer switch 5S8 to A, turn MON INPUT to AUD, adjust MIX 4. Audition can be heard over both loudspeakers.
To monitor a network program: Plug headphones into the PHONE jack and set PHONE selector switch 5S12 to NET.
To talk-back to studio: Set input selector 5S1 to CR MIC and mixer switch 5S5 to A. Turn MON INPUT switch 5S11 to AUD. Adjust monitor gain.
Remote Talk-Back (REM 1 or REM 2): Select CR MIC (5S1), move mixer switch (5S5) to A, turn up MIX 1, and set MON INPUT to AUD. This provides a talk-back system with remote operators.
To feed cue to remote line: Turn REM 1 (5S9) or REM 2 (5510) to CUE position. Cue is fed from the Monitor output.
To put a remote program on the air: Set REM 1/2 to PGM, use key switch 5S4 for REM, set mixer switch 5S8 to P, adjust MIX 4 and MASTER gain, set MON INPUT to PGM, and adjust speaker levels.
To audition a remote program: Follow remote program procedure, but move mixer switch 5S8 to A. Turn MON INPUT to AUD and adjust loudspeaker levels.
To cue turntables TT1/TT2: Preset key switches 5S2/5S3 to TT1/TT2. Turn MIX 2/3 counterclockwise to CUE position (do not turn past detent if not cuing). Turn MON INPUT to CUE and adjust speaker level. Cue can be heard on both control room and studio loudspeakers.
PHONE Monitoring: Plug headphones into the PHONE jack and use the PHONE selector switch (OFF, REM, NET, PGM) to select the desired output for monitoring and cuing.
Diagrams:
- Figure 20: Control Panel of Type BC-5B Consolette (shows layout of knobs, switches, and VU meter).
- Figure 21: Control Circuit (schematic diagram of control circuitry).
Maintenance
The BC-5B Consolette is designed for easy servicing. The top cover is secured by four Camloc fasteners, and the front panel is hinged at the bottom.
Tubes: Tubes should be checked periodically using a tube tester or by measuring socket voltages (refer to Tube Socket Voltage chart).
Fuse: A 3-amp time lag fuse (Type 3AG) is located at the right front of the preamplifier mounting shelf.
Care of Variable Attenuators: Remove cover, apply Davenoil to contacts, rotate knob, wipe clean, and apply a thin film of Davenoil.
Care of Switches, Relays and Sockets: Switch and relay contacts require minimal maintenance. Tube socket contacts can be cleaned by inserting and removing tubes.
Replacement of Input Transformers and Fuseholder: Loosen preamplifier mounting shelf, remove top cover and front panel if necessary. Remove screws between amplifier boards. Loosen cable clamp, lift shelf, and tilt back to access transformers and fuseholder.
Replacement of Output Transformers and Attenuators: Tilt up the mounting shelf for program and monitor circuit boards. Remove four screws from each corner.
Power Supply: The power supply chassis is secured by four screws. Remove screws and carefully turn upside down to access components.
Servicing of Etched Wiring Boards: Components can be replaced by following specific instructions for removal and installation, using a low-wattage soldering iron. Avoid excessive heat or force.
Diagrams:
- Figure 22: Replacement of Components in Printed Circuits (diagrams showing removal and installation steps).
- Figure 23: Fixed Pads for Type BC-5B Consolette (diagrams of fixed pads).
- Figure 24: Internal View of Consolette (photograph labeling internal components).
- Figure 25: Overall Schematic Diagram (comprehensive electronic schematic).
- Figure 26: Overall Connection Diagram (detailed wiring diagram).
Tube Socket Voltages: Charts provide voltage readings for various tube sockets in pre-amplifiers, program amplifiers, monitor amplifiers, and the power supply.
Parts List
A comprehensive list of parts is provided, including symbol numbers, descriptions, and stock numbers for various components such as pre-amplifiers, amplifiers, attenuators, capacitors, resistors, switches, transformers, sockets, and miscellaneous items.
