Radio Studio Automation System

Having completed work on the 1970s radio studio, the next step in recreating the AM/FM station where I worked back in the ’70s and ’80s is to build up a vintage automation system.

For an FM station back in the day, it was common to have programming handled by an automation system. The equipment required to accomplish this task included, but was not limited to, the following:

  • A control unit to manage operation of the system and switch audio sources
  • One or more multi-playback cart machines, typically a “carousel” device
  • Multiple reel-to-reel playback decks, which were loaded with pre-recorded syndication tapes such as the one shown above

I’ve been interested in building up an automation system for some time, but work on the ’70s studio took precedence. And, I hadn’t been able to find a carousel cart machine or control system. That changed one day in a chance visit to eBay. I saw a Gates carousel cart machine for sale and acquired it. In a conversation with the seller, I found that he had a vintage Gates control unit that he was interested in selling. It came to pass that I acquired the control unit, and so the project begins…

(Note that the product descriptions below are based on information contained in the Gates literature.)


Gates SSC Switching Center

The central part of the automation system is the Digital Touch-Control SSC. This unit is the switching center and control point of the Gates KSP-10 program automation system. Nearly all of the control commands, control responses, audio programming, auditioning, logging, etc., are routed through the SSC for switching and processing.

The photo below shows the SSC controller as it arrived at the beginning of the project.

The SSC System Switching Center can connect up to 10 system sources to the control and output circuitry of the system. Both sub-programmer-controlled sources and main-programmer-controlled sources connect to the SSC Switcher. A nine source extender for the SSC is available for expanding the system from 10 to 19 source capability.

The rear panel of the SSC as it arrived is shown above. The unit was in generally good shape and all parts appeared to be present, including cabling to the source machines.

Gates KSP-10 Programmer

The Gates KSP-10 Digital Touch Control System Programmer provides fully automatic control of an automation programming system when used in conjunction with Gates SSC Switching Center. It can sequentially call on up to 10 audio sources, such as cartridge, reel-to-reel, network, remote, or audio console output. Time correction and sub-programmer block advance information may also be entered into the magnetic cartridge memory of the KSP-10. A stored event within the tape cartridge memory may be changed at any time by accessing that event and rewriting it. An entry error may be immediately corrected by following it with an ERROR entry, then rewriting it. This eliminates the necessity of reprogramming the entire memory tape because of an entry error or any desired change in programming information.

Unassigned events, time correction, and sub-programmer block advance information space may be reserved in the memory tape by entering a “Skip” event at any place desired in the memory sequence. They may be later accessed and programmed to change or expand the operating sequence. Five digits of information (source numbers, time correction entries, etc.) are stored in approximately one second of tape time. The average half hour in a Top-40 format would require almost 5 seconds of memory tape, so a typical 18-hour broadcast day can be programmed on a 3-minute cartridge.

An important verification feature of the KSP-10 permits the use of audio tape for encoding the BCD signals in the memory cartridge. Each digit must be verified by reading the recorded signal in the “write” portion of the read/write head before an entry sequence is complete. If tape drop-outs are encountered, the KSP-10 will automatically re-enter the command until full verification is received. Each incomplete entry will receive an error code as a part of the re-entry cycle, so the incomplete entry will always be skipped in the playback service.

The magnetic memory portion of the KSP-10 consists of a cartridge tape transport similar to Gates’ Criterion Compact. The front panel of the tape transport contains only an LED power indicator. Full control of the tape deck is obtained through the manual and automatic operation of the associated programming section of the KSP-10.

In this implementation, an ITC PD-II record/play cart machine is used as the storage device. Operation is the same as described above. The PD-II as it arrived is shown below.

ITC PD-II cart machine

In addition to a thorough cleaning and component replacements as needed, the cabinet will be refinished in a black satin textured powdercoat to match the rest of the studio gear. An internal view of the cart machine as it arrived is shown below.

PD-II cart machine internal view

The programming functions described above are housed in a small desktop chassis, permitting easy interaction with the system.

Audio Control Center

The ACC-1 and ACC-2 audio control centers provide a consolidated program output and monitoring unit for the Gates program automation system. Solid-state modular amplifiers, as used in Gates studio audio consoles, provide outstanding performance, with program amplifier output capability up to +26 dBm (+8 dBm nominal), and plug-in monitoring amplifiers at 10 watts (+40 dBm) per channel.

Both the monophonic ACC-1 and stereophonic ACC-2 control centers accept 25 Hz high-pass filter(s) for use in automation systems with reel-to-reel tape audio sources. The ACC-2 stereo audio control center also provides for the installation of an optional L+R sum channel output amplifier. Power supplies and all modular amplifiers plug into the rack-mount chassis.

The audio control center front panel facilities include VU metering, monitor gain control, and meter/monitor selector switch for visually and aurally checking program output, audition, and external audio source such as an off-air monitor. In stereophonic ACC-2 units, a fifth switch position provides an accurate check of channel phasing.

Unfortunately, an actual ACC-2 unit could not be found on eBay or elsewhere. Therefore, in this implementation the functions of the ACC-2 are accomplished with WA-6107 amplifier cards and related hardware housed in a small card frame. A control panel linked to the card frame permits operator interaction with the system. The WA-6107, described in the blog posting “Gates Executive Audio Console Restoration, Part 3: Further Enhancements,” is based on a design used in the Gates Executive audio console, which was produced within the same general time frame as the SSC. The controller is designated the WA-ACC2.

Gates Carousel Cart Machine

The Gates G-824 Carousel tape unit is a rotary drum mechanism for tape cartridges that can be operated by manual, automatic, and random-access controllers. Each drum holds a maximum of 24 standard cartridges, and revolves to allow positioning of the cartridges against the stationary transport.

The G-824 positions cartridges in sequence unless an optional random access unit is employed. G-824 mono and stereophonic units are compatible with most radio automation systems. Modular solid-state electronics provide for the NAB standard controls of 1000 Hz, 150 Hz, and 8000 Hz cue tones In addition, logic control of the start-stop functions may be used.

Exclusive Gates features adapted from the Criterion 80 cartridge machine for improved reliability include the microset head assembly and vapor-blasted large diameter capstan drive for increased torque and superior audio reproduction.

Cartridges in the G-824 can be randomly played with optional accessories. A manual remote control or a random-access programmer for automated use are also available.

The Carousel machine that I purchased on eBay was in generally good condition when received. The machine was divided into four major subassemblies for shipment, as shown below.

carousel cart machine disassembled

The front trim panel was removed and sent off to be refinished by a powder-coat vendor.

The transport tape mechanism, shown below, appears to be in good shape, although a full disassembly will be needed to thorough clean and check the unit.

carousel cart machine transport deck

Three motors are used in the machine. One is for the tape transport (shown above) and the other two are used to move the cartridges and drum (shown below). All three motors will be removed and thoroughly cleaned.

carousel cartridge drum and related components

The carousel cart machine is quite heavy and access to components will be a challenge after the unit is installed in a rack. All of the detailed work, therefore, will need to be done before reassembly.

Audio Source Machines

In addition to the G-824 carousel cart machine, three additional audio sources are provided in this implementation:

  • Ampex AG-440 stereo reel-to-reel tape deck
  • ITC PD-II stereo playback cart machine
  • External audio (console output)

As noted previously, the SSC system can accommodate up to 10 input sources in the basic configuration.

The PD-II cart machines, as described above, were in generally good condition when they arrived. However, the AG-440 tape deck, also purchased on eBay, was a mess. The eBay ad described the unit as “clean” but it was far from that. In fact, I don’t believe that I ever received a piece of hardware with so much dirt. Cleaning began right out of the box and was done outside so as to not mess up the shop. In desperation (and clearly a kill-of-cure move), I used a garden hose to wash off the machine. (Never done that before.) Fortunately, it was warm day and the deck quickly dried.

The AG-440 after cleaning is shown below.

AG-440 tape deck after cleaning

With the AG-440 cleaned-up and in the shop, an assessment of the scope of the project was possible. For starters, both reel motor shafts were bent, rendering them unusable. Fortunately, a search on eBay turned up a pair of NOS reel motors for a reasonable price. The reel turntable pads had long since deteriorated, but replacements are available from Full Track Productions of Seattle.

From the photo above, it is clear that the tape head cover is non-functional. Repair of that problem seems possible without too much effort. Also, the take-up reel tension arm is corroded. That’s probably fixable too without too much work.


All hardware for the system described here is housed in a 42-RU rack cabinet, except for the DTMF encoder, which is housed in a small desktop cabinet. A functional block diagram of the system is shown below.

functional block diagram of the automation system

This project is just getting underway. It will be a long process. Updates will be posted here as the work moves forward.