StudioTech M46-00180 manual Simple Installation, Design Philosophy

Simple Installation

The Model 46 uses standard 3-pin XLR- type connectors to allow convenient inter- connection in most broadcast and general audio environments. For flexibility, access to the 2-wire party-line intercom interfaces can be made using the connectors pro- vided on both the front and back panels. In permanent installations the back-panel connectors will typically be utilized. In other settings, such as field television pro- duction, front-panel-access allows inter- com belt packs to be rapidly connected, without requiring access to the inside of a rack enclosure or necessitating the use of a secondary input/output (I/O) panel.

The Model 46 is housed in a rugged steel enclosure that is designed to be “road tough.” It mounts in one space of a stan- dard 19-inch rack enclosure. The mains input source can range from 100 to 240 volts, 50/60 Hz allowing direct operation virtually anywhere in the world. A switch- mode power supply, contained within the Model 46’s enclosure, provides conver- sion of the mains input power into the DC voltage required by the intercom power supply circuits. Also contained within the unit is a DC-to-DC converter that creates the voltages required by the analog and digital circuitry. These efficient power sup- plies help to ensure cool, reliable opera- tion in a variety of settings.

Design Philosophy

While the “bits and pieces” that make up the Model 46 have been described in conventional terms, the real strength of the unit rests in how it integrates and per- forms in the “real world.” Before beginning the Model 46’s design process, conversa- tions with industry experts quickly made it

apparent that installing and configuring existing 2-wire-to-4-wire interface units was invariably a time-consuming, aggravat- ing process that required the talent of an expert to achieve reasonable results. And even under those constraints the resulting audio performance was often mediocre. Any new design had to look at the applica- tion in a different way. This led to the over- riding Model 46 design goal: create a “new breed of cat,” fundamentally changing how broadcast 2-wire-to-4-wire interface equip- ment fit into actual applications.

An important first step was to eliminate the requirement that a senior technician, along with a screwdriver, be present dur- ing every installation. (It was universally acknowledged that their time can be better spent elsewhere!) The need to adjust trim potentiometers, fabricate special cabling and connector straps, use nulling earpiec- es, etc. had to be eliminated. For example, in virtually all instances, input and output levels fall within just a few dB of their nomi- nal values and, as such, could be support- ed with a limited number of configurable choices. In addition, it was acknowledged that in this application analog audio cir- cuitry was capable of providing excellent audio performance, but that the required manual nulling process was operation- ally taxing. By adding digital control to the analog circuitry, automatic nulling couldbe performed—the best of both worlds!

The next step was to identify resources that would improve the installation process and make operation more reliable. This led to the inclusion of multiple LED level meters, allowing continuous monitoring of the input and output signals. It also turned out that in many applications only a small number of user devices, such as belt packs, are