radio broadcasting, announce-booth, or voice-over applications. The fourth mode provides a hybrid function, supporting both push-to-talk and tap-to-enable/tap-to- disable operation. This operation is similar to that found in many broadcast intercom system user stations.
The two buttons associated with the talk- back functions can be configured to oper- ate from either of two modes. One of the modes supports a “push-to-talk” function. This is typically used for on-air broadcast applications. The other mode provides a hybrid function, the operation of which is discussed in the previous paragraph. The hybrid mode is especially useful when the Model 233 is used in a production-support application.
The main button mode configures how the main output, when it is in the “latched” on state, responds to talkback activity. One choice momentarily turns off the main output when talkback is active, returning the main output to the on state when the talkback function has ended. The other choice “unlatches” the main output in response to a talkback function.
Cue Sources
The Model 233 supports the connection of up to four external audio sources, each of which can be selected for routing to the stereo headphone output. The sources are line input 1, line input 2, intercom channel 1, and intercom channel 2. Each source can be individually assigned to the left channel, the right channel, or both the left and right channels. This allows a wide variety of stereo and mono head- phone mixes to be created.
For application flexibility, two line-level audio sources can be connected to the Model 233. Possible signal sources
include off-air receivers, wireless IFB sys- tems, and audio consoles. The connected signals can be from two independent sources, or could be from a stereo audio feed such as would be associated with a broadcast music event. Two level trim po- tentiometers, located on the bottom of the unit, allow signals with wide nominal audio levels to be cleanly interfaced.
Audio signals associated with a single- or dual-channel intercom system can be routed to the headphone output. The Model 233’s intercom interface is com- patible with standard party-line intercom systems from manufacturers such as RTS™ and Clear-Com®. A broadcast-type IFB (interrupted foldback) circuit can also be connected to the intercom input. This “listen only” signal is often found in televi- sion broadcast applications.
Sidetone
The Model 233 includes an integrated sidetone function that allows the output of the compressor circuit associated with the microphone preamplifier to be routed to the stereo headphone output. This provides a confidence signal to the user, allowing them to hear exactly what is being sent to the main and, if desired, talkback outputs. This sidetone signal can be a critical element when creating an effective communications environment.
In on-air television and radio broadcast settings the Model 233 user’s own micro- phone audio signal is typically returned to the headphone output by way of a cue audio source. But there are cases where this signal is not available, such as when “mix minus” cue feeds are utilized. This type of cue feed includes everything but the user audio, a requirement when sig- nificant time delays, typically associated
