Sonifex TB-6D 6-Way Desktop Talkback Intercom

A typical application would be to distribute talkback and audio feeds around a radio or TV studio complex. The TB-6D and rack-mounted TB-6R units are daisy-chained together from location to location, and the radio station output from an off-air receiver is distributed on input EXT 1 of each unit.

The EXT 2 input could be used in the news or sales area for monitoring local sources such as a PC audio output. Linking the studios in this way allows all locations to talk to each other together with the ability to monitor two external feeds, with independent control of monitor muting and headphone or speaker levels.

Some common locations that can benefit from routing with a TB-6D intercom unit include:

• Reception area
• News area
• Sales area (in conjunction with PC soundcard)
• Main on-air studio 1
• Production studio/On-air studio 2

Up to 7 locations or studios can communicate with each other. On each panel, there are 6 front-panel buttons for talkback selection and 2 for external inputs. When a button is pressed, the button lights up and the talkback is active to that location.

The buttons work with both a momentary and latched operation. If you simply press the button, talkback will be on and can be cancelled by pressing the button again. If you press and hold the button, the selection is cancelled when released.

So, if you wanted to listen to an external input, such as the radio station feed, or off-air monitor, you could simply press the EXT 1 button. If you receive talkback from another studio when the external input buttons are also pressed, the external inputs can be either muted or mixed, depending on the setting of an internal jumper. The talkback outputs and input are balanced signals on a 15-pin male D-type plug and the talkback input can be adjusted from using a rear-panel preset pot.

You can speak to the separate locations using the onboard front-panel electret mic or there is a separate external mic input on a 3-pin XLR female connector, into which you can plug a suitable gooseneck microphone.

There is a rear-panel switch to select between the electret and separate input mic. The mic input gain range is adjustable via a rear-panel preset pot.

The unit can monitor two external sources. The EXT 1 input is a balanced stereo input on a rear panel 9-pin D-type socket, while the EXT 2 input is an unbalanced stereo input on the 9-pin D-type socket as well as dual RCA sockets. EXT 1 is useful for monitoring a distributed signal, such as a radio tuner off-air feed, or an outside source routed from an ISDN codec. EXT 2 is useful for monitoring a local source, such as a portable minidisc/flashcard recorder/player, or the unbalanced soundcard output from a PC editing/playback package.

If you already use a mixer which has a talkback input and output, or continuous talkback output, or just a line-level output which you want to use, by changing internal jumpers, the intercom can be configured to use these connections instead of the onboard microphone and speaker/headphones. For example, if you have a mic channel on a mixer assigned to talkback and the presenter is using headphones for monitoring the mixer talkback, the TB-6D can be used purely for talkback switching and for monitoring external inputs.

For monitoring, you can use either the built-in 1W loudspeaker, or headphones on a 1/4" unbalanced stereo jack. The headphones provide 150mW into 32- to 600-ohm headphones. When the headphones are used, the speaker is automatically muted.

Additionally, the monitor speaker can be muted via a remote contact on the 9-pin D-type External Input connector, for example, when used in an area with live microphones. Both monitor and headphone levels are fully adjustable using the front-panel volume control.