Some info about IBF?

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bipin lama
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Joined: Tue Jul 05, 2016 8:44 am

Some info about IBF?

Post by bipin lama » Tue Jul 05, 2016 8:52 am

hey guys,
i am new here and as total in broadcast field. This is my first post here. i am working in a very very new television station. we are doing shows without IBF. and producers are finding it very hard to coordinate shows and communicate with hosts. can somebody please tell me in detail how this IBF works? what sort of equipments are needed? and how to get it? i know i sound very very novice but sorry for the inconvenience and i would be glad if you guys will take some time and explain to me how it works.
thanking you in advance

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Re: Some info about IBF?

Post by PID_Stop » Tue Jul 05, 2016 9:29 am

First, welcome to the forum!

IFB stands for Interruptible Foldback; in short, it's a feed that goes to the talent, and usually consists of the main program mix, which can be interrupted by the producer to give cues.

It's easy to build a simple IFB system: set up a mic and preamp for your producer, so you have a line-level feed that matches the level of your mixing console; then bring that and a feed from your console to a switch that normally passes the mixer feed unless the producer hits the switch. The output of the switch then goes to a headphone amplifier to drive the talent earpiece.

Most professional intercom systems -- ClearCom and RTS, for example, also sell equipment to support IFB so that the same control room panels and headsets that serve as intercom can also create feeds for the talent. Naturally, this becomes a bit more involved and more expensive, but it's a better solution if you have a larger system.

There is one special case for IFB that you also need to be aware of: if the talent is in a remote location, and feeding your facility in a way that creates delay (satellite, digital microwave, IP transmission), instead of using the full program mix from your console, you need to use a "mix-minus". This is a special mix containing everything except the remote talent's mic, so that he does not hear himself delayed in his ear. The mix-minus is created by your mixing console, often through an auxiliary bus or submaster, where you assign every source by the remote mic to the feed. Some broadcast consoles have built-in mix-minus outputs, which can greatly simplify things.

Hope this gets you looking in the right direction!

-- Jeff

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Re: Some info about IBF?

Post by Shane » Thu Jul 07, 2016 12:05 pm

Like Jeff said, it can be as simple or as complex as you need.

I once built an IFB into a Harris Medalist 10 console.

Every channel on the Medalist had a push-on/push-off CUE button, including whatever channel you chose to use as the operator's mic. Having CUE on the operator's mic was kind of useless except you could use it for a cough switch ... but the locking feature made that unhandy.

Anyway, I took the catch bail out of the switch so it was momentary (PTT) instead of locking and rewired the output to a little store bought preamp I tucked inside the front lip of the console. The effect of the switch then became IFB where whatever mix minus or program feed was coming out of the console was interrupted by pressing this switch and the operator could then give cues "down the line." Power for the preamp was borrowed from a voltage bus of the console - I wanna say it was the +5V bus.

Just an example of how one could achieve the desired result with a little modification to an audio console that didn't already have the feature.
Mike Shane, CBRE

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