Telephone interviews are tricky things to record. It makes life a lot easier if all the presenters can hear what the interviewee is saying. In order to do that, you need some way to take the audio from the telephone line and connect it to the mixer. From there it can be sent to everyone’s headphones. It also helps if everyone can ask the interviewee questions quickly and easily. That means sending the audio from everyone’s microphones and sending it back down the telephone line.
Connecting the audio from the telephone line to the mixer is fairly straight forward: Just connect it to a spare channel on the mixer. However, you can’t just connect a spare output from the mixer back into the telephone line now, otherwise the interviewee will hear their own voice coming back down the line at them! This is where you need a mixer with auxiliary outputs like the Soundcraft EPM12. By connecting one of the auxiliary outputs from the mixer to the telephone line and turning up the auxiliary knobs for each of the presenters’ microphones we send the audio from the studio down the telephone line to the interviewee without sending them their own voice too.
So, how is the telephone line connected to the mixer? We’ve tried a couple of different ways in the past, but currently we use a D&R Telephone Hybrid-2 (sometimes called a telephone balance unit) to provide an interface between the telephone line and the mixing desk. These are expensive bits of kit, but provide the best quality connection between the mixer and the telephone line. They are designed to cut out echo and line noise and generally make the audio presentable. To supplement the hybrid, we use just about the most basic telephone handset available, the BT Décor 1100. The phone handset is necessary in order to make any outgoing calls as the hybrid doesn’t have a number pad. The Décor 1100 is a good choice because it has fairly large numbers which are easy to stab a finger at and has an LED on the top which flashes when the phone rings. This means you can turn the ringer off on the phone (useful in broadcast environment) and still tell when someone is calling you! The quality of the telephone handset doesn’t affect the quality of the recording: All the audio is diverted from the handset when the hybrid is active.
A much cheaper way to record telephone conversations for broadcast is to use a telephone recording adapter. This particular model connects into your telephone socket with an adapter so you will all have to share the telephone handset in order to speak to the interviewee! Other similar devices work by being connected between the base of the telephone and the handset itself, which means you need a telephone which has a detachable handset. Fortunately lots do, including the Décor 1100. Devices which work in this way have the advantage that you can all hear the caller via your headphones and the caller can hear you all via the microphones.
All of these methods are dependent on the quality of your telephone line and the connection to the interviewee. It is better for reliability and quality if they are on a land line rather than a mobile. One way to get a good quality recording regardless of the quality of the telephone line, is if the interviewee is able to record their side of the conversation and send it to us so we can mix it all together afterwards. Then it sounds like we were sitting in the same room as our interviewee when we spoke to them.
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