Review: CSI PT/PR400 Portable Sound Feed System
Posted Aug 10, 2006

When you watch sports, news, or almost any live broadcast where on-air talent needs to be fed information while on camera, you'll likely catch a glimpse of a very discreet earpiece. While this earpiece can be wired, it can also be just as wireless as the plethora of wireless microphones found in any video gear catalog.

What the talent is wearing is usually referred to as an IFB, which means either interruptible feedback or interruptible fold back. IFBs use an in-ear monitor that can vary greatly, from the acoustically accurate systems musicians use on stage to the voice-only clear tubes used for news and security. You can select the earpiece that is most applicable to your situation. This review evaluates one new wireless system that helps get audio to the talent.

Some microphone manufacturers also market IFB systems that cost thousands of dollars. This is a hard pill to swallow when the quality of the audio is not paramount. What is important is that you can get the audio to the talent, and, in some cases, that it be loud enough that the talent can hear you over their own speaking, other people on the set, and whatever else is going on. Think of the frustrated newscaster suddenly reaching his or her hand to their ear to press in the earpiece and hear the IFB better.

Enter the PT/PR400
I tested the Conference Systems, Inc., (CSI) PT400 and PR400 Portable Sound Feed System. This is an 800MHz, frequency-agile system that is very simple and proved to be very capable in the field. It has 16 channels, user-selectable with a simple rotary switch. (See the Frequency Chart for an exact list of frequencies used.) Both the transmitter and the receiver take two AA batteries that easily lasted our typical shoot day.

ChannelFrequency (MHz)
CH 0798.3
CH 1802.5
CH 2794.8
CH 3799.0
CH 4803.2
CH 5795.5
CH 6799.7
CH 7803.9
CH 8796.2
CH 9800.4
CH A804.6
CH B796.9
CH C801.1
CH D805.3
CH E797.6
CH F801.8

Frequencies for the PT400.

The transmitter has a mic input that can be fed with any of several different condenser microphones available from CSI. We opted to use an existing dynamic desk mic, so we ran it through our mixer to get enough "umph" to properly feed the transmitter.

The receiver has a mono feed that we used with an OTTO headset with the clear tube and a set of in-ear forms that help to cancel outside sound. There is a simple volume control on both the transmitter and receiver to even out sounds between people who speak at different volumes, and people with different hearing sensitivities.

This system is actually designed for tour groups. It is part of several systems available from CSI, and there are numerous accessories, including portable cases that will hold or charge up to 16 receivers. These are often used in museums or tourist attractions so a tour guide can speak directly to the ear of numerous people, in whatever language the tour is in, about a specific subject.

For instance, one tour guide could be talking about the Mona Lisa, to 20 listeners, in Russian, at barely a whisper, and yet each tourist could hear the tour guide clearly. With frequency agility, multiple systems can be used in the same place simultaneously.

But we are going to use this system for IFB because it is convenient, effective, and affordable. It also has specific features that we need for IFB, including the ability of the listener to really crank up the sound to overcome whatever else is going on. It is quite compact and takes up very little room—about the same as a normal wireless mic.

The PR/PT400 On Set
We used it in the production of the cooking show I work on. Often we need to give direction to the host while we are in the middle of shooting a segment. Sometimes a bowl or pot is in the way of getting a good shot. We don't want to stop the entire production just to move the bowl out of the way. A system like the PR/PT400 allows us to whisper in his ear and tell him to move the bowl. He hears us and in the middle of his discussion with the guest, he casually reaches over and moves the bowl out of the way. It is really the best interactive TV you can ever have.

For our on-set testing, the CSI system proved very simple to set up. Pop in the batteries, set the frequencies, adjust audio levels, and away you go. The only problem we encountered was that the Sony wireless mic system we were using was also right at 800MHz, and we had to adjust frequencies to make sure the CSI system wasn't competing with our mics.

At first test, the CSI worked fine. Then when we turned the host's mic on, and found he could hear nothing from the IFB. The Sony transmitter was inches away from the CSI receiver on the host's belt and the transmitter's signal completely overwhelmed the CSI receiver, blocking the signal that was trying to get through. By moving the Sony frequency up and the CSI signal down, we got it to work. Frequency agility is nice. This is an example of why there is actually a "frequency coordinator" at large events like the Super Bowl.

Unlike with another system we had used in the past, our host had no problems hearing the direction we gave him, despite everything going on.

We also discovered a few interesting features of the CSI system. The transmitter has a built-in mic that can provide some audio to the receiver without anything plugged in. The receiver has a built-in speaker that let us know it was receiving audio, even when there was no earpiece plugged in. Now, the quality of the internal mic and speakers are not very useful for production purposes, but we did find them helpful when debugging the frequency issue.

It's nice to have that back-up to know the IFB transmitter and receiver are working on their own.

A Sound Investment?
Compared to other IFB systems, the CSI PT/PR400 is pretty affordable, with a list price of just $323. Then add the mic of your choice—from headset, to desk mic, to handheld. You can add as many receivers as you need.

There is also an optional LT400 Large Area Transmitter so you can use these systems more as they are designed, and various charging systems if you will be using the system on a regular basis.