Line In for AV Support

First in a series of blogs on portable / installed audio amplification issues.

We recently posted a series of articles exploring key performance features of headphones and headsets. With Infocomm approaching, the largest AV conference of the year, we’ll shift the focus to PA gear.

To someone who hasn’t dealt with a PA system before but is now faced with having to operate or even set one up, they can seem complicated or even a little intimidating. This article will focus on connecting a media source to the PA system. (Note the PA system could be portable or installed such as the Classroom Infrared Audio System). Increased integration between LCD projectors, interactive whiteboards, media players, and computers is now more critical than ever in business presentations, conferences, and classrooms. It’s just as true for outdoor events as well. In order for the audio portion to go from a computer (or other source) to the PA system and then be amplified out to the audience, portable and installed speakers have a ¼” auxiliary input (AUX IN) and/or RCA left and right stereo inputs (LINE IN).

So what are AUX IN and LINE IN functions and why are they so important? They are line level inputs (the term “line” refers to the connecting “cord”, or “cable” as opposed to a “wireless” signal)  which accept audio signals from another source such as from a computer or TV, MP3 player, DVD player, or a multimedia player. This article will focus on how you connect these sources to a PA.

PresentationPro rearPA916 rear panel - wired mic & line in PI30-PS rear panel

The line in shown on the PresentationPro, PowerPro, PI30-PS (from left to right) offers audio support for multimedia presentations.

To connect an audio source to the to the line in, first select the appropriate cable to connect to the output jack on the audio source. The other end of the connecting cable plugs into your choice of either the ¼” plug or the RCA stereo plugs. The lengths of typical audio cables range from 6 – 25’, adequate for a broad variety of applications. Once the appropriate cable is connected between the audio source and the speaker, the instructor or presenter simply needs to turn on the power switches to begin the presentation.

For some indoor installations, power can be another critical issue besides the connectivity of the speaker. The 30 Watt PresentationPro (shown above left) is powerful enough so a single speaker can be used in each classroom, minimizing installation time and costs. “We decided to go with the PresentationPro speaker as its quality and volume allowed us to only have to install one unit per classroom,” said Steve Lewey, Project Manager for the Lake Washington School District in Washington State, which installed fifteen hundred PresentationPro units throughout the district.

Still for others, the need can be more complex. Dysart Unified School District, the fastest growing school system in Arizona, installed projectors in 450 classrooms and needed to connect multiple devices to their speakers. “With a projector and whiteboard combination, teachers have many options, such as hooking-up to their laptops to show pre-made slides or solving a problem directly on the whiteboard,” shared network specialist for the district, Ezra Williams. The PI30-PS powered array speaker (shown above right) offers fixed and variable line outs so general amplification for the entire class could be run in addition to a dedicated system for students with special needs. “Teachers who have hearing impaired students in their classroom find the amplification to be extremely helpful,” Williams said.

The VoiceSaver PA285 portable PA and the Performer Plus (2455AV-02) multimedia player/recorder also feature line-in capabilities.

Click here to read the second article in the PA series about using wireless mics or read an overview about the entire series.

This blog was amended 8/2/11 to include the PA419.



Helping teachers and students with educationally appropriate classroom AV equipment since 1947.