There are lots of situations where an AV Distribution Amplifier is necessary. For example, let’s say that you want to set up an audio-video (AV) system for a college classroom, where half-a-dozen monitors are to be fed with video and audio signals from a single VCR. Or perhaps you want to set up a small video duplication facility, with a "master" VCR or VCD (video CD) player feeding up to five recording VCRs plus a video monitor (so that you can keep an eye on recording quality).

All the parts are mounted on a large double-sided PC board, so building the unit is really easy. This is the composite video version - only a few minor changes are required to distribute S-video signals.

Another possibility is that you want to set up a stand at a trade show, with the output from a DVD player fed to a video projector, three or four monitors and a sound system.

In situations like these, there’s more to it than just hooking everything up with the necessary cables and some multi-way connectors. Distributing video and audio signals to multiple destinations has to be done properly, or signal losses and corruption can make the results very disappointing. Blurred pictures with "ringing" and colour "bleed", together with weak and muffled sound, are inevitable unless the system is properly set up.

In general, the way to prevent these problems is to use an "audio-video distribution amplifier". This provides enough gain (or amplification) to compensate for the losses involved in "splitting" the video and audio signals to feed multiple loads. It also ensures that the video cables can all be terminated in the right impedance, to prevent ringing and other distortion.

Commercial AV distribution amplifiers are available but they’re not exactly cheap. That’s why you might like to consider this design. The kit costs less than half as much as a comparable commercial unit.