There are three ways to connect external devices.
1. By component (YPbPr or RGB) input. This is the best way. Component signal transmits separately three picture components – luma and two chroma signals or three colors. This method has best horizontal resolution, minimal noise and best color rendering. But your tuner may not be equipped with component input, you should check it in tuner specifications.
2. By S-Video cable (black mini-DIN connector). This is the next way by quality. S-Video has two separate signals – luma and chroma. This method has good horizontal resolution, good noise characteristics and good color rendering.
3. By VHS (composite) cable (RCA connector also called "tulip"). This is the next way after S-Video. With this connection luma and chroma components are mixed together in one signal. This mix splits back to color and luminosity in tuner. The mixing and following splitting reduces the quality of picture.
4. By RF modulated signal through antenna input. This is the worst method. In this connection type the modulated sound adds to mixed videosignal and all this mix modulates by radio frequency as in TV signal. All these mixings and modulations cut frequency ranges, add noise, cause crosstalks between signal components and these components can not be perfectly split back to source signals. That's why this method may be used only if all other methods are unavailable.
You should remember that by component, S-Video and VHS cables only video signal may be transmitted. To transmit the sound you need to connect the separate audio cable. If you have 4-th or 5-th series tuner model, you also need adapter from RCA ("tulip") connector to mini-jack. If the external device is monophonic, you also need to set in Behold TV application settings which channel – left or right, transfers the sound. For this click the right mouse button and in "Audio channel" item of context menu select the channel to which the device is connected. On correct choice the sound must be heard in both speakers.
For VHS system it is quite sufficient to connect it by VHS/composite cable. Since the VHS cassette tape has luma and chroma signals mixed together there is no fundamental difference where this signal will be split – in VHS system (when connected by S-Video) or in tuner (when connected by VHS/composite cable). The main thing is to check that VHS player is not set to transcode from one color system to another, inthis case VHS player will split signals, transcode color signal and mix signals back. When connecting other devices (DVD-player, satellite receiver) component or S-Video connection may provide a great increase in quality.