Henry Engineering SAM Stereo Audio Monitor - Digital and Analog Stereo Level and Phase Meter
The Stereo Audio Monitor (SAM) is a stereo level and phase meter that incorporates Single Stereo Display* technology. SAM provides a visual indication of the levels and phase relationships of a stereo audio signal. The unit indicates the usual Left and Right channel levels, and also displays the Sum and Difference components of the stereo signal. SAM's dual tri-colored Single Stereo Displays show this information in an intuitive and easy-to-comprehend format. Both analog and AES/EBU digital signals can be monitored with SAM. Its compact size allows monitoring three stereo audio sources in only 1 RU of rack space. (*Patent pending)
SAM consists of two independent LED displays. The main Single Stereo Display arc of 17 tri-color LEDs provides an accurate indication of stereo audio levels over a range of -25 to +3 VU. The LEDs show the Left channel in green and the Right channel in red. When both channels are present, the LEDs will be yellow. By watching the Single Stereo Display, an observer can easily read the levels of both audio channels, see the balance between the channels, and instantly see if a channel is missing. In addition, a blue "Peak" LED indicates audio peaks that exceed 0 VU. Extensive field testing has determined that, after a short adaptation period, an observer can quickly see more useful information from SAMs Single Stereo Display than from watching a pair of traditional VU meters. The ballistics of the display conform to industry standard VU meters, and show the perceived loudness of most program material with reasonable accuracy.
Below the Level display is the tri-color Phase display, an array of 10 LEDs. These indicate the levels of the Sum (L+R) and Difference (L-R) components of the stereo signal. The Sum is shown in green, with the Difference shown in red. These colors will accurately indicate the relative levels of the Main (baseband) and Stereo Subcarrier components of an FM or TV broadcast signal. With typical stereo program material, the display will appear mostly green, with yellow or red indicating the amplitude of L-R content. Excessive red levels would indicate phase error or a polarity reversal in the audio system. In any case, the LED Phase display is easier to read and interpret than a lissajous pattern on a vectorscope, especially for non-technical personnel. The Phase display can operate in "VU" mode (showing average levels) or in "Peak" mode to provide better indication of high frequency L-R information.
The Stereo Audio Monitor accepts an analog stereo input or an AES/EBU input if ordered with the optional plug-in AES decoder. The AES/EBU source can be either balanced (XLR) or unbalanced (BNC). The Level and Phase displays can be independently calibrated over a wide range of operating levels. The Phase display can be calibrated to the same reference as the Level display, or it can be used to show "headroom before clipping" to ensure adequate headroom in the audio system. A headphone Monitor jack is provided for aural monitoring.
The Stereo Audio Monitor is powered with a built-in AC power supply. It is 1/3 rack width and can be rack-mounted with the optional rack-mount shelf, or wall or cabinet mounted using optional cabinet/wall mounting brackets.
