The VMDA-4 2-Channel Multi Format Audio Monitor from Wohler Technologies permits selectable monitoring of analog or AES sources, with excellent full-range fidelity far exceeding that of an ordinary monitor in a 1U rack-size. The unit monitors up to 4 stereo analog or AES audio sources. Individual lighted push buttons select and indicate which of the 4 sources is being monitored. Two or more pairs of the analog inputs may be summed (as pairs) by pressing the desired buttons simultaneously (note that AES inputs cannot be summed).
A separate lighted push button switches between the selected analog or digital source(s). Two front-firing midrange-tweeter speakers and a compact high-performance woofer are arranged in the bi-amplifier design. The summed bass feature is important for audible detection of out-of-phase conditions. Speaker amplifier limiters prevent accidental damage to speakers from high input levels.
Volume and Balance controls are standard, but can be reconfigured as A volume/B volume via an internal jumper. A front panel mute function is engaged by tapping the Analog/Digital selector button briefly. The button’s light blinks while speakers are muted. Muting may also be activated from a switch remoted from the rear panel. Electronic rather than acoustic cancellation of bass frequencies provides positive audible detection of out of-phase (reversed polarity) audio feeds. The VMDA-4 also features 10-segment LED bargraph meters that provide visual indication of input levels. Fast and averaging phase LEDs gives visual alert of out-of-phase conditions, and indicate whether the source is stereo or mono. A three-way toggle switch selects between the analog or digital inputs. Muting may also be activated from a switch remote
from the rear panel (optional extra). An auxiliary analog output of the selected analog or digital source is provided on the rear panel.
The unit is completely magnetically shielded to allow interference-free operation immediately adjacent to all CRT video monitors. Its lighter weight and shallower-depth chassis (compared to similar-type units) makes it suitable for portable and mobile vehicle applications.