User manual

VMDA Series User Manual P/N 821115 Rev-C.5

INSTALLATION

Mounting

The unit should be mounted where convenient for operating persons, ideally at approximately ear level for best

high frequency response. Its superior magnetic shielding eliminates concerns about locating it adjacent to most types of

CRT monitors, including even high-resolution color monitors.

Heat Dissipation

Heat dissipated by the speaker amps is conducted directly to the left side of the chassis; no special considerations for

cooling are necessary as long as the ambient temperature inside the rack area does not exceed approximately 40°C

(104°F).

Sympathetic Vibration

Sympathetic vibration from other equipment (cables, etc.), in the rack may be serious enough to interfere with the

unit’s sound quality out in the listening area. The use of thin card stock and/or felt or foam weather-stripping

type materials between adjacent vibrating surfaces, or tying up loose cables, etc., may be required to stop vibrations

external to the unit.

Mechanical Bracing

Even though the unit is fairly heavy, the chassis is securely attached to the front panel at eight points along its

surface, not just at the four corners of the chassis ears. This feature will reduce or eliminate rear bracing

requirements in many mobile/portable applications. The weight of internal components is distributed fairly

evenly around the unit.

Audio Connections

Connection of the audio feeds is straightforward. The system block diagram located on pages 20 and 21 may be

referred to for clarification of the general signal paths into and out of the VMDA unit.

Electrical Interference

As with any audio equipment, maximum immunity from electrical interference requires the use of shielded cable.

However, satisfactory results can sometimes be obtained without it. The internal circuitry common is connected

to the chassis. Unbalanced sources may also be applied to the balanced inputs. The gain is 6 dB greater with a

single-ended source connected across both “hot” terminals than when connected between either input and

common. Note that the unused input terminal of a balanced input should be connected to common, rather than

being left floating, to insure best immunity to noise.

AC Power

The unit's AC mains connection is via a standard IEC inlet, with safety ground connected directly to the unit's

chassis. The universal AC input (100-240VAC, 50/60Hz) switching power supply is a self-resetting sealed

type, with automatic over-voltage and over-current shutdown . There is no user-replaceable fuse in either the

primary or secondary circuit.