OPERATING AUDIOVISUAL EQUIPMENT
Audio equipment principles
Sound reproduced by audio equipment is most satisfactory when it closely resembles the original performance. The quality of sound reproduction is affected by the type and quality of equipment selected and by the operator’s skill in using the equipment.
Factors:
Characteristics of the original sound
Environment conditions in recording and playback
The capability of the recording medium to capture all the frequencies of the original sound
The capability of the playback system to reproduce program material in full frequency and without distortion
The ability of the operator to manipulate the equipment
Controls on sound equipment
AMPLIFIER OFF-ON SWITCH
- this may be a separate switch, or it may be combined with the volume or tone control.
VOLUME CONTROL
- stereo equipment has a volume control for each channel or a balancing control to adjust volume between left and right speaker channels.
TONE CONTROL
- if only one tone control is provided, it usually serves to eliminate high frequencies. If two controls are provided, one regulates the bass, the other the treble tones.
Speaker placement
General suggestions will be helpful:
Place speakers at about the ear level of listeners
When using one speaker in a long room, set the speaker off center at the front of the room and direct it diagonally across the listening area
If a speaker is enclosed in the case of a record player or tape recorder, the same rules for speaker placement will apply
If two speakers are used, more them apart, facing the audience, until the sound seems to come from between them. Check from several positions in the listening area for dead spots or interference and readjust speaker positions if necessary
Microphones
Kinds:
Unidirectional microphones
Bidirectional microphones
Omnidirectional microphones
Microphones for cassette recorders
Lavalier and lapel microphones
Wireless microphones
Microphone placement
A microphone placed close to the performer will not pick up many sounds reflected from surfaces in a room. However, while an intimate feeling can be created by recording close to the microphone, the effect of “room presence” may be lost and an unnatural voice quality may result. Always test and retest to determine the best placement of the microphone with reference to performers.
Record players
Stylus required:
Standard
Microgroove
Microgroove (monophonic)
Stereophonic
Generalized record player
In the accompanying drawing, principal parts of a typical school record player are identified. Basic controls and features permit the machine to be used for a variety of types of records.
