|We use a
variety of devices to convert energy from one state to another.
These devices are known as transducers. They are
|The most common
upstream transducer is a microphone. Microphones are sensitive
to shock waves in air. When they sense a shock wave, they
produce a pulse of electrical energy. The stream of electricity, pulsing in a way that corresponds to the shock waves, is
known as the signal flow.
| Don't remember how sound waves are
produced and travel? Look here
for a - B/W - video!
mike, a condenser
mike, and a ribbon
mike. An electret
mike is a widely-used form of the condenser. Also a loudspeaker
(the reverse of a dynamic mike!)
||Here are four short videos
from Shure, a maker of popurlar professional microphones. The
link will take you to Part One. Parts 2-4 will be revealed in
the right panel.of "up next" videos.
Guide to Microphones
||From Audio-Technica, this
site offers a
clear foundation, including a discussion of signal flow.
||A pdf tutorial on how to use
||This site will introduce you
to the various types of microphones used in broadcasting and in
recording studios. Remember, they're upstream transducers! It is
a small sample (only 20 or so), and includes a few of the older models
of RCA ribbon microphones such as the 44B and 77DX. Many of these
classics still exist, and continue to provide superb audio quality.
You can even take a tour of the Neumann factory. Pay particular
attention to mike types, frequency response, and polar patterns. This
information is provided with each microphone and also, generically, as
a link ("Types of Elements") at the very bottom of the first
page ("RCA Type 44-BX") of the microphone tour. Direct
links are here.
||Notice here the photo of a parabolic
microphone, which actually is a normal dynamic (cardioid) microphone
on a parabolic reflector mount.
"needle" bounces in the record's groove. The needle's
connected to a wire coil in the cartridge, placed near a permanent
magnet. Each time the needle moves, current flows. The very low output
(signal strength) requires an amplifier to be near the tone arm,
usually under the turntable base. This funky video shows an
optical "record," too.
||The audio tape is a plastic
ribbon many feet in length. Standard reel-to-reel tape speed is 7-1/2
inches per second. The audio recording on the tape exists as many,
many little areas of magnetism. As the tape is drawn past the head,
each area of magnetism creates electrical flow in the tape head. These
signal impulses are sent directly to an amplifier.
||Uses a tiny, tiny magnetic
record/playback head similar to what's in a tape recorder. The disk
itself is coated with very fine metallic dust. Because the disk spins,
the record/playback head can be made to move along an extremely thin
spiral track from the center of the disk to the outermost rim. As the
head passes over spots on the track that are magnetized, electrical
impulses are created in the head. These are sent to an amplifier in
the disk drive.
||A loudspeaker, or simply
speaker, is an electromechanical transducer which converts an
electrical signal into sound.
explanations, with home-made visual aids.