Moog Music MF-104Z Analog Delay - Manual (Page 6)

6
A delay circuit produces a replica of an audio signal a short time after
the original signal is received. If you listen to the original (direct)
signal and the delayed signal together, the delayed signal will sound
like an echo of the direct. To make a whole series of echoes that die
out gradually, you feed the delayed output signal back to the input.
You can determine how far apart the echoes are by adjusting the
delay time of the delay circuit, and you can adjust how fast the
echoes die out by adjusting the amount of feedback from the delay
circuit output to its input. In addition, you can determine how loud
the echoes are by adjusting the mix between the direct signal and the
delayed signal.
Today there are three types of delay devices: tape, analog, and
digital. The first delay devices used magnetic tape to create the delay.
The sound was recorded on a moving tape, and then played back
after the tape had moved a few inches or so. Then, during the early
`70's, large-scale semiconductor analog delay circuits became
available. These were called bucket brigade delay chips, because they
functioned by passing the audio waveform down a chain of several
thousand circuit cells, in analogy to water being passed by a bucket
brigade to put out a fire. Each cell in the chip introduces a tiny delay.
The total time delay depends on the number of cells and on how fast
the waveform is `clocked', or moved from one cell to the next. Analog
delays were less noisy, easier to use, and more reliable than tape echo
units, and came to be more widely used.
More recently, digital delay units have come into use. In a digital
delay unit, the sound signal is first converted to numbers. The
numbers are stored in a digital memory for a certain time, and then
retrieved and reconstructed into the delayed audio waveform. One
significant difference between analog and digital delay units is that
the particular frequency and overload contours of well-designed
analog devices generally provide smoother, more natural series of
echoes than digital delay units. Another difference is that the echoes
of a digital delay are static because they are the same sound repeated
over and over, whereas a bucket brigade device itself imparts a
warm, organically evolving timbre to the echoes.
The design of your MF-104Z Analog Delay is unique because it
combines authentic, finely-tuned vintage analog bucket-brigade
delay circuitry with analog-synthesizer-style voltage control of delay
time, feedback, and direct/delay mix.
WHAT IS AN ANALOG DELAY?