Soundtoys EchoBoy - Manual (Page 6)

Slow the tape down and the time it took for the signal to get on to the tape and then be picked
up by the playback head increased and thus the delay time increased. Speed the tape up and
the opposite happened, the delay time got shorter. This provided early engineers with the
ability to create variable length, short “slap back” delays. If you took the output of the playback
head and fed it back into the input of the tape machine via a mixer you were able to create
repeating delays and echoes. The speed of the tape machine determined the delay time and the
amount of the tape output fed back into the input determined the number of repeats in the
echo.
When you shove a lot of signal onto analog tape the signal has a tendency to saturate and
impart a very natural compression that is fat, warm and crunchy. In addition to the compression
tape also adds a very characteristic type of distortion that is pleasing to the ear. This is
especially true in the upper frequencies and bottom end. It’s kind of like that “loudness” control
on a cheap stereo; hype the high and low end except for with tape it’s sounds really full, rich,
punchy, crunchy, fat, phatt and all around great.
With tape being a fully analog and non-linear medium, the sound of the echo would change
quite drastically depending on how hard you “hit” the tape, how fast or slow the tape was
moving, any EQ in the audio path etc. In addition, the sound of the individual repeats would also
change drastically each time they were fed back from the playback head with increasing
amount of distortion, noise, wobble from the tape machine and loss of high end. They did not
sound “natural” but they sure sounded GOOD! In fact one of the things engineers still drool
over is the sound of a high quality tape machine being hit hard with gobs of hot signal and used
as a delay. This is especially true for vocals with that classic “vocal slap” being one of the most
common tricks of the trade.
As technology progressed self contained tape echo machines like the original tube Echoplex,
then the transistor Echoplex appeared along with other tape echo devices like the WEM
Copycat, Roland RE-201 Space Echo and the like. There were also “platter” devices like the
Binson Echorec that recorded signal to a magnetic spinning disc that had a variable playback
speed and head. All of these tape-based units provided a warm, fully analog sound in a
relatively compact unit with integrated control of echo time, feedback, mixing and sometime
EQ. In addition, some units provided more that on playback head allowing for various types of
echo patterns. A real boon the individual musician and used extensively on both studio an
stage.
Fast forward to the late 70s and solid state echo devices started to appear based on what are
known as “bucket brigade” analog delay chips. These chips would grab a tiny piece of analog
audio (no digital conversion here) and move the snippet of sound from one “bucket” in the chip