Specifications

Chapter 32: TL Space TDM and TL Space Native 191
TL Space Overview
The following sections provide information on
the concepts of reverb and convolution reverb.
Reverb Basics
Reverberation is an essential aspect of the sound
character of any space in the real world. Every
room has a unique reverb sound, and the quali-
ties of a reverb can make the difference between
an ordinary and an outstanding recording. The
same reverb principles responsible for the
sound of a majestic, soaring symphony in a con-
cert hall also produce the booming, unintelligi-
ble PA system at a train station. Recordings of
audio in the studio context have traditionally
been captured with a minimum of real reverb,
and engineers have sought to create artificial re-
verbs to give dry recorded material additional
dimension and realism.
The first analog reverbs were created using the
‘echo chamber’ method, which is comprised of a
speaker and microphone pair in a quiet, closed
space with hard surfaces, often a tiled or con-
crete room built in the basement of a recording
studio. Chamber reverbs offered a realistic,
complex reverb sound but provided very little
control over the reverb, as well as requiring a
large dedicated room.
Plate reverbs were introduced by EMT in the
1950s. Plate reverbs provide a dense reverb
sound with more control over the reverb charac-
teristics. Although bulky by modern standards,
plate reverb units did not require the space
needed by a chamber reverb. Plate reverbs func-
tion by attaching an electrical transducer to the
center of a thin plate of sheet metal suspended
by springs inside a soundproof enclosure. An
adjustable damping plate allows control of the
reverb decay time and piezoelectric pickups at-
tached to the plate provide the return reverb sig-
nal to the console. An alternative and less ex-
pensive analog reverb system is the spring
reverb, most commonly seen in guitar amplifi-
ers beginning in the 1960s. Similar to the plate
reverb in operation, the spring reverb uses a
transducer to feed the signal into a coiled steel
spring and create vibrations. These are then
captured via a pickup and fed back into an am-
plifier.
Since the advent of digital audio technology in
the 1980s, artificial reverberation has been cre-
ated primarily by digital algorithms that crudely
mimic the physics of natural reverb spaces by
using multiple delay lines with feedBack. Digital
“synthetic” reverb units offer a new level of re-
alism and control unavailable with older analog
reverb systems, but still fall short of the actual
reverb created by a real space.
Components of Reverb
Reverberation sound in a normal space usually
has several components. For example, the sound
of a single hand clap in a large cathedral will
have the following distinct parts.Initially, the
direct sound of the hand clap is heard first, as it
travels from the hand directly to the ear which is
the shortest path. After the direct sound, the
first component of reverb heard by a listener is
reflected sound from the walls, floor and ceiling
of the cathedral. The timing of each reflection
will vary on the size of the room, but they will al-
ways arrive after the direct sound. For example,
the reflection from the floor will typically occur
first, followed typically by the ceiling and the
walls. The initial reflections are known as early
reflections, and are a function of the reflective
surfaces, the position of the audio source and
the relative location of the listener.