Recording - January 2014 - 61

An experienced live recordist will test the
room before committing to a mic position,
and may use additional mics at different
distances to have more control of instruments vs. space after the fact, assuming the
closer mics are sufficiently dry and
detailed. (I won't delve into considerations
for surround recordings here-that's a
whole separate article!)
Room-in-a-box
As our readers know, the desire for
more control of individual elements in a
mix led to the transition to multitrack
recording and close-miking, where each
instrument is recorded dry, in as much isolation as possible. These dry studio
recordings created the need for reverb to
be added during the mix, and gave rise
to a host of techniques for doing so-from
real spaces to mechanical reverb simulations to the digital wonders we take for
granted nowadays.
Since modern digital reverbs simulate not
only real spaces, but also the mechanical
reverbs of old, we should understand what
they entail. Why? So that when you're after
the sound of a particular period or style
(think of the retro-style r&b recordings that
are in vogue these days, right down to the
vintage-sounding drums and mixing techniques), you can understand how a plugin's "spring" or "plate" works in terms of the
sound you're trying to re-create authentically. It pays to have at least a passing familiarity with the original technologies!
Probably the earliest technique for
adding reverb to a recording after-the-fact
was to use a live chamber. This was (and
still is) usually a small, well-isolated,
empty room near the studio, with concrete or otherwise reflective walls and surfaces (an unused storage area, for example). Loudspeakers and mics were placed
at opposite ends of the room, facing
away from each other.
A blend of tracks from the mix was split
off from the mixing console and sent over
tie-lines (room-to-room audio wiring) to the
speakers in the chamber, which then
pumped sound into the space. The mics
would pick up the resultant ambience/reverberation, and send it back to the console
over separate tie-lines, to be blended with
the dry tracks in the finished mix, restoring
the richness that was sacrificed to close-miking. Consoles would typically have a separate level control for each track feeding the
chamber. The original mix levels would be
unaffected, but the amount of reverb is controlled for each track-the more level from a
track that's sent to the chamber, the more
reverb is applied to the instrument or voice
on that track.
This arrangement should sound familiar
to anyone who's ever sat at a mixing console-it's called Send & Return wiring,
and is still the primary way reverb is
added to a mix (though the reverb is

probably being generated by a plug-in
nowadays). This lets you use one reverb
to treat many tracks with a different
amount per track, offering the advantage
of a common "space" for your sources
and greatly reduced CPU load compared
to giving each track its own reverb.
Each track in the mix has one or more
Sends, which duplicate the signal in that
track and send the copy to the effect (in
this case reverb) with level control. The
various tracks' Sends are combined and
feed the reverb, and the reverberant signal is then brought back to the console
via a Return-an Aux (auxiliary) channel
that blends it into the main (Left-Right) mix
bus, along with the actual mix of the original (dry) tracks. Whether the reverb
device is an actual room, a mechanical
box, or a digital effect, the hookup is the
same. My apologies to those readers
who already have this down, but I know
from my students that, for mixing novices,
this wiring is a difficult concept to grasp!

Ones and zeroes
Of course, these days you'll most likely
get your reverb effects digitally. From the
'80s on, there have been many different
brands and models of digital reverb
boxes, all with their own distinctive reverb
qualities. However, the majority of people
looking for state-of-the-art reverb now will

Mechanical means
Live chambers provided some excellent
reverb for many recordings in the '50s and
'60s, but they did take up precious space.
More compact mechanical devices were
pressed into service-Plate reverbs and
Spring reverbs. A plate reverb is a large
(around 3' by 6') flexible metal sheet suspended in a frame, with transducers at
both ends-one side to supply the audio
signal to be effected, the other to pick up
the reverb-like vibrations of the plate when
stimulated. Plates were popular in the '60s
and '70s, tend to have a smoother, tighter
sound than a real space-more like a burst
of bright, dense reverb, instead of a gradual buildup of early reflections. They
impart less of a sense of three-dimensional
space than a chamber or real room, but
they have a great, explosive tail that
enhances drums and percussion, and even
sounds good on voices.
Spring reverbs consist of a set of (usually at least 3) coils (springs) in a box, with
transducers arranged as with a plate. The
springs vibrate when stimulated with

turn to plug-ins, which simulate anything
you could want, from real spaces, to
mechanical devices (as above), to the classical digital reverb hardware units.
When digital reverb hardware first
appeared, the boxes were big-ticket
items, making significant demands on
the meager computer/CPU resources of
the day. High-end units from companies
like Lexicon and AMS defined the big,
wet, arena-like ambience of many '80s
recordings. Eventually, the technology
trickled down to boxes that smaller project studios could afford, and as computer power hit the big time, most of the
popular models were ported over into
software plug-ins, which eventually overtook their hardware counterparts in
sound quality and flexibility.
Reverb plug-ins employ a few different
methods for generating their effects, and
the method in use determines the specific
controls that are presented to the user for
adjusting his/her reverb sound. The most
widely used approaches are algorithmic,
modeling, and convolution.

audio, producing a reverb-like sound, but
with a distinctive "boingy" quality. You
know the sound-there's a spring reverb
in most guitar amps, and that sound
defined the wet guitar tones of surf music
back in the day. In the studio, some companies (like Orban and AKG) even made
larger, fuller-sounding spring reverb units
that could serve as general reverbs for
places that didn't have the room for a
richer-sounding chamber or plate. [If you
know of a place where old Hammond
organs go to die, look there for
Hammond spring reverbs that may still be
working just fine-they are great!-LzR]

RECORDING January 2014

Recording - January 2014

Table of Contents for the Digital Edition of Recording - January 2014