Mujitsu and Tairaku's Shakuhachi BBQ

I came across these notes that could be useful to anyone doing any recording.

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AMBIENCE CLINIC

By Julian McBrowne

Dec 1, 2004 12:00 PM


FIG. 1: Using two mono reverbs can be a good alternative to using a stereo
reverb. In this example from Mark of the Unicorn's (MOTU's) Digital
Performer 4.12, the source track is bused to two mono instances of MOTU's
eVerb plug-in, which are panned left and right.

Anyone who has ever mixed a piece of music knows how important ambience is.
Adding space to an instrument or to a vocal track can bring it to life and
give it a sense of depth. For many years, delay and reverb were used heavily
and often without much subtlety. From the tape slap and echo chambers used
in '50s music to the over-the-top effects of '80s pop, conspicuous ambience
was frequently applied.

Musical tastes have changed since the '90s, and it's become fashionable in
pop music to mix the vocals drier. Clients and producers specifically
request less reverb, but they still want to hear space around a vocal, a
dramatic coloration for a solo instrument, or a heightened sense of
separation between foreground and background. Applying ambience has become
trickier than it was in the old days — you can't just crank up the reverb
send anymore. Instead, you have to be subtle and use a range of techniques.

This article discusses ways to tweak reverbs and delays to create other
ambience options that go beyond the “same old thing.” Chances are that your
current setup has the potential to dial in unusual and original effects.

REVERBERANT PARAMETERS


Reverb and delay are the two basic building blocks of ambience. Reverb is
designed to simulate the sonic characteristics of a real physical space:
room type, size, and surface. After selecting an appropriate setting, you
can then determine its virtual size by manipulating the decay time.

One way to achieve a subtle yet effective ambience is to drastically reduce
the decay time of a reverb patch. More intense presets such as churches,
large plates, or concert halls — which typically have decay times of three
to four seconds — work best for achieving subtle ambience. Decrease the
decay time to 0.5 seconds, and increase the predelay to 100 ms or more to
create a sound that's spacious without being wet. That technique allows you
to retain the sonic character of the space in a shorter, more concentrated
package, although you may have to increase your send levels to make those
effects work in your mix.

Many reverbs also include EQ controls. Highpass and lowpass filters are the
norm, but some processors have even more elaborate EQ capabilities. Using a
lowpass filter to reduce the high-frequency content of the ambience can
quiet a noisy track. Cutting highs in the reverb on an acoustic guitar
track, for example, can subtly deemphasize occasional finger squeaks.
Similarly, a not-so-bright reverb may be a better choice for a snare track
that has lots of hi-hat leakage. At the other end of the sonic spectrum,
adding highs to a short, intense reverb can increase the impact of the
effect.

More elaborate reverb processors allow you to go even deeper and manipulate
the balance between the room reflections (called early reflections) and the
sustained reverb sound. You can experiment with creating ambiences that are
all reflections, all reverb, or a blend of your choice. Experimenting with
ambiences also allows you to see how your processor is able to simulate so
many different spaces with so few controls.

DOUBLE-DIPPING


When working in a DAW environment, it's always tempting to use multiple
instances of your most expensive reverb plug-ins — the ones that have the
most features and the longest list of presets. Unfortunately, those plug-ins
can significantly tax your CPU. Even if you have a reasonably powerful
system, you may still need to find effects alternatives as you run out of
processor power. One way to lower CPU usage is to set up the reverb as a bus
effect and send multiple tracks to the same plug-in, rather than using
individual inserts that require an instance of the plug-in for each insert.
You can also bounce tracks to disk or freeze them once you've applied
effects.


FIG.2: In MOTU's Digital Performer 4.12 (pictured above), a single reverb
plug-in is being fed by three different-length delays, which are functioning
as predelays.

Another way to save CPU resources is to use two instances of a
power-efficient mono reverb plug-in to create a unique stereo effect (see
Fig. 1). That approach offers interesting sonic possibilities and also works
with hardware processors. If your hardware effects unit has multiple effects
engines, then you can build a powerful stereo patch with an individual
engine dedicated to each side of a stereo return.

Whether in software or hardware, start with each side of a stereo return set
to the same patch, and then modify one side. One way to accomplish that is
to add a hefty amount of predelay, which results in the reverb sounding as
though it's moving across the stereo spectrum. Keep in mind that the
ambience doesn't have to be symmetrical. If you choose a predelay time that
has an exact rhythmic relationship to the tempo of the song, then you can
create an ambience that throbs with the beat.

RHYTHM NATION


Delay times that are synchronized with a song's tempo can help generate
bounce and flow in a mix. To make that happen, you'll have to accurately
compute the delay times that fit your song's tempo. Many delay plug-ins
automatically calculate that for you. If, however, you are using a
hardware-based processor or your song was recorded into a DAW without a
click, then you may need to calculate the delay times. Shareware or freeware
delay calculators are available on the Web (you'll need to know the song's
tempo to use them), or you can use simple math (see sidebar “Finding Delay
Tempos”).

If you mix live music, then you may have developed a knack for turning the
delay knob at the right moment to send a phrase or word into a sonic spin.
When mixing in the studio, however, there are more accurate ways to set a
delay to kick in at a precise moment. In a DAW environment, one method is to
generate a dedicated delay-effect track.

To make a dedicated delay-effect track, create a new track with the same
output assignments as those on the original track. Copy and paste the
section (a word, note, or phrase) that you want delayed into the new track.
Set the track's aux send to a reasonable level, set the aux send to
prefader, and then turn the track's volume all the way down. Put a delay on
the aux bus or aux track (depending on your software), and set the delay to
100 percent wet with a tempo setting that works with the song. When the song
arrives at that section on the delay track, the delayed signal from the
targeted section will play back precisely at the appointed time.

By applying long delays to whole phrases, it's possible to create rhythmic
call-and-response effects. To achieve cascading rhythmic repeats, increase
the amount of the regeneration or feedback. Higher feedback levels increase
the number of repeats. Shorter delay times increase the frequency of the
repeats.

Mixes featuring rhythmically delayed phrases are in fashion in contemporary
pop music. The delayed portion, however, is often not a sonic replica of the
original line. It's often treated with an extreme effect, such as telephone
EQ, deep distortion, or a rotating speaker sound. An extreme effect can help
focus attention on the delayed line.

Despite the popularity of rhythmically timed delays, they don't benefit
every song. Sometimes it's better to throw away the bpm chart and dial in
the delay that feels right.

PUTTING THE PRE IN DELAY


One very useful way to tweak a reverb patch is to postpone its onset with
predelay. A reverb with predelay adds simulated depth to a close-miked
recording because it imitates the delayed reflections of a larger space. A
definitive separation between the dry sound and the simulated reflections of
a reverb helps to maintain clarity even with an extreme effect. Many
engineers set predelay values that are related to the tempo. (Usually you
have to use shorter note values than quarter-note or even eighth-note
delays; otherwise, your predelay will be too long.)

Unfortunately, the predelays built into many reverb plug-ins and processors
sound muddy and indistinct. One way to get a cleaner-sounding (and
potentially longer) predelay is to use a dedicated delay line before the
reverb. Turn the reverb's predelay off, and dial it in from the dedicated
delay processor or plug-in. If it's patched the right way, then it's
possible to make one reverb return do double or triple duty with several
different predelay values (see Fig. 2).

I created a short, predelayed hall reverb and panned it to the rear channels
recently for a surround mix of a track featuring a spunky, percussive horn
arrangement. Every horn stab from the front resulted in a short reverb kick
from the back of the surround space. That effect works in a stereo
environment as well and can give a horn section (or other percussive
element) a memorable ambient space.

TIME MACHINE


A classic technique for creating depth without an obvious reverb effect is
based on a popular Eventide Harmonizer patch called Micropitchshift. The
idea is to create a slightly detuned, slightly delayed effect on either side
of the primary signal. It's best if the delay values are small and are
different for the left and right sides.

Delay times of 12 to 14 ms and detuning as slight as plus or minus 5 or 6
cents can be effective. Traditionally, one side is pitch-shifted up and the
other side is pitch-shifted down. I recommend configuring that as a bus
effect rather than an insert because a little bit goes a long way. If you're
too heavy-handed with that effect, then it will send your song straight back
to the '70s.

WORKING THE MIC


Some ambience qualities are determined before the signal even reaches the
microphone. The sonic character of your recording space impacts everything
you commit to tape or disk. Take advantage of a great-sounding room to
create ambience that is based purely on mic technique.


FIG. 3: Using differing mic distances creates a natural sense of space
between the lead and background vocals.

If you record a lead vocalist three-to-four inches from the mic and the
backing vocals six-to-eight inches from the mic, then the lead vocal will
always sound more present or up front than the backing vocals. Even in mono,
the difference in depth is clear (see Fig. 3). The farther the vocalists are
from the mic, the more the mic will pick up the ambient or room sound.

THE FULL MONTY


This article has mainly focused on techniques for creating small, intense
spaces that are subtle. But when the time comes for that big-ballad lush
reverb, lots of predelay combined with a rich vocal plate is the way to go.
Predelay values in the neighborhood of 110 to 120 ms produce a clear
distinction between the vocal and the space around it. That is the time to
bring on your most luxurious sounding reverb.

A real plate reverb or a live chamber can make this ambience truly
spectacular. If you're working in a DAW environment, this might be the time
to crank up that CPU-hungry, convolution plug-in.

SPACING OUT


When working with ambience processors, the bottom line is that there are no
rules. You do want to keep the ambience subtle most of the time, but don't
be afraid to try some arrhythmic delays and asymmetrical effects. An unusual
or a seemingly inappropriate effect can sometimes rocket your mix to
exciting and unexpected heights. A willingness to experiment and to take a
counterintuitive approach can lead to new discoveries and push your music
into uncharted territories.



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Julian McBrowne is an engineer, producer, and self-styled digital-audio guru
who lives in southern Vermont.

FINDING DELAY TEMPO


If you're working in a DAW and your song is in sync with its metronome, the
software can calculate the delay time for you. But what if your song wasn't
recorded in a software-based environment or recorded to a click? Below are
tips on how to figure out delay times in ms so that you can set your delays
and predelays.

To calculate the tempo in beats per minute (bpm), count the number of
quarter notes that go by in ten seconds, then multiply the result by 6:

6 × (number of quarter notes in 10 seconds) = bpm

Next, divide 60,000 (the number of ms in a minute) by the bpm of your song.
The result will be the length of a single quarter note expressed in ms:

60,000

----------------------------------------------------------------------------
----
= (quarter-note value in ms)
bpm


You can multiply or divide that number to find the ms value of different
note lengths:

(quarter-note value in ms)

----------------------------------------------------------------------------
----
= (eighth-note value in ms)
2


2 × (eighth-note value in ms) = (half-note value in ms)

Assuming that you're in 4/4 time, multiplying the quarter-note value by four
results in the whole-note value. If you're in a more relaxed dub-style mix,
you might want to know the quarter-note-triplet value, which can be
calculated by dividing 40,000 by the bpm:

40,000

----------------------------------------------------------------------------
----
= (quarter-note-triplet value in ms)
bpm


Once you've found some useful values, jot them down in your mix notes and
use them for all of your effects settings.



..............

Have fun,
Kel.