Topics This Week
In producing a piece of music, we use a mixer
and effects devices to combine and process different musical parts. A
mixer has a number of channels that accept audio inputs and combines them to
produce a stereo output by routing and processing those signals in various ways.
Each channel is usually laid out as a strip of controls that is replicated for
each physical or virtual input. These controls typically include level, placement
in the stereo image (panning), equalization controls, and effect routing controls.
The key to understanding any audio production system, whether it's a portastudio
or a large professional facility, is understanding how audio signals are routed
between studio components.
Follow this link to see signal
flow in a typical recording studio.
Level and Gain-staging
Each component of the system either increases or reduces level. In addition,
any time a signal is passed through an electronic circuit in an analog system,
noise is added. Ideally, the level at each stage is optimized to provide the
highest level without distortion. The ideal signal level will have the least
this link for more details on audio levels.
In a virtual studio like Reason, we still need to be aware of audio levels
at various stages. Levels in Reason are controlled at three places:
provides a way for us to monitor signal level at various places in
the mixer. There are some important distinctions in how signal level is displayed.
Since the amplitude of an audio signal is always changing, level is measured and
displayed at discreet time intervals.
- the output of
an individual instrument
- the channel
fader in the mixer
- the Master Fader
controlling the mix output level
- Peak level metering displays actual levels at discreet peak levels. This
would detect any high transients.
- Peak level indicators are usually LEDs with give an indication when certain
level thresholds have been crossed.
uses peak level meters to display level at:
- the channel
- the input of
- the master fader
Board Connections and Functions
The mixing board is the central nervous system of a recording studio or PA
system. Every audio signal passes through it, and is processed, routed, and
combined with other source signals to create the final stereo mix of a multitrack
production. All mixing boards, whether physical or virtual, share a similar
set of components. We'll start with some basics by looking at the Reason mixer,
then compare these functions to a common hardware mixer, the Mackie 1604.
The Reason mixer is laid out like many small desktop mixers, and
performs three basic functions:
- Every mixer has a number of input channels that are essentially the
same. These accept input from separate audio sources and control their output
and routing inside the mixer.
Routing - Signals can be routed from within
a channel to and from external devices.
- The master section is where the mixed output signals are
link for a look at the signal path
within a mixer.
Reason Mixer: 14 Channels, a Master section, and four separate sends and returns.
this mixer, there a six basic controls:
- Mute and Solo
- Master Fader
this link to learn more about the controls
in the Reason mixer.
Signal Flow in GarageBand
The Reason mixer is very similar to most hardware mixers. In Reason however,
all the connections are made within an easy, self contained software environment.
Things get more complicated in the physical world where there are a variety
of signal levels, and connectors to take into consideration. In spite of this,
the basic functions and controls will be the same as in the virtual Reason mixer.
The Mackie 1604 is a very common hardware mixer used for a variety of applications.
Let's compare what we've see in Reason with this device.
Connections in the Mackie
sources (This link has a 108k graphic.)
- Low level input from a microphone. The signal needs to be boosted to
- Line level signal, often from a synthesizer or sampler.
- Input from the multitrack record deck.
- A patch point which routes a signal out from then back to an individual
- The processed signal from and effects processor.
- Amplifies the low level signal from a microphone. Adjustable.
inputs - Line level input from an individual multitrack tape
- Diverts the audio signal from the module, usually for external processing
or a cue mix.
- Output not affected by the channel fader. Most often used for cue
- Output sent after channel fader. Most often used for effects sends.
- Usually some type of equalization and in some larger boards compression.
- Determines placement in the stereo field.
- Only the output of the selected module is heard.
- The output of the selected module is not heard.
- Controls the output of the module.
- Controls the destination of the module output.
controlled in the Master
section of a mixing board.
- Controls the final output of the mixing board to the mixdown deck.
- Controls the levels of submix groups.
send masters - Controls the level of the combined channel sends.
(most often headphones)
Mix (most often control room speakers)
- Continue work on your final project. If you're having trouble with any aspect
of this assignment, seek help from the MTEC-111 tutors available in B10. Check
the times listed in the Announcements section of Course Companion.
- Try all the basic mix functions we looked at today and set up a basic mix
of your Reason project.
- Where are two
places where level can be controlled on an input/output module of a hardware
- What is gain
staging and what should we do with audio levels in a console to achieve a
clean, noise and distortion-free signal in a mixing board?
- What controls
the main stereo output of a mixing board?
- What part of
an input-output module do we use to route an audio signal to an effects processor?
- Where is the
signal from an effects processor brought into the signal path in a mixing
- What part of
an input-output module do we use to adjust the position of that module's output
in a stereo mix?
Mixing board (console, desk)