Virtual audio mixing console for the IBM
PC and compatible MS-DOS computers
Developed 1990 - Bob Lentini
Read "Live Sound" Review
(Excerpt from
the original SAC Product Proposal)
What
is S.A.C?
S.A.C. is the acronym for Software Audio Console - an audio console
graphically represented on a computer screen interfaced with a small
19-inch rack of audio circuitry with no physical knobs and switches.
The primary piece of equipment used for controlling audio signals, in
both live and studio applications, is the audio mixing console.
Generally, a professional audio console contains 24 to 60 input
channels, 2 to 24 output channels, and 2 to 8 auxiliary send channels.
The physical dimensions of these consoles can range from about 6 to 10
feet in length and 2 to 3 feet in depth.
The standard audio consoles of today contain hundreds of physical
controls in the form of knobs and switches. This is how the audio
signals are manipulated by the operator.
Enter S.A.C., the Software Audio Console. S.A.C. changes the very
principles of audio console design and opens the doors to many new
wondrous capabilities which standard consoles cannot even dream of
offering.
S.A.C. is designed with all audio circuitry (hardware) built into
standard 19-inch rack-mounted modules. There are no physical knobs or
switches of any kind present on this hardware. The console is controlled
via a computer software interface. The entire console is drawn on a
computer screen and all controls are operated using the computer
keyboard and a graphics input device called a mouse. Every switch and
knob function of a standard console is duplicated via Analog-Digital
Voltage Controlled Attenuator circuits. The computer software interface
gives the operator the feel of a standard console and much, much more.
Original SAC DOS-Based GUI
Why S.A.C?
There are many reasons why S.A.C. should prove to be far superior to
standard audio consoles.
The size of the audio circuitry will be reduced to a standard 19 inch
rack about 24 inches in height. The operator will no longer have to
stretch across 6 to 10 feet of hardware in order to reach all controls.
In live applications the benefits are tremendous. Instead of the typical
10 to 15 feet of space needed in the center of the audience for the
console and related effects equipment, only a small table large enough
for a personal computer and monitor is necessary. Also, since the main
hardware (all audio circuitry) stays backstage in a rack, large
expensive 250-foot 50-pair audio snakes are no longer necessary. All
microphone connections remain backstage. Also, since S.A.C. recognizes
the MIDI standard, most or all modern effects equipment can remain
backstage as well, capable of being controlled directly by the computer
MIDI interface. Only two standard mic cables connect the console
operating position to the audio circuitry backstage.
Since S.A.C. operates entirely through Voltage Controlled Attenuator
Devices, built-in compression/limiting control is part of each audio
channel. Also, built-in noise gating is present on each channel. Imagine
a 60 input standard console with 60 gates and 60 compressor/limiters
externally mounted on equipment racks. Imagine the mess of cables needed
to interconnect all of this equipment. Then imagine S.A.C. replacing it
all with one small rack and no external cable harnesses.
Programmability and automation are two more important S.A.C. advantages.
S.A.C. will be able to remember thousands of EQ, volume, effects, and
switch settings, and instantly reset the entire console to any
pre-programmed condition with the click of the mouse. Presets will be
savable in hard disk files which can be catalogued and instantly
retrieved using the computer interface. Presets can also be sequenced
manually or automatically within songs. Since S.A.C. also recognizes
MIDI data, any MIDI sequencer can actively operate S.A.C. by sending
MIDI controller information in sync with MIDI time code to automate a
mix.
Flexible fader grouping is another S.A.C. advantage. The operator can
simply point, click, and adjust randomly assigned groups of faders at
any time during a mix.
Lighting has
moved in this direction for years. Now its time for audio to catch up
and go beyond. S.A.C. is definitely the "Audio Wave of the Future."
Original SAC DOS-Based GUI
The S.A.C. Prototype
We have applied our efforts to creating the first S.A.C. prototype for
the Live Sound Reinforcement
industry. The first S.A.C. board, now referred to as the SAC1000, is a
60 input, stereo output sound
reinforcement console.
Each of the 60 inputs contains a 9 band graphic
equalizer section with 27 frequency choices; variable LO->CUT
and HI-CUT filters; 12 auxiliary sends for effects and monitors; 8 SUB
assigns plus a direct stereo buss assign; a noise gate and compressor;
and PRE or POST in place
stereo solo.
The 8 sub modules contain 8 matrix output sections and 8 auxiliary
return sections with 3 band, 9
frequency EQ.
The master module contains all 12 auxiliary master sends and a full CUE
and TALKBACK section.
This list of features far surpasses the current industry standards and
gives S.A.C. a leading edge right from the start.
The software interface is written completely in assembly language for
the IBM PC and compatible MS-DOS computers.
We have chosen assembly
language because of its unmatched speed and efficiency. The
Software uses the Hercules graphics
standard or the VGA graphics standard and will later offer large screen
monitors with 1664 x 1200 resolution as an option.
Screenshot of first color version of SAC
Although there is talk of future developments
along the lines of what S.A.C. represents, currently no major >manufacturer
is showing any signs of immediate release of such a product. This gives
the S.A.C. project a tremendous potential advantage to lead the way and establish a
standard years ahead of the competition.
Read AES 1992
Review in Live Sound Magazine
December 1992
Anthony McLean,
Editor
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