The Company
Soundstream Inc. was founded
in 1975 in Salt Lake
City, Utah
by Dr. Thomas
G. Stockham, Jr. It was
the world’s first
audiophile digital audio recording company, providing
commercial services for recording and computer-based editing.
Soundstream provided worldwide on-location recording services to
Telarc,
Delos,
RCA,
Philips,
Vanguard,
Varèse Sarabande,
Angel,
Warner
Brothers,
CBS,
Decca,
Chalfont, and other labels. It also leased
or sold some recorders (a total of 18 were manufactured). Although
most recordings were of
classical music, the range included
country,
rock,
jazz,
pop, and
avant-garde.
The first digital recording of a symphony orchestra was made in
1976 by Soundstream's prototype 37kHz, 16-bit, two channel
recorder.
New World Records, who
recorded the
Santa Fe Opera's
performance of
Virgil Thomson's
The Mother of Us All, provided Soundstream with a stereo
feed from their multitrack console. Soundstream demonstrated its
recording of the opera at the Fall 1976
AES Convention. Critiques of the recording,
most notably from Telarc's
Jack Renner
and Robert Woods, led directly to the improved 4-channel, 50kHz
sample rate recorder that was used for all of Soundstream's future
commercial releases. The New World Records issue of
Mother of
Us All was not from the digital recording made by
Soundstream.
Also in 1976, Soundstream restored acoustic (pre-electronic)
recordings of
Enrico Caruso, using
'blind deconvolution'. These were released by RCA as "
Caruso - A Legendary
Performer". In subsequent years Soundstream restored much of
RCA's Caruso portfolio.
Soundstream’s first commercially released recording (popular music
on the
Orinda label) in 1978
was a month shy of the world’s
first
digitally recorded commercial release. For the ensuing three
years, 50% of all classical music recorded digitally used
Soundstream equipment.
Unlike its competitors, Soundstream's analog circuitry was
transformerless, permitting a frequency response to 0
Hz (
DC). This accounted
for the ‘bass drum heard round the world’ review of the 1978 Telarc
recording of
Frederick Fennell: The Cleveland Symphonic
Winds. Soundstream collaborated with Telarc for several years,
producing legendary symphonic recordings; the earliest ones are
chronicled in Renner. The care with which Telarc selected and used
its microphones and audio console, combined with the Soundstream
recorder, created a gold standard for audiophile recording. Telarc
has re-released many of its original Soundstream recordings in SACD
format, with a
DSD-equivalent
sampling rate of 50 kHz.
Soundstream recordings made before the advent of the
CD were released as high-quality
vinyl LP albums. Despite analog playback,
many of these releases were sufficiently impressive to gain an
early acceptance for digital audio. The recording industry’s
transition to digital was further facilitated by the many
demonstrations given by Dr. Stockham, whose articulate explanations
of digital audio theory and practice were renowned.
In 1980, Digital Recording Corporation (DRC) acquired Soundstream.
DRC attempted to develop a home digital player that would use a
photographically reproducible ‘optical card’ as opposed to the
mechanically pressed CD. This effort was eclipsed by the rise of
the CD, leading to the company’s demise in 1985.
The Technology
The company developed its four-channel recorder in 1977. The
Soundstream Digital Tape Recorder (DTR) consisted of a modified
Honeywell 5600E instrumentation
transport and
analog and
digital
circuitry designed and built by Soundstream.
The Digital Tape Recorder
The Digital Tape Recorder was a
portable four-channel digital audio processor containing the analog
to digital converters, tape-data recovery and clock generation
circuits, and the digital to analog converters. External hardware
(tape drive, editing system, and digital delay unit) connected to
the DTR through connectors on the back panel. The unit measured
20"x18"x10" and weighed 67 pounds.
Analog signals entered the DTR through standard XLR connectors at
the rear of the unit. There, a differential input amplifier routed
the signal through the front panel attenuation fader to the input
low-pass (anti-alias) filter.
The filtered analog signal passed through a custom
sample and hold and was digitized by an
Analogic MP8016 16-bit Analog
to Digital Converter operating at a 50kHz sample rate. A 3-bit sync
pattern and an even parity bit were added to each 16-bit sample to
form a 20-bit word that was serialized and transmitted by interface
electronics to the tape transport where each audio channel's data
were written to two separate tape tracks.
During tape playback or while recording and monitoring from tape,
the redundant tracks of recorded data from the transport were sent
to data recovery circuitry. Because the data recorded on tape are
necessarily bandwidth limited, the data recovery circuitry
squared-up the data signals and then created clocks to match the
incoming data streams. Additional circuitry located word boundaries
and converted the data to parallel format. In the event of tape
dropouts, an error avoidance scheme selected the unaffected track's
data.
The selected data were then clocked into an Analogic MP1926A
Digital to Analog Converter at the original crystal-controlled
sample rate. The analog signal from the converter was routed to the
output low-pass (reconstruction) filter. Voltage and current gain
sufficient for +20
dBm into 150 ohms was provided
by the output buffer amplifier which signal was then output at the
XLR connector on the DTR's rear panel.
The Honeywell Tapedeck (or Honeywell Transport)
Soundstream modified Honeywell 5600e Instrumentation Tape Drives
(HTD) used custom high-frequency 18-track record and playback
heads. The two outer tracks were reserved for ancillary data -
SMPTE time code and the like. The
remaining sixteen tracks were used to record up to eight channels
of digital audio - two redundant tracks for each audio channel.
Each track in a redundant track pair were as widely separated as
possible to minimize playback errors due to tape defects (dropouts)
- audio channel one was recorded on tracks 1 and 9.
At the front of the HTD, Soundstream installed Track Selector
hardware. The left side selector allowed the operator to choose
which audio channel pair (1,2; 3,4) was assigned to which tape
track pair (1,2; 3,4; 5,6; or 7,8). The right side selector
controlled the application of record circuitry power for each of
the eight tracks.
The HTD initially used 1"
Ampex 460
reel-to-reel tape at 35ips. Later, Soundstream switched to Ampex
466 tape which allowed for the slower tape speed of 30ips.
Ancillary Equipment
Digital Audio Interface
The Digital Audio Interface (DAI) was the input/output path between
the Digital Editing System and external hardware. The DAI received
raw source data from session tapes and passed the data on to the
editing system's computer for storage. Finished (edited) data
passed through the DAI from the editing system's computer to a DTR
for creation of a master tape. During the editing process, data
from the editing system's computer passed through the DAI to a
Digital Audio Conversion Unit (DAC Box) in the editing room.
The DAI resided in the Editing System's computer and contained a
one-megabyte FIFO. Realtime input/output capacity was eight
channels of 16-bit audio data at any of the then standard sample
rates.
Digital Delay Unit
To allow for a preview channel during the LP cutting process,
Soundstream built a digital delay unit (DDU). Digital data from
tape could be delayed by a user selectable time: 3ms to 1.308s in
increments of 5.12ms. Delay was accomplished by the use of a
variable-depth FIFO or ring buffer.
S-1610 Adapter
So that users of the
Sony PCM-1610 Digital
Audio Processor could take advantage of Soundstream's editing
system, the company developed the S-1610 Adapter. The adapter was a
bidirectional two-channel format converter. Data from the Sony
PCM-1610 were converted to the format used by the Soundstream DTR
so that the data appearing at the input to the Digital Audio
Interface looked to the DAI as if it had come from a DTR.
Similarly, finished (edited) data in Soundstream format were
restored to the Sony format by the adapter. Sony data were
imported/exported at either of the two sample rates 44.1kHz or
44.1/1.001kHz.
Any metadata in the Sony format were lost in the format conversion.
This was a format conversion only, the adapter did not do sample
rate conversion.
M Adapter
So that users of the
3M Digital Mastering System
could take advantage of Soundstream's editing system, the company
developed the M Adapter. The adapter was a bidirectional
eight-channel format converter. Data from the 3M Digital Mastering
System were converted to the format used by the Soundstream DTR so
that the data appearing at the input to the Digital Audio Interface
looked to the DAI as if it had come from a DTR. Similarly, finished
(edited) data in Soundstream format were restored to the 3M format
by the adapter.
DAC Box
Essentially derived from the DTR's playback circuitry, the DAC Box
was a four channel device used by the Soundstream editors to
audition audio data during the editing process. Audio played from
the computer through the Digital Audio Interface into the DAC
Box.
The Digital Editing System
Soundstream’s digital editing system was the first instance of a
computer used to edit commercial recordings. It consisted of a
Digital Equipment
PDP 11/60 computer, Soundstream’s interface
to transfer data between its recorder and the computer’s disks (a
pair of Braegen 14" disk drives), digital-to-analog playback
hardware, and editing software. For all intents and purposes, this
system was the very first
digital audio workstation.
In
addition to its own facility, Soundstream installed editing systems
at Paramount Pictures
(Hollywood), RCA (New York), and Bertelsmann
(Germany). A system was delivered to the U.S.
Department of Justice to aid the analysis of bootleg
recordings.
Editing could be performed at sample accuracy (i.e., 1/50,000 of a
second); any mixing was performed digitally.
The sound system in the editing room in the Salt Lake facility used
a Threshold preamp, a Sumo "The Power" amp, and
Infinity RS4.5 speakers.
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