APOGEE AD-1000 REFERENCE STANDARD ANALOG TO DIGITAL CONVERTER
Apogee's AD-1000 multi-purpose stereo analog to digital converter is one of the most versatile and successful pieces of audio equipment ever introduced by Apogee Electronics Corp. It quickly became an industry favorite and while hardly new technology, the AD-1000 is still prominently featured in the "available gear" lists of numerous recording studios.
Says one industry professional familiar with the unit: "Based on what many of the largest studios in Nashville use I can certainly see a pattern: Apogee. For example in the studio recording complex The Sound Kitchen in Nashville (where many platinum records have been recorded) they use Apogee AD-1000 converters in 5 of their largest studios, that's almost one in each studio! They have plenty of them...! The Apogee AD-1000 is not sold anymore, it was 20-bit but they say it is better sounding than some of the 24-bit converters Apogee markets today."
This particular unit was acquired new directly from Apogee and was used lightly in a home environment for transferring analog sources such as radio broadcasts and reel-to-reel audiotapes to DAT.
It comes with power cord, separate power supply unit, and special Apogee cable for linking the two, including SPDIF and WC connections. Additional cables for the unit's various inputs and outputs are available on request.
Check out our other Pro Audio and Video Equipment in our eBay store
More on the AD-1000, from Apogee's literature:
The AD-1000 is a multi-purpose stereo analog to digital converter combining a high quality dual-stage, triple servo, analog ‘front end’ with 20 bit resolution. This combination provides unmatched sonic performance of 20 bit resolution, optimized for 20- and 16-bit applications such as digital tape recorders, disk-based audio workstations, and CD premastering. The AD-1000 includes Apogee’s UV22® Encoding system, as used by mastering facilities worldwide to capture 20 bit detail in 16-bit formats such as CD and DAT.
Descended from the industry standard AD-500E, the AD-1000 adds 20-bit resolution with selectable UV22® encoding, ADAT® optical output, digital oscillator and transparent microphone preamps. Portable 12 volt operation and dual stage, triple servo, direct coupled microphone preamps with phantom power let you take reference standard conversion wherever you go. Effective input peak metering and “Over” indication ease the adjustment of separate mic gain and multiturn CAL controls. Select the acclaimed SoftLimit™ function to position your recordings above the competition.
A special version of Apogee’s UV22 process captures 20 bit resolution and detail into 16-bit formats such as CD, DAT and ADAT. UV22 encoding is the overwhelming choice of mastering engineers world wide for condensing high resolution sources onto CDs. Outputs can be ADAT optical or simultaneous AES and S/PDIF to support multiple recorders. Optional outputs include SDIF, SDIF-II and Tascam TDIF™. With the inputse lector set to DIGITAL, AES or S/PDIF inputs are converted to all outputs. A built-in digital oscillator outputs all popular “0” reference levels for precise headroom setting. Patented Apogee Low Jitter Clock technology assures all digital outputs are free of the negative
effects of clock jitter.
The AD-1000 can operate as a Sync Master or lock to external AES, S/PDIF or Word Clock. Film and Video are supported by NTSC color, monochrome and PAL inputs. Transfer and repair operations are further enhanced with Apogee’s “1.001” circuit, allowing pull-up and pull-down.
Additional Details from the AD-1000 Manual:
Analog Input Circuitry
The AD-1000 features a proprietary balanced discrete front end with a combined noise and distortion measurement
in the 0.001% range. The unit features XLR input connectors that will accept input levels from microphones
and line levels up to +28 dBu. The common mode rejection is typically 100 dB – surpassing even the
finest transformers – and provides very stable performance over a broad temperature range. Also incorporated,
in front of the active circuitry, is a passive RF filter with hand-selected resistors and capacitors – matched to
better than one part per thousand – to roll off any outside interference, without the typical intermodulation distortion
byproducts of active circuitry.
Input Selector and Gain Controls
The input selector is an 11-position switch providing maximum input flexibility. When the switch is in the center
MUTE position, the digital output still delivers a ‘digital black’ condition (all 0’s) used for sync in many mastering
and video applications. Rotating the selector clockwise, the next five positions select microphone input gain
in 10 dB increments. Used in conjunction with the LEFT and RIGHT input level controls, up to 54 dB of gain is
available (40 dB from the input selector and an additional 14 dB if the LEFT or RIGHT controls are fully clockwise).
This combination allows the setting of the coarse gain with the input selector and fine calibration using
the LEFT and RIGHT controls. (Note: The LEFT and RIGHT controls can be bypassed and the gain can be routed
to the multi-turn CAL pots if desired. See page 31 for details of this procedure.)
Line Level Inputs +4 dBu and –10 dBV
Two CAL positions are available by rotating the INPUT SELECTOR counter-clockwise from twelve o’clock. These
positions correspond to +4 (Pro) and –10 (Consumer) line level inputs. When either of these positions are selected,
the multi-turn CAL trim pots are enabled. (Note: The CAL pots can be bypassed and the gain can be routed
to LEFT and RIGHT controls if desired. See page 31 for details regarding this procedure.)
48 volt phantom power is supplied to both microphone inputs when this selector is in the ON position and the
input selector is in any MIC or the 12 o’clock mute position. The phantom voltage ramps up and down slowly
for quiet activation and uses highly accurate resistors for optimum performance.
Included with the AD-1000 is Apogee’s highly acclaimed Soft Limit circuitry. (This feature has functioned as many
an engineer’s “secret weapon” to get extra level in their masters.) Soft Limit functions as a selective peak limiter.
Typical peak limiters are very abrupt and can spread unwanted harmonics. With the AD-1000, once an input
signal passes the threshold, Soft Limit gently removes the peaks by rounding them off, making the limiting
action very difficult to hear. The result is ‘hotter’ sounding program material.
Apogee has long been known for filter technology – the result of years of proven, proprietary designs. The AD-
1000 continues this tradition with the ultimate in filter performance. A quadruple stage, progressive passive filter
is inserted between the analog inputs and the analog to digital converter.
20 Bit Conversion and UV22®
The AD-1000 resolves analog detail to the 20-bit level to capture accurately every subtle nuance of the analog
input signal. The output can be either 20-bit resolution or 16-bit. Apogee’s UV22 Super CD Encoding system
may be utilized when working with 16-bit recording formats. Used by virtually all major mastering facilities,
UV22 captures the resolution and detail of the 20-bit conversion in a 16-bit word length; information that would
normally be lost.
It is unusual to use an analog to digital converter in a stand-alone environment. We have included every popular
sync source capability via the ground-isolated BNC connectors (with additional loop through). Sync is selected
via the front panel SYNC SOURCE SELECTOR SWITCH. Sync source capabilities include: CRYSTAL (selects
the internal crystal reference from the sample rate switch); WORD CLOCK (locks to any external clock from 32
to 54KHz, including full vari-speed operation); AES/EBU, S/PDIF; VIDEO and SYNC (NTSC [525line/59.94Hz],
Monochrome [525line/60Hz], PAL [625line/50Hz] are provided).
An accurate 10 PPM internal crystal provides sample rates of 32, 44.1 and 48 KHz and the 0.1% derivatives
44.056, 44.144, 47.952 and 48.048 KHz (useful in film and video transfer work). The AD-1000 also has ability to
multiply or divide incoming AES, S/PDIF, Optical and Word Clock sync by 1.001 for added flexibility. (1.001 is
the ratio between monochrome video – originally used in mastering CD’s – and NTSC video.)
A simple but very effective LED metering system has been incorporated into the AD-1000 that indicates levels
below converter clipping and is designed to be used with the hosts’ metering. The –12 LED for each channel
can be customized. The –12 labeling is nominal; in fact the threshold of this LED is tied to the digital oscillator
level and can be varied from –20 to –12 below 0dBfs. This is done by adjusting various switches on the top of
the AD-1000. The –12/Threshold LEDs also serve an additional function. When a signal is within 0.05dB of the
nominal gain of the AD-1000 oscillator setting, these LEDs flash rapidly. This is used to calibrate the analog to
digital conversion levels.
When Soft Limit is engaged, the –2 LED acts as a Soft Limit Threshold indicator. When this threshold is achieved,
the –2/SL will light. When Soft Limit is not engaged, the LED will signal when a peak of –2dBfs is achieved.
Two separate Red LEDs indicate “overs” (digital clipping) when three or more samples in a row reach “all ones”.
A separate transformer-isolated AES/EBU output is provided on the rear of the unit. Also provided is a fiber
optic output connector which can supply either TOSLINK or ADAT format. S/PDIF and WORD CLOCK outputs
are available on a high density 15-pin HD connector. (SDIF outputs are also optionally available on this connector).
Additionally, the WORD CLOCK output is driven by the internal Low Jitter Clock via a high speed optoisolated
Apogee Patented Low Jitter Clock
The C768 Ultra Low Jitter Slaving Clock references to an external clock source and provides a ‘flywheel’ effect
by smoothing out short-term timing irregularities or jitter. This low jitter slaving clock locks in a predictable and
very accurate phase relationship with the incoming reference. The result is superior sonic imaging with excellent
soundstage detail. Whenever possible, the AD-1000 should be the digital timing source for the digital