Specifications

Soft Limit™
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 lim-
iter. 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.
Filters
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 fil-
ter 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.
Sync Sources
It is unusual to use an analog to digital converter in a stand-alone environment. We have included every popu-
lar sync source capability via the ground-isolated BNC connectors (with additional loop through). Sync is select-
ed 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).
Sample Rate
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.)
Metering
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.
For additional information, see Section 6, page 33.
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”.
Digital Outputs
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 connec-
tor). Additionally, the WORD CLOCK output is driven by the internal Low Jitter Clock via a high speed opto-
isolated driver.
AD-1000 Operating Manual
Page 12