The ADC-104 24-bit, 96-kHz
A-to-D Converter Module

• Four channel (4 Analog Channels), 24-bit, 96-kHz A-to-D conversion
• Conversion at 44.1, 48, 88.2, and 96 kHz sample rates
• Word length (jumper selected) = 24, 20, 18, and 16-bit, TPDF dithered
• THD+N = -104 dBFS (0.00063%) measured at -3 dBFS, at any of the standard sample rates
• Dynamic range = 116 dB A-weighted
• SNR = 116 dB A-weighted, 114 dB un-weighted
• Frequency response < +/- 0.1 dB 20 to 20 kHz at Fs = 48 kHz
• Four highly trimmed balanced audio inputs per module
• Built in Digital Distribution Amp with eight digital audio outputs (four per AES stream)
• Input level range +8 to +27.5 dBu for 0dBFS (+28 dBu on special order) - 10-turn pot, 2 dB/turn
• Simultaneous AES and ADAT outputs
• One bi-directional AES/EBU digital audio reference port – high-Z or 75 ohm
• Total jitter immunity
• Phase Accurate A-to-D conversion across any number of channels
• Digital output impedance = 75 or 110 ohm (jumper selected)
• All digital I/O = transformer coupled
• Nine segment true-digital LED meter
• Power presence LEDs (-15. +15, +3.3, and +5V)
• Front edge test points
• 240 mA quiescent draw @ ±15 V, 265 mA peak

The four-channel ADC-104 System 1000 A-to-D converter's performance is outstanding. The 24-bit, 96-kHz capable module is the companion of the DAC-104. System power can be either an internal PS-302, or one of three external power supplies, such as the PS-202. The digital modules are extensively shielded and happily coexist with analog modules, even microphone preamplifiers, making this system ideal for mixed signal applications, such as in edit suites.

One of the primary benefits of the ADC-104 has to do with jitter. The new UltraLock™ technology from Benchmark eliminates jitter-induced problems that normally result from a jittery reference input.

Problem #1: Jitter on clock signals cause phase modulation sidebands to be created at a converter’s sample and hold circuit. Jitter causes a timing uncertainty in the conversion process that in turn creates new “audio” that is not harmonically related to the original audio signal. This “audio” is unexpected and unwanted. It will cause a loss of imaging in the stereo signal and when severe, creates what some have called muddiness (a lot of extra low and mid frequency sound that was not in the original).

Problem #2: A jittery clock signal greatly degrades the digital filters in both A-to-D and D-to-A converters. This deterioration in performance allows, aliasing signals to get past the filters and the resulting audio can have significant inter-modulation distortion. Practitioners of Digital Audio do not generally understand this problem.

Many designers of digital audio converters use the clock signals that are recovered by an AES receiver to time the converter chip. While these receivers do have a wide-band Phase-Lock-Loop, they do not have the ability to significantly reject jitter, and at some frequencies will actually amplify it. Converters designed this way can sound very poor by comparison to conversion that has had its sources of jitter eliminated. Unfortunately, the practice of using receiver clock signals to time a converter’s operation, is ubiquitous in low-end “professional” and card-frame converter systems.

UltraLock™ technology by itself sets the Benchmark converters apart from the pack. But add to that the very low distortion, low noise, stable analog circuitry, for which Benchmark is well known, and you have a low cost, ultra high performance converter system that will wow even the purists.

The price of the ADC-104 is $1495. Call sales at 1-800-262-4675 for more information.

ADC-104 Manual (PDF)