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Rostec Engineering   Administration: Christianehøj 43, 2860 Søborg, Denmark   -   Email rostec@rostec.dk   -   Phone +45 3967 6438
       ROSTEC AD8 A/D Converter       High Performance 8 channel 192 kHz 24 bit A/D Converter
Electrical and mechanical specifications Analog to Digital interface. * 8 balanced analog line inputs at the back panel, D-SUB 25 female, TASCAM STANDARD. * 4 transformer balanced AES3 outputs (8 channels) at the back panel, D-SUB 25, YAMAHA STANDARD. * 1 USB 2.0 Digital interface, TYPE B connector. * The USB connection is compatible with Mac OS X 10.6.8 or later. Windows is not supported. * A/D Resolution: 24 bits. * Sampling frequencies: 44.1k, 48k, 88.2k, 96k, 176.4k, 192k. * AES latency: less than 0.2 mSec. * USB latency: down to 1.5 mSec (3.0 mSec roundtrip) This is highly dependent on the host computer speed and sampling frequency! * Interchannel Gain Mismatch: 0.1 dB. * Linearity inside passband (passband ripple): 0.035 dB. * Frequency response: 2nd order analog anti-aliasing filters at 1 Hz - 120 kHz +/- 0.2 dB.  Brick-wall digital filters at 0.5 x Fs * THD+N: 0.00045 % at 1 kHz unweighted. * THD: 0.00013 % at 1 kHz unweighted (see detailed FFT distortion analysis in the manual). * Crosstalk between adjacent channels: -120 dB, 20 Hz - 20 kHz, analog input terminated by 75 ohm. * Noise: 115 dB RMS, A weighted, 20 Hz - 20 kHz measurement bandwidth. * Analog input level: +18 dBu +/- 0.2 dB (EBU standard), switchable to +10 dBu +/- 0.2 dB (for vintage mixing consoles, equipment etc). * Analog level accuracy, calibrated version: +/- 0.01 dB. * Analog input headroom: + 30 dBu. * Hum residue from analog power supply, 1st, 2nd, 3rd and 4th harmonic: less than -134 dB referenced to 0dBFS. Clock system: * Word clock input:: BNC, unbalanced, unterminated (1 kohm), min. 0.2 Vpp, max. 10 Vpp. * Word clock output: BNC, unbalanced, impedance 75 ohm, 5 Vpp no load, 2.5 Vpp into 75 ohm. * Internal AES GRADE 2 crystal oscillator. * Temperature stability: +/-2 ppm from 0 degC to +70 degC. * Ageing: 2 ppm per year. * Word clock frequencies: 44.1k, 48k, 88.2k, 98k, 176.4k, 192k. * Internal crystal oscillator jitter: 2 ps rms. * Word clock output jitter: 50 ps rms. * AES data jitter: 50 ps rms. * Clock input capture range: +/- 80 ppm. * Lock time approx:  0.2 - 0.4 sec. Power supply: * Linear analog, passively cooled, high power, very low noise. * Thermal and electrical overload protection. * Mains voltage:190 - 264 VAC 50-60 Hz. Nominal 230 VAC (115 VAC version available by request). * Power consumption: 15 Watts. General: * Sturdy steel casing, magnetically and electrically screened. Size 210 mm x 210 mm x 42 mm. * Analog and digital circuits are magnetically and electrically isolated by internal metal screening and separate ground systems. * All digital inputs and outputs are ESD protected to 23 kV 15 A surge (IEC61000-4-2 and IEC61000-4-5). * All analog inputs are ESD protected to 2000V, human body model.
AD8 is a truly high performance 192 kHz 24 bit A/D converter in a half size 19”magnetically shielded metal enclosure. It features High-End true class A analog circuits with the same transfer characteristics as vacuum tubes and cutting edge Analog to Digital Conversion with impressive specifications. It connects easily to your system via the flexible class-compliant bit-perfect USB and AES interfaces. Several units can be connected to create larger multi-channel systems, and older systems can easily be upgraded with extra high quality channels for critical recordings, leaving the old channels on the system for less important stuff. The user interface is straight forward and intuitive with at clear “What You See Is What You Get” readout on a bright OLED display. A high accuracy calibrated version is available intended for industrial measurements and processing.
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With its true class A and carefully designed analog circuitry, Rostec AD8 represents a sound quality that is far richer and fuller than what you normally will find in the standard digital interfaces flooding the market today. AD8 is constructed with a throughout balanced architecture, meaning that audio signals, analog as well as digital, are routed internally as balanced signals, and all analog signal switching is performed by hermetically sealed relays with gold contacts. There are no digital analog switching circuits, no digital level adjustments, and there are no digital processing going on, except from the Analog to Digital conversion processes. The analog circuits feature individual soft clippers with a threshold just a little bit above digital clipping. This means that you can ride the converter hard and continuous at the clipping level in your DAW without getting the usual ugly digital sound break-up. At clipping level, the analog circuits still have an extra headroom of 12 dB above digital clipping, ensuring that any clipping of peaks in the program material is handled elegantly with no pumping, blanking or recovery artifacts. Also, the power supply is pure analog for a clean and noise-free internal electrical environment. Professional sound engineers know all too well that equipment with switch-mode power supplies tend to have a flat and dimensionless sound. The electrical switching pulses from a switch-mode power supply travel easily through air and common ground systems, and these sharp pulses presses  periodically the analog circuits into slew-rate-mode, which impedes the circuits ability to transfer micro details. We certainly don’t want any of that devastating digital noise pollution here, thank you! This highly sophisticated design gives AD8 a large dynamic range, huge headroom and ultra low noise and distortion, and the result is a very satisfying firm, tight and solid sound. At the same time, the sound is clear, open, warm and natural, with an impressive amount of details and with an astonishing depth and perspective. Gone is the ugly, cold, flat and lifeless sound you get from the typical standard digital interfaces or sound cards. This is classical analog quality at its very best, and digital technology used wisely. Readings for audio enthusiasts: In the design of AD8, special care and attention has been paid to maintain phase and amplitude linearity of the full dynamic range, all the way down to the level where the signal drowns out in the circuit noise. Maintaining the absolute linearity at the low end of the dynamic range is essential for allowing the human ear to detect the environment correctly. Back in the stone age humans were depending on their hearing to detect precisely from which direction the attacking tiger was sneaking up on you, and this information is mostly found in the low level parts of the sound. Many years have passed, but we still have this ability, and we use it when we listen to music and pin-point the position of the musical instruments and performers. Maintaining low level linearity in the A/D conversion process is mandatory for delivering the correct and full experience of any audio recording. In most standard digital interfaces, this lower portion of the audio signal is polluted with digital noise and non-harmonic ground based noise from switch mode power supplies and digital processing, which means that the ear detects this part of the signal as sound garbage with no clear relationship to the music. The result is, that the environmental information is degraded and partly lost, and the ear loses portions of the depth and perspective details, giving the music a flat, lifeless and dimensionless expression. 
Features • 8 channels of Analog to Digital conversion to the DAW via USB. * 8 channels of Digital from the DAW routed via USB to AES output. • 192 kHz 24 bit high-end latest generation converters. • Dynamic range 115 dB (higher internally, but limited by opamp noise). * USB 2.0 class compliant bit perfect interface. • Transformer balanced 110 ohm AES outputs. * Industry leading Low Latency performance. • Easy interfacing via standard D-sub 25 and USB B connectors. • Internal low jitter Grade 2 word clock generator. • Exceptional high immunity against jitter and digital noise from computer work stations. • Word clock Input has a "sweet spot" detector, providing auto-slicing and signal clean-up. • Word clock input accept from 0.2 Volts to 10 Volts. • Electronically balanced analog input buffers. • Combination of JFET and BJT cascode technology for exquisite sonic performance. • Analog and digital true balanced architecture throughout the unit. • Linear low noise analog power supply. • Internal magnetic and electrical screening. • Digital Inputs and outputs are ESD protected to 23 kV, IEC 61000-4-2 and 15 A surge, IEC 61000-4-5. • Sturdy steel metal casing, half size 19” 1U height. • Affordable price. High value for money.
Two units fit nicely on a 19” rack shelf