MASTERING ANALOG TO DIGITAL CONVERTER USER MANUAL VER.7/sep 2010 Use ver.
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Quick Start………………………………………….…….3 Introduction..……………………………………...............4 Operation- Internal jumper settings.......................…..…...5 Operation- Typical setup -Balanced Signal Source….…...6 Operation- Analog input alignment……………...…….…8 Operation- Unbalanced Signal Source…….......................9 Sampling frequencies and External synchronization…....11 SuperShaper-HR ™ Noise shaping and dithering…..........13 Rack mount shelf.......................................….....................
Input volume knob sets the input sensitivity with range from mute to +4dB=-10dBFS. This is factory default. The knob can be disabled with internal jumpers which can select either the knob or internal precision 10 turn trimpots. Refer to Sample rate selection. Sets the desired sample rate. When used with external clock select FS closest matching that of supplied external wordclock. Selects output wordlength as stated. The 20 and 16 bit "flat dither" setting corresponds to signal dithered with flat dither.
Introduction to Stereo96 Series Converters The MYTEK Stereo96 series consists of two 1/3 rack units- the Stereo96 ADC and the Stereo 96 DAC. They are also a part of an extended family of 1/3 rack units which also includes 192kHz capable converters, SRC and Studio Clock. Stereo96 converters can be used as stand-alone devices for a variety of studio applications such as mastering, recording and playback, whenever the highest quality conversion is required.
JP2, JP5 - insert front two internal 10 turn trimpots as the input gain control- use requires input calibration with a sinewave generator. JP3, JP6 - set gain at fixed -15dBFS=+4dBm (1.228VRMS measured btwn pins 2 and 3) - provides precision matching of L/R sensitivity at standard fixed gain. JP1, JP4 - insert front stereo potentiometer as the input gain control- used typically for most applications. Turn it all the way up for unbalanced consumer -10dBV sources.
Typical Setup Balanced signal source Stereo96 ADC is equipped with 2 XLR analog inputs. For best signal to noise performance it is recommended the signal source has a typical low impedance output with standard +4dB line level balanced signal. Alternatively a weaker unbalanced signal source can be used as described in subsequent paragraph. In typical setup the ADC is running on its internal clock with the rest of equipment synchronized to Mytek clock either through digital output signal or wordclock.
4. Select output wordlength- 24 bit full output is recommended. 16 and 20 bit output are meant to be used when the destination (recorder such as CDR, ADAT tape machine) limits the wordlength. 20 bit output is dithered with flat dither. 16 bit output can either be dithered flat (recommended for multitrack recording) or 16 bit noiseshaped (recommended for final masters, printing to CDR or DAT machine).
Analog Input Alignment When using internal trimpots analog input level needs to be aligned using an approx 1kHz sinewave fed from +4dB balanced source. The alignment does not affect audio quality, only input sensitivity. The alignment is performed using 10 turn trimpots inside the unit (see: "Internal Jumpers"). A small tweaker or screwdriver is necessary. You have to arbitrarily decide what will be your studio "0 VU" analog/digital reference level. It is usually between -20 and -14dB.
Unbalanced Signal Source Operation Stereo96ADC can be operated with weaker consumer level unbalanced signal sources. Follow these steps in such case. 1. Unbalanced cable used to feed the unit must have signal connected to pin 2 of XLR, ground (shield) connected to pin 1 and 3. 2. Setup all other connections. 3. Select desired clock source (sync), either internal or external.
6. Synchronize the destination either to digital input sync or to wordclock sync, depending on system configuration. The quality of recorded signal does not depend on how the digital destination is synchronized with Mytek AD converter. 7. Record- adjust input level by adjusting level at the source. Unless you are printing final CD master, we do not recommend recording too hot. There is no sonic benefit of pushing the level up to 0dBFS.
Sampling frequencies and External Synchronization In typical setup the ADC is running on its internal clock with the rest of equipment synchronized to Mytek clock either through digital output signal or wordclock. In this configuration Mytek ADC serves as a very stable low jitter house clock which increases the integrity and robustness of the rest of the system. Because of careful design this clock is as good or better than dedicated studio clock generators.
and must not be used for critical projects downsampling. Some such as Faulkner Downsampler (http://www.audiosignal.co.uk/freeware.html) provide excellent results for 88.2>44.1 but don't work for 96k. 88.2k is also easier to upsample to DSD. 96k sample rate, has in our opinion, a marginally better perceived sound quality than 88.2k but the difference is very small and difficult to perceive for most people. If the record is going to be mixed in analog domain, 96k might be a desirable choice for tracking.
Mytek “SuperShaper-HR” ™ Noise Shaping and Dither The Stereo96 A/D converter employs SuperShaper-HR ™ - a sophisticated psychoacoustically optimized noise shaping and dithering algorithm. SuperShaper-HR ™ uses 9th order high resolution noise shaping filters with proprietary filter coefficients developed by Mytek Inc. The appropriate noiseshaping curve is programmed into noiseshaping filters. This feature allows for preserving most of 24 bit performance in 16 bit data output.
More information about use of noise shaping in high resolution recording can be found in the following Audio Engineering Society Preprints ( http://www.aes.org ): “Coding Methods for High Resolution Recording Systems” Preprint Number: 4639 Convention: 103 1997-09 Author: J. Robert Stuart This paper reviews the recording and reproduction chain from the viewpoints of digital audio engineering and psychoacoustics. It also attempts to define the audio requirements of a transparent digital audio channel.
“Optimal Noise Shaping and Dither of Digital Signals” Preprint Number: 2822 Convention: 87 1989-10 Author: Michael Gerzon Author: Peter G. Craven This paper discusses optimizing noise shaping, with or without dither, using filtered error-feedback round a quantizer. “Psychoacoustically Optimal Noise Shaping” Preprint Number: 2965 Convention: 89 1990-09 AES Journal Vol:Issue: 40:7/8 Page: 611 Year: 1992 Author: Robert A.
Rack Mount Shelf The Stereo96 ADC is 1/3 rack space wide and 1U tall. Mytek provides a 1U rack mount shelf as accessory to mount up to 3 of 1/3 rack units. The units are attached to shelf with small screw connecting the shelf to bottom through a threaded hole on the bottom of the unit. When mounting the unit to the rack, you must follow these procedures to ensure that you do not cause any damage to your unit: 1. Remove the rubber feet.
Companion Stereo96 DAC Stereo96 DAC is a two channel hi-end Digital to Analog converter for recording and mastering applications. The main feature of this converter is its outstanding sound quality which makes it suitable for the most demanding projects when preserving the original signal quality is required.
Specifications Conversion: Linear, 128x oversampling at 44.1/48kHz 64x oversampling at 88.2/96kHz Resolution: 24 bit Sample rates: 44.1kHz, 48kHz, 88.2kHz, 96kHz or wordclock 25-100kHz Dynamic Range: 120dB A-weighted, 117dB Total THD+Noise: -105dB (<0.0005%) Internal clock jitter:<10picoseconds Analog Inputs: +4dBm balanced or unbalanced, 10kOhm Digital outputs: Hi-speed (25-100kHz) AES/EBU and SPDIF Optical TOSLINK SPDIF/ADAT External Sync.: Wordclock in and out.
Warranty This Stereo96ADC digital audio converter is warranted by Mytek to the original purchaser against defects in workmanship and materials used in manufacture for a period of one year from the date of purchase. Faults due to customer misuse, unauthorized modifications or accidents are not covered by this warranty. No other warranty is expressed or implied. Any faulty unit should be sent, shipping prepaid, to the manufacturer service center.
