User manual LAVRY AD122-96 MKIII REV 1.4

[. . . ] Model AD122-96 Mark III 96kHz Mastering Quality Analog to Digital Converter Operations Manual Lavry Engineering, Inc. Box 4602 Rolling Bay, WA 98061 (360)598-9757 http://www. lavryengineering. com/ email: techsupport@lavryengineering. com Revision 1. 4 May 20, 2009 AD122-96 MKIII Operations Manual This page left blank. intentionally. AD122-96 MKIII Operations Manual MKIII PREFACE The MKIII is our 4th generation gold series analog to digital converter. The first gold AD, model AD122 (developed under our old company name ­ dB Technologies) was the first converter to reach 122dB dynamic range which is 20 bits of true performance. [. . . ] The converter power line signal rejection is very high (120dB common mode rejection) but use of high quality shielded audio cables is recommended. The XLR pin polarity is: Pin 2 non-inverting and Pin 3 inverting with +POLARITY setting. The digital output AES/EBU connector (XLR) provides transformer coupled output for both AES/EBU and consumer formats. A simple XLR to RCA adapter or adapter cable can be used to feed a coaxial SPDIF input. SYNC\WC INPUT (XLR connector) is used for external synchronization to digital audio or to a word clock synchronization source. The four BNC connectors provide channel one and channel two data, word clock out, and word clock in. They can be used for synchronizing additional converters to each other or an external TTL word clock. Regarding Termination: For simple systems where there is only one device feeding the AD122-96MkIII's Word Clock Input with a short BNC cable, termination is probably not necessary. If you encounter problems getting the AD122-96MkIII to lock properly, or there are other devices in the "chain;" termination may be necessary. If the AD122-96MkIII is the only unit being fed the Word Clock signal, connect the cable using a BNC "T" adapter plugged into the "Word Clock Input. " On the other side of the "T", place a 75 Ohm BNC terminator connector. If the Word Clock is chained to other devices using "T" connectors, be sure that there is a 75 Ohm terminator on the "T" of the LAST device in the chain and that none of the other devices have INTERNAL TERMINATION. Alternately, if there is only ONE device with internal termination, it can be wired at the "end of the chain" in place of the terminator. The important point is that there is only ONE termination and it is located at the end of the chain. The same approach may be used to chain the Word Clock output of the AD122-96MkIII. In this case, there is no "T" on the AD122-96MkIII Word Clock Output. As described above, the "T" adapters should be placed on the Word Clock input of the devices the AD122-96MkIII is feeding, with the termination ONLY at the very end of the chain. Maintenance The Model AD122-96 MKIII is an auto calibrating converter requiring no periodic adjustments. The unit's reliance on linear power supplies and discrete class A analog circuitry generates significant amount of heat (25 watts maximum). The temperature rise is no cause for concern, but allowing for some airflow is always a benefit from a long-term reliability standpoint. Use a soft cloth (and plain water, if necessary) to clean fingerprints. 10 AD122-96 MKIII Operations Manual Part II: Specifications Analog Inputs: The analog signal can be amplified by 0-12dB utilizing the front panel screw adjust trim pots. Fullscale signal with 0dB gain is 24dBu, (full-scale signal with 12dB gain is 12dBu). Input impedance over 0-100 kHz: greater than 20k ohm (pin 2 to pin 3). Noise Floor at 44. 1-48KHz sampling: -130dB ±1dB from full scale A weighted -126dB ±0. 5dB from full scale unweighted Noise Floor at 96KHz sampling: -127dB ±1dB from full scale A weighted -123dB ±1dB from full scale unweighted. [. . . ] The key to a smooth transition was to make the slopes of the linear and non linear portions are precisely equal to 22 bit accuracy (as always, such precision is much more apparent to a listener of 16 bit data then to a viewer of "9 bits graph". Unlike the "analog soft knee", the digital soft saturation is a precise transformation. The user may not drive the signal further and further into the saturation region (compromising between "hotter recording" and "acceptable distortions"). The +3dB setting provides perfect linearity to -6dBFS of the incoming signal (-3dBFS of the processed signal), and the +6dB setting provides perfect linearity to -12dBFS of the incoming signal (-6dBFS of the processed signal). [. . . ]