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Model AD122-96 MX

 

 

Master Analog to Digital 

Converter 

          
 
     

 

 
 

 

Operations Manual 

 

 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 

Summary of Contents for AD122-96 MX

Page 1: ...Model AD122 96 MX Master Analog to Digital Converter Operations Manual ...

Page 2: ...Lavry Engineering Inc P O Box 4602 Rolling Bay WA 98061 360 598 9757 http www lavryengineering com email techsupport lavryengineering com Revision 1 0 March 1 2013 ...

Page 3: ...ring engineers as well as Mix engineers can utilize clipping as a means of dynamic range control without the down side of attack and release times associated with compressors and limiters Although the MkIII model already had a reputation for clean clipping the MX model extends the useful range of clipping to even higher levels The MX model retains the Lavry exclusive Soft Saturation modes which in...

Page 4: ...AD122 96 MX Operations Manual This page left blank intentionally ...

Page 5: ... jurisdiction LIMITS AND EXCLUSIONS LAVRY ENGINEERING DOES NOT BY VIRTUE OF THIS AGREEMENT OR BY ANY COURSE OF PERFORMANCE COURSE OF DEALING OR USAGE OF TRADE MAKE ANY OTHER WARRANTIES EXPRESS OR IMPLIED INCLUDING WITHOUT LIMITATION ANY WARRANTY OF MERCHANTABILITY FITNESS FOR A PARTICULAR PURPOSE TITLE OR NONINFRINGEMENT AND ALL SUCH WARRANTIES ARE HEREBY EXPRESSLY DISCLAIMED LAVRY ENGINEERING EXP...

Page 6: ...een 7 Default Parameters Screen 7 Bar Graph Display Screen 8 Warm up and Calibration 9 Factory Defaults 9 Software Version 9 Hardware Interconnections 10 Maintenance 10 Part II Specifications 11 Appendix I αβC αcoustic βit Correction 12 Noise Shaping Curves 15 Appendix II AD122 96 MX Input Considerations 16 Appendix III AD122 96 MX Soft Saturation 18 Appendix IV Viewing Noise Floor on AD122 96 MX ...

Page 7: ...ge 96 kHz narrow lock range 88 44 kHz or 96 48 kHz conversion rate 2X sync rate Vernier Transfer Function Correction The exceptional performance of Lavry Engineering s AD122 96 MX is due to design innovations in both analog and digital sections The performance of the low noise high linearity converter is optimized by a set of proprietary algorithms utilizing a digital vernier technique which provi...

Page 8: ...buttons Pressing EXIT again will cause the unit to go to the main screen To Scroll Through Screens If the screen cursor is present you need to remove it by pressing EXIT When the screen cursor is not present the UP DOWN buttons serve to move from screen to screen To Edit Screens Press ENTER to introduce the screen cursor at the first editable location Each additional pressing of ENTER will move th...

Page 9: ... the IO 96 interface Lock range narrow lock range utilizing VCXO internal voltage controlled crystal oscillators or wide lock range internal low jitter VCO Possible choices for the SYNC WC INPUT XLR connector are XLR AES LOCK 44 1 Phase synchronous XLR AES LOCK 48 0 Phase synchronous XLR AES WIDE LOCK Phase synchronous XLR AES LOCK 88 2 Phase synchronous XLR AES LOCK 96 0 Phase synchronous XLR AES...

Page 10: ...ovide an effective means of retaining higher bit content in a lower bit format it shifts the noise energy away from hearing sensitive frequency regions to less sensitive ones See Appendix I for a complete discussion of αcoustic βit Correction Dither choices are OFF no dither HPDF high pass probability density function FLAT recommended for data compression applications Noise shaping choices are NSO...

Page 11: ...ion when recording audio signals so the lower line should always display DC REMOVAL ON during audio recording Polarity POLARITY corresponds to analog input signal connection with pin 2 non inverting POLARITY corresponds to analog input signal connection with pin 3 non inverting Note that polarity reversal works for both balanced and unbalanced analog input signals The analog inputs XLR connectors ...

Page 12: ...ding on a DC offset Monitoring low level signals such as noise floor requires prior setting of DC removal at the audio control screen DC REMOVAL ON 2 Viewing the noise floor takes some getting used to The display shows a true picture of peak and peak hold information the blinking of LED s is due to low level quantizations Peak readings are at about 11dB higher than the rms noise for flat noise spe...

Page 13: ...a tone at 25 dBFS feeding the analog inputs For a few seconds after the tone is switched on the level displayed on the meters will change slightly until finally settling on 25 dB Factory Defaults The AD122 96MX can be reset to the factory defaults by holding down the EXIT button while turning On the AC power Continue to hold down the EXIT button until the unit finishes initializing and the main sc...

Page 14: ...k properly or there are other devices in the chain termination may be necessary If the AD122 96MX 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 th...

Page 15: ...a test tone signal to frequency above Nyquist approx 30KHz Output Bits 16 to 24 bits user selectable Total Harmonic Distortion and Noise Specified for 22 24 Bits output balanced inputs 0 00005 for signals lower than 40dBF 0 0004 for signals lower than 20dBF 0 0008 for signals lower than 6dBF Channel Separation Greater than 120dB 0 20KHz Sync Inputs connect to only one input at any time XLR connect...

Page 16: ...stics b Recording engineers preference of dither type high pass or flat and noise shaping curves often depends on characteristics of the music involved The Model AD122 96 MX offers High Pass or Flat Dither type and four noise shaping curves Model AD122 96 MX allows the user to use dither with or without noise shaping Operating noise shapers without dither is undesirable so the unit automatically s...

Page 17: ...ed a preference for smoothly varying noise shaping curves Peaks and notches seem to irritate the listener admittedly while turning the volume up In addition despite the temptation to optimize the noise shaping curve to the average listener s hearing threshold given a significant variation from listener to listener requires reasonable compromises in tailoring such a curve In other words smooth the ...

Page 18: ...gure 7 shows a 100 dB tone of 16 bit word width with no dither or noise shaping Note the presence of all of the odd harmonics created when the truncation process turned the tone into a 1 lsb square wave Figure 8 shows the result of applying additional processing to this signal and truncating the result thereby creating additional distortion components Fig 9 16 bit input signal 100 dB Fig 10 16 bit...

Page 19: ...oise Quantization noise is shifted from these areas to high frequencies where the ear is less sensitive Noise shaping curves should be selected based upon listening tests of specific material to be dithered Fig 12 1kHz input signal 100 dB HPDF dither with multiple noise shapers shown Figure 12 compares High Pass dither with NS2 NS3 and NS4 noise shaping curves High Pass dither gives more noise sha...

Page 20: ...evel itself The source material may have its own noise level but the A D manufacturer is in no position to decide which part of the material is signal and which part is noise Is it undesirable noise or is it the intentional recording of the wind blowing through the trees Thus any signal must be reproduced accurately All we can do and all we should do amounts to avoiding additional A D noise A D no...

Page 21: ...nal with available 0 12 dB of front panel gain adjustment 2 Balanced input with grounded shield The unit handles up to 24dBu of peak signal with available 0 12 dB of front panel gain adjustment 3 Unbalanced input with floating shield The unit handles up to 24dBu of peak signal with available 0 8 dB of front panel gain adjustment 4 Unbalanced input with grounded shield The unit handles up to 24dBu ...

Page 22: ...ansfer functions The plots show input versus output value between 20dBFS and 0dBFS The algorithm for soft saturation is fundamentally different from classical audio compression A compression algorithm provides time varying gain as a function of signal power The gain variations are slowed down attack and decay envelopes to minimize distortions a sudden step in signal gain generates a time decaying ...

Page 23: ...an exponential curve was based on the nature of the distortions crudely speaking less distortion energy at higher harmonics 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 digi...

Page 24: ...dth 05 Computing the mean and standard deviation yields close to perfect results mean and stdev mean gn 0 001 stdev gn 1 001 Gaussian noise energy is measurable via a rms root mean square meter The proper measurement of converter noise should be done using a rms instrument such as Lavry Engineering s Model 3000 Audio Precision test system or others However the known bell shaped curve coupled with ...

Page 25: ...kup of non random noise such as power line hum Explanation for the 8dB factor The Gaussian bell shape curve is unbounded Theoretically speaking very high amplitude may occur but very high amplitudes occur very seldom it has been said that waiting a few trillion years may produce a million volt spike Practical observations show that most of the peaks occur within 3 5 times of the standard deviation...

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