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Содержание AZX+

Страница 1: ...orrector Digital Audio Restoration Modules OWNER S MANUAL 1999 CEDAR Audio Ltd Manual version 1 00 February 1999 interstage Phistersvej 31 2900 Hellerup Danmark Telefon 3946 0000 fax 3946 0040 www interstage dk pro audio with a smile ...

Страница 2: ...bstantially in accordance with the appropriate section of its accompanying product manual for a period of one year from the date of supply to the Company s immediate customers 4 2 The Company will make good at its own expenses by repair or replacement any defect or failure that develops in the System within one year of supply to the Company s immediate customer 4 3 The Company shall have no liabil...

Страница 3: ... a straight line basis over a one year write off period or b repair or replacement of those components of the System that do not meet the warranties contained within this Document The foregoing states the entire liability of the Company to the Licensee 10 CONSEQUENTIAL LOSS Even if the Company has been advised of the possibility of such damages and notwithstanding anything else contained herein th...

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Страница 5: ...AFETY 3 SETUP 4 AUDIO CONNECTIONS 5 FRONT PANEL INDICATORS AND CONTROLS 7 OPERATING THE BRX DEBUZZER 10 OPERATING THE AZX AZIMUTH CORRECTOR 14 SPECIFICATIONS 18 EMC REGULATIONS 18 PART 2 An introduction to audio restoration BUZZ REMOVAL 20 AZIMUTH CORRECTION 24 ...

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Страница 7: ...PART 1 Operations manual ...

Страница 8: ...s in the Series X design and all the units in the family are designed for professional use Additional Series X features include the following Q Flexibility Each model in the Series X range will handle a wide range of audio restoration requirements Q Portability Each Series X is a compact lightweight unit designed to fit a standard 1U rack space Q Audio interfaces Series X incorporates a 24 bit dig...

Страница 9: ...afree standingunit thesuppliedrubberfeetshouldbefixedtothe base of the unit Q Power sources The Series X features a universal power supply that will work safely on any mains supply in the ranges 85V to 260V 50Hz or 60Hz AC only The unit should always be grounded or earthed and power connectors should be routed so that they will not be walked on or pinched The Series X is connected to the mains pow...

Страница 10: ...n the following Q mains connection lead Q this manual Q rack mounting hardware Q four self adhesive feet Installation site To maintain reliability and prolong operating life observe the following environmental considerations Q the nominal temperature should be maintained between 5 and 35 Celsius Q relative humidity should be in the range 30 to 80 non condensing Q strong magnetic fields should not ...

Страница 11: ... output of the Series X should be connected to the SPDIF input of a recording device or external DAC Q Digital AES EBU format audio data The AES EBU format is used by professional digital audio devices You should connect the AES EBU output from your source to the AES EBU input of the Series X using a single cable terminated with an XLR plug The AES EBU output of the Series X should be connected to...

Страница 12: ...PAGE 6 CEDAR BRX debuzzer 1 2 3 4 10 11 12 13 14 CEDAR AZX azimuth corrector 1 2 5 6 7 8 9 14 ...

Страница 13: ...essor on signals close to full scale may result in slight clipping This can be avoided using the attenuator 4 BRX Process ON OFF and LEDs Q When OUT the input signal is echoed at the outputs Q When IN the processed signal is directed to the outputs Use this control for before after monitoring of the signal The signal delay and attenuation are not affected by this control 5 13 Process controls Refe...

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Страница 15: ...The BRX debuzzer ...

Страница 16: ...n level compared with the rest of the signal you should initially set the BUZZ POWER to 12 o clock rather than to maximum If the fundamental frequency is set wrongly then the process will not be able to identify the buzz The FREQUENCY knob has three modes of operation preset value selection fine continuous adjustment and coarse continuous adjustment You may select between them as follows Q Preset ...

Страница 17: ... processing would be more effective if 50Hz was correctly selected Tracking indicators The BRX searches for a buzz fundamental in a small window centred on the displayed fundamental frequency The width of this window is approximately 1Hz at a setting of 50Hz and increases with increasing frequency If a consistent buzz is detected within this window one or more of the tracking indicators will light...

Страница 18: ...eeds to correctly identify the buzz or hum both in terms of its frequency spectrum and its amplitude It now remains only to determine how much of the noise is removed from the signal Your final step therefore is to reduce the ATTENUATION control turn it anti clockwise to a level just above that at which the buzz becomes audible In doing so you will minimise the possibility of any signal being remo...

Страница 19: ...The AZX azimuth corrector ...

Страница 20: ...s the timing error To aid rapid setup and accurate processing you can monitor the output Q before or after processing Q in stereo Q with the left and right channels summed mono sum Q with the right channel subtracted from the left mono difference The display indicates the time shift being applied to the signal A positive number indicates that the right channel is being delayed with respect to the ...

Страница 21: ... will be able to set manually the amount of time correction applied to the signal with a resolution of up to 1 of a sample You do this by rotating the ADJUST knob until the desired time shift is shown in the display Q Coarse and fine adjustment If once in MANUAL mode you press the ADJUST knob and then release it without rotating it you will toggle between the COARSE and FINE adjustment modes The C...

Страница 22: ...or mode PRE POST Q POST The time shift shown in the display is applied to the signal Q PRE The value shown in the display is ignored and the signal is unaffected by the TIME SHIFTER This control allows you to make quick glitch free A B comparisons of the signal before and after azimuth correction Monitor mode STEREO MONO SUM DIFFERENCE Q STEREO The left and right signals from the TIME SHIFTER are ...

Страница 23: ...ime relationship using the ADJUST control Do so until you find the TIME SHIFT at which the perceived signal is minimised Hint You can often recognise this by noticing that vocalists and solo instruments disappear from the mix leaving just the reverberation behind 5 Return to STEREO mode and use PRE POST to compare the uncorrected and corrected signals 6 If you are satisfied with the results restar...

Страница 24: ...nnectors and good quality shielded cable suitable for digital audio Declaration of conformity Date of issue 1 February 1999 Equipment CEDAR Series X Manufacturer CEDAR Audio Ltd Address 9 Clifton Court Cambridge CB1 7BN UK This is to certify that the aforementioned equipment when used in accordance with the instructions in this manual fully conforms to the protection requirements of the following ...

Страница 25: ...PART 2 An introduction to audio restoration ...

Страница 26: ... best restored using one of CEDAR s various decrackle time domain processes and we will not consider it further here On the other hand a buzz that has an indistinct time domain structure may be more easily characterised by its harmonic content and then analysed and treated in the frequency domain Historically audio engineers have used a number of conventional filtering techniques to eliminate buzz...

Страница 27: ...PAGE 21 Figure 2 Figure 3 Figure 1 ...

Страница 28: ...d side effects caused by the first problem you exacerbate the second Thirdly the offending frequencies may not be entirely constant so the filter s teeth may not always be appropriately placed and you will hear the buzz come and go during the course of the material you are playing These problems make comb filters which are nonetheless implemented on a number of audio processing platforms unaccepta...

Страница 29: ...PAGE 23 Figure 5 Figure 4 ...

Страница 30: ... can be described in its entirety by just three parameters its frequency amplitude and phase The frequency and amplitude describe to a good approximation the perceived pitch and volume of the signal The phase however is of no audible significance until we combine more than one such sinewave For the moment let us consider two sinewaves of the same frequency and amplitude but different phases Figure...

Страница 31: ...PAGE 25 Figure 2 Figure 3 Figure 1 Figure 4 ...

Страница 32: ...wever none of these attacks the heart of the problem these small but significant non synchronisations of the left and right channels CEDAR corrects these problems by eliminating the timing errors that cause them It does this by identifying any monophonic component in the stereo sound and then measuring the timing difference between the left and right channels of the signal If any such error is det...

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Страница 34: ... CEDAR s processes detect and correct Q The second effect is the smearing caused by the length of tape covered again in the direction of tape travel by the offset head In general terms the head will then average the signal lying underneath it at any point rather than measuring the instantaneous value The degradation caused by this will be smaller than that caused by the primary error and the effec...

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Страница 36: ...factured by CEDAR Audio Ltd 9 Clifton Court Cambridge CB1 7BN United Kingdom Serial number Inspected QC Engineer interstage Phistersvej 31 2900 Hellerup Danmark Telefon 3946 0000 fax 3946 0040 www interstage dk pro audio with a smile ...

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