The S - DMX Digital Audio System user Manual 527-028 Issue 3 © 2000 AMS Neve plc own the copyright of all information and drawings contained in this manual which are not to be copied or reproduced by any means or disclosed in part or whole to any third party without written permission.
S-DMX User Manual CONTENTS S-DMX 1 OPERATING INSTRUCTIONS 3 System Overview 3 Installation 4 Operation 6 Using the S-DMX THEORY OF OPERATION Overall Functional Description MAINTENANCE 19 19 23 General Maintenance 23 Trouble Shooting 24 SPECIFICATIONS 25 Electrical 25 Dimensions 26 Options 26 APPENDIX A 27 Board Edge Connector Details APPENDIX B Set-Up Procedures for MIDI Equipped S-DMX S-DMX FRONT PANEL Issue 3 11 27 29 29 31 Page i
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S-DMX User Manual OPERATING INSTRUCTIONS System Overview The S-DMX is a dual independent channel microprocessor controlled digital audio processor. It offers two completely independently delayed channels with precisely controlled delay times. The delay times are adjustable without any sacrifice in the 18kHz bandwidth which remains constant irrespective of the amount of delay selected. A total delay of over thirty two seconds is possible with this unit, split over the two channels.
S-DMX User Manual Installation The model S-DMX can be operated with a line input voltage of 110, 220 or 240 Volts, adjustable externally. Before connecting the equipment to primary power, check that the line voltage setting is correct (see the voltage setting on the back of the unit): if the line voltage is not specified assume, for safety, a line voltage setting of 240 Volts.
S-DMX User Manual Mains Wiring All mains leads supplied with equipment manufactured at AMS Neve are wired in accordance with the European (I.E.C.) colour code. The code is as follows: BROWN LIVE BLUE NEUTRAL GREEN/YELLOW EARTH Fuse Replacement All power supply rails within the S-DMX are protected by current limiting and also against over voltage.
S-DMX User Manual Operation Input / Output Level And Mixing Section The input may be switched between two channel operation (stereo input) and single input, dual output operation (mono input using channel ‘a’ as source). The two outputs may also be mixed if desired to create or enhance various effects. If the input is two channel and the outputs remain unmixed the stereo LED will illuminate to indicate true stereo operation.
S-DMX User Manual The selected channel may be ‘fired off’ in single shot mode by pressing the enter key ‘#’ and may be repeatedly triggered by multiple depressions. The message ‘tr.-A’ or ‘tr.-B’ will appear. The pitch of the loop may be varied in a similar way to normal operation by pressing the ‘C’ key after the appropriate channel selector ‘A’ of ‘B’. A pitch may then be entered via the keypad or the nudge controls used.
S-DMX User Manual The loop may also be read out on a ‘one-shot’ basis. This is accomplished by pushing the # key. After the # key has been pressed the edited loop will be read out once and will not be read out again until the # key is pressed again. The loop may now be read out continuously by pressing the ‘D’ key. The loop may also be audio triggered. In this case the ‘locked in’ audio will be read out if an audio signal of sufficient level to illuminate the green LED is applied to channel ‘a’.
S-DMX User Manual Loop Editing When in the lock in mode the nudge buttons may also be used for loop editing. In this case the beginning and the end of the loop may be adjusted (i.e. increasing or decreasing the length of either end of the loop is possible, within the limits). Pitch shifting in the lock in mode is also possible; the effect obtained can be likened to varispeed on mechanical tape loop systems.
S-DMX User Manual General If more than four numeric characters are typed, or the user attempts to enter a delay, outside the limit of the unit an error message ‘Err’ will be displayed to warn the operator. The correct entry may then be typed. - The above refers to normal operation mode. See ‘The Dual Lock In Function’ section for special use. Power Switching and Reset When the unit is first switched on or if ‘reset’ is depressed the unit will be initialised.
S-DMX User Manual Using the S-DMX Back To Basics A digital delay line (DDL) as its name implies, is a device that receives a given signal at its input and after a defined lapse of time (programmed by the user) reproduces that exact same signal at the output. The DDL, as in the case of the S-DMX, should not alter or modify the signal no matter what delay is programmed. The S-DMX has two such delay lines which are independently programmable.
S-DMX User Manual Switch On: When power is switched on, the computer is initialised and the output of the unit is governed by the last store location selected and also the last function selected. If the ‘D’ key is pressed followed by the ‘0’ key all store locations will be cleared. In real terms this means that outputs ‘a’ and ‘b’ will occur effectively in synchronisation with their input signals until a delay is keyed in.
S-DMX User Manual The case above is taken for simplicity, obviously the S-DMX is far more flexible than the example shows; the example is only used as a guide to the techniques involved. Mixing When using the S-DMX alone, mixing of the two delayed channels can be accomplished by use of the output mix control on the front panel of the unit.
S-DMX User Manual Editing with the keypad To remove 100mS from the beginning of the loop first press the ‘A’ key. When the ‘A’ key is pressed the present starting point of the loop (i.e. 0) will be displayed. Now enter the new start point in milliseconds (i.e. 100); the ‘a’ channel identifier LED will flash until the splice point has been entered by pressing the # key. A loop start point of zero can now be entered via the keypad.
S-DMX User Manual The Pitch Change Pitch Change is available on both channel ‘a’ and channel ‘b’ and therefore the following notes will apply to both channels. Remember that any effect selected using the ‘C’ key will always be in addition to the programmed delay, and also that an inherent effect of the pitch shifting process is an inbuilt delay which varies continually.
S-DMX User Manual Understanding and Using The Pitch Changer The AMS Pitch Changer employs a very fast microprocessor which examines the digitised musical signal within the memory and performs a number of tests to isolate two points in time which have the highest correlation with each other in terms of waveshape.
S-DMX User Manual The pitch ratio has the following geometric progression: ( 2) 12 n where n is the number of semitones above unison. Let us see the chromatic scale of A’ as our example: Note A A# B C C# D D# E F F# G G# A Issue 3 Fundamental (Hz) x Pitch Ratio Frequency Frequency (Hz) Increase 440 ´ (12 2 ) = 440 ´ 1 440 440 ´ ( 2 ) = 440 ´ 1059463 . 440 ´ (12 2 )2 = 440 ´ 1122462 . 493.8833 0 12 1 440 ´ ( 2 ) = 440 ´ 1189207 . 12 3 466.1638 523.
S-DMX User Manual It is important only that you remember the relevant pitch ratios since the fundamental frequency can be any value; these are summarised below: Chromatic French Name Scaling (Tonic Solfa) unison (1) Do 2 3 Pitch Ratio 1 1.059 Re 4 1.122 1.189 5 Mi 1.260 6 Fa 1.335 7 8 1.414 So 9 10 1.498 1.587 La 11 1.682 1.782 12 Te 1.
S-DMX User Manual THEORY OF OPERATION Overall Functional Description The balanced inputs to the unit are fed to the input cards which process the signals into unbalanced form, these signals are then fed through low pass filtering to prevent aliasing components appearing at the outputs of the unit.
S-DMX User Manual In each sampling period, the following sequence occurs: 1. Write channel ‘a’ data into RAM. 2. Read channel ‘a’ data from RAM address offset ‘A’, into DAC A. 3. Convert channel ‘b’ / sample channel ‘a’ 4. Write channel ‘b’ data into RAM. 5. Read channel ‘b’ data from RAM address offset ‘B’, into DAC B. 6. Convert channel ‘a’ / sample channel ‘b’. Delays are altered by changing address offsets ‘A’ and ‘B’.
S-DMX User Manual The supplies are as follows:Voltage Current Rating +5V 6A +15V 1A -15V 1A +12V 0.5A -5V 0.5A Communication to and from the central processor is accomplished via the display board which contains the drive for the 7 segment display together with the display itself and the ‘Nudge’ buttons. It is driven by I/O ports on the microprocessor board and is connected by ribbon cables.
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S-DMX User Manual MAINTENANCE General Maintenance Access All printed circuit board assemblies can be accessed by removing the top cover plate, five DZUS fasteners hold the plate in place. To loosen the DZUS fasteners a 90 degree anti-clock-wise rotation is all that is required. For cleaning purposes it will also be necessary to remove the bottom plate. The bottom plate is held on by four DZUS fasteners.
S-DMX User Manual Trouble Shooting Before embarking on the checking procedures outlined below, ensure that all the power supplies are at their correct potential and that all the fuses are intact; also check the input wiring external to the S-DMX for shorts. Possible causes are listed in order of probability and therefore should be checked in strict order.
S-DMX User Manual SPECIFICATIONS Electrical Input Impedance (Zin): 10kW : Electronically balanced. Input Sensitivity: 10 dBV : Ref. 0.775 Volts. Inputs: Two independent inputs. Maximum Gain: 20 dB. Output Impedance: 150Ω : Compensating Electronically balanced. Maximum Output Level: + 20 dBV. Outputs: Two independent outputs. Distortion: Less than 0.035% at 1 kHz; full output. Dynamic Range: 90 dB / 15 bit equivalent. Frequency Response: 20 Hz to 18 kHz : -3 dB, + 0 dB.
S-DMX User Manual Computer Control: Time Entry: By numeric keypad; least significant digit = 1ms. Display: 7 Segment digital readout of selected delay time or pitch ratio. Memory: 9 Memory locations capable of storing ‘a’ and ‘b’ entries of delay and pitch change. Reset: The computer is initialised when this is depressed. - The computer is also initialised on switch on.
S-DMX User Manual APPENDIX A Board Edge Connector Details With component side facing and the edge connectors on the left the following applies: FACING REAR FACING REAR Issue 3 AA: Component side on edge connector A AB: Solder side on edge connector A BA: Component side on edge connector B BB: Solder side on edge connector B Page 27
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S-DMX User Manual APPENDIX B Set-Up Procedures for MIDI Equipped S-DMX 1. The 25 way D-type to 5-pin adaptor must be plugged in before the unit can be set-up. 2. Hold the D-key on the keypad down and reset the unit. 3. The display will read ‘SET’. Assigning a Midi Channel to the S-DMX 4. S-DMX channel A and B are selected by pressing the corresponding button on the keypad. The display will read ‘A=nn’ or ‘B=nn’; nn being the midi channel number already selected. 5.
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