Sequential Pro One Technical Manual Download

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Summary of Contents for Pro One

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Page 2: ...MODEL BOO Manual No TM100A PRCLONE SYNTHESIZER TECHNICAL MANUAL by Stanley Jungleib 1 Sequentid Circuits Inc i 3951 North 1st Street Sari Jose CA 95134 408 946 5240 TELEX 364412 INTR 706 ...

Page 3: ... h t 1 9 8 1 by SEQUENTIAL CIRCUITS INC All rights reserved Printed in USA The contents o f this manual are the property of SCI and are not to be copied or reproduced without our prior written permission Data sheets reprinted in the Appendix are courtesy o f RCA and o f Curtis Electrornusic Specialties ...

Page 4: ...CTION GENERAL OSCILLATOR A OSCILLATOR B M1XER NOISE EXTERNAL FILTER FINAL VCA ENVELOPE GENERATORS MODULATION SOURCES LFO MICROCOMPUTER KEYBOARD SWJTCH MATRIX DAC GLIDE GATE AND TRIGGER LOGIC POWER SUPPLY 3 0 DOCUMENT LIST 3 1 DOCUMENT NOTES SECTION 4 MECI IANICAI INTRODUCTION 4 0 i 4 1 4 1 OPENING CASE AND REMOVING PCB 4 1 4 2 REVISION LO 1 I PCB MOUNTING MODIFICA ION 4 2 4 3 REVISION 1 01 1 1 POW...

Page 5: ...NCE 5 4 DIGITAL INTERFACE SECTION 6 PARTS 6 0 CHASSIS 6 1 PCB 1 SECTION 7 GLOSSARY APPENDIX DATA SHEETS CA3280 DUAL OPERATIONAL TRANSCONDUCTANCE AMPLIFER CEM 3310 VOLTAGE CONTROLLED ENVELOPE GENERATOR CEM 3320 VOLTAGE CONTROLLED FILTER CEM 334013345 VOLTAGE CONTROLLED OSClLLATOR ...

Page 6: ...e will operate normally that is without pitch bend or modulation These procedures are presented in the order recommended for a Pro One assumed to be completely operational Real world problems may require you change the order of some tests Therefore each is written t o be performed independently You must play the Pro One throughout these tests or use the ascending and descending scales preprograrnr...

Page 7: ... plating Replacement J wires can be ordered as SCI S 051 3 If the keyboard doesn t work at all check its connector The GATE LED should light whenever a key is pressed If still there is no sound check Final VCA para 1 8 4 Switch DRONE an You should hear a continuous tone The frequency will change as you play various keys but t h e tone itself is not interrupted Switch DRONE off 5 Switch REPEATJEXT ...

Page 8: ...own to 2 1 and 0 NOTE When switching octaves with a key depressed it is normal to hear the pitch jump between octaves 4 Switch OSC A OCTAVE to 2 and switch OSC A SYNC on Rotate OSC A FREQ knob 0 10 to check sync function 5 Switch OSC A SYNC off Switch OSC A SAWTOOTH off Switch 05C A PULSE on The difference between the Ibrassylr sawtooth and tfwoody pulse should be obvious Rotate OSC A PULSE WIDTH ...

Page 9: ...ooth and dull1 triangle wave should be obvious The triangle waveshape has very little harmonic energy Switch OSC I 3 TRIANGLE off 5 Switch OSC B PULSE on Rotate OSC B PULSE WIDTH knob 0 10 listening for the timbral effect of varying harmonics The pulse will degenerate to dc or very nearly dc 99 duty cycle at the extreme knob settings resulting in no or very little sound Find the setting where t h ...

Page 10: ...se Leave knob set to 0 3 Turn MIXER OSC B knob 0 10 Check for smooth voEurne increase OSC B should be as loud as OSC A Leave knob set to 0 4 Turn MIXER NOlSE EXT knob 0 10 Check for smooth noise volume increase Sincenoise is unpitched it does not track the keyboard Leave knob set to 0 5 External audio input is checked during t h e BACK PANEL test para 1 10 TMlOOA 12 81 ...

Page 11: ...ain absolute zero beat over more than a few seconds but get as close as you can 4 Slowly raise the PITCH wheel while listening for beats then lower the wheel Beating should not increase significantly as the pitch is raised or Powered Increased beating probably indicates a difference in oscillator scaling which can be corrected by retuning The wheel range should be at least a fourth above and below...

Page 12: ...tune the pitch If it does detune t h e filter look into the Filter Envelope Generator circuit far the source of the offset I t is normal to hear an increasing transient as you advance ENVELOPE AMOUNT This is the voltage peak between t h e ATTACK and DECAY periods which becomes audible because the Envelope Generator is being triggered Although the knobs are set to 0 it still takes a finite time to ...

Page 13: ...PLIFIER TEST PATCH 1 Patch according to Figure 1 6 2 With AMPLIFIER ATTACK set t o 6 the attack time should be about 1 second heard as a rising volume which then snaps backr9 tosilence Return knob t o 0 3 Increase AMPLIFER DECAY knob to 6 This should give about 1 sec decay time Return knob to 6 4 Rotate AMPLIFER SUSTAIN knob 10 10 I t should smoothly increase amplitude Leave knob set to 10 5 Incre...

Page 14: ...cy rises consistently then snaps back to the t initial frequency para 2 19 3 Switch LEO SAWTOOTH off and LFO SQUARE on This will give a futrillM effect with the interval expanding with increased LFO AMOUNT A t 4 5 on t h e dial t h e higher note will be an octave above the initial frequency At about position 8 the range will be t w o octaves para 2 19 4 Switch LFO SQUARE off and LEO TRIANGLE on A ...

Page 15: ...ECT MOD The WHEEL test results will be the same as the DIREC T results cxcept the MOD wheel is also effective as an attenuator in series with any of the MODULATlON AMOUNT knobs In other words the MOD wheel and the AMOUNT knobls must both be advanced t o engage modulation 8 Now that the modulation sources have been checked with OSC FREQ A the four remaining destinations can be tested Patch accordin...

Page 16: ...sconnect cable 3 Plug one end of mono phone cable to 52 CV IN This should disable the keyboard Connect other end t o CV OUT Unit should play normally Remove cable 4 If a GATE source is avaitable connect to GATEjCLK IN and switch MODE to REPEATJEXT check that the envelopes are gated and sequencer advanced with each pulse 5 GATE OUT can be checked with a voltmeter The output goes from 0 to 5V when a...

Page 17: ...PRO BNE TUN1NG CHECK FLgW CHRRT OFFSET SCRLE SCRLE Figure 1 9 PRO ONE TUNING FLOW CHART ...

Page 18: ...roi the filter and amplifier envelope generators KEYW D Figure 2 1 shows more functional detail The integrated microcomputer contains a central processor unit CCPU read only memory ROM3 and random access memory RAM The CPeJ foliows the program in ROM by which it f reads the keyboard SEQUENCER ARPEGGIATE and MODE switches and forms the appropriate output signals The CPU uses RAM to keep track of th...

Page 19: ...over 1V of control through R131 R120 OSC A OFFSET trimmer adjusts initial frequency through R124 When centered R1210 MASTER TUNE is 7 5V summed through R126 R133 adds the OSC A OCTAVE voltage which is switched in precise 1 volt steps Precision resistors are used throughout this circuitry to allow octave transposition without having to retune R119 OSC A FREQ The switch circuit itself takes advantag...

Page 20: ...Figure 2 1 PReONE FUNCmONAL BLOCK DIAGRAM ...

Page 21: ...MICRO COMPUTER ...

Page 22: ...Figure 2 2 PRO ONE ABSTI ...

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Page 24: ... U OP U U5 GL K A R t m OSC A BFR U w wp v t m WHITE NOISE Figure 2 2 d P R W N E ABSTRACT SCHEMATIC TMlOOA 12 81 ...

Page 25: ... adjusts OSC A SCALE by determining t h e current gain of the precision multiplier through the temperature compensation KO circuitry R122 and C103 compensate the precision multiplier R134 at pin 14 converts t h e current output of the precision multiplier into a drive voltage for t h e 3340 s exponential current generator R137 at pin 13 sets the reference current for the generator d 1 3 6 0 6 comp...

Page 26: ...pect to the sawtooth by R171 CVs for OSC A pulse width modulation are summed and inverted by U104 8 yielding a basic control range of 0 t o 5V into W102 5 R165 OSC A PULSE WIDTH knob connects through R169 5109 MOD TO OSC A PW selects the modulation buss summed through R166 R170 sets the summer gain t o 1 C l l 8 filters noise which may be generated by rotating R165 U102 9 S SYNC is a 5 V source wh...

Page 27: ...y C115 to prevent synchronization to noise OSC B s output circuitry differs from OSC A by having the SAWTOOTH and PULSE outputs amplified by differential buffer U105 1 with a gain of 1 For the TRIANGLE output R197 contributes enough negative dc voltage to pull the triangle level down to be symmetrical about ground level rather than positive going so as to not offset modulation destinations Figure ...

Page 28: ...5 exceeds the threshold set by divider R1112 and R1114 with EXT grounded AGATE goes low The application of the AGATE signal is discussed below To prevent oscillation around the threshoId point C130 briefly retains the peak voltage 2 5 FILTER The Pro One s low pass filter is based on t h e CEM 3320 integrated voltage controlled filter CVCF The control scale for its cutoff frequency matches the VCO ...

Page 29: ...the absence of an input signal R1122 develops suitable drive voltage from the OTA s current output U108 7 5532 voltage follower can drive 600 Ohm loads so is not bothered when R1125 3 s grounded by a mono plug connected to 38 2 7 ENVELOPE GENERATORS U116 Filter and U J17 Amplifies Envelope Generators are based on the CEM 3310 IC Its output is 0 to 5 Vdc changing over t h e time periods set by the ...

Page 30: ... 1K x 8 bits of ROM which is mask programmed with instructions and 64 x 8 bits of dynamic RAM LlOl controls the 8021 s internal clock circuit establishing a frequency of about 3 MHz When power is first turned on U113 17 RESET is pulled high by C153 The positive going pulse d e a r s the internal registers and sets the program counter to 0 Dl14 discharges C 153 on power off All input to t h e micro...

Page 31: ...ing pressed and released and decides whether to refresh the DAC with a new key number and output the TRIGGER and GATE Actually the matrix harware works on negative logic To check t h e first row U113 outputs the number 1 1110 1EH on the data driver This means pins 5 through 8 are high whiie pin 4 POO pulls the first row low The receiver inputs CP10 17 are being pulled high by internal pull up resi...

Page 32: ... DRONE switch The easiest way to check for a stuck key is to disconnect the keyboard cable The GATE should go off 2 12 DAC U112 DAC is an Analog Devices AD558 8 bit unit but for best accuracy only the most significant 6 bits are used By no accident t h e DAC is scaled to provide t h e exact voltages which the VCOs and VCF require to piay sernitones which is 83 mV 1 12 step If given the number 01 t...

Page 33: ...aximum so plenty of current is available to charge C141 and the GLIDE output will follow the KYBD CV very closely However as the GLIDE knob is raised Iabc sourced by Q105 Is inhibited reducing t h e rate of charge t o C141 It will thus take longer for the GLIDE output to approach KYBD CV This creates a slew between t h e discrete voltage steps output by the DAC When 5118 is switched t o AUTO 3149 ...

Page 34: ...E goes high it pulls Q102 base to ground switching 4162 on and discharging the LFOrs timing capacitor in the same manner as 0 S C A is synced to OSC B 2 15 POWER SUPPLY The power supply design is straightforward As shown on t h e inset on schematic 5D121 t h e primary circuitry was originally included on the PCB itself Revisions 1 0 and 1 1 This proved to be mechanically unreliable most frequently...

Page 35: ...hassis mounted components A1 though the back panel jacks mount directly to the PCB for designation they are considered to be chassis mounted Component Numbers are sequenced according to their position on the original PCB When it sometimes becomes necessary t o later add a component to the PCB its designator will usually not be in sequence This helps identify the modification Signals are continued ...

Page 36: ...BACK PANEL d FIGURE 3 0 INTERCONNECTION ...

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Page 42: ...e the possibility of switch breakage we have recommended enlarging the hole for the power switch and glueing the top of the switch While these modifications have provided adequate protection for most units a more secure mounting for revision 1 0 1 1 PCBs is described in para 4 2 Inspection and modification of the primary power connector system is also covered 4 1 OPENING CASE AND REMOVING PCB 1 Sw...

Page 43: ...MODELS 4 2 REVBION 1 011 1 PCB MOUNTING MODIFICATION To adequately protect the power switch on early Pro Ones an additional bracket must be retro fitted t o eliminate vertical movement resulting from PCB flexibility Figure 4 1 shows four views of the modification Order Bracket Kit SCI Z 204 1 Open the Pro One and remove PCB as described in para 4 1 2 Drill two holes through PCB as shown in Figure ...

Page 44: ...Figure 4 1 REVISION 1 a 1 l PCB MOUNTING MODIFICATION s TMlOOA 12 81 A PCB TDP VlEW I3 PCB S lLIE VlEW C BACK ...

Page 45: ...ove them and install the 5 pin connector system order SCI DZ 049 With the 5 pin system it is still possible to reverse the connection but this won t damage anything Figure 4 2 REVISION E O l l POWER CONNECTOR MODIFICATION 4 4 REPLACING AND ADJUSTING WHEELS Whenever you open the case inspect both wheeIs or cracks which usually occur perpendicular to the set screw If you see a cracked wheel replace ...

Page 46: ...te 0 volts when centered So probe P102 6 or the wiper of R1 itself with DVM With one hand hold the wheel firmly in center detent position Use a screwdriver to trim t h e shaft of Rlato read as close as possible to OV Move wheel up and down trimming for best repeatability of OV at center detent then tighten set screw The deadband diodes following R1 make this trim much less critical 8 R2 MOD wheel ...

Page 47: ... DVM to back panel CV OUT jack 2 Hit C O and note reading The reading will be approximately 0 883V The absolute value of this reading is not critical 3 Hit C3 and note reading which shoukd be the value read in step 2 plus exactly 3V If necessary adjust R l l g l DAC SCALE for the exact reading e g 3 083 4 Repeat steps 2 and 3 as required t o establish an exact 3 V difference between CV OUT played ...

Page 48: ...ID r C R120 R128 R135 R l l l l RllXI R1E38 OSC A OSC A OSC A lV DAC VCA 3101 OFFSET SCALE HI TRIM TRIM SCALE BALANCE a140 Rl48 R 157 JUNIPER U113 R I182 oscB oscB oscB OPTIONAL 8021 OPTIONAL OFFSET SCALE HI TRIM ...

Page 49: ...t can be made 1V TRIM 10 Switch OSC A OCTAVE to 0 11 Switch OSC B OCTAVE t o 1 12 Hit CO and adjust OSC A FREQUENCY for zero beat 13 Switch OSC A OCTAVE t o 3 and adjust R1111 lV TRIM for zero beat 14 Switch OSC A OCTAVE t o 1 and 2 and check for less than 2 Hz beating OSC B SCALE h I 15 Switch OSC A OCTAVE to 1 16 Switch 0513 B OCTAVE to I 17 Turn OSC A FREQUENCY t o 5 18 Turn OSC 0 FREQUENCY to ...

Page 50: ... 29 Switch OSC A OCTAVE to 1 30 Turn OSC A FREQUENCY t o 0 31 Switch 6SC B sawtooth off 32 Using an external reference tuning fork piano or Prophet adjust R120 OSC A OFFSET so key A2 pitch is A 440 33 Switch OSC A OCTAVE to 3 34 Switch OSC B OCTAVE to 3 35 Turn OSC B FREQUENCY to 0 36 Switch on OSC I 3 sawtooth 37 Hit Cl and adjust R140 OSC B OFFSET for zero beats 5 3 AMPLIFIER BALANCE 1 Patch acc...

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Page 52: ...and filter is unknown Nothing is heard from the Pro One because the envelope generators are not being gated First the system somehow decides what key out of 63 it wants t o play It then sets up the key number in binary form on DO D5 This might be done with a six bit output port DAC EN is normally high To latch the key data to the DAC DAC EN Is momentarily forced low Data is then latched on the ris...

Page 53: ... SWITCH SAl 5 050 KEYBOARD T1 E 102 36 VCT TRANSFORMER W L E 075 11 16 WIRE DIP RIBBON CHASSIS HARDWARE E 0 17 FUSEHOLDER 4 1 8 FUSEHOLDER CAP M 070 JIG SET SCREW M 073PITCH WHEEL DETENT CLIP M 204 BRACKET WHEEL M 352 WHEEL MOLDED 1 M 357 KNOB 6 1 PCB 1 C 045 1 5OV C 012 0150V MYLAR C 045 I 50V C 039 1000 pF POLY C 012 01 50V MYLAR C 045 1 50V C 012 01 50V MYLAR C 045 1 50V C 039 1000 pF POLY C 01...

Page 54: ...5V ELECT C 049 150 pF DISC C 045 I 50V C 049 150 pF DISC C 045 1 50V C 050 1 10V ELECT C 045 1 50V C 008 OD1 5OV MYLAR C 043 a039 50V MYLAR C 012 a 0 1 5OV MYLAR C 014 A2 50V MYLAR C 045 1 50V C 043 039 50V MYLAR C 014 OZ 50V MYLAR C 021 2 2 25V TANT C 051 2 2 10V TANT C 021 2 2 25V TANT C 025 2200 25V ELECT D 005 1N914 D 001 IN4002 lOOV 1 AMP L 001 LED LARGE 5 00 16 PIN DIP SOCKET E 094 470 UHIND...

Page 55: ...K R 029 1M R 025 lOOK R 061 4 7M R 110 lOQK R 211 5K TRIM 1 TURN TOP AD3 R 146 Z6 7K R 142 5 62K R 090 1 2M R OX2 82QK R 110 lOOK R 139 1 32K R 225 25K TRIM 1 TURN TOP AD3 R 006 470 R 116 2 21M R 018 47K R 228 lOOK POT LIN NO BUSHING R 217 lOOK TRIM 1 TURN TOP ADS h R 018 47K R 110 lOOK R 606 470 R 029 1M R 110 lOOK R 061 4 7M R 025 lOdK R 211 5K TRIM 1 TURN TOP ADJ R 146 26 7K R 142 5 62K R 025 l...

Page 56: ... 100K R 228 lOOK POT LIN NO BUSHlNG R 025 LOOK R 110lOOK j R 012 IOK R 025 lOOK R 092 llOK R 026 200K R 057 120K R 110 lQOK R 015 20K R 092 llOK R 025 lOOK R 054 33K R 026 200K R 025 lOOK R 228 lO0K POT LIN NO BUSHING R 012 EOK R 030 2 2M R 082 820K R 026 200K W 064 T41K R 016 30K R 006 470 R 025 lOOK R OX4 56QK R 075 l 8K R 012 1OK R 083 820 R 018 47K R 012 10K R 084 560K R 025 lOOK R 082 820K R ...

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Page 58: ...F P V V Y g g P W S W Y F C C C v m C C C C C C v F r s 0 0 0 0 0 0 h J b J m N 0 0 0 0 b W b 4 W o b e r d C 5 V b N r O i P d r O W C n S W I 2 w N N N N N M W N N w o o o b W h 0 N O l D W V m m Q m U m 0 E 0 I w Ocr 5 4 W c 0 0 C Z Z Cn VI W S ...

Page 59: ...11 7905 5V REG U 120 1 404 78M05 5V REG W121 1 406 78M15 ISV REG PCB HARDWARE AND SOCWTS M 031 6 32LOCKWASHER EXTERNAL TOOTH M 035 6 32 NUT SMALL M 071 6 32 X 114 PMS J 007 16 PIN DIP 5 045 28 PIN DIP FOR U 113 ...

Page 60: ...er or common alternating current accurnulator acknowledge analogidigiaal hybrid analog to digital converter adjust adapter attack decay sustain release ENV GEN address bus high voltage arithmetic logic unit ammetes amplifier FIN YCA amount approximate assembly attack attenuation attenuator auxiliary average VCO B bit number LS5 MSB balance binary coded decim a1 buffer black blue brown battery desi...

Page 61: ...mparator central processor unit rectifier module designator chip select cutoff center control voltage clockwise carry data diode designator digital power or ground diode array designator digital to analog converter decibel data bus data bus high vol tage direct current decoding decoder detection detector data in dual in line plastic package disable discharge demultiplexing demultiplexer data out d...

Page 62: ... keying faot footswitch G gate GEN generation generator GLD glide GND ground ERN green M HEX hexadecimal base 16 Hz Hertz I I Eabc IC IN INIT INT INV IJO 3RQ inhibit input solid state switch amplifier bias current OTA CC integrated circuit input initial interrupt inversion inverter inputloutput interrupt request J jack female pins JSTK joystick K kilo KBD KYBD keyboard L LD LED LEO LFT LIM LIN LOG...

Page 63: ...significant bit medium scale integration master summer master tune multiplexing multiplexer nano no connection normally closed contact neutral normally open contact nominal norrna1 noise non volatile memory output solid state switch obsolete off set orange oscillator VCO operational transconductance amplifier output overflow h pico plug designator polyphonic modulation pitch bend program counter i...

Page 64: ...esignator random access memory record reference regulation regulator release resonance revision right ripple clock read oniy memory reset restart switch analog switch signal switch array designator successive approximation register second select sequencer serial sample and hold sheet signal signal to noise ratio serial number scratchpad CRAM spare parts kit speaker static RAM source smale scale i ...

Page 65: ...rcuit designator upper universal asynchronous receiver transmitter ultra LSI unison universal syncl ronous asynchronous Volts V supply analog circuit V supply digital circuit voltage to current converter voltage controlled amplifier AMP voltage controlled filter FILT voltage controlled oscillator OX DAC output voltage violet very LSI POT M U X output voltage volts per octave volume pedal voltage o...

Page 66: ...SECTION 8 APPENDIX ...

Page 67: ... the ampl fier dependence upon thermal and processing var ables The CA3280 has all the generlc charac terlstrcs of an operat onalvoltage arnpl fler lContlnued on Pale 2 IExcellent matchingof the twoamplifiers far all characterinim Internal current driven linearizing diodss reduw the emernel rnput arrmntto an omel component Differential amplifier emitters brought owl for use in emitterarupled dual ...

Page 68: ...ng tempera twre rang are g5 to 125 for the W 2 8 0 A and 0 to 7 0 for the CA3280 The CA3280 1s also supplied as a h e r r n e t c Gold CHIP HGsuft xl V o l n t r o l l d fihera a V d t a v n t m l l e d oscicillrton Muitiplien Dernodulaton 1 Sample and b l d rn Instrumemation arnplifimrs Function gmermon r Triangle mwtto sinem e convenen h m p e m o n Audio preamplifiers Ig A1 LINEhAlfATIOH YI AI ...

Page 69: ...haracteristics I DKar CLmREKl nd r le6 arDB hYPLFICR BIAS C V M L M Imtl ph Fig 1 3 Supply current 6s8 funcrion of diode YY Fig 14 Input offnet cumrnt ss s turntion of current mntilisr hiss mrrmi Fig 15 lnput offset m h g e ass fumrion af Fig 16 h k arrtwt tspe s68 b h m of mptifiar biea current smptifier bi4 current ...

Page 70: ...designs In addi tion much care has been given t o the accuracy repeatabiiity and tracking of the parameters from unit to unit without ex ternar trimming The times are t o a first order determined only by the external resistor and capacitor and constant of phy sics KTB Wide tolerance rnono lithic resistors are not used to set up the time constants or the control scale Finally all four control input...

Page 71: ... pin 6 For voltages greater than 7 5 volts a series current limiting resistor must be added between pin 8and the supply Its value is calculated as follows RE VEE 7 211 070 The circuit was designed for a positive supply of 15 volts Voltages other than I5 volts will cause the peak threshold voltage t o be either at a mfn imum of 3 3 V c or a t a max imum of 5 5 volts Gate and Trigger Inputs The gate...

Page 72: ...dominanrly in the second than a ten octave range with harmonic The device further little control voltage feed includes a minus two volt regu through Another input controls lator te ensure low power dis the resonance in a modified sipation and consequent low linear manner from zero to low warm up drift even with k15 1 distortion oscillation For those volt supplies Circuit Block and Connection Diagr...

Page 73: ... a positive supply of I 5 volts any voiltage between 4 9and I8volts may be applied to pin 14 The only effect other than power dissipation is the maximum possible peak to peak output swing in accordance with Operation of Each Filter Stage Each filter stage consists of a variable gain cell followed by a high input impedance buffer Note 1 25mV VC lSSrnV Most of th s error occurs In upper two octaves ...

Page 74: ...ency Control and Ground Pins k6V Voltage Between Resonance Control and Ground Pins 2V 18V Current Through Any Pin f40mA Storage Temperature Range 55 Cto 150 C Operating Temperature Range 25 C to 75 C The output impedance of the variable gain cell although high has a finite value This imped ance is reflected back to the input as an b C resistance of nominally 1 rnegohrn in parallel with the feedbac...

Page 75: ...Note that due to the lconfiguration of the resonince feedback the reso nance frequency of the high pass w l l be approximately 2 4 times higher than that of the low pass while the resonance frequency of the band pass and all pass will be f 2 4 42times lower than that of the low pass for the same component values For the state variable resistor Ra adds positive feedback to increase the maximum 0 wh...

Page 76: ...hould be takgn not to 0verload the input to the filter If the signaE output of stage one is allowed to become clipped then not only w1l1the apparent resonance of the signal at the filter output appear to be reduced but the D C level of the output signal will shift When the resonance control is advanced until sustained osc llatians are produced ad vancing the resonance control further will merely i...

Page 77: ...etween buffers The maximum recommended A C loads are f250pA Since the D C level a t the filter output is at some non zero voltage 6 9 volts for Vcc 15V a coupling capacitor will be required somewhere in the signal chain either a t the filter output or the following device inputs Note that if the resonance feature is being used the filter output is already D C blocked by the resonance input couplin...

Page 78: ...Ground Pins 6 OV Current Into VEE Pin 50mA Voltage Between Control and Ground Pins L 6 W Voltage to Gate and Trigger lnput Pin5 VEE to VCC Storage Temperature Range 5 5 to 150O Operating Temperature Range 25 to 7 5 seen from the envelope equa tions the sustainlfinal voltage error the asymptote error and the control voltage feedthrough are aBI affected by Rx A prac tical maximum of 240K is recommen...

Page 79: ...lexibility Voltage Rejection Circuit Since pin 16 outauts a 4 to The purpose of 0 1 seeblock diagram is to greatly reduce the control voltage feedthrough During the attack phase the base of Q1 is brought negative effectively disabling it and allow ing Q2 t o control the charging current During the decay and release phases however the base of 0 1 is at ground causing neg ative voltage excursions on...

Page 80: ...ions makes these VCOs extremely Although a low voltage stable and eliminates the need process has been used t o reduce for a temperature compensation die slze cost and Isakage cur resistor The highly accurate rents an on chip 6 5 volt zener v exponential and linear control diode allows the device ta inputs are virtual ground operate off f15 volt supplies summing nodes allowing mul as well as 15 5 ...

Page 81: ...ce in multiplier gains at any two input cur rents within the range of 20 FA to 180 pA per p A difference between the two corresponding outputs Note 3 This spec represents the difference between the actual tempco of the rnultipl er output voltage expressed relat ve to the maximum output excursions and the ternpco required to precisely cancel the tempco of the exponentla1 scale factor qtKT1 Note 4 T...

Page 82: ...from greater than 5mA down to less than the input bias current of the buffer thus allowing for a typical fre quency range greater than 500 000 7 The most accurate portion of this current range from 5QnA to 1QOpA should be used for the most critical portion of the desired frequency range Consideration of this crit cal range determines the value of I Voltage Between VCCand VEE Pins 24V 0 5V Voltage ...

Page 83: ...ier current gain Since the multiplier current gain set by the ratio of the pin 2 current to pin 1 cur rent should be near unity and RS should be 1 8K the control input resistor is the co nponent which should be selected for the desired contro scale For the industry standard scale of 1 octavelvolt the input summing resistors become 100k The recommended method for trimming the control scale is to tw...

Page 84: ...the adjusted octave wouId become increas ingly flat and vice versa Typically the error produced by the multiplier is much less than the above example How ever if maintaining a tighter tolerance is required for the particular application the mul tiplier error may be trimmed out for each device The trimming prbcedure requires that both R Z and RS be made adjustable f30 about the nominal value RZ is ...

Page 85: ...g portion The resulting waveforms are shown in Figure I and provide a wider variety of synchronized sounds than possible through conventionaFly synchronized oscillators Simple capacitive coupling a s shown in the Black Diagrams allows hard synchron ization on both the rising and falling edge of a rectangbe wave Figure 4 shows circuitry for allowing only one or the other of the edges to synchronize...

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