Orban 674A Operating Manual Download

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Summary of Contents for 674A

Page 1: ...674A Stereo Equalizer OPERATING ANNUAL...

Page 2: ...band pass filter for any settings of TUNING or BANDWIDTH controls Equalization Ranges 6dB peaking EQ Reciprocal Tuning Ranges 20 60Hz 40 150Hz 1 0 310Hz 230 750Hz 480 l900Hz l l 4 5Hz 2 8 9 0kHz 5 9...

Page 3: ...Tuning Notch Filtering Full Electronic Crossover Partial Electronic Crossover and Individual Driver Equalizer Stage Monitors 1 3 Dance Bars 14 Recording Studios 15 Motion Picture Sound 15 Broadcastin...

Page 4: ...ale or other proof of purchase Please fill in the Registration Card and return it to us If the Registration Card has become lost or you have purchased the unit used please photocopy the image of the c...

Page 5: ...ters are overlapped 200 2000Hz the 674A can be used as a combined graphic parametric equalizer and tunable electronic crossover Separate lowpass and highpass outputs are provided for this purpose Each...

Page 6: ...IC s RFI suppression on input output and power leads Balanced output optional order retrofit kit as required Holes for XLR type connectors are provided retrofit kit available FRONT PANEL DESCRIPTION...

Page 7: ...ection instructions The power transformer can be strapped for 1 15 volt or 230 volt 50 or 60Hz AC operation If the unit was ordered for 230 volts a tag on the power cord warns of the modification The...

Page 8: ...chassis apron and install each connector with a pair of 4 40 1 4 flat head screws nuts and lockwashers On each channel in turn connect jumper wires from the barrier strip to the XLR s as shown in Fig...

Page 9: ...sformers were not installed at the factory refer to the installation instructions furnished with the transformer retrofit kit available directly from Orban The transformers supplied with this kit have...

Page 10: ...ndix for further details Nominal input level is between 10 and 4dBm The absolute overload point is 26dBm The two outputs of each channel of the 674A are unbalanced unless fitted with the optional tran...

Page 11: ...se imperfect the wiring techniques in the diagram are not universally applicable If you follow the diagram and hum or noise appears don t be afraid to experiment If the noise sounds like a low level c...

Page 12: ...t calibration accuracy Calibrations are approximate and are intended primarily as reference guides However placing an EQ control on its center detent accurately defeats the equalization in that band W...

Page 13: ...DTH control the peak gain remains constant while the skirts of the curve vary 672 4A EQUALIZER CURVES AT 0 8 5 1 4 4 410 Fig 4 BOOST CUT CURVE FAMILIES Using the Highpass And Lowpass Filters Be sure t...

Page 14: ...LOWPASS filter IN and adjust its TUNING control until the AC VTVM reads 3dB Then switch the LOWPASS filter OUT and switch the HIGHPASS filter IN Adjust the HIGHPASS FILTER TUNING until the AC VTVM re...

Page 15: ...e This is most readily done by the differential method the reference channel and the channel under adjustment are swept out of phase and their outputs are summed The channel under adjustment is tweake...

Page 16: ...m so that the ring frequency will not reappear when the system gain is increased when more ring modes are tuned out later This procedure may be repeated with the new ring frequencies as they appear Us...

Page 17: ...o he desired crossover frequency 200 2000Hz The bands in the EQ section which are tunable above the cutoff frequency can be used for EQ The lowpass filter is still available to shape the upper cutoff...

Page 18: ...voided because of its potential for subliminal irritation If a third octave analyzer is available to monitor the acoustic response of the system it is not necessary or desirable to exactly match the c...

Page 19: ...hpass filters which effectively remove both low and high frequency acoustical noise from the track without affecting dialog 4 Ability to use the equalizer as a standard octave band graphic by setting...

Page 20: ...em noise with minimal effect on voice quality Use one band for each major 60Hz harmonic with BANDWIDTH control adjusted close to narrowband The 674A may also be used in the AM program line to equalize...

Page 21: ...asure the voltage from circuit ground to both positive and negative unregulated supplies This can be readily measured across the two large filter capacitors This voltage may be expected to vary widely...

Page 22: ...hes at or slightly below the clipping level at IkHz 2 DC offset a Disconnect the oscillator from the 674A input b Move all IN OUT switches to IN Measure the DC voltage appearing at each output of the...

Page 23: ...r from 200 2000Hz k Switch the highpass and lowpass filters OUT 6 Equalizer Swept Response The following procedure should be performed on each of the eight equalizer bands in turn As you perform the t...

Page 24: ...d and serves to set the DC output of IC2I7 and IC2I8 to OmV to avoid clicks when EQ IN OUT switches S 1 0 1 SI02 are operated The alignment requires only a DVM with stable zero and a resolution of at...

Page 25: ...If you lack these tools correct disassembly and reassembly without damage will be virtually impossible a Nutdriver 1 4 6 shaft Xcelite L8 Vaco S86 b Nutdriver 1 4 magnetic 6 shaft Xcelite L 8 M Vaco...

Page 26: ...ty Replacement of Bandwidth and Tuning Pots These pots can be replaced without further disassembly if careful desoldering technique is used It may be helpful to clip off each terminal of the pot to re...

Page 27: ...each of the OVERLOAD LED s from its lens by gently pulling back 3 Remove the six knobs from the rotary control using the tools and techniques described for the EQ Board Assembly above 4 Using a 6 slo...

Page 28: ...oldering iron to melt the solder on the solder underneath side of the PC board Do not use a soldering gun or a high wattage iron As soon as the solder is molten vacuum it away with a spring actuated d...

Page 29: ...ppear to drift excessively freeze spray may aid in diagnosing the problem Freeze spray is also invaluable in tracking down intermittent problems But use sparingly because it can cause resistive short...

Page 30: ...cribed in order Input Buffer The signal enters the 674A in balanced form Cl C3 shunt RF from the input leads to the chassis These capacitors are not effective at VHF and higher frequencies therefore f...

Page 31: ...ns occurs Thus the peak cut function appears at the output of IC2I9A and is passed to the equalizer output through the remaining amplifiers in the main audio path Note that the full peak boost and cut...

Page 32: ...assing through the equalizer a click may be heard because the program is interrupted for a few milliseconds while the switch is changing state Highpass Filter Output Buffer The highpass filter consist...

Page 33: ...One diode is connected to a 10 volt bus created by voltage divider R7I9 R72I the other diode is connected to a 10 volt bus created by R7I3 R7II If the instantaneous output of any amplifier exceeds 10...

Page 34: ...y The regulators VR80I and VR802 are frequency compensated by C803 C804 at their outputs to prevent high frequency oscillations If C803 or C804 are ever replaced be sure to use low inductance aluminum...

Page 35: ...high frequency rolloff which is 3dB down at 16kHz and which rolls off at 6dB octave thereafter The absolute clipping level of the 674A input is 26dBm If such clipping occurs it will cause the OVERLOA...

Page 36: ...ifference between the voltages at the two terminals A third terminal is connected to chassis ground and is available for the connection of the shield of the two conductor shielded wire that would be u...

Page 37: ...Orban normally maintains an inventory of tested exact replacement spare parts to supply any present or normal future demand quickly at nominal cost When ordering parts from the factory we will need a...

Page 38: ...503 14 Cl 18 Not Used Cl 19 Same as Cl 1 7 C 1 20 Not Used Equal izer Board Rear C201 Metal 1 i zed Pol yes ter 1 00V 47uF 1 0 21441 474 PLE 60F474K100 2 C202 Same as C201 C203 Metal 1 i zed Pol yes...

Page 39: ...ame as C205 Used if required C231 Polyester Radial 100V 01uF 10 21441 310 2 C232 Same as C23 1 C233 Polyester Radial 100V 015uF 10 21441 315 2 C234 Same as C233 C235 Same as C205 Used i f requ i red C...

Page 40: ...5 1 9 c 52 1 Same as Cl 1 7 C522 Not Used C523 Same as Cl 1 7 C524 Not Used Output Board 1 C601 Tantalum 15V 22uF 101 C602 Same as C601 C603 Same as C601 C604 Same as C601 C605 Aluminum 25V 22uF C 6 O...

Page 41: ...TOR ARE Diode Signal 22101 000 FSC 1 N4 1 48 Many 61 NOTE This is a silicon sma 11 signal diode ultra fast recovery high conductance It may be replaced with 1 N9 1 or in Europe with BAY 61 BV 75V imin...

Page 42: ...9 IC221 Same as IC219 IC222 Same as I C2 1 9 IC223 Same as 1 C2 1 9 IC224 Same as IC219 Range Board 2 IC501 Same as 1 C2 1 9 IC502 Same as IC219 Output Board 1 IC601 Same as I Cl 03 IC602 Same as I Cl...

Page 43: ...coated I D five color bands or printed value Orban P N 20040 XXX Power Rating 1 8 Watt 70 C Tolerance 1 Temperature Coefficient 100 PPM C U S Military Spec MIL R 10509 Style RN55D Manufacturers R Ohm...

Page 44: ...Log 116 Same as R115 Equalizer Board Rear 201 Pot Concentric 100K 100K CCW Log 203 Same as R201 221 Same as R201 223 Same as R201 241 Same as R201 243 Same as R201 26 1 Same as R201 263 Same as R201 2...

Page 45: ...VN 20D1 BM25KO 16 20739 000 CTS 270 SERIES Input Board 3 SI 01 Switch Assembly DPDT Range Board 2 5501 Switch Assembly OPDT 5502 Same as S501 5503 Same as S501 5504 Same as S501 26110 000 SCH F SER1ES...

Page 46: ...02 EQ FRONT 30505 000 03 EQ REAR 30510 000 03 0UTPUT 1 BOARD 30515 000 03 RANGE 2 BOARD 30520 000 02 OVERLOAD 2 BOARD 30525 000 03 INPUT 3 B0ARD 30530 000 02 SUBASSY FILTER 1 0020 000 02 SUBASSY FILTE...

Page 47: ...l Instruments Optoelectronics Div 3600 Hi 1 1 view Ave Palo Alto CA 96306 HP Hewlett Packard Corporation 1 501 Page Mill Road Palo Alto CA 9 306 INS Inters i 1 Inc 10710 N Tantau Avenue Cupertino CA 9...

Page 48: ...EW PO T OU FLEX 0 LE NUViE P VTVOW PO M i TO F AN E PC LEFT HP F LT X SWCTttt R HT HPF LTER WVTt LE PT LP FVLYEP SVfVTCM R1 HT UP F L TER U SWTCM JOWvPtR z UOVJG NO PLACES 44 Orban Associate Inc TITLE...

Page 49: ...rmn Orban Associates Inc T TLE ASSEMBLY DRAWING RANGE BOARD 2 30515 000 03 FLEX CAEl FOUR PO5XT10W UP TO RAW EPCfc Flex cpb le flex cable FOORPOSmOVi FOURPOSmOU UP TO 0PT6 RAU E PCP RAUC E PC P Orban...

Page 50: ...PLACES A USED AS WEED BY TEST 3 iOUWYSEREO WODES C ORRESPOOC To P us OM COtOMECTOR S h vo BE WIRES V0R CR Rvm To BQ FROWT PCS MA COUUEtTOR ACOWlPOMEMT WvOV WT W PM P rtlSOS I OOO TO SS ftSSSWSCSV VWH...

Page 51: ...SUOE Pot LF LNP o P U HEAPEP r POSITION COMIO CTOR P M Z7 atS3 Olt FRON VMPOT SOftW 3...

Page 52: ...TOP OP EQURUXER l UEEtf PA WEESE TEST MOTEb UNLEEE OTWERWEE S EC F EV Orban Associates Inc TITLE ASSEMBLY DRAWING EQ BOARD REAR 30505 000 03 48...

Page 53: ...OK S Ic ZVbA jA5S8 Y 1 R339 402 K 1 1 A __USXC IT3A 7lT 07 R359 4 0 ZK i A CU3 CUS at to at iu Slot A Y OUT RtOT A9 9K CtOZ ZZpF 31 oPTtONALT RtOMOOK Rt 03 C 5 K 1 2 RUT 10OK 5 FROWStDlA 3 o da OUT 1...

Page 54: ...c B a 7 Cd 4 3 7 50...

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Orban 674A, Operating Manual

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