786 manual - HARMAN Professional
Contents
1. IN position references the center tap of the output transformer to the chassis ground The combination of the two switches associated with the audio output connectors ensures that the 786 is versatile enough to interface with any equipment and can deliver clean audio to the output free of hum and interference See the Figure 5 for details of the Ground switch operation Chassis Ground Binding Post 77 The green Chassis Ground binding post is supplied to give the user another method to provide com prehensive grounding options for any installation It is easy to think of the binding post as being syn onymous with the ground pin on any AC power cord The ground pin on an AC cord should NEVER be removed shorted out or lifted The post allows the chassis ground to be connected to another ground source if desired ie a chassis ground system provided by another piece of gear Wire may be connected to the binding post by securing the stripped end of the wire through the hole in the post located under the hardened plastic nut top of the post Access to the hole is gained by unscrewing the top part of the post far enough to reveal the hole underneath Insert the stripped end of the wire and tighten the top nut part of the binding post to secure the connection Signal Ground Binding Post The black Signal Ground binding post is located nextto the Chassis Ground binding post and works in much the same way providing comprehensive grounding op2. TSE Tape Saturation Emulation a signal may be amplified and converted to the digital domain ready for use in another digital medium This allows the user to choose a mic for any applica tion with the knowledge that the qualities of that mic as well as the essence of the recorded signal will be preserved through the amplification and conversion process Mic inputs on the 786 are transformer isolated eliminating the traditional electrolytic DC blocking caps in the signal path which as audiophiles know can color the sound of a mic especially if they are not premium quality Another benefit of the dbx 786 is the high Common Mode Rejection Ratio CMMR with its ability to reject hum and Radio Frequency RF interference With the published frequency range of 2Hz to 200kHz at 3dB as well as a specially designed high frequency hard wire bypassable EQ circuit the 786 will effectively and clean ly amplify any signal presented at the input while preserving the desired charactersitics of both the source and the microphone All coarse gain adjustments are done through relay switching as opposed to audio pots keeping every possible component out of the audio signal path in keeping with the pris tine design philosophy Understanding Console Signal Path IT Introduction Recording and PA consoles operate at a nominal level of 4dBu while microphones operate at a level of typically about 50dBu Microphone signals must be amplified to the app
3. dB pad engaged 2115 dB at 60 Hz 110 dB at 1 kHz gt 75 dB at 10 kHz gt 90 dB at 60 Hz gt 65 dB at 1 kHz gt 55 dB at 10 kHz Male XLR Pin 2 hot Transformer balanced unbalanced RF filtered Balanced 406 unbalanced 200 Balanced typically 30 dBm into 600 Unbalanced with UNBAL switch engaged typically 24 dBm into 600 15 dB to 65 dB voltage gain in 5 dB steps Additional 5 dB to 5 dB voltage gain 20 Hz to 20 kHz 0 0 1 dB 2 Hz to 200 kHz 0 3 0 dB Typically 128 dBu 150Q source impedance unweighted 20 Hz to 20 kHz measurement bandwidth 0 005 typical at 4 dBu out 1kHz 35 dB gain 0 0009 typical at 24 dBu out 1kHz 35 dB gain lt 0 007 SMPTE 4 1 35 dB gain lt 2 0 degrees 20 Hz to 20 kHz Typically 105 dB 20 Hz to 20 kHz 11 EQUALIZER Shelving Frequency Gain Slope FUNCTION SWITCHES HF EQ 12 dB OCT 48V Super Low Z 20 dB Pad Invert Unbal Rear Panel Ground Rear Panel INDICATORS HF EQ 12 dB OCT Peak 448V Super Low Z 20 dB Pad Invert Power OPTIONS Digital output module Analog output module POWER SUPPLY Operating Voltage Power Consumption Fuse Mains Connection PHYSICAL Dimensions Weight Shipping Weight Specifications Sweepable from 5 kHz to 40 kHz Sweepable from gt to 16 dB Selectable 6 dB octave or 12 dB octave Enables high frequency shelving equalizer Changes equalizer slo
4. from the 786 to the mic Use the 48V Phantom Power switch on the 786 for all other microphones which require phantom power Turn the 786 s large Gain control counterclockwise to the 15dB position and the Fine con trol to OdB and apply power to the 786 Make sure your console s gain slider is at approxi mately nominal level 0d B and begin to slowly increase the gain of the 786 using the large Gain control You should increase the gain until the recording device is operating at nominal signal input level Refer to Figure 2 below for hooking up the 786 to a console Figure 2 Bypassing a console s mic pre with the 786 to your system u Connection 2 Using the 786 to connect a mic directly to a recorder 1 Make microphone connections as shown on the previous page being careful to start with the Gain control in the 15dB position 2 Connect the 786 s audio outputs directly to the audio inputs of your recorder see figure 3 This will require the disconnection of the console s audio output to the specific track of the recorder 4 Enable the record function of the specific track of the recorder and open the specific tape track return in the console which corresponds to the track to which the 786 is connected As you raise the Gain control you should begin to hear the input of the 786 running through the recorder and returning to your console as a tape return NOTE When recording in
5. the gain in a sweepable fashion between 5dB and 5dB If you set the Gain control to 45dB of coarse gain and the Fine control to 3dB of fine gain your overall gain will be 442dB Spectrum Control Use this control to set the frequency where the EQ section boosts or cuts 3dB The range of this control is 5kHz to 40kHz Obviously there is no fundamental frequency material at the 40kHz frequency how ever due to the slope of the EQ curve frequencies in the audio range are affected Also boosting at this frequency emphasizes harmonic information that is sometimes referred to as air or space in the sig nal This control is calibrated to the frequency at which 3dB of boost or cut occurs when the Detail con trol is set at 16dB or 16dB respectively Detail Control This control adjusts the amount of boost or cut of the high frequency shelving EQ The range is gt to 16dB co is typically better than 30dB The cut and boost curves are symmetrical from 16dB boost to 16dB cut ie a 2dB boost produces a shelving curve that is the mirror image of the shelving curve produced by a 2dB cut When the control is set to oo the band acts like a low pass filter whose slope is determined by the 12d B OCT switch 12dB OCT Switch and LED Engage this switch the adjacent LED will light to set the slope of the shelving curve to 12dB Octave Leaving the switch in the out position sets the slope to a gentler 6dB Octave rate For example a 1
6. 2dB setting for the slope can let you create a sense of air without the stridency caused by too much boost ing of upper mid range frequencies Figure 4 on the next page shows the behavior of the 786 s EQ sec tion HF EQ switch The hardwired EQ in out switch bypasses the EQ circuit in the audio path Settings on the Detail and Spectrum controls as well as the 12dB Octave switch are nullified by disengaging the HF EQ switch 6 10 20 a H a E a o x PT qe gt gt olw 2 2 o a 3 o x PTT TTT rt jest N ao 2k 3k 4k 5k 6k 8k 10k 20k 30k 50k 2k 3k 4k 5k 6k 8k 10k 20k 30k 50k Hz Hz 16dB Cut 5kHz 6dB Octave Slope A 16dB Boost 12kHz 12dB Octave Slope B 16dB Cut 5kHz 12dB Octave Slope Cc D 16dB Boost 12kHz 6dB Octave Slope 16dB Cut 12kHz 6dB Octave Slope 16dB Cut 5kHz 12dB Octave Slope Cut 5kHz 6dB Octave Slope Cut 5kHz 12dB Octave Slope cour Figure 4 Audio Precision plots of the 786 s EQ section Peak LED The Peak LED is located to the left of the VU Meter It is set to light when the signal level is within 3dB of hard clipping The LED monitors three different points in the signal path output of the Gain control stage the output of the Fine control stage and the output
7. 383 USA Tel 219 462 0938 Fax 219 462 4596 contents Introduction 2 About Mic Preamps eresse sacian ae SUCK eme E Cp adc eed ac Crea 2 Understanding Console Signal Path 3 Connection To Your System 4 Operating Controls 6 Front Panel Description ascia GRE oC E RR olo CE TOR e Me Oe 6 Rear Panel Description 14423 coe vows COS ERE ER TCR E dee Oe eia 8 Technical Support Factory Service 10 Warranty MPH 11 Specifications cip eee rte EAT PCR ac oW i p REC R PRA e S 11 Block Diagtalh eo xevo ret be aat D eX EC Rico CR ERI adrian 13 Warranty Registration Card Introduction Introduction About mic preamps When you use a microphone to record vocals and acoustic instruments make recordings to DAT or sample acoustic sounds you want the best definition and character possible from your microphone Sometimes the electronics of recording or PA consoles color the sound of a microphone or add noise to the signal In the 1960s it became popular to use an outboard mic preamp rather than using the one usually installed on a console Engineers and technicians took the preamps out of famous vintage con soles and installed them in lunch boxes or cases with a power supply and audio connectors
8. 9 3 kg 25 0 Ibs 11 3 kg Note 0 dBu 0 775V RMS Specifications are subject to change without notice 12 22uelequr puno pj 4i J2u40 sueJ 3nd3n e u2su Lo d ne324 wnnoade 44 O4 bas um H K 12141422J 031 Ye D un ey au J yeg hejay puayayimg weng pug he 23 e u2su2p ampow 244 W QW 86 L T UueJbeiq A2019 987 U23304 hae303 wey 251207 V 9 J hey hey hey M ab n le O lt zo O lt IN IN IN panu aseyf pej qpoz Z Moq 4adnc 13 dbx PROFESSIONAL PRODUCTS H A Harman International Company 8760 South Sandy Pkwy Sandy Utah 84070 Phone 801 568 7660 Fax 801 568 7662 Int Fax 603 672 4246 Questions or comments E mail us at customer dbxpro com or visit our World Wide Web home page at www dbxpro com 18 0531 A 1 19 98
9. This was done to bring the benefits of the characteristic sound or transparency of sound to another recording or PA console In years since the business of designing stand alone preamps has grown significantly as the quality and space dedicated to stock preamps installed in most middle cost consoles has declined usually consisting of only one op amp and some supporting transistors without a transformer During this period of years worth of development it has been proven that better performance is inherent in designs that incorporate larger circuit boards dedicated to the mic pre and larger transformers on both input and output stages resulting in better frequency response and dynamic range as well as better noise specs There are two differing philosophies when it comes to preamp design whether to color the sound with the preamp or not to color the sound with the preamp The dbx 786 is designed with the latter philos ophy in mind We wanted to create a pristine mic pre that would carefully reveal the very subtle nuances of any source device To that end the 786 uses premium parts and as short a signal path as possible to colorlessly amplify a signal to useable levels With the increased popularity of digital recording tech niques and equipment it has become absolutely necessary to provide a preamp that operates within these new transparent parameters With the optional digital output featuring dbx TYPEIV Conversion System with
10. at installation Connect this equip ment only to the power source indicated on the equipment rear panel To reduce the risk of fire or electric shock refer servicing to qualified service personnel or equivalent ELECTROMAGNETIC COMPATIBILITY This unit conforms to the Product Specifications noted on the Declaration of Conformity Operation is subject to the following two conditions this device may not cause harmful interference and this device must accept any interference received including interference that may cause undesired operation Operation of this unit within significant electromagnetic fields should be avoided use only shielded interconnecting cables DECLARATION OF CONFORMITY dbx Professional Products 8760 S Sandy Parkway Sandy Utah 84070 USA Manufacturer s Name Manufacturer s Address declares that the product dbx 786 conforms to the following Product Specifications Safety EN 60065 1993 IEC65 1985 with Amendments 1 2 3 EMC EN 55013 1990 EN 55020 1991 Supplementary Information The product herewith complies with the requirements of the Low Voltage Directive 73 23 EEC and the EMC Directive 89 336 EEC as amended by Directive 93 68 EEC dbx Professional Products Vice President of Engineering 8760 S Sandy Parkway Sandy Utah 84070 USA January 19 1998 European Contact Your Local dbx Sales and Service Office or International Sales Office 68 Sheila Lane Valparaiso Indiana 46
11. dbx PROFESSIONAL PRODUCTS Precision Mic Preamp Owner s Manual RISK OF ELECTRIC SHOCKO DO NOT OPEN ATTENTION risque DE CHOC ELECTRIQUE NE PAS OUVRIR WARNING ro REDUCE THE RISK OF FIRE OR ELECTRICO SHOCK DO NOT EXPOSE THIS EQUIPMENT TO RAIN OR MOISTURE The symbols shown above are internationally accepted symbols that warn of potential hazards with electrical products The lightning flash with arrowpoint in an equilateral triangle means that there are dangerous voltages present within the unit The exclamation point in an equilateral triangle indicates that it is necessary for the user to refer to the owner s manual These symbols warn that there are no user serviceable parts inside the unit Do not open the unit Do not attempt to service the unit yourself Refer all servicing to qualified personnel Opening the chassis for any reason will void the manufac turer s warranty Do not get the unit wet If liquid is spilled on the unit shut it off immediately and take it to a dealer for service Disconnect the unit during storms to prevent damage U K MAINS PLUG WARNING A moulded mains plug that has been cut off from the cord is unsafe Discard the mains plug at a suitable disposal facility NEVER UNDER ANY CIRCUM STANCES SHOULD YOU INSERT A DAMAGED OR CUT MAINS PLUG INTO A 13 AMP POWER SOCKET Do not use the mains plug without the fuse cover in place Replacement fuse covers can be obtained from your
12. eturned products will be accepted at the factory without a Return Authorization Number Please refer to the Warranty below which extends to the first end user After expiration of the warran ty a reasonable charge will be made for parts labor and packing if you choose to use the factory ser vice facility In all cases you are responsible fortransportation charges to the factory dbx will pay return shipping if the unit is still under warranty Use the original packing material if it is available Mark the package with the name of the shipper and with these words in red DELICATE INSTRUMENT FRAGILE Insure the package properly Ship prepaid not collect Do not ship parcel post 10 Specifications Warranty This warranty is valid only for the original purchaser and only in the United States 1 The warranty registration card that accompanies this product must be mailed within 30 days after pur chase date to validate this warranty Proof of purchase is considered to be the burden of the con sumer dbx warrants this product when bought and used solely within the U S to be free from defects in materials and workmanship under normal use and service dbx liability under this warranty is limited to repairing or at our discretion replacing defective materials that show evidence of defect provided the product is returned to dbx WITH RETURN AUTHORIZATION from the factory where all parts and labor will be cove
13. hase reverse switch Connection f The 786 is the perfect partner for your microphone providing you with two channels of audio purist quality preamplification The 786 delivers up to 70dB of sonically transparent gain to reveal the detail and audio signature of even the most esoteric studio mics It transforms their low level output signal to a clean high level high current output for direct connection to the line level inputs of your mixer DAT machine sampler or any other recording medium that accepts line level analog input 1 Bypassing a console s preamp with the 786 1 Mount the 786 in a 2U rack space The 786 requires a two rack space height and a standard 19 inch rack space width It can be mounted above or below anything that doesn t obstruct the vents of the 786 Ambient temperatures should not exceed 95 F 35 C when equipment is powered Make sure that AC power is not connected to your 786 Connect your mic cables to the audio inputs of the 786 Set the front panel of the 786 to the desired settings including phantom power and Low Z Connect the audio output of the 786 to the console s LINE INPUT and ensure that the con sole s input selection switch is set to LINE and the console s gain control is set at its nominal operating level ie 4dBu NOTE If you are using a mic with a separate power supply such asa tube microphone make sure that you are 5 not sending 48V phantom power
14. he chassis and earth ground are touched simultaneously WARNING FOR YOUR PROTECTION PLEASE READ THE FOLLOWING WATER AND MOISTURE Appliance should not be used near water e g near a bathtub wash bowl kitchen sink laundry tub in a wet basement or near a swimming pool etc Care should be taken so that objects do not fall and liquids are not spilled into the enclosure through open ings POWER SOURCES The appliance should be connected to a power supply only of the type described in the operating instructions or as marked on the appliance GROUNDING OR POLARIZATION Precautions should be taken so that the grounding or polar ization means of an appliance is not defeated POWER CORD PROTECTION Power supply cords should be routed so that they are not likely to be walked on or pinched by items placed upon or against them paying particular attention to cords at plugs convenience receptacles and the point where they exit from the appliance SERVICING To reduce the risk of fire or electric shock the user should not attempt to service the appliance beyond that described in the operating instructions All other servicing should be referred to qualified service personnel FOR UNITS EQUIPPED WITH EXTERNALLY ACCESSIBLE FUSE RECEPTACLE Replace fuse with same type and rating only MULTIPLE INPUT VOLTAGE This equipment may require the use of a different line cord attach ment plug or both depending on the available power source
15. ip meter you may choose to do A B comparisons with the phase reverse switch in both positions for best results Out of phase signals are more obvious in the lower frequency range due to the size of the waveforms Out of phase signals may sound empty hollow or weak in the low frequencies Use the phase reverse switch to determine if the source device is out of phase with the rest of the program material CHANNEL TWO MAI RED 4 968 425 5 2822 UNBAL GROUND OUTPUT Audio Input and Output Connectors Each audio input connector on the rear panel of the 786 is a gold plated Neutrik XIR female connec tor The no compromise approach to the 786 required that we use gold plated connectors due to their high conductivity and resistance to corrosion The connectors are default wired in BAIANCED mode pin 2 hot AES convention although supplying an unbalanced signal presents no difficulty to the 786 by grounding pin 3 Un balance Switch The Unbalance switch is associated only with the Output connectors of the 786 When it is in the IN position the output of the 786 is switched from balanced to unbalanced See Figure 5 on page 9 In the OUT position the 786 s outputs are balanced in the pin 2 hot configuration Note that when the output is unbalanced via the switch there is a 6dB drop in output signal level and the meter is still cal ibtrated for a balanced signal Ground Switch The Ground switch when in the
16. local retailer Replacement fuses are 13 amps and MUST be ASTA approved to BS1362 SAFETY INSTRUCTIONS NOTICE FOR CUSTOMERS IF YOUR UNIT IS EQUIPPED WITH A POWER CORD WARNING THIS APPLIANCE MUST BE EARTHED The cores in the mains lead are coloured in accordance with the following code GREEN and YELLOW Earth BLUE Neutral BROWN Live As colours of the cores in the mains lead of this appliance may not correspond with the coloured markings identifying the terminals in your plug proceed as follows The core which is coloured green and yellow must be connected to the ter minal in the plug marked with the letter E or with the earth symbol or coloured green or green and yellow The core which is coloured blue must be connected to the terminal marked N or coloured black The core which is coloured brown must be connected to the terminal marked L or coloured red This equipment may require the use of a different line cord attachment plug or both depending on the available power source at installation If the attachment plug needs to be changed refer servicing to qualified service personnel who should refer to the table below The green yellow wire shall be connected direct ly to the unit s chassis WARNING If the ground is defeated certain fault conditions in the unit or in the system to which it is connected can result in full line voltage between chassis and earth ground Severe injury or death can then result if t
17. of the EQ stage VU Meter The VU Meter is a custom dbx meter and monitors the output signal of the 786 It is calibrated at 0VU HdBu 48V Phantom Power Switch and LED This switch activates phantom power for condenser microphones on pins 2 and 3 of the XLR mic input Make sure to connect your microphone before activating the phantom power to prevent high voltage arching which may damage your microphone Super Low Z Input Switch and LED Typically microphones have an output impedance of 1509 The 786 is set to operate in this range with out any adjustments necessary In some instances a microphone may operate at a much lower imped ance like 200 ie some ribbon microphones The Super Low Z switch optimizes the input circuit of the 786 for proper damping of these low impedance microphones and to ensure that the input trans former is always fed by the same impedance for consistent performance 20dB Pad Switch and LED This switch inserts a 20dB attenuator circuit into the signal path from the microphone input The pad is inserted before the signal is routed through the mic pre gain stage Use the 20dB pad to attenuate sig nals from hot sources such as high output microphones or when the source is a line level device Phase Reverse Switch and LED This switch inverts the phase of the input source 180 Note that it usually takes years of engineering experience to properly hear phase relationships If your console has a phase relationsh
18. pe from 6 dB octave to 12 dB octave Sends regulated 48 VDC through 6 81KQ 0 1 metal film resistors to pins 2 and 3 of the input XLR Optimizes input stage for use with 20Q low impedance microphones Attenuates the input signal by 20 dB Reverses pins 2 and 3 of the input XLR connector Unbalances the output A 6 dB drop in level will occur In Balanced Mode references the center tap of the output transformer to chassis ground through a 10kQ resistor In Unbalanced Mode references pin 3 of the out put XLR and the center tap of the transformer to chassis ground Green LED to indicate when EQ is engaged Yellow LED to indicated when 12 dB octave mode is selected Red LED to indicated when signal is within 3 dB of clipping Sense points are out put of M8 gain module Course Gain output of Fine Control and output of equal izer section Red LED lights when phantom power is being delivered to input XLR connector Yellow LED lights when Super Low Z mode is selected Green LED lights when 20 dB pad is engaged Yellow LED lights when pins 2 and 3 of the input XLR are reversed Blue LED lights to indicate the 786 is powered Contact dbx for further details Contact dbx for further details 100VAC 50 60Hz 120VAC 60Hz 220 240VAC 50 60 Hz 50 Watts maximum 100V 500mA 250V Slow Blow 5mm X 20mm 120V 500mA 250V Slow Blow 5mm X 20mm 220 240V T250 mA 250V 5mm X 20mm IEC 320 Receptacle 3 5 H X 19 W X 11 25 D 20 5 Ibs
19. red up to a period of two years A Return Authorization number must be obtained from dbx by telephone The company shall not be liable for any consequential damage as a result of the product s use in any circuit or assembly dbx reserves the right to make changes in design or make additions to orimprovements upon this product with out incurring any obligation to install the same additions orimprovements on products previously manufactured The foregoing is in lieu of all other warranties expressed or implied and dbx neither assumes nor authorizes any person to assume on its behalf any obligation or liability in connection with the sale of this product In no event shall dbx or its dealers be liable for special or consequential damages or from any delay in the perfor mance of this warranty due to causes beyond their control Specifications INPUIS Connectors Type Impedance Optimum Microphone Impedance Maximum Input Level CMRR CMRR with 10Q imbalance in one leg of input XLR with 1509 source impedance OUTPUTS Connectors Type Impedance Maximum Output Level SYSTEM PERFORMANCE Course Gain Control Fine Gain Control 0 1 dB Bandwidth Frequency Response EIN THD Noise IMD Deviation From Linear Phase Interchannel Crosstalk Female XLR Pin 2 hot Transformer balanced unbalanced 1 44kQ 20 Hz to 20 kHz 150Q or 20Q with Super Low Z switch engaged gt 13 dBu or gt 33 dBu with 20
20. ropriate level for a console to process it properly If a signal is not raised to the appropriate level the signal will be masked by the console s internal noise especially when one tries to increase the level of a low signal using the con sole faderor gain knob All consoles have a preamp usually labeled Gain as the first stage of an input strip allowing the user to boost a signal to an appropriate level before the other processes of the input strip act upon the signal EQ dynamics panning etc Unfortunately console preamp circuits are often not given enough room on the circuit board or high quality parts It is for this reason that outboard pre amps have become so popular See Figure 1 below for a typical input strip s signal flow Mic Line Switch 1 4 line input XLR mic input Phase Rev Switch Gain Preamp Lo Cut Filter and Group y 1 4 output A Inserts Routing 5 a Mute I EQ in out QOOOOO reme smn I Buss to gt gt Main Outputs Equalization OOOO isons Y OOOO O 1 4 output AW Direct Out 5 Figure 1 Signal flow of Typical Console Input Strip The gain or preamp stage occurs before all audio critical processes act upon the incoming signal The preamp s color is then processed as part of the signal The only processes ahead of the preamp stage are the input selection stage and the p
21. t option card is installed in your 786 Connecting a custom designed digital output module in the option port provides full 24 bit AES EBU and S PDIF output capa bilities for the 786 The digital outputs of the 786 operate simultaneously with the analog outputs pro viding the possibility of running to two different devices at the same time analog and AES EBU or S PDIE For more information on the digital output option contact dbx customer service Be sure to fill out your warranty registration card provided in this manual and return it to dbx as soon as possible This will enable us to notify you of other output options that will become available in the future Technical Support If you require technical support contact dbx Customer Service Be prepared to accurately describe the problem Know the serial number of your unit this is printed on a sticker attached to the rear panel If you have not already taken the time to fill out your warranty registration card and send it in please do so now Factory Service Before you return a product to the factory for service we recommend you refer to the manual Make sure you have correctly followed installation steps and operation procedures If you are still unable to solve a problem contact our Customer Service Department at 801 568 7660 for consultation If you need to return a productto the factory forservice you MUST contact Customer Service to obtain a Return Authorization Number No r
22. this way you should use a compressor limiter in the path before the recorder The perfect com panion product to the 786 is the dbx 160SL Stereo Compressor Also when recording with this method remember that desired gain changes to the recorder can only be made via the GAIN controls of the 786 While this is much less convenient itis often desirable to go directly to tape bypassing all console electronics in favor of a pristine sig nal A good compressor becomes vital to this process NOTE For optimal performance after applying power to the 786 let it sit for approximately 5 minutes before use so that the internal DC servos can cancel any DC offsets Figure 3 Connection of the 786 to a recorder Note that the 786 may be connected to any recorder from a large format analog recorder shown to a MDM such as an ADAT or DA 88 Operating Controls Front Panel Gain Control Use the Gain control to adjust the output level of the 786 Note that the Gain control is used as a coarse adjustment ranging from 15dB to 65dB of gain in 5dB increments The Gain control is not a pot orin other words the signal does not go through this control The Gain control is a relay based system which tells the 786 how much gain should be applied to the signal You should always set the Gain control to one of the detents Do not set the Gain control between detents Fine Control The Fine control further adjusts
23. tions for any installation Some systems are built on a star grounding principle where all the signal grounds are brought directly to one cen tral point and grounded to earth at the same location The Signal Ground binding post allows easy access to the signal ground system of the 786 without having to remove the cover of the 786 and locate a good place to take the signal ground out of the box 8 BALANCED FLOATING OPERATION Chassis Jensene O Output O Transformer 10k 1W Ground Switch openO eupn 9 Unbalance Switch open Switch ChassisO Ground BALANCED GROUND H REFERENCED OPERATION ChassisO 1 Ground i T 2 Jensene O Output O Transformer Ground Switch closed0O Unbalance Switch open UNBALANCED FLOATING OPERATION ChassisO 3 Jensene O Output O Transformer Ground Switch openO 4 up Unbalanced Switch closed switch 6dB drop in output level ChassisO Ground UNBALANCED GROUND O REFERENCED OPERATION T 3 ChassisO Ground I T 2 Jensen O Output O Transformer Ground Switch closed0 enpo Unbalance Switch closedn g Switch 6dB drop in output level ChassisO ChassisO Ground Ground Figure 5 Ground Unbalance switch operation Note The shorting link between chassis ground and signal ground should be left installed unless another grounding scheme is used 1 4 Inch Anchor Bolt We have provided a 1 4 anchor bolt on the rear panel of the 786 to aid in securing the unit in yo
24. ur rack Since the 786 is a heavy unit we recommend securing the 786 to a rear rack rail to avoid unnec essary stress on the front panel and front rack rails of your rack The anchor bolt provides no electrical or audio benefit to the 786 and no grounding or electrical wires should be connected to it AC Power Switch Located beside the AC Power connector the AC Power switch turns the 786 ON and OFF When the switch is in the DOWN position revealing the red portion of the switch the AC power to the 786 is ON When the switch is in the UP position no AC power is being supplied to the 786 regardless of other power connections AC Power Connector The AC Power connector is a standard IEC 320 power inlet receptacle for use with any IEC type power cord included with the 786 Connect this cable to any 50Hz or 60Hz AC power source of the correct line voltage for your area Make sure this voltage is also correct for the voltage marked on the back of the 786 Always make AC power connections with the AC power switch in the OFF position see above The 786 consumes a maximum power of 50 watts Warning Be sure to verify both your actual line voltage and the voltage for which your 786 is wired as indi cated on the back panel of the unit Connection to an inappropriate power source may result in exten 9 support and factory service sive damage which is not covered by the warranty Output Option Panel This panel is removed when an outpu
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