THEATER SPEAKER SILENCER User`s Manual
Contents
1. without incurring any obligation to change or improve products manufactured prior thereto Section 3 THEORY of OPERATION SPEAKERS 3 1 Signal from the program source is muted by a dual reed relay Output of the program source is left open while the input of the power amplifier is loaded with a low impedance RC network From that point forward there is no audio signal at the output of the power amplifier 3 2 Ten to 15 milliseconds later a 15 ohms power resistor is connected in parallel with the speakers in order to avoid an open circuit at the speaker output of the power amplifier 3 3 Another 10 to 15 milliseconds later the speaker output is opened thus creating a totally silent speaker environment The complete sequence takes 25 to 35 milliseconds 3 4 Reverse sequence results in de muting Although there is no a c signal at the power amplifier output during the switching sequence steps 2 and 3 uses heavy duty 30 amperes relays for noise free and long life operation Note Muting signal is muted after 3 to 5 milliseconds De muting signal is released after 25 to 35 milliseconds Section 4 SIGNAL CONNECTIONS The LP 28 Theater Speaker System model is inserted twice in the audio monitoring chain The first insertion is made between the output of the program source such as a mixing console graphic equalizer or active crossover and the input of the power amplifier The second insertion lies between the speaker output of t2. Connection to the LP 28 should be made on the 9 pin D connector as follows Left channel use pins 4 and 5 Right channel use pins 7 and 8 Dip switch setting LEFT LEFT RIGHT LL m RIGHT INT 5 2 Open collector logic The LP 28 remote control can be driven from an open collector circuit with external or internal pull up voltage 5 2 1 External pull up Supply voltage should be maintained in a range between a minimum of 5 volts and a maximum of 28 volts Connect the positive rail of the power supply to pin 9 left or pin 3 right Connect the negative rail to pin 4 left or pin 7 right Connect the collector output to pin 5 left or 8 right V D V Dip switch setting LEFT RIGHT LL INT The dip switch setting is important to avoid a conflict between internal and external power Supplies 5 2 2 Internal pull up Connect the collector output to pin 5 left or 8 right Connect the emitter output to pin 4 left or pin 7 right Dip switch setting J EE RIGHT se INT 5 3 Positive logic remote switching This mode enables direct control of the LP 28 from a positive logic circuit For example the logic signal may be taken across a lamp or an LED circuit Logic voltage should be maintained between a minimum of 5 volts and a maximum of 24 volts Connection should be made as follows Connect the logic output to pin 9 left or pin 3 right Connect the reference lev
3. logic level The LP 28 can accept both Referring to the front panel the MODE switch allows selection of the dc steady mode red indicator or the pulse mode yellow indicator Each channel is equipped with a MODE switch for an independent channel selection 7 2 Format The two channels can operate independently or can be coupled for use as a stereo pair The FORMAT switch changes from single channel format to dual channel format When the dual format is selected red indicator the logic command applied to either of the two remote ports will drive both channels As an example the left channel port may be controlled from the mixing console mute switch while the right channel is controlled from the record or rewind command of a tape recorder 7 3 Link Two or more LP 28 may be linked together in a multi channel installation Each section left and right has its own link bus The LINK switch routes the logic signal to the corresponding link bus If at least one unit is in dual format all channels will be linked together 7 4 Test The test switch may be used for channel test during installation check or maintenance or whenever speaker muting should be made from the amplifiers location This function is very useful to freeze a channel when the studio theater is used with a monitoring format not requiring this speaker The test function is independent from link and format switch settings 12 7 5 Summary of switch functions MODE se
4. not complicated but the flexibility provided by its operating features merits familiarization with its connections and controls We welcome your suggestions and comments on our products and on this manual 1 2 Unpacking and inspection Your new LAFONT LP 28 was carefully packed at the factory Save all the packing material they will prove valuable should it become necessary to transport or ship this product We recommend careful examination of the shipping carton and its contents for any sign of physical damage which may have occurred during transportation lf damage is evident notify the transportation company without delay Only you the consignee may institute a claim against the carrier for damage lf necessary contact your supplier or as last a resort your LAFONT importing agent who will fully co operate under such circumstances Your shipping carton should contain The LP 28 The a c power cable This instruction manual 1 3 Mounting Do not install this unit in a location subjected to rain moisture dust or mechanical vibrations If the unit is installed in an equipment rack console or other area along with high heat producing equipment adequate ventilation should be provided to assure longest component life Also while internal circuits susceptible to hum pickup is sufficiently shielded from moderate electromagnetic fields avoid mounting the unit immediately above or below large power transformers or any radiating equi
5. THEATER SPEAKER SILENCER LP 28 User s Manual THEATER SPEAKER SILENCER LAFONT AUDIO LABS 10 rue Levassor ZI des Garennes 78130 Les Mureaux France Tel 33 1 34 74 65 39 Fax 33 1 34 74 67 73 Section 1 1 1 1 2 1 3 1 4 1 5 Section 2 Section 3 Section 4 4 1 4 2 Section 5 5 1 5 2 5 2 1 5 2 2 5 3 5 4 Section 6 Section 7 7 1 7 2 7 3 7 4 7 5 Section 8 8 1 8 2 Section 9 Scetion 10 Table of contents Introduction and precautions Preface Unpacking and inspection Mounting Power connection Safety warning Warranty Theory of operation Signal connections Pre amplifier connections Post amplifier connections Remote control connections Remote control from a switch Open collector logic External pull up Internal pull up Positive logic remote Tally Link connections Operating procedures Logic mode Format Link Test Summary of switch functions DC offset Input DC Output DC Service and calibration Schematics O1 KFA WWW N N ak L O O CO WO OC 11 12 12 12 12 13 13 13 14 15 Section 1 INTRODUCTION and PRECAUTIONS 1 1 Preface Thank you for using this LAFONT product We have prepared this instruction manual to enable you to achieve optimum utility and performance from your new ADR Foley processor LP 28 We encourage you to read and make use of the material contained in this manual Installation and operating of the LP 28 is
6. cial parts and components are available from Lafont Audio Labs See schematics for part reference 13 Serial N HR LAFONT Audio Labs Made in France OUTPUT OUTPUT RIGHT o O O Model LP 28 NPUT 10 Specifications NPUT Maximum power 1000 watts per channel Logic input opto isolated Logic level 5V to 28V pulse or DC Logic voltage reference internal or external Power requirements 115VAC 60Hz 240VAC 50Hz Physical size 19 x1U rack cabinet 483x44 5x225mm LINK BUS C EXT INT 0 o 0 oO 0 o 0 oO 0 O e o9 0 oo O a S In the interest of continuous product improvement and development LAFONT Audio Labs reserves the right to change and modify any of the above specification or feature whenever in Our opinion such a change produces an advantage mutual to our customers and ourselves OOO Manufactured by Distributed by LAFONT Audio Labs GASCOm 10 rue levassor Z des Garennes Phone 01 905 469 80 80 78130 Les mureaux France Fax 01 905 469 11 29 Fax 33 34 74 67 73 E mail sales sascom com E mail Lafont Audio wanadoo fr Web www sascom com slow blow FUSE 117V 500 mA 230V 315mA 14
7. d This path uses Speakon NL4 type of connectors or equivalent Mating connectors are supplied with the unit Use pin 1 for high hot and pin 1 for signal return the standard code for monophonic signal The LP 28 can accept high currents up to 30 amperes Depending on your installation it is advisable to check for correct cable gauge 12 AWG is recommended for optimum performance Section 5 REMOTE CONTROL CONNECTIONS The LP 28 can be controlled remotely from a switch or a logic level A special port is provided for connection to the remote controller Use off a screened cable is recommended to reduce the risk of radio interference 9 pin sub D connector pin out tally output collector n C L R TALLY right channel high ref logic positive supply opie left channel low ref logic ground 54321 left channel logic drive o 09000 O tally output emitter right channel low ref logic ground right channel logic drive left channel high ref logic positive supply OOnNOOBRWND Remote switching mode is independent between left and right channel For example the left channel port may be driven from a latched switch while the right channel port is controlled from an open collector logic pulse 5 1 Remote control from a switch A momentary or latching single pole switch not supplied is suitable The contacts of the switch should be isolated from any other application Several switches may be paralleled
8. ear of the unit will isolate the logic ground from the chassis T GROUND H ON Section 2 WARRANTY Lafont Audio Labs warrants to the original purchaser all parts except front panels knobs cases and cabinets of every Lafont product to be free from defects in materials or workmanship as hereinafter provided for one year from the original date of purchase Lafont Audio Labs will at his option repair or replace any equipment covered by this warranty which becomes defective malfunctions or otherwise fails to conform with this warranty under normal use and service during the term of this warranty at no charge for parts and labor This warranty does not cover defects malfunctions or failures resulting from shipping or transit accidents abuse misuse operation with faulty associated equipment modification alteration tampering or normal wear and tear Lafont Audio Labs shall not be responsible for any incidental or consequential damages sustained by any customer as a result of or any cause associated with products including without the limitation the delivery or non delivery thereof or the performance or non performance thereof This is the only warranty applicable to Lafont products In the interest of continuous product improvement and development Lafont Audio Labs reserves the right to change and modify any specification or feature whenever in our opinion such a change produces an advantage mutual to our customers and ourselves
9. el ground to pin 5 left or pin 8 right Pins 4 and 7 are not used Dip switch setting JL LEFT RIGHT EXAMPLES INT OV 5 4 Tally Right channel mute information is available on the remote connector Output is made via an opto coupler The collector emitter resistance is low when channel is muted There is no serial resistor Maximum current rating is 50mA and breakdown voltage is 30 volts Application example mute indicator using an LED with a resistor in series may be connected directly across the tally output For a 10 mA LED with a 5 volts supply use a 270 ohms resistor with 12 volts supply use a 1 kohm resistor Pin out details Pin 1 collector Pin 6 emitter 10 Section 6 LINK CONNECTIONS A 10 pin ribbon cable connector is provided to link two or more LP 28s in a multi amplifier system Connectors should be paralleled as shown below UNIT 1 UNIT 2 UNIT 3 10 cm 4 Connector pin out pins are internally connected in pairs 1 2 right channel link 3 4 n C 5 6 logic ground link GND 7 8 n c LEFT RIGHT 9 10 left channel link pecoccocc LINK BUS 11 Section 7 OPERATING PROCEDURES LEFT RIGHT MODE LINK TEST MODE LINK TEST FORMAT l l l l l l l OO O wea OO O O LEFT RIGHT DC olo fi O O DC olo TL DUAL olo SINGLE 7 1 Logic mode Any of the three remote control circuits described above may present a momentary pulse or a steady latched
10. he power amplifier and the input of the speaker cabinet All connectors are accessible from the rear panel of the unit INPUT OUTPUT INPUT OUTPUT L R TALLY EE E ESS E ano Sj BREE Gur 9 pan 0 0 2 2 e2 ose en O NA LINK BUS LEFT CHANNEL RIGHT CHANNEL CHANNEL CHANNEL 4 1 Pre amplifier signal connections Both inputs and outputs are fully balanced and floating on XLR connectors The audio path is not referenced to the chassis ground of the LP 28 Current IEC wiring convention calls for pin 2 to be high hot and pin 3 low cold In a balanced system the distinction is arbitrary provided there are no phase inversions through the unit the LP 28 maintains phase Should inputs and or outputs be unbalanced it is not important which of the two Signal pin is grounded so long as it is consistent on all inputs and outputs Nevertheless in the interest of maintaining international standardization we suggest the IEC recommendation is followed We recommend that two conductor shielded cable be used even in an installation using unbalanced wiring This takes advantage of the ability of the input to reject common mode noise hum and reduces the possibility of radio interference RFI 4 2 Post amplifier connections Connection between the amplifier output and the speaker cabinet is unbalanced but it is also floating i e not referenced to the input circuit or to the LP 28 chassis groun
11. lects latched or pulse mode logic at the remote input FORMAT logic coupling of the two channels LINK enables coupling of logic circuits between several units TEST activates local muting for channel check 8 Warning DC offset Any d c voltage present at either input or output of the power amplifier will result in an audible transient when switching 8 1 Input d c voltage may be produced by either the program source equipment or the input stage of the power amplifier In both cases the solution is to insert two non polarized electrolytic capacitors in series with the input of the power amplifier 100uf 25V 8 2 D C coming from the output stage of the power amplifier is more critical It should normally not exceed 3mV to 5mV for a good quality amplifier but it may vary with load or temperature Some amplifiers have a d c offset auto compensation or a preset potentiometer If the d c offset voltage is too high large capacitors should be inserted in series with the speakers This solution is suitable for speakers with an impedance greater than 4 ohms only A d c isolation kit is available from Lafont Audio Labs Part ref LP 282 Section 9 Service and calibration Timing of the LP 28 switching sequence is calibrated at the factory and require no further calibration No special preventive maintenance is required There are no user serviceable part inside the unit Servicing should be performed by a qualified technician Spe
12. pment 1 4 Power connection Connection is made by means of an IEC standard power socket Before connecting the unit to the mains power ensure that the operating voltage is correct for your local supply The rear panel voltage label indicates the voltage required for satisfactory operation of the unit Should the fuse need replacement it should be replaced only with the same type and value of fuse For 115Vac use 500mA 250V 5 x 20mm slow blow fuse For 230Vac use 315mA 250V 5 x 20mm slow blow fuse 1 5 Safety warning For safe operation the LP 28 must be connected to a good mechanical ground This provides a current path for any voltage which might appear on the chassis due to an electrical fault in the network Without this path the unit could be an electrical shock hazard In addition a good quality ground on the chassis provides shielding from external fields and minimizes radiation of internal fields to the outside world This unit is fitted with 3 pin power socket The earth lead should not be disconnected Do not use a ground lifting adapter and never cut the ground pin on a three prong plug To avoid electrical shock do not remove cover Refer servicing to qualified personnel only The LP 28 should not induce hum by ground loop or mains interference as the audio path have a separate ground circuit and is not referenced to the chassis or logic ground Nevertheless if such noise should occur the ground lift dip switch at the r
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