M460L — Input Module

M460L INPUT MODULE The M46OL combination INPUT/EQUALIZER module, designed input signals orig' inating from either microphone Iine accep source. The unit processes the input signal required and routes the appropriate points within the mixing console system . Input The INPUT SELECTOR switch SW1 provides choice connecting the input transformer either the MICROPHONE source directly or via dB PAD . In either case, the input impedance the unit times higher than the source impedance .

In the LINE position, the M46OL operates as bridging amplifier_ presenting 30k ohm impedance the source. Both Mic and LINE inputs are transformer coupled _ With the INPUT SELECTOR the OFF position, inputs are disconnected and the module input terminated Preamplifier The secondary side connected the 4-110 Preamp/High-pass filter The 4-110 serves as low-noise preamp and raises the input levels sufficiently for further processing within the console system SENSITiVITY control R12 permits continuous level adjustment all input signals, allowing total range dB HIGH_PASS Filter Switch SW17 incorporated the HIGH-PASS filter control R1o/11_ With R10/1 positioned fully counterclockwise, SW17 passes the output the 4-110 directly the equalizer insert switch SW13.

Once R0/11 rotated away from the extreme counterclockwise position, dBloctave high-pass ter inserted The dB rolloff point continuously adjustable from 25 250 Hz . . ` EQUAL ZER_Section The output the 4-110 preamplifier routed one the norm- ally closed contacts the EQUALIZER INSERT switch SW13 allow bypassing the equalizer. Additionally _ the preamp output fed Z1, the first four cascaded summing amplifiers 21 through 24 _ through serve as mixing and isolation amplifiers They are used mix the primary input signal with correction signal derived from the outputs the 4-126 filter networks, resulting in raising lowering the Ievel selected portions the audio spectrum.

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M46OL NPUT MODULE ` 8-109 Booster Amplifier The 8-109 booster amplifier operates with gain recovers the loss incurred when the fader placed dB "in hand" position. dB and its nominal 15 Main Outputs and PAN Control The output signal the 8-109 amplifier feeds the left and right main outputs via PAN switch SW14 and PAN control R24 through R27 also provides the feed for the DRECT output and via SW16_ for the SOLO ouiput Additionally feeds are supplied the POSTFADE RS, FB and PA channels via the appropriate switches and level controls PRE/POST Selector Switches and Level Controls PRE/POST selection the RS, FB and PA channels facilitated by switches Sw18, SW19, Sw2o and SW4 espectively each switch followed by its associated level control _ The oulputs the level controls are fed the summing outputs via individual channel assignment switches Following the assignment swi tches these outputs are fed their appropriate mixing buses via summing resistors Auxiliary_Functions DC controls and logic functions are provided through the INPUT SELECTOR switch SW1 and the CHANNEL ON switch Sw21 operate external mute control functions independently for both microphone and Iine sources as may required particular console system _ Additional control contacts are available the SOLO switch, the PA switch, the PFL switch and the CHANNEL ON switch allow operation external relays and/or ilumination the CHANNEL ON button Power SuPply Decoupling An active power supply decoupling network consisting through provides high degree isolation between the M460L and the +/ volt supply rails.

Transistors 05 and 06 serve as current monitors and wili Iimit the current flowing through the pass tran- sistors 03 and 04 the event that excessive power supply demands should arise as result component failure. 2-4

M46OL INPUT_MODULE This concept adding correction signal together with the incoming signal form the equalized signal directly responsible for the Iow noise and distortion capabilities this unite The compound signal as generated along the entire processing chain appears the output 24 From here routed one the normally open contacts the EQUAL IZER INSERT switch SW13 Thus with SW13 depressed, the equalized signa fed the output amplifier 8-109A .

addition, SW13 depressed, the LED indi cator activated 8-109A Qutput Amelifier and INSERI The 8-109A amplifier raises the signal -10 dBm nominally . The output actively balanced and fed the "insert point" pins 22 and module connector P1 This feature allows the use insert jacks, permitting the insertion ancillary equipment into the main mixing signal patn. PHASE Reversal The signal returned the module via pins routed through the PHASE REVERSAL switch SW2 switch Sw21 and and the CHANNEL ON PREFADE LISTEN (PFL) The bridging takeoff for the PFL output and Sw2i picked up between Sw2 CHANNEL ON Switch The CHANNEL ON switch Sw21 controls all outputs the exception the PFL output the module with FADER Fol lowing Sw21 the signal brought ou[ the module via pins 20 and for insertion balanced fader _ The output the fader returned the module on pins and PI _ The input side the fader aiso serves as pickup point for the PREFADE REVERBERATION SEND (RS)_ the PREFADE FOLDBACK (FB) and the PRE- FADE PUBLIC ADDRESS (PA) channels via switches SW1B SW19, Sw2o and SWL respectively 2-3

ML6OL INPUT_MQDULE Input Sensitivities: Line: Mic Pad: Mic: +10 dBm (ref 600 ohm source) dBm (ref _ 150 ohm source ~LO dBm (ref_ 150 ohm source) -50 -70 Frequency Response: +/ - 0.25 dB irom Hz 20 kHz (Equalizer bypass position) Noise: -125 dBm EIN maximum SENSITiViTY (20 Hz to 20 kHz ) Harmonic Distortion: Less than 25% THD from Hz 20 kHz +28 dBm less Less than at kHz +28 dBm output Source Impedances: Line: Mic 50_ 600 ohms, balanced/unbalanced 50 onms balancedfunpalanced Input Impedances Line: Mic OOO onms 500 ohms Output Impedance: Less than 100 ohms (at outputs 8-109 8-109A amplifiers only ) Load Impedance: 600 ohms balanced (at insertion point) _ Output Level : dBm nominal , +30 dBm maximum (at outputs 8-109 8-109A amplifiers only ) _ Phasing: Input and output terminals designated by numbers are phase.

Power Requirements: +/ - 25 volts dc , 90 MA nominal, 250 mA maximum 1-1

M460L INPUT MODULE Ambient Temperature: Dimensions: . degrees Celsius wide 14.15" high (41 mm 360 mm 165 mm) deep Weight: ozs (1250 gms .

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M46oL INPUT MODULE 23 ) PRE/POST REV SEND switch Sw18: Allows the choice the pick-off point for the REV SEND signal; either prior (PRE ) after (Post the channel fader 24) PRE/POST FOLDBACK switch Sw2o: Allows the choice the pick- off point for the FOLDBACK signal, either prior (PRE) after (PoST) the channel fader _ 25) FOLDBACK LEVEL controls R17/18: Controls the level FB2 output buses FBI and 26 ) FOLDBACK LEVEL controls R19/20: Controls the level FBL output buses FB3 and 27) PRE/post FOLDBACK switch SW19: Allows the choice the pick- off point for the FOLDBACK Signal, either prior (PRE) or after (Post) the channel fader 28) HIGH FREQUENCY sec tion, BOOST/CUT control R21 Continuously variable from 15 dB +15 dB Sets gain loss high frequency content the program material with reference the nominal level 29) MId FREQUENCY section Boost/cut control R22: Continuously variable from -15 dB +15 dB Sets gain Or loss mid frequency content the program material with reference the nominal level 30 ) LoW FREQUENCY section BoosT/cut control R23: Continuously variable irom -15 dB +15 dB .

Sets gain loss low frequency content the program material with reference the nominal level 31 ) PAN control R24 R27: Positions channel signal between assign- ec mixing buses (Teft and right) . 32 ) CHANNEL ON swi tch Sw21 When depressed_ feeds the signal main outputs, a5 wel| as the PA FB, RS and SOLO outPuts Additionally , SW21 equipped with contacts provide externa conirol functions Note that (he PFL OUtPut not routed through SW21

MLGOL INPUT_MODULE INPUT SELECTOR switch Sw1 Selects the signal source, icrophone direct, microphone via 20 dB Pad, Iine feed i.e 2 ) PHASE switch SW2 : When depressed, this switch wil reverse the polarity the output signal relative the input signal and wil operate the associated LED PUBLIC ADDRESS switch Sw3 : With switch depressed signal fed the PA output - the output PRE/POST PUBLIC ADDRESS switch SW4: Allows the choice the pick-off point for the PUBL IC ADDRESS signal _ either prior (PRE ) after (Post) the channel fader_ REV SEND switches SWS and SW6: With either Sw tch depressed the output gnal fed the appropriate RS output FOLDBACK switches Sw7 , Sw8 SW9 and SW1O: With any switch depressed, the output signal fed the appropriate FB outpyt HIGH FREQUENCY section, FREQUENCY

M46o SERIES INPUT MODULES d) the PHASE switch so that the output is again in Release phase with the input. 14 _ sensitvity control adjusted for DIR output level With the input KHz and an Attenuator setting of 15 dBm in hand, 0 dBm at response from 30 Hz to 20 KHz. Confirm that check the frequency the DIR output remains at dBm +/ - 0.25 dB _ the module input selector to the OFF posi tion and a) Switch absolute output noise level of -65 dBm confirm and or bandwidth of 20 Hz to 20 KHz .

Again this better over to an equivalent input noise of -125 dBm . corresponds DIR/FIL output on the test jig inserts 20 KHz Note: The filter and be used for this step eliminating the noise may need for an external filter 15 _ b ) sensiti- vity control for 20 dB in hand and Set the input confirm absolute output noise level of -85 dBm or better _ an sensitivity control fully CCW (30 dB in hand) the the With output noise level should be -88 dBm or better.

c) d) (cut/boost controls in the posi= tion) and Insert equalizer repeat steps a) and b) _ b ) confirm an absolute output noise level of Note: In step -80 dBm or better_ e) Switch equalizer off _ 16 . a) With the sensitivity control fully CW, increase the input level and confirm maximum DIR output capability of +30 dBm at 1KHz without clipp ing- b ) Confirm nominal supply current of 150 mA when the output is driven to signal level of +30 dBm .

17 _ a) Decrease the input level until the output level is +28 dBm. Measure the total harmonic distortion, which should be from 30 Hz to 20 KHz and less than 0.1% at KHz . 0.25% b ) equalizer and repeat step a) _ (Ensure that the Insert cut/boost controls are set to the 0 position) c) Switch the equalizer off and to 0 dBm.

return DIR output level Page of

M460 SERIES INPUT MODULES iv) With cut/boost control set at +15 dB BOOST rotate FREQ _ ADJUST control to obtain maximum output (Max_ output should occur at the position marked KHz) _ Confirm cuT/Boost range of +/- 15 dB _ With cut/boost controls set at +15 dB Boost, decr - ease the input frequency to 4.5 KHz and confirm an output level drop of dB Increase the input frequency to 7.5 KHz and confirm an output level drop of dB _ Confirm Q of using the procedure outlined in a) step viii) _ Other values of can be determined in similar manner Return HF cut/boost control to the position _ vi) vii) viii) ix) d) Switch off the equalizer (EQ LED indicator off and all cuT/Boost controls in the position) _ 12 _ a) Select the DIR output on the test jig- b ) Apply Khz, -10 dBm signal to the MIc input.

c) Depress the CH ON button (illuminated) and note that the Ch ON LED indicator on the test jig iluminates (Mic LED indicator on test jig should also iluminate) d) Rotate the input sensitivity control and the test jig Atten- uator fully CW_ e) Confirm DR output level of +15 dBm +/- dB _ f) Adjust the jig Attenuator to obtain 15 dB in hand (a direct output level of dBm should result) 13_ a) Using dual trace oscilloscope, connect one set of leads to the red input binding post and the ground post .

Connect the other set of leads to the red output binding post and its corresponding ground post _ b ) Confirm that the phase of the input signal is the same as that of the output signal c) Depress the PHASE switch and confirm that the polarity of the output is reversed relative to the input signal _ Page of

coniro| R7/8: Continuously variable from 25 400 Hz In the PEAKING mode, the frequency calibration refers the center irequency tne bell-shaped PEAKING response curve. the SHELVING mode, the calibration defines the dB corner Point from the maximum available SHELVING boOST cut dB _ 13) LOW FREQUENCY section

R9: Allows adjustment the 0-factor the PEAKING filter for va ues 10 . R9 inoperative the SHELVING mode 14) Low FREQUENCY section MODE SELECTOR switch SW12: When depressed, the LF section the equalizer operates the SHELVING mode . When released, the PEAKING mode selected. 15) EQUALIZER INSERT switch SW13: When depressed, this switch inserts the EQUAL ZER section into the signal path and activa tes the associated LED . When released, the unequalized input signal bypassed directly the 8-109A output amplifier 16 ) PAN switch SW1z: When depressed, enables PAN control (R24 R27) 17) PRE-FADE-LISTEN switch SW1s: When depressed the signal origi- nating ahead the fader and CHANNEL ON switch fed the PRE output 18) SOLO swi tch SW16: When depressed fader and CHANNEL ON swi tch fed the signal following the the SOLO output- 19) HIGH PASS FILTER control RIO/11: Allows continuous adjustment cut-off point frequencies from 250 Hz . Filier OFF with controi fully ccw (in detent position) 20) SENSiTiViTY control Ievel control range R12: Provides continuously 30 dB for al| input sources adjustable 21 ) PUBL IC ADDRESS LEVEL output bus control R13/1L: Controls level 22) REV SEND LEVEL control R15/16: Controls level output buses RSI and RS2 6-2