Figure 2-2a. PM4000 Stereo Input Module (upper portion of module)

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input is available at odd-numbered busses, and the right input at even numbered busses (and, of course, L&R in are available to the L&R stereo bus). In L position, the right input is deactivated, and the left input connector is available to all group busses and the L&R sides of the stereo bus. Similarly, in R position, the right input is available to the various busses. In L+R position, the left and right inputs are combined to mono, and this mono mix is then available to the various bus outputs. (Actually, this switch also affects the signal available to the cue and aux busses, too.) The LED in the BAL/PAN switch is engaged when the balance or pan function is active. When the switch is up, the rotary control has no effect, and a 3 dB pad is placed in line to all bus outputs. For a stereo pair, 3 dB of padding is the equivalent to placing a pan control at mid position, and thus assures that the total power available from a pair of outputs is equal to the power that would be available if all the signal were panned to one output were. It means there will be no sudden change in level if, with the pan pot centered, you engage or disengage the BAL/ PAN switch. 3. ST (Stereo) This locking switch assigns the channel output directly to the stereo bus. An LED in the switch turns on when the signal is assigned to the stereo bus. The left and right inputs will be routed to the corresponding left and right sides of the stereo bus only if the adjacent, rotary signal selector switch [2S] is set to the ST position.

4. +48V

NOTE: The consoles microphone power supply is not intended for A-B powered microphones. External supplies may be used with these devices, in which case the consoles phantom power should be turned OFF on the appropriate channels. The optional input transformers, if installed, do not affect phantom power operation. 5S. GAIN This pair of concentric rotary knobs provides 50 dB of continuously variable adjustment for the left and right input preamplifier gain. A setting of -70 (full clockwise rotation) provides maximum gain for low-level mic inputs, whereas a setting of -20 provides minimum gain for low-level line inputs or hot mics. These settings provide 30 dB less overall gain when 30 dB pad is engaged [6]. The two controls are clutched so that you can adjust gain simultaneously for both inputs, but you can also reduce the gain of the left input relative to the right if you need to compensate for inputs which vary in level. In an emergency where you run short of conventional singlechannel inputs, you can use this split gain control to accommodate two different sources, one miclevel (right side) and one line-level (left side). Use care, however, to avoid crosstalk if you split an input module in this manner. 6. 30 dB (pad switch) Engaging this pushbutton switch attenuates the left and right input signals 30 dB and turns on an LED in the switch. The PAD should be used in conjunction with the GAIN controls to obtain the precise channel sensitivity necessary for a given source. If youre not sure whether an input is high line level or mic level, begin with the pad engaged, and the GAIN controls at -20 (+10) position. Then rotate the GAIN controls clockwise. If you still dont get enough level, or if the signal is noisy with a lot of gain, then turn down the GAIN, disengage the pad and reset the GAIN controls as necessary. NOTE: By adjusting the GAIN controls, you may be able to get the same overall level with or without the pad engaged. Listen for noise and distortion, though; if the signal is noisy, dont use the pad. If there is a lot of distortion, use the pad. 7S. L-PEAK-R This pair red LED turn on to indicate when the signal present after the corresponding left and right preamps is too high in level. The LEDs trigger 3 dB below clipping, and should therefore flash on only occasionally.

Figure 2-2b. PM4000 Stereo Input Module (middle portion of module) NOTE: A signal processor (effects device) can be set up before it is needed, its levels adjusted using the always active INSERT OUT signal, and then the processor can be inserted on cue in the channels signal path by pressing this switch. 17. AUX 1 - 8 (Send level & Pre/Off/Post switches) There are 8 rotary AUX send level controls with concentric PRE/OFF/POST switches. The switch mutes (turns off) the send, or derives signal before (PRE) or after (POST) the channel fader and equalizer. The inner rotary control determines how much of the selected signal source is applied to the correspondingly numbered auxil-

Page 2-10

iary mixing bus. When the switch is in the center (OFF) position, no signal is applied to the auxiliary bus. NOTE: When the input signal select switch [2S] is set to stereo mode, then the left input signal can be assigned to odd-numbered aux busses, and the right input to even numbered busses. With a mono signal-select setting, the same mono signal is available to all aux busses. NOTE: In some applications, it is preferable to have the PRE position be Pre-Fader & Post-EQ rather than PreFader & Pre EQ. The PM4000 is equipped with internal switches that make it easy to change the Pre of each AUX send in this manner. This functional modification can be performed on a channel-by-channel basis, and for any or all AUX sends within each channel. Refer to the OPTIONAL FUNCTIONS section of this manual for additional information. NOTE: All eight aux sends perform identical functions, as shipped. Color coding helps associate the channel send controls with the Aux Master LEVEL controls. If you reset the "Pre" function for the sends of some busses, or on some channels, it is a good idea to attach a note to the console indicating how you have set it up. 18S. AUX ST 1 These are two pair of concentric level controls and switches. Depending on how you set the outer switch on the right-hand control, they can function as either an independent pair of Aux sends, similar to the eight individual AUX sends, or they can function as a single stereo Aux send with level and balance controls. The outer PRE/OFF/POST stitch on the lefthand control set determines whether the send is off, derives signal before the fader and equalizer, of after them (just as with the individual aux sends). This function affects both sides of the AUX ST 1 output, whether used for stereo or dual mono sends. The outer switch on the right-hand control set determines whether AUX ST 1 functions as a stereo send (switch set to the left BAL PAN position) or as a pair of mono sends (switch set to the right LEVEL LLEVEL R position). When the send is set for stereo mode, the inner rotary control on the left determines the overall LEVEL applied to the Stereo 1 L & R auxiliary mixing buses, and the inner rotary control on the right serves to either PAN a mono signal between the L & R sides of that stereo pair (if the input signal selector is in one of the mono modes) or to BALance a stereo signal across the L & R, sides of the pair.

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2.1.3 The Master Module (1 - 8) These eight modules are identical, except that each controls a differently-numbered set of Group Master, VCA Master and Matrix Output channels. MATRIX SECTION 28. SUB IN This rotary control adjusts the level of the signal from the MTRX SUB IN connector applied to the modules MTRX OUT. MTRX SUB IN 1 is applied only to MTRX OUT 1, MTRX SUB IN 2 to MTRX OUT 2, and so forth. 29. LR (Matrix mix level controls) These 2 rotary controls adjust the level of signal from the left and right sides of the stereo mixing bus applied to the modules MTRX OUT. Signal is available for this mix only if there something has been assigned to the stereo bus, either directly from the input modules ST switches [3], or indirectly via the GROUP TO ST switches [40]. 30. (Matrix mix level controls) These 8 rotary controls adjust the level of signal from the correspondingly numbered group mixing busses applied to the modules MTRX OUT. There will only be signal available, however, if the correspondingly numbered master modules GROUP TO MTRX switch [41] is engaged. The signal applied to the matrix mix is nominally derived post-group master fader, but an internal jumper switch in each master module permits this to be changed to a pre-group master fader signal. 31. MTRX MASTER The Matrix Mix level controls [29, 30] permit a mono mix to be derived from the eight group busses and the stereo bus, while the SUB IN control adds an additional signal to the mix. The MTRX MASTER control then sets the overall level of this 11-source mix just before it is routed to the matrix output connector. 32. INSERT (Matrix insert) The matrix circuit has an insert Out/In patch point located just before its master level control. The OUT jack is always active. If this switch is engaged (LED illuminated), the IN jack becomes active. Thus, engaging the INSERT switch can insert a signal processor in the matrix channel, or it can substitute an external line-level input instead of the mixed matrix signal.
Figure 2-3a. PM4000 Master Module (matrix section of module)

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33. CUE (Matrix cue) Pressing this switch part-way down causes momentary contact; pressing it further locks it down. When the CUE switch is illuminated, the modules matrix mix signal (post insert point, pre MTRX MASTER) replaces any other signal in the Cue output and the Phones output unless an input CUE switch is engaged. (Bus cue signals are overriden by input cue.) The MTRX CUE signal is Mono, regardless of how many matrix channels are cued. 34. ON (Matrix On) This locking, illuminated switch turns on when the MTRX OUT is ON. When the MTRX OUT is turned OFF, its signal may still be previewed with the adjacent CUE switch [33]. AUX SEND MASTER SECTION 35. LEVEL (Aux send level) This rotary control adjusts the overall level from the correspondingly numbered auxiliary mixing bus to the AUX OUT connector. 36. INSERT (Aux insert) The aux send master circuit has an insert Out/In patch point located just before its master level control. The OUT jack is always active. If this switch is engaged (LED illuminated), the IN jack becomes active. Thus, engaging the INSERT switch can insert a signal processor in the aux channel, or it can substitute an external line-level input instead of the mixed aux signal. 37. CUE (Aux send cue) Pressing this switch part-way down causes momentary contact; pressing it further locks it down. When the CUE switch is illuminated, the correspondingly numbered auxiliary send replaces any master cue signal in the Cue output and the Phones output unless an input CUE switch is engaged. (Bus cue signals are overriden by input cue.) The aux cue signal is mono, regardless of how many aux sends are cued. 38. ON (Aux On) This locking, illuminated switch turns on when the AUX OUT is on. When the AUX OUT is turned off, the feed to the VU meter is also off, although the signal may still be previewed with the adjacent CUE switch [36].

Figure 2-5a. PM4000 TB Module (upper portion of module)
59. (TB/OSC To Group Bus Assign) These locking switches assign the Talkback or Oscillator signal to group mixing busses 1 through 8. An LED in each switch turns on when the signal is assigned to the bus.

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oscillator when it is not actually in use. NOTE: Even though the oscillator may not be assigned to any busses, it is still possible that you would inadvertently select it when preparing to use the talkback feature, or that some signal could leak into busses (albeit at low levels). Hence, leave the oscillator OFF when it is not actually being used for testing or calibration. 67. PINK 10K 1K 100 OFF These 5 interlocking switches set the oscillator to 100 Hz, 1 kHz or 10 kHz operation when the nearby SWEEP switch is in fixed frequency position (disengaged). They also permit selection of a pink noise source, or turn off the oscillator/ noise source altogether. 68. SWEEP (switch and rotary control) Engaging the SWEEP switch removes the oscillator from its fixed frequency mode (i.e., generating exactly 100 Hz, 1 kHz or 10 kHz). The nearby rotary control then may be used to adjust the oscillator output from approximately 0.2 to 2 times the set fixed frequency. For example, when the oscillator is set for 10K Hz (switch [67]), the sweep mode enables you to adjust the actual oscillator frequency between 2 kHz and 20 kHz. 69. LEVEL OSC This rotary control adjusts the oscillator output level applied to the OSC OUT connector as well as any mixing busses to which the signal may be assigned. This control does not affect the Talkback level. 70. +48V This switch turns phantom power on and off in the XLR Talkback Input connector. Power can be turned on, however, only if the MASTER PHANTOM POWER switch is on. An LED in the switch turns on when phantom power is being applied to the TB input. When both the Master and this switch are on, +48 volts is applied to both pins 2 & 3 of the TB input XLR connector for powering a condenser microphone. Although phantom power will not harm most dynamic and other non-phantom powered microphones or line-level devices, connection of an unbalanced, source to the channel input could partially short the consoles phantom supply, cause undue loading, and induce hum. Therefore, it is a good practice to turn off the TB phantom power unless it is actually in use. NOTE: The consoles microphone power supply is not intended for A-B powered microphones. Use an external

139. MONITOR OUTPUT B (L, R) This pair of XLR connectors output the Monitor B selected signal. The MONITOR B OUT will be muted when the Talkback function is activated, but are unaffected by the CUE function. These connectors are useful for driving studio or stage monitor amps and speakers, or a headphone distribution system (with external power amp). 140. DC POWER INPUT This multi-pin, locking connector accepts a special umbilical cable from the consoles external power supply (Model PW4000). The cable should be carefully mated, making sure the locking ring is securely hand tightened to avoid inadvertent disconnection.
Figure 2-15. PM4000 Rear Panel: DC Power Input Connector (see Fig 2-17 for Pin ID)

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2.4 The PW4000 Power Supply
Figure 2-16. PW4000 Power Supply (Front and Rear Panels) 141. POWER This alternate-action switch turns on the AC input to the supply, and thereby provides the necessary output voltages to the console via the umbilical power cable. Pressing the switch a second time turns off the power. 142. Operation Monitor This panel of LEDs indicates when power is present at the various power supply outputs, as well as other aspects of the power supplys operation. A row of NORMAL LEDs is illuminated when +48V, +12V, +19V, and -19V outputs are operating. Below that is a corresponding row of UNUSUAL LEDs, one or more of which illuminates if the output is not within normal tolerance. There is also a green POWER indicator that is illuminated when power is turned on, a red THERMAL indicator that is illuminated when the power supply has overheated (and automatically shut down), and a digital indicator that displays the AC line voltage input to the power supply. 143. (Grille) The power supply is cooled by a pair of quiet running fans that pull air through front-panel grilles and exhaust it through vents at the back. A reticulated foam element behind each grille filters the air entering the power supply. NOTE: Filter elements are cleanable. Refer to Section 9.

Channel High Pass Filter Oscillator/Noise Generator CH Preamp & EQ Peak Indicators Channel LED Meter
12 dB/octave Switchable sine wave @ 100 Hz, 1 kHz, 10 kHz or pink noise Red LED 6 LEDs

Page 3-1

VU Meters (0 VU = +4 dBu output) 24 or 32 channel consoles
2 large meters 12 small meters
40 or 48 channel consoles

16 small meters

VU Meter Peak Indicators Phantom Power

LED (red) +48 V dc

Dimensions (W x H x D)

Weight

48 Channel 40 Channel 32 Channel 24 Channel 48 Channel 40 Channel 32 Channel 24 Channel
2086 x 346 x 1121 mm 1846 x 346 x 1121 mm 1586 x 346 x 1121 mm 1346 x 346 x 1121 mm 183 kg 161 kg 137 kg 115 kg
Illuminated meters: STEREO L, R Illuminated meters, all switchable: #1 - #4; GROUP (1 - 4) / MTRX (1 - 4) / AUX (1 - 4) #5 - #8; GROUP (5 - 8) / MTRX (5 - 8) / AUX (5 - 8) #9; AUX ST1 L / MONITOR A L (pre-MONITOR control) #10; AUX ST1 R / MONITOR A R (pre-MONITOR control) #11; AUX ST 2 L / TB #12; AUX ST 2 R / OSC Illuminated meters, all switchable: #1 - #8; GROUP (1 - 8) / MTRX (1- 8) / AUX (1- 8) #9; GROUP 1 / MTRX 1 / AUX ST1 L #10; GROUP 2 / MTRX 2 / AUX ST1 R #11; GROUP 3 / MTRX 3 / AUX ST2L #12; GROUP 4 / MTRX 4 / AUX ST2R #13; GROUP 5 / MTRX 5 / MONITOR A L (pre) #14; GROUP 6 / MTRX 6 / MONITOR A R (pre) #15; GROUP 7 / MTRX 7 / TB #16; GROUP 8 / MTRX 8 / OSC Built into each VU meter, the LED turns on when the pre-line amp level reaches 3 dB below clipping Available at balanced inputs (via 6.6 current limiting/isolation resistors) for powering condenser microphones; may be turned ON or OFF via rear-panel Phantom Master switch. When Master is ON, individual channels may be turned OFF or ON via +48V switches on the mono input, stereo input and talkback modules 82-1/8 x 13-5/8 x 44-1/8 inches 72-11/16 x 13-5/8 x 44-1/8 inches 62-7/16 x 13-5/8 x 44-1/8 inches 53 x 13-5/8 x 44-1/8 inches 403 Ibs. 7 oz 354 Ibs. 14 oz 301 Ibs. 15 oz 253 Ibs. 7 oz
PW4000 Power Supply Specifications
Power Requirements Japan 100 V, 50/60 Hz 48 Channel 40 Channel 32 Channel 24 Channel 1500 VA 1100 W 1000 W 900 W 800 W 1250W 1250W
CSA/UL General DC Output Voltages
120 V, 60 Hz 230/240 V, 50/60 Hz
Fuses Dimensions Weight (W x H x D)
Main (x3) Sub (x1) 480.0 x 186.0 x 460.6 mm 36 kg
19V 13A +12V 8A +48V 0.7 A 250 V 6A 250 V 2A 18.8 x 7.3 x 18.1 inches 79.4 pounds

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INPUT CHARACTERlSTlCS
Connection CH IN ST CH IN 1 ~ [ch (*1) 1 ~ 4ch PAD Gain Trim -70 -20 Actual load Impedance 3 For use with Nominal Sensitivity (*4) 50 ~ 600 -90 dB (0.025 mV) -60 dB (0.775 mV) mics -40 dB (7.75 mV) and 600 lines -10 dB (245 mV) Input level (*3) Nominal -70 dB (0.25 mV) -40 dB (7.75 mV) -20 dB (77.5 mV) +10 dB (2.45 V) Max before Clip -48 dB 3.09 mV) -18 dB (97.6 mV) +2 dB (0.976 V) +32 dB (30.9 V) Connector In Mixer (*2) XLR-3-31 type

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Figure 4-3. Schematic of an Outlet With a Lifted Neutral If the PW4000 is plugged into one socket of the two outlets with lifted neutral, and a rack of signal processing equipment or power amplifiers is plugged into the other, fuses would probably blow upon turning on the system, and some of the sound equipment could be destroyed. Figure 4-2. Testing a 2-wire AC Outlet and a 3-Prong to 2-Prong Adaptor If you detect any voltage between the larger slot (white wire) in an outlet and the ground-terminal (round prong, green wire) when there is no load on that line, you should contact a licensed electrician to check it out and correct the situation.
4.2.4 Improperly Wired AC Outlets: Lifted Grounds
A "lifted ground" condition exists if the ground or green wire from the outlets safety ground is disconnected or missing. In older wiring, the heavy green wire was sometimes omitted from internal wall wiring in favor of letting the metal flex conduit or pipe suffice as the ground path from the electrical service entrance. This method of grounding is generally acceptable, as long as the metal conduit in the wall is intact and all the screws holding the joints together are secure. However, a single loose screw in a conduit joint inside a wall can remove the safety ground from the next outlet box in the line, and from all the subsequent boxes on that same line.
WARNING: In AC power wiring, black is hot, and white is neutral-the opposite of most audio signal wiring and speaker wiring. It is safer to consider all AC wiring as potentially lethal. It is possible someone miswired the system, or that a short circuit has developed. Test the voltages yourself, and be safe. Although the white wires (neutral) and the green wires (ground) in the AC wiring are technically at the same potential (voltage), and should measure the same potential using a voltmeter, the ground prong connections at the outlets should be connected to the grounding bar that was driven into the earth as an additional safety precaution in case something should happen to the wires running from the service entrance transformer to the building or within the equipment itself. If a short should occur within the equipment, hopefully the electricity will find its
4.2.5 Improperly Wired AC Outlets: Lifted Neutral
If the neutral becomes lifted at a power outlet, it is possible that items plugged into the outlet will be fed the full 220 to 240 volts available from the power service instead of the desired 110 to 120 volts. Such outlets may operate, but the voltage can swing from 0 volts to 220 or 240 volts AC (or whatever the maximum voltage at the service entrance), creating a shock hazard and possibly damaging your equipment.

experienced audio engineers. Sometimes, in poorly designed sound equipment (which sometimes includes expensive sound equipment), ground loops occur inside the chassis even though the equipment has balanced inputs and outputs. In this instance, little can be done to get rid of the hum short of having a skilled audio engineer redesign the ground wiring inside. Its better to avoid this kind of equipment. It is also best to avoid unbalanced equipment in professional sound systems (unless the equipment is all going to be very close together, connected to the same leg of the AC service, and not subject to high hum fields). If all connections are balanced and the equipment is properly designed and constructed, such ground loops will not induce noise. Unfortunately, much of the socalled professional sound equipment sold today is not properly grounded internally, so system-created ground loops can create very real problems. Figure 4-5 shows a typical ground loop situation. Two interconnected pieces of equipment are plugged into grounded AC outlets at separate locations, and signal ground is connected to earth in each of them. The earth ground path and duplicate signal ground path form a loop which can pick up interference. Normally, this kind of ground loop should not cause any noise in the audio circuits if (a) the circuits are truly balanced or floating, and (b) the audio common is maintained separately from the chassis ground within the equip-

4.3.2 Ground Loops

AC line-frequency hum is, without question, the single most common problem in sound systems, and the most common cause of hum is ground loops. A ground loop occurs when there is more than one ground connection path between two pieces of equipment. The duplicate ground paths form the equivalent of a loop antenna which very efficiently picks up interference currents, which are transformed by lead resistance into voltage fluctuations. As a consequence, the reference in the system is no longer a stable potential, so signals ride on the interference. Ground loops often are difficult to isolate, even for

input to the equalizer should now be -2 dBu (616 mV), which can be checked with a voltmeter. 5. Assume that the maximum rated output level of the equalizer in this example is +18 dBu (6.16 volts). Adjust the master level control on the equalizer so that its output level is 20 dB below the rated maximum, or -2 dBu (616 mV). If the equalizer has no built-in VU meter, use an external voltmeter to confirm this level. NOTE: If the graphic equalizer is placed in the consoles group or stereo INSERT IN/OUT loop, the nominal sensitivity of the input is +4 dBu, which may seem to be 6 dB less sensitive than required for the necessary headroom. However, any boost applied with the EQ will raise the nominal level of the signal at the EQ output, so this may help preserve adequate headroom in the console. Remember, though, that applying boost with an equalizer can reduce headroom within the EQ itself, so you may want to turn down the EQs output level to preserve the headroom. 6. Finally, starting with the attenuator(s) on the power amplifier at maximum attenuation (maximum counterclockwise rotation), slowly decrease the attenuation (raise the level), observing the amplifiers output level. When the POWER output is 1/100 of the maximum rated power (1/10 of the maximum output voltage), the amplifier has 20 dB headroom left before clipping. A 250 watt amplifier would operate at nominal 2.5 watts, or a 100 watt amplifier at 1 watt, on average level passages in order to allow 20 dB for the loud peaks. To operate this system, use only the controls on the console, and avoid levels that consistently peak the consoles VU meter above the zero mark on its scale, or that drive the amplifier above a safe power level for the speaker system. Any level adjustments in the other devices in the system will upset this established gain structure. If, for a given amount of headroom, portions of the program appear to be lost in the noise, the answer is not to turn up the levels since that will merely lead to clipping and distortion. Instead, it will be necessary to use either a compressor, or to manually ride the gain of those console faders that are required to raise the level when the signals are weak. This effectively reduces the required headroom of the signal, allowing the lower level portions of the program to be raised in level without exceeding the maximum level capability of the system. Compressors can be used in the INSERT IN/ OUT loops of individual channels (say for a vocalist with widely varying levels), or at the group, aux or stereo master INSERT IN/OUT points or after the Matrix Outputs when the overall mix has too much

Page 5-5

dynamic range. Of course, another alternative is available: add more amplifiers and speakers so that the desired headroom can be obtained while raising the average power level.

Figure 7-3. Front Panel View and Block Diagram of PM4000 Mix Matrix Page 7-8

7.2.4.1

The Mix Matrix In General Sound Reinforcement
Instead of feeding the house sound system directly from the Group outputs [130], or the Stereo output [133], the sound system can be fed from the Matrix outputs [131]. The Group busses and Stereo bus would then be used for mixing sub-groups of different sources; i.e., brass, drum/percussion, lead vocals, backup vocals, rhythm guitars & bass, lead guitar, keyboards (in stereo), and so forth. The Group Master Faders and Stereo Fader would control the overall level of each subgroup of input channels. The matrix channels can be used to create four stereo or eight mono mixes from those groups. The mix matrix outputs then feed the power amps and speakers for various zones in the main house, as well as other areas (dressing rooms, lobby, remote feeds, etc.) The advantages to this approach are numerous. For example, if the brass level is too high in all outputs, only one Group Master Fader need be adjusted (for the brass subgroup). On the other hand, if there is too much vocal near the front of the audience (due to spill from the vocal stage monitors), you can adjust the one matrix mix level control, corresponding to the vocal Group, in the matrix channel that feeds the near-stage house speakers. Similarly, if your system is designed with larger speakers near the front of the house, having better low frequency output than the rear fill speakers, then those speakers should be fed the bass-heavy instruments. By adjusting the matrix mix level controls for the drum/percussion and bass guitar Groups so that more of these subgroups goes to the matrix outputs that feed the near-stage speakers, and less to the rear fill speakers, the overall sound quality in the house will be improved. For program fades, you have a choice: you can use the Group Master Faders, in which case the previously established balance for each zone of the sound system reappears as soon as these Faders are returned to their correct settings. Or you can use the MTRX MASTER controls, in which case the previously established program (group) balance remains, but youll have to recreate the zone-to-zone balance when you bring up the MTRX MASTER controls. Of course, you can always use the Group ON/off switches [45] or Matrix ON/off switches [34] to mute the output to the speaker system, thereby eliminating any uncertainty in re-establishing program levels. If the PM4000 internal slide switches are reset so that the Group-to-Matrix and Stereo-to-Matrix feeds are derived pre-fader (as described in Sections 6.12 and 6.13), then the Group and Stereo Master Faders will not

7.2.4.3

Other Uses For The Matrix Sub Inputs
If a stereo or 4-track recording is to be played during intermission, or even as an adjunct to the live program, it is not necessary to use up input channels or effects return inputs for the tape. Instead, the tape recorder outputs can be connected to the MTRX SUB IN, mixed

Page 7-9

into the corresponding matrix channels, and fed to the house sound system which is driven by the matrix outputs. A related use for the MTRX SUB IN connectors is to inject a test signal for speaker setup and testing. While the PM4000 test oscillator can be assigned to the Group or Stereo busses, which, in turn, feed the matrix, it is likely that the Group and Stereo Master Faders will not be set at nominal levels for the show. Assuming the speaker system is fed from the matrix outputs, and assuming the sound check is already completed and the Group and Stereo Masters are set at the desired levels, one would not want to reset those Masters just to run a test signal to the speakers. Instead, you can run a patch cable from the OSC OUT connector [135] to one MTRX SUB IN connector [110], set the MTRX SUB IN control [28] at nominal (#10), adjust the MTRX MASTER control [31] as required, and check the speaker system. You can then re-patch the OSC OUT cable to the next MTRX SUB IN, and test the next channel of power amps and speakers, until all amplifier/speaker circuits have been tested. This is one way to get pink noise into the system for spectrum analysis and graphic EQ adjustment. If you need one more group beyond the eight Groups and the Stereo bus, you can use one or two of the Aux Send busses for that group. You can then connect a patch cable from the corresponding AUX SEND OUT connector(s) to the MTRX SUB IN connector(s), using a Y or splitter if necessary to feed more than one matrix channel from a single Aux bus. These AUX SEND Master controls then serve as group masters. A more expensive, but more elegant approach to using Y cables is to use an external distribution amplifier (D.A.) which provides separate, buffered outputs from a single input. The D.A. outputs could then be connected to the various MTRX SUB INS.
into two MTRX MASTER controlled outputs that are ideally suited to the first scene. You can use the next two mix matrix channels to create a differently balanced mix for the next scene, and so forth. The only trick, if you think about it, is that each pair of matrix outputs must still feed the same pair of power amplifier and speaker channels. This may not be a problem if you have time to move the two output cables from one pair of matrix outputs to the next in between scenes. Alternately, you could use an external mixer (such as a Yamaha M206) to mix the several matrix outputs together for feeding the amplifier. a more expensive approach, but easier to implement.

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With eight auxiliary sends, and four aux returns, its easy to utilize the most sophisticated effects. The aux returns, which can each be used for a mono or stereo source, have two-band, sweep-frequency equalization. If even more returns are needed, input channels may be used (they each have four-band parametric equalization with plenty of overlap between bands). Built-in talkback capability make it easier for the producer or director to speak with crew or talent.
stage; an extensive input-priority in place cue system, plus a solo mode that mutes other channels for faster setup and faster troubleshooting during sound checks.

8.2 Setup Concepts

8.2.1 Deriving A Stereo Mix From Groups 1-8.
There are a number of ways to obtain a stereo mix with this console. One technique is to utilize Groups 1-8 for subgrouping input channels. The post Group Master Fader [49] signals then can be assigned to the stereo mixing bus using the GROUP-TO-ST switches [40] and the Group PAN controls [39]. The Stereo Master Faders [58] then become the overall stereo output control for the mixed groups. In this setup, the input channel direct-to-STereo assign switches [3] would not normally be utilized, except on those input channels which may be used for effects returns (in lieu of the aux returns). This is a very straightforward means of achieving a stereo mix (or dual mono output mixes) with subgroup control, and without using the mix matrix or VCA system.
8.1.5 Sound Reinforcement
The PM4000s electronically balanced inputs are of the highest quality [and input transformers can be installed internally where the extra isolation is required ??]. Input channel sensitivity is now broadly adjustable from -90 dBu to +4 dBu by means of a 30 dB attenuation pad plus a Gain trim control with 50 dB range, so fader mix settings can uniformly aligned for faster visual confirmation of the nominal position; theres plenty of gain when its needed, and noise is minimized when the extra gain is not needed. Four band parametric equalization, plus a sweep-frequency high pass filter, facilitate broad tonal adjustments or pinpoint corrections. Eight group busses can be used to sub-mix various vocal and/or instrumental sections, and these can be remixed to mono or stereo for the house feed by means of either the stereo bus, or the 11x8 Mix Matrix. If the Mix Matrix is used to feed the house, then the stereo bus can perform as two additional group busses. With another eight auxiliary busses, each switchable for pre or post input fader pick-off, there is no shortage of effects sends or foldback (monitor) sends. The consoles standard configuration provides at least four stereo input modules, any or all of which can be used for auxiliary returns (internal jumpers can be adjusted to prevent potential feedback from inadvertent output-toinput assignment looping). Eight VCA Masters provide another means to deal with groups of inputs; use the conventional groups where it is necessary to insert a signal processor in the group signal path, or use the VCAs where it is necessary to affect all the outputs from a given input channel. Scene changes can be handled with the VCA groups, or with the eight Master Mute groups, that, with the press of a Master Mute switch, turn on or off assigned groups of input channels. The PM4000 has other useful features for sound reinforcement, such as: numerous LEDs to display switch status and signal levels with far more reliability than conventional lamps; an all aluminum chassis with aircraft-style ribs and braces that affords low weight and high strength; a low profile that blocks fewer seats in the house while providing a good sight line to the