Shure M367 User Guide

SIX CHANNEL MICROPHONE MIXER

Model M367 User Guide

DESCRIPTION

The Shure M367 is a portable, six–input, two-output (mono), battery-powered microphone and line level mixer/preamplifier. Its transformer–isolated design, low-noise performance, and compact and rugged construction make the M367 an ideal choice for studio and mobile broadcast, electronic news gathering (ENG), and electronic field production (EFP) applications.

This versatile mixer can also be used for the following:

• Digital transmission links

• Digital video/audio recording media (ISDN, hard disk recording, and DAT)

• Sound reinforcement

The M367 comes with rubber feet, detachable power cord, and spare power line fuse. It can be rack mounted using the optional Model A367R rack mount kit.

FEATURES

• Six selectable mic/line inputs

• Selectable mic/line output and dedicated line output

• Transformer-balanced inputs and outputs for sup erior

of RFI and electromagnetic hum

• Professional mechanical VU meter–LED backlighting for high

reliability, no lamp replacement

• Headphone monitoring 3.5 mm, (1/4 in.)

• Output peak limiter with switchable threshold and bi-colored

LED indicator

• Peak indicator LED, and switchable low-cut filters on each

1/4 in. return monitor input

• AC power or (2) 9V battery operation

rejection

input

ADDITIONAL FEATURES

• 48 Vdc or 12 V phantom power for condenser microphones

• 1 kHz tone oscillator

• Mutes all input channels when activated

• Tone level control is on the master

• Wide–range input gain controls handle ho t signal levels attenuators

• Customized operation via internal DIP switches, trim pots, and optional alternate wiring

• Battery check switch and low battery warning indication

• Power-on LED

• Input expansion via mix bus jack to link M367s or other mixers

• Rugged all metal chassis with protective end caps

• Detachable AC power cord

without

C8511 (Rev. 4)

Printed in U.S.A.

FRONT PANEL CONTROLS AND INDICATORS

2 3

PEAK

543

FRONT PANEL CONTROLS AND INDICATORS

FIGURE 1

1. Input Gain Control: For best performance, adjust each Input

Gain Control so the associated Input Peak LED illuminates red only on the loudest signal peaks.

2. Input Low-Cut Filter Switch: Provides low-frequency roll–off

to reduce wind noise and rumble. When using the filter, the frequency response is down 7 dB at 150 Hz. Roll-off slope is 6 dB per octave.

3. Input Peak LED: Illuminates at 6 dB below clipping.

4. Limiter Switch: Activates a fast-acting, peak-responding

limiter optimized for speech. An internal modification can provide a slower release time for music signals (see DIP Switches).

5. Output Peak/Limiter Bi-Color LED:

8 9

1kHz TONE

OFF ON

PEAK

OFF ON

-20

LIMITER

MASTER

PEAK

+12

M367

9. Power-On/Off Switch: Turns the mixer on and off.

10. Power-On LED:

Green = power on

Flashing =

low batteries (about 30 minutes of operation remaining)

11. Dual function control knob:

Headphones Gain Control: Rotate to adjust headphone level. Pull/Monitor Switch: When using headphones, pull out to listen to audio from the MONITOR IN jack. Add attenuated program signal using DIP switch 4 (see DIP Switches).

BATT

CHECK

PULL/MONITOR

POWER

PHONES

Red = output signal at +12 dBm

(6 dB below clipping)

Green = output signal at limiter threshold

(when limiter is on)

6. Output Level (VU) Meter: Meter response approximates true

VU characteristics (about 300 ms rise and fall, 1% to 5% over shoot). For a slower response, see Internal Modifiable Func-

tions. 0 VU is switchable between +4 and +8 dBm (see DIP Switches). When using batteries, use the BATT CHECK

switch to illuminate the meter.

7. 1 kHz Tone Oscillator Switch: Sends a 1 kHz tone to all out-

puts and mutes all inputs. The MASTER control adjusts tone level.

8. Battery Check Button: Press and hold to show battery level

on the VU meter. Press once to illuminate the VU meter for 10 seconds, or set DIP switch 6 to toggle the meter light (see DIP Switches).

WARNING

The headphones circuit can produce high volume levels that can damage the user’s hearing. Make sure headphone volume setting (PHONES) is low (Full CCW before putting headphones on.

12. Headphones Outputs: Stereo 1/4 in. and 3.5 mm phone

jacks.

13. Master Gain Control: Sets mixer output gain. Set to 0 dB

position for unity gain.

REAR PANEL CONNECTORS AND CONTROLS

FIGURE

1. Mic/Line Level Output Switch: Sets output to microphone or line level.

2. Phantom Power Switch: Adds 12-volt phantom power to all inputs set to MIC. Use DIP switch 7 to increase voltage to 48 volts (see DIP Switches).

3. Mic/Line Level Input Switches 1-6: Sets input to microphone or line level. Phantom power is disabled for inputs set to LINE.

4. M267/M367 Mix Bus Level Switch: Set to M267 when connecting to a SHURE M267, FP42, FP51, M67, or SE30. Use the M367 setting with another M367 or SHURE FP32A.

IMPORTANT

Unless required, leave the mix bus LEVEL switch in the M367

position. The M267 setting may increase mixer out-

t noise up to 30 dB, depending on the MASTER output

pu setting.

5. Mix Bus Jack: Allows you to connect the M367 to another mixer. The mix bus connection is "two-way" and pre-master. When two M367 mixers are connected, all 12 inputs appear at both mixers' outputs. The MASTER gain control of either M367 can be adjusted without affecting the other mixer’s output.

The output level of each M367 mixer drops by 6 dB when connected through the MIX BUS, increase the Master Gain to compensate.

For a balanced mix bus connection between two M367s, use a mix bus cable with two 1/4 in. stereo (tip, ring, sleeve) plugs. When connecting other types of Shure mixers, construct a mix bus cable with a 1/4 in. mono phone plug (tip = signal, sleeve = ground) and the appropriate connector for the other mixer's mix bus jack (see Figure 3).

NOTE

BALANCED

TO M367 #1 TO M367 #2

UNBALANCE

TO M367 TO M267

MIX BUS CONNECTIONS

FIGURE 3

6. Channel Inputs: These female XLR inputs are transformerbalanced to provide superior rejection of hum, RFI, and other interference.

7. Monitor In Jack: Accepts mono line-level signals (tip = signal, sleeve = ground) for "tape return" or a communications channel input. See Pull/Monitor switch description.

You can also modify the MONITOR IN jack to accept a stereo

input and provide a stereo sum monitor signal (see Internal Modificable Functions ).

Mixer Output:

The Line output is preset to line level, but can be modified to a true

output impedance or changed to microphone level (see Inter-

600 nal Modifiable Functions ).

9. Power Connector: See AC Operation .

10. Time Delay Fuses: The slide-out compartment contains two power line fuses. The outer (toward you) is a spare.

M367: 0.125A, 250V fuse M367E: 0.063A, 250V fuse

For continued protection against fire, replace with the same type and rating of fuse.

These male XLR outputs are transformer-balanced.

WARNING

N.C.

AC OPERATION

Limiter Threshold

= +16 dBm

= +8 dBm = +4 dBm = 0 dBm

Use the supplied power adapter to connect the M367 to a power

outlet.

M367: 100-120 VAC, 50/60 Hz M367E: 220-240 VAC, 50/60 Hz

The operating voltage can be switched internally (see Internal

Modifiable Functions).

NOTE

Appliance inlet is the main disconnect device (to power off the

M367, you must unplug the power supply).

BATTERY OPERATION

Open the battery compartment by grasping the sides of the compartment, squeezing to release the locks, and pulling the compartment outward. Insert two 9-volt batteries.

During battery operation, use the BATT CHECK button. Press and hold to show battery level on the VU meter. Press once to illuminate the VU switch for 10 seconds, or set DIP switch 6 for continuous illumination (see DIP Switches).

BATTERY LIFE

With two fresh 9-volt alkaline batteries, the M367 operates for about eight hours. Some mixer features decrease battery life, as illustrated in the following table.

SETTING LEVELS

1. Set the MASTER gain knob to the full off position.

2. Activate the 1 khz tone oscillator by setting the 1 KHZ TONE switch to ON. Adjust the MASTER gain until the VU meter needle indicates "0". Adjust the input levels on the equipment connected to the M367 outputs accordingly. Deactivate the tone by setting the 1 KHZ TONE switch to OFF.

3. Adjust the Input gain controls based on the incoming signal levels. The input PEAK LEDs should flicker red only on loud input peaks.

4. Observe the output on the VU meter and adjust the MASTER gain to obtain the desired levels. try to keep the average levels around "0 VU". The PEAK LED adjacent to the VU meter should illuminate only on loud output peaks.

DIP SWITCHES

234567

Access the DIP switches by removing the battery compartment

and top cover. Use the following table to set the switches (Bold = factory setting.)

S701

Momentary use of headphones or meter illumination will not appreciably affect battery life.

Mixer Operation Battery

No Signal 40 9

With +4 dBm continuous output 45 8

With six mics at 12 V phantom power 55 6.5

With six mics at 48 V phantom power 70 5

With output to headphones 50 7

With meter illumination continuously on 75 4.5

*until Power LED begins to flash, allowing approximately 30 minutes to replace batteries.

NOTE

Current

(mA)

Battery

Life

(hours)*

CONNECTING M367 OUTPUTS TO TELEPHONE LINES

Use the XLR outputs at line level to drive dc-biased, "dialed up" telephone lines. A slight increase in distortion may occur. Use the M367 limiter with the limiter threshold set to +4 dBm. Modify the M367 output impedance to 600 W for proper fidelity (see Internal Modifiable Functions). When connecting the M367 to a telephone line, you must use an FCC-Registered interface adapter between the mixer and telephone line.

Function Up

Switch

1 Meter 0 VU 0 VU = +4 dBm 0 VU = +8 dBm

2 Limiter

Threshold

4 Program to

Monitor

5 Monitor In

Gain

6 VU Lamp (Batt

Check button)

7 Phantom

Power

Normal High

Timed (Turns off

after 10 seconds)

12 Vdc 48 Vdc

See Figure 4

Off On (adds attenu-

Down

ated program signal

in headphones with

Pull/Monitor switch

on)

Toggled (press on,

press off)

LIMITER THRESHOLD SETTINGS

FIGURE 4

SPECIFICATIONS

Frequency Response

20 to 20,000 Hz ± 2.0 dB (channel controls centered)

Total Harmonic Distortion

0.25% THD at +4 dBm output, 55 to 20,000 Hz

Voltage Gain

Output

Actual

(Internal)

Actual

(Internal)

Mix Bus (M367)

Mix Bus

(M267)

Clipping

Level

+23 dBV

Clipping

Level

+11 dBV

Input

Low-Z Mic

W

(150

Line

Monitor

Mix Bus

(M367)

MixBus (M267)

Line Mic Phones

87 dB 40 dB 103 dB 66 dB 27 dB

)

37 dB -11 dB 53 dB 15 dB -25 dB

10 dB -38 dB 26 dB -- --

50 dB 2 dB 66 dB -- --

12 dB -- --

Inputs

IMPEDANCE Input

Input

Mic 19 to 600 W 1 kW -10 dBV

Line £10 kW 50 kW +36 dBV

Monitor £1 kW 13 kW 0 dBV

Mix Bus

(M367)

Mix Bus

(M267)

Designed for

Use With

930 W bal.;

1860 W unbal.

3.5 kW 3.5 kW -17 dBV

930 W bal.;

1860 W unbal.

Outputs

IMPEDANCE Output

Output Designed for

Use With

Mic Low-Z inputs 1 W -31 dBV

Line 600 W 150 W +18 dBm

Phones 8 to 200 W 300 W +11 dBV

Mix Bus

(M367)

Mix Bus

(M267)

930 W bal.;

1860 W unbal.

3.5 kW 3.5 kW -28 dBV

930 W bal.;

1860 W unbal.

Equivalent Input Noise

£ –127 dBV with 150 W source, 400 to 20,000 Hz

Output Noise

Master level full CCW: –100 dBV, 400 to 20,000 Hz

Master level full CW: –80 dBV, 400 to 20,000 Hz

Hum and Noise

Equivalent Input:

£125 dBV, 20 to 20,000 Hz

Output: –95 dBV (Master CCW), –75 dBV; (Master CW), 20 to

20,000 Hz

Common Mode Rejection Ratio

65 dB at 100 Hz, –20 dBV input

Polarity

Mic/Line In to Mic/Line Out Non-Inverting

Mic/Line In to Phones Non-Inverting

Mic/Line In to Mix Bus (tip) Inverting

Monitor to Phones Non-Inverting

Mix Bus to Mic/Line Out Inverting

Overload and Shorting

Shorted outputs, even for prolonged periods, cause no damage. Microphone inputs of up to 3 Vrms cause no damage. Line and monitor can withstand signals of up to 30 Vrms.

Input Peak Indicators

6 dB below clipping level

Output Peak Indicator

Lights red at 6 dB below clipping level

Output Clipping Level

£ +18 dBm at line output into 600 W

Low-Cut Filters

7 dB down at 150 Hz; 6 dB/octave slope (3 dB down at 260 Hz)

Tone Oscillator

1 kHz ± 20%

Limiter

Threshold: Switchable: 0, +4, +8, +16 dBm

Attack Time: 1 ms ± 0.5 ms Release Time Constant: 100 ms ± 30 ms Indicator: Green when limiting by 1 dB or more

Phantom Power

12 V Phantom: 12 V through 340 W 48 V Phantom : 48 V through 3.4 kW

AC Power

M367: 100–120 Vac, 50/60 Hz, 100 mA

M367E: 220–240 Vac, 50/60 Hz, 50 mA; no-signal current drain

25 mA

DC Power

18 Vdc nominal at 40 mA typical no-signal, 45 mA typical at +4

dBm output; 13.5 Vdc minimum

Batteries

Two 9 V alkaline batteries

Battery Life

Up to 8 hours* at +4 dBm output in continuous use.

*(see Battery Operation)

Temperature Range

Operating: -18° to 57° C (0° to 135° F) Storage: -29° to 74°C (-20° to 165° F)

Overall Dimensions (H x W x D)

71.9 mm x 308 mm x 233 mm (2 13/16 in. x 12

5/32 in. x 9 5/32 in.) including feet.

Weight (without batteries)

3 kg (6.6 lb)

Measurement conditions (unless otherwise specified): operating voltage 120 Vac, 60 Hz (18 ±1 Vdc for dc test); operating temperature 22°C (72°F); input signal 1 kHz; internal DIP switches 1–7 open; Power switch on; Mic/Line switches to Line; low-cut switches to flat; Limiter out; Phantom power off; Mix Bus to M367; channel 1 gain full CW; channel 2 through 6 full CCW; Master full CW; Phones level full

W

CCW; Line output terminations 600

(pins 2 and 3); Mic output ter-

minations 150 W (pins 2 and 3); Phones (1/4"–ring) 300 W to ground;

W

Phones (1/4"–tip) 300

Bus 930

(M367 position) or 3.5 kW (M267 position), not connected

to ground; Phones (3.5 mm) unloaded; Mix

unless specified; 1 kHz input signal.

REPLACEMENT PARTS

Foot Kit (4 in kit)........................................................... 90S8100

M367 Fuse, 0.125 A, 250 V ........................................... 80E380

M367E Fuse, 0.063 A, 250 V .........................................80G380

Knob

Master .......................................................................... 95A8238

Channel Gain, Phones................................................. 95B8238

Line (Power) Cord

M367 ............................................................................ 95A8389

M367E.......................................................................... 95B8389

OPTIONAL ACCESSORIES

Rack Mount Kit.................................................................A367R

STATEMENT OF CONFORMITY

This certifies that the Shure M367E Microphone Mixer meets the specifications and regulations embodied in Vfg 243/1991, amended 1992. The Bundesamt für Zulassungen in der Telekom munikation has been notified that this device has been marketed and has been provided the right to verify the device or system for compliance with the specifications. Conforms to European Union directives, eligible to bear CE mark ing; VDE GS-Certified to EN 60 950; meets European Union EMC Immunity Requirements (EN 50 082-1, 1992): RF radiated (IEC 801-3): meets Criterion A, ESD: meets Criterion B, EFT (IEC 801-

4): meets Criterion B.

GENERAL INFORMATION

Changes or modifications not expressly approved by Shure, Inc. could void your authority to operate this equipment. This equipment has been tested and found to comply with the limits for a Class B digital device pursuant to Part 15 of the FCC Rules and as set out in the Radio Interference Regulations of the Canadian Department of Communications. These limits are designed to provide reasonable protection against harmful interference in a residential installation. This equipment generates, uses, and can radiate radio frequency energy and, if not installed and used in accordance with the instructions, may cause harmful interference to radio communications. However, there is no guarantee that interference will not occur in a particular installation. If this equipment causes harmful interference to radio or television reception, determined by turning the equipment off and on, try to correct the interference by one or more of the following measures:

1. Reorient or relocate the receiving antenna.

2. Increase the separation between the equipment and receiver.

3. Connect the equipment into an outlet on a circuit different from

that to which the receiver is connected.

4. Consult the dealer or an experienced radio/TV technician for

help.

INTERNAL ADJUSTMENTS

NOTE

Only qualified service technicians should perform these

modifications.

These internal adjustments require only removal of the top

cover:

1. Remove battery compartment.

2. Remove four screws securing two plastic end caps and one ground-bonding screw on the side opposite the battery compart ment.

3. Slowly slide cover up and off chassis.

VCA DISTORTION TRIMPOT (R607)

DO NOT ADJUST! This potentiometer is precisely calibrated on

each mixer for minimum distortion.

VU METER ADJUSTMENT (R684)

This trimpot adjusts the VU meter to indicate 0 VU at a preset output level. The factory setting is +4 dBm. The user adjustment range is -10 dBV to +4 dBm (-6 dBV to +8 dBm with DIP switch 1 down).

To set the VU meter to a value other than the factory setting (0 VU = +4 dBm), proceed as follows:

1. Connect a 600 W load to an XLR output set for Line.

2. Connect an ac voltmeter with 1 MW or greater input

impedance (Fluke 77 or equivalent) in parallel with the load.

3. Set the 1 kHz tone oscillator switch to the ON position.

4. Adjust the 1 kHz tone oscillator level with the Master gain

con-

trol until the ac voltmeter reading is at the level desired

5. With the M367 top cover removed, adjust the VU Level Calibration trim pot R684 with a screwdriver until the VU Meter reads 0.

6. For 0 VU settings between +4 and +8 dBm, set internal DIP switch S701 position 1 "down", and perform steps 1 through 5.

VU METER

CALIBRATION

TRIMPOT

R684

(ACCESSED

THROUGH

HOLE IN

UPPER FRONT

PC BOARD)

DIP SWITCH

INTERNAL ADJUSTMENTS

FIGURE 5

VCA

DISTORTION

TRIMPOT

R607

S701

INTERNAL MODIFIABLE FUNCTIONS

NOTE

Only qualified service technicians should perform these

modifications.

Perform all modifications through solder points accessible on

the main PC board.

DISASSEMBLING THE M367

1. Remove the mixer top cover as previously described.

2. Carefully remove three multi-pin cable assembly connectors from upper front PC board (nearest front panel). Remove the three Phillips head screws securing the PC board. Remove up per front PC board.

3. Carefully remove four multi-pin cable assembly connectors from upper rear PC board (nearest rear panel). Remove the three Phillips head screws securing the PC board. Remove upper rear PC board.

4. Perform modification (refer to appropriate following procedure). Note that all modifications can be performed without removing the main PC board.

5. Reassemble M367 by performing above steps in reverse, assembling the Phillips screws in the order indicated on the upper front and upper rear PC boards.

CHANGING LINE LEVEL OUTPUT IMPEDANCE TO 600 W

Locate resistor R621 (near IC U602 pin 8) on the main PC board and remove it. Locate empty pads X621 (near resistor R621). Solder a 430 W, 1/2 W resistor through the holes at X621.

CHANGING UNSWITCHED LINE OUTPUT TO MIC LEVEL

Locate resistor R632 (near output transformer T601) and remove. Locate empty pads X632 (near transformer T601). Solder a jumper wire through the holes of X632.

CHANGING MIXER AUDIO LEVELS IN HEADPHONES (Pull/Monitor Switch Activated, DIP Switch S701 Position 4 Closed)

Locate empty pads X649 (near Phones potentiometer R648). Solder a 68 kW, 1/4 W resistor through the holes at X649 to hear program audio 12 dB down from standard headphones level with Pull/ Monitor switch on (pulled out). Solder a 24 kW, 1/4 W resistor through the holes at X649 to hear program audio 6 dB from standard headphones level with Pull/Monitor switch on (pulled out).

CHANGING LOW-CUT FILTER CORNER FREQUENCY (3 DB DOWN POINT)

To decrease corner frequency:

1. Calculate new capacitor value for lower low-cut corner

frequency. Use the following formula:

C in mF= (85/frequency) - 0.33

Example: for 200 Hz corner frequency,

85/200 9 0.43

0.43 - 0.33 = 0.1

For 200 Hz corner frequency, use a 0.1 mF capacitor.

Pad Channel Pad Channel

X421 1 X451 4

X431 2 X521 5

X441 3 X531 6

2. Locate the following empty pads: Find all pads near ribbon cable assemblies W811, W812 and

W813.

3. Solder a new capacitor through the holes of the empty pads

for each channel to be modified.

To increase corner frequency:

Note: Low-cut corner frequencies much higher than the factory

preset of 260 Hz may excessively attenuate desired low- to mid-frequency program material.

1. Locate the following capacitors near empty pads:

Capacitor

C425

C435

C445

X421 1 C455 X451 4

X431 2 C525 X521 5

X441 3 C535 X531 6

Pad

Channel

Capacitor Pad

Channel

2. Remove the indicated capacitor for each channel to be

modified.

3. Calculate new capacitor value for higher high-cut corner fre

quency. Use the following formula:

C in mF= (85/frequency)

Example: for 400 Hz corner frequency,

C = (85/400) = 0.21

For 400 Hz corner frequency, use a 0.22 mF capacitor.

4. Solder a new capacitor through the holes of the empty pads

for each channel to be modified.

SLOWING OUTPUT METER FROM "True VU" BALLISTICS

Locate empty pads X691 (at left of VU meter M1). Solder a 100

mF x 6.3 V electrolytic capacitor through the holes of X691. Observe capacitor polarity as marked on the PC board. The response time is now 500 ms with no overshoot. To further slow the meter response, use a larger capacitor value.

CHANGING MIC LEVEL OUTPUT IMPEDANCE

Locate resistor R631 (near output transformer T601) and

remove it. Locate empty pads X631 (near T601). Solder desired value 1/4 W resistor through the holes of X631. For example, use a 150 W, 1/4 W resistor for 150 W output impedance.

Capacitor must be non-polarized; ceramic or film type;

NOTE:

16V rating or higher.

ADAPTING LINE OUT TO DUAL BANANA JACK

TIP

RING

SLEEVE

Add a dual banana jack, balanced, line-level output capability by purchasing a commercial unit (Sescom XLR F-3BP or equivalent), or obtaining a female XLR connector (Radio Shack 274-011 or equivalent), a dual banana jack (ITT 2269 or equivalent), a small utility box, and a short length of high-quality shielded output cable and constructing the adapter shown in Figure 6.

CHANGING MONITOR IN HIGH GAIN (DIP Switch S701 Position 5 Down)

Locate resistor R647 (near Phones potentiometer R648) and remove it. Locate empty pads X647 (near R647). Solder a 330 W,1/4 W resistor in the holes of X647 for 6 dB gain boost with DIP switch S701

position 5 down (input impedance equals 6.5 k

in this position).

CHANGING MONITOR IN JACK FROM MONO INPUT TO STEREO SUM INPUT

Locate empty pads X645 (near Monitor In jack J863). Solder a 1 kW, 1%, 1/4 W resistor in the holes of X645. The Monitor In jack will now accept a stereo input signal (tip left, ring right, sleeve ground), and sum these signals to the monitor circuit.

231

DUAL BANANA JACK OUTPUT

FIGURE 6

Connect this adapter to the M367 Line output.

CHANGING MONITOR IN TO AUX IN

NOTE:

This modification disables the M367's monitor function.

Remove resistors R642 and R647 (near Phones potentiometer

R648).

Locate empty pads X601 (near output transformer T601) and

X643 (near Monitor In jack J683).

Solder a jumper wire from X643 to X601. The Monitor In jack is now an unbalanced (tip positive, sleeve ground) Aux In jack, with an input impedance of 11 kW and a maximum gain to Line Out (loaded with 600 W) of 17 dB. The Aux In signal is only controlled by the Master control.

To change Aux In gain, locate resistor R605 (near X601). Care fully remove R605 and replace it with a surface-mount resistor (0805 package) of the desired value. If replacing R605 with 15 kW, maximum Aux In to Line Out gain equals 14 dB and input impedance equals 16 kW; if replaced with 6.8 kW, maximum Aux In to Line Out gain equals 20 dB and input impedance equals 7.8 kW.

If using a true stereo feed to drive the M367 Monitor In and another stereo device, the source impedance must be 20 W or less to maintain at least 40 dB separation in the stereo device. Use a stereo distribution amplifier or buffer to maintain optimum stereo separation.

NOTE

MASTER GAIN REMOTE CONTROL

This modification disables both the M367's monitor function and

its front-panel Master gain control.

NOTE

1. Remove resistor R641 (near Monitor In jack J863).

2. Remove resistor R746 (near Master potentiometer R706).

3. Locate empty pad X702 (near Master potentiometer R706). Solder one end of a 100 W, 1/4 W resistor in the hole of X702. Solder an insulated wire to the other end of the 100 W resistor. Locate empty pad X644 (near jack J863). Solder the other end of the insulated wire to X644.

4. Locate empty pad X701 (next to empty pad X702). Solder an insulated wire to X701. Locate empty pads X645 (near jack J863). Solder the other end of the insulated wire to the empty pad X645 nearest channel 6 input connector J856.

5. Construct a remote control potentiometer/cable assembly as shown in Figure 7.

MASTER GAIN REMOTE CONTROL

FIGURE 7

Recommended parts are:

Potentiometer, 10-25 kW, linear taper (Radio Shack 271-1715) 1/4 in. Stereo Phone Plug (Switchcraft 280) Ferrite Bead Rings (Ferronics 21-031J) Capacitors, ceramic, 0.001 mF, 50 V Cable, 2-conductor, shielded, 50 ft maximum (15 m) Ferrite bead rings and capacitors should be as close to the phone plug as possible.

6. Insert the phone plug in the Monitor In jack. The remote control potentiometer now controls M367 gain with a control taper similar to that of the Master gain control.

CHANGING LIMITER RELEASE TIME TO ONE SECOND

R6 =

–

= 49.4 k:

150,000

52,30018,000

105,000

Remove resistor R741 (about 15 mm behind ribbon cable

assembly W813).

CHANGING LIMITER THRESHOLD PRESETS

1. Select the equivalent resistor values for the desired limiter thresholds from the following table. Then fill in the following work sheet with the resistor selections.

Limiter Threshold

(dBm into 600 W)

0181081

1211193

2 25 12 105

3 30 13 122

4 35 14 139

5 41 15 156

6 47 16 175

7 54 17 194

8 62 18 215

971

(kW)

equiv

Limiter Threshold (

dBm into 600 W)

(kW)

equiv

6. Calculate resistor R6 value as follows:

Select a 1/4 W, 1% resistor closest in value to R6 and solder it to the holes of X734.

7. Calculate resistor R7 value as follows:

R7 =

–

Select a 1/4 W, 1% resistor closest in value to R7 and solder it to the holes of X735. (See Changing Limiter Threshold Presets: Samples Calculations later in the Appendix for an example of limiter threshold preset component calculations.)

CHANGING LIMITER THRESHOLD PRESETS: SAMPLES CALCULATIONS

For the following limiter thresholds:

DIP Switch S701 Limiter Threshold R

Position 2Position

–

dBm

equiv

–

(above)

DIP Switch S701 Limiter Threshold

Position 2 Position 3

up up high _____ kW = R1

down up med. high _____ kW = R2

up down med. low _____ kW = R3

down down low _____ kW = R4

–

dBm

equiv

–

2. Remove resistors R721, R731, R732, R733, R734 and R735 (surrounding IC U704).

3. Locate empty pads X732, X733, X734 and X735 (surrounding IC U704).

4. Select a 1/4 W, 1% resistor closest in value to R1 (from the work sheet), and solder it to the holes of X732.

Note: Use parallel or series combinations of resistors to match the chosen values as closely as possible if 1% resistors are not available.

5. Calculate resistor R5 value as follows:

R5 =

–

Select a 1/4 W, 1% resistor closest in value to R5 and solder it to the holes of X733.

up up high 12 105

kW=R1

down up med. high 8

up down med. low 4

down down low 0

62 kW=R2

35 kW=R3

18 kW=R4

1. Obtain a 105 kW, 1/4 W, 1% resistor and solder it to the holes of X732.

2. Obtain a 150 kW, 1/4 W, 1% resistor and solder it to the holes of X733.

62,000

105,000

= 151.4 k:

3. Obtain a 52.3 kW, 1/4 W, 1% resistor and solder it to the holes of X734.

35,000

4. Obtain a 49.9 kW, 1/4 W, 1% resistor and solder it to the holes of X735.

105,000

= 52.5 k:

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