Peavey Mark III Series Musician Operating Guide

General Description

The Peavey Mark III Musician represents the fourth generation of a highly popular series, combining extensive manufacturing and playing experience into a completely redesigned electronics chassis and package. Significant engineering effort was dedicated to details ensuring an effective instrument amplifier capable of producing the dynamics, harmonics, and tonal textures vital in contemporary music.

The preamp and equalization circuitry are key features. The Musician preamp includes Peavey's exclusive pre and post gain controls for total control over dynamics and gain per input preamplifier. The pre gain acts as the primary gain control, while the post gain functions as an individual "master control" for each channel, particularly useful in AUTOMIX mode. This design addresses the demand for high-output pickups requiring maximum performance from the amplifier's signal processing.

The unit features a new series of color-coded knobs for improved function identification and "touch indexing." It utilizes the latest BI-FET and CMOS devices for signal processing, enabling versatility previously found only in sophisticated recording studios.

The AUTOMIX function is simplified with LED indicators and active CMOS analog switches. Channels A and B are voiced differently: Channel A features active equalization, while Channel B uses passive equalization. Each channel has an equalizer assign switch for routing through or bypassing the six-band graphic equalizer, offering significant tonal variation when switching channels, especially with AUTOMIX.

The new phasor circuit employs advanced engineering techniques to overcome issues with older FET-based designs, offering a versatile phasing effect and timing oscillator. The reverberation unit uses a fully complementary circuit, driving the reverb coil in the feedback loop for maximized performance of the Hammond Type IV delay line.

A comprehensive patching facility is included, capable of driving any known power amplifier or line-level effects device. The patch panel offers stereo capability with separate outputs for Channels A and B, plus a compensated line output that closely matches the amplifier's speaker sound for direct patching into mixers. Each output can drive 600-Ohm loads to over 2-Volt levels.

The power output section uses eight high-voltage, ultra-fast output devices mounted on a large aluminum heatsink. It includes a built-in matching transformer for optimum performance with 8- or 4-Ohm loads and can drive loads as low as 2 Ohms. A reduced damping factor provides tube-type overload qualities and tonal color.

The Mark III Musician is presented as a sophisticated musical instrument amplifier, representing a significant advancement in technology. Experimentation with its features is encouraged to discover its advantages.

Visual Description: The document displays an image of the Peavey Mark III Musician amplifier. It is a rack-mountable unit with a black chassis, featuring a prominent Peavey logo, numerous knobs, input/output jacks, and indicator lights on the front panel. The amplifier is shown with a black road case or cabinet.

Front Panel Controls

The front panel of the Peavey Mark III Musician amplifier features a comprehensive array of controls for sound shaping and operation. A diagram on page 2 illustrates the layout of these controls, which are numbered for reference.

Input Jacks

• Input Jacks 1 & 2 (Numbered 1 & 2): Provide both high gain (1) and low gain (-6 dB) inputs to accommodate varying instrument signal levels. Using both inputs simultaneously with two instruments automatically gain-balances them.

AUTOMIX System

• AUTOMIX Jack (Numbered 3): A special switching jack with a double detent. Proper insertion of an instrument plug (all the way, to the second click) activates the AUTOMIX circuitry, indicated by illuminated LED active channel indicators. This system allows the use of both channels simultaneously or alternately via a remote footswitch.
• Pre Gain Controls (Numbered 4): Determine the input preamp gain, affecting sensitivity rather than power output. Settings interact with post gain controls and input signal amplitude.

Channel A Equalization

• Low Active EQ Control (Numbered 5): An active shelving control for boosting or cutting low frequencies. Vertical position is flat; counterclockwise cuts, clockwise boosts. Caution against overboosting to avoid excessive power draw and potential overdrive.
• High Active EQ Control (Numbered 6): An active shelving control for boosting or cutting high frequencies. Similar operation to the low EQ control. Avoid extreme high-frequency boosts to prevent residual noise, strident sound, and emphasis of string noises.

Channel B Equalization

• Low EQ Control (Numbered 7): Controls low-frequency emphasis, offering substantial effect compared to passive networks. High settings can result in a "bassy" sound.
• Middle EQ Control (Numbered 8): Tailors mid-range frequencies, allowing significant changes to Channel B's voicing due to its advanced circuit design.
• High EQ Control (Numbered 9): Controls high-end boost, offering dramatic effect. Overboosting highs is generally not recommended due to potential strident sound and noise emphasis.

Master Controls & Effects

• Post Gain Controls (Numbered 10): Act as master volume controls for each channel. Low settings may require high pre-gain settings, potentially reducing dynamic range. For clean response, maximize dynamic range by using lower pre-gain and full post-gain settings.
• Phasor Color Control (Numbered 11): Adjusts the amount of internal feedback for the phasing effect. Subtle changes occur in counterclockwise positions; deep phasing effects are achieved clockwise. Extreme clockwise settings introduce regeneration, most noticeable in the last quarter turn.
• Phasor Rate Control (Numbered 12): Controls the speed of the built-in phase oscillator, offering a wide range from very slow to extremely rapid. Features an integral switch that cuts off the phase circuit when in the full counterclockwise position, overriding the footswitch. It is recommended to cut off the phasor when not in use to avoid modulating residual noise.
• Reverb Control (Numbered 13): Controls the amount of gain in the reverb return amplifier. The reverb system works on both channels, with the return signal amplified and remixed with clear signals. Strong drive system allows adequate reverb at low settings.

Patching and Assignment

• Graphic EQ Assign Switch (Numbered 14): Allows "pre-programming" to route either or both channels through or bypass the graphic equalizer, enhancing tonal variation, especially with AUTOMIX.
• Graphic Equalizer (Numbered 15): A six-band active EQ circuit with carefully selected frequency points and precise bandwidth (Q). Offers a 30 dB range (±15 dB boost/cut) per band. Caution is advised against overboosting frequency extremes when using the graphic EQ in conjunction with channel EQ.
• Channel A Out/In Jacks (Numbered 16): Stereo jacks for patching effects units "in line" or for stereo operation. Tip provides channel output, ring provides return input.
• Channel B Out/In Jacks (Numbered 17): Similar to Channel A Out/In jacks.
• Preamp Out (Numbered 18): Provides a straight preamp signal (sum of both channels plus reverb) at approximately 2 Volts RMS with a low impedance (600 Ohms) output. This output can be used for patching accessories "in line" with the amplifier's signal path.
• Line Out (Numbered 19): A compensated line output designed to match the amplifier's speaker system's frequency response rolloff, reducing the need for direct boxes. It includes a rolloff of extreme low frequencies to prevent console overload. Output level is 2 Volts RMS, unbalanced, 600 Ohms.
• Power Amp In (Numbered 20): Input for connecting auxiliary units directly to the power amplifier section.

Indicators and Connectors

• Pilot LED (Numbered 21): Indicates when the electrical supply is switched on and delivering power.
• AUTOMIX Remote Switch Socket (Numbered 22): A standard DIN type socket for connecting the supplied remote footswitch. Proper alignment of the plug is necessary to prevent damage.

Visual Description: The front panel diagram on page 2 shows a layout with numbered circles and rectangles corresponding to the controls. Inputs are on the left, followed by EQ and gain controls, effects controls, graphic EQ, and output/patching jacks on the right. Indicator LEDs and the remote switch socket are also visible.

Rear Panel Features

• Fuse (Numbered 23): Located in the fuseholder cap. Must be replaced with the correct type and value to prevent equipment damage and warranty voiding. Repeated fuse blowing indicates a need for service.
• Power Switch (Numbered 24): A three-position switch (OFF, ON, ON) for domestic units. One ON position is used for proper grounding, yielding the lowest residual hum or popping. Export models may have a simpler on/off switch.
• Line Cord (Numbered 25): A three-wire (mains) cable with proper grounding facilities for safety. The ground pin should not be removed. Grounding adaptors may be used if necessary, but proper grounding is recommended for reduced shock hazard and noise.
• Speaker Outputs (Numbered 26): Standard 1½" phone jacks providing both 8-Ohm and 4-Ohm taps from the output transformer. Deliberate impedance mismatching and damping factor reduction contribute to tube-like overload characteristics. Operating into loads higher than 8 Ohms may result in less power. Operating into lower impedances (e.g., 8-Ohm tap into 4 Ohms) is acceptable if proper ventilation is provided.
• Line Cord Retainer (Numbered 27): Two large molded retainers on the rear panel for storing the mains cable during travel. The cable should be completely unwrapped during operation for maximum heat dissipation from the rear panel/heatsink.

Important Warning: Under no conditions should the back-mounted heatsink or the cooling grille on top of the amp be blocked off or obstructed during operation. Operating below 4 Ohms on an 8-Ohm tap or below 2 Ohms on a 4-Ohm tap will activate the internal voltage/current limiting circuit and the automatic thermal protective circuitry, which is self-resetting.

Specifications

• Output Power: 210 watts RMS @ 1% THD into 4 ohms; 300 watts RMS @ 1% THD into 2 ohms.
• Sensitivity: 15 mV @ 1 KHz (Tone Controls Flat, Volume 12:00).
• Input Impedance: 220 K ohms.
• Signal-to-Noise Ratio: 70 dB (50 K ohms source impedance).

Specifications are subject to change without notice due to ongoing improvement efforts.

Safety and Operation Notes

WARNING: To prevent electrical shock or fire hazard, do not expose this appliance to rain or moisture.

Hearing Protection

Exposure to extremely high noise levels can cause permanent hearing loss. The susceptibility varies, but prolonged exposure to sufficiently intense noise will cause hearing loss. The U.S. Government's Occupational Safety and Health Administration (OSHA) has specified permissible noise level exposures based on duration. Exceeding these limits may result in hearing loss. It is recommended that persons operating this amplification system wear earplugs or protectors to prevent hearing loss when exposure exceeds specified limits.

Operational Cautions

CAUTION: This amplifier is designed with adequate power reserve for modern music, which may require occasional peak power. Extended operation at absolute maximum power levels is not recommended as it could damage the associated loudspeaker system. Maximum power can be obtained with very low gain settings if the input signal is very strong.

General Safety Precautions

• Read all safety and operating instructions before use and retain them for future reference.
• Obey all cautions on the unit and in the instructions.
• Do not use the product near water (e.g., bathtub, sink, swimming pool, wet basement).
• Locate the product to ensure proper ventilation; do not place it flat against a wall or in a built-in enclosure that impedes airflow.
• Keep the product away from heat sources like stoves, heaters, radiators, or other heat-producing amplifiers.
• Connect the product only to a power supply of the type marked on the unit or as specified in the manual.
• Never break off the ground pin on the power supply cord.
• Handle power supply cords carefully; do not walk on them or place equipment on them. Periodically check cords for damage.
• Unplug the power supply cord when the unit is unused for long periods.
• Metal parts can be cleaned with a damp rag. Vinyl covering can be cleaned with a damp rag or an ammonia-based household cleaner if necessary.
• Take care to prevent objects from falling into the unit or liquids from spilling through ventilation holes or openings.
• Have the unit checked by a qualified service technician if the power supply cord or plug is damaged, something has fallen or spilled into the unit, the unit does not operate correctly, or the unit has been dropped or the enclosure damaged.
• Do not attempt to service the equipment yourself; all service should be performed by a qualified technician.

Block Diagram Description

Page 6 includes a block diagram illustrating the internal signal flow of the Musician amplifier. Key components shown include input stages, preamplifiers (Pre Gain), equalization circuits (EQ), AUTOMIX circuitry, graphic equalizer (Graphic EQ), effects units (Phasor, Rev. Drive, Rev. Return), line amplifier (Line Amp), preamp output, power amplifier input, and the output transformer with speaker outputs (4 Ohm, 8 Ohm). The diagram shows how signals are processed through various stages, including routing options via the AUTOMIX and EQ assign switches.

Company Information: © 1980 Peavey Electronics Corporation. Printed in U.S.A. 80344001. Peavey Electronics Corporation, 711 A St., Meridian, MS 39301.