Electro-Harmonix MIG-50 - User Manual

MIG-50
50W All Tube Guitar Amplifier
Congratulations on your purchase of the Electro-Harmonix MIG-50, an all tube, two
channel, 50W guitar amplifier head. The EHX MIG-50 is a faithful reissue of the
Sovtek MIG-50 with modern enhancements to both the electronics and mechnical
design. The MIG-50 comes installed with three 12AX7 preamp tubes and two 5881
power tubes.
IMPORTANT SAFETY INSTRUCTIONS
 Read these instructions.
 Keep these instructions.
 Heed all warnings.
 Follow all instructions.
 Clean only with a dry cloth.
 Do not block any ventilation openings.
 Do not install near any heat sources such as radiators, heat registers, stoves, or
other apparatus (including amplifiers) that produce heat.
 Do not defeat the safety purpose of the polarized or grounding-type plug. A
polarized plug has two blades with one wider than the other. A grounding-type
plug has two blades and a third grounding prong. The wide blade or the third
prong are provided for your safety. If the provided plug does not fit into your
outlet consult an electrician for replacement of the obsolete outlet.
 Protect the power cord from being walked on or pinched.
 Unplug this amplifier during lightning storms or when unused for long periods of
time.
 WARNING: To reduce the risk of fire or electric shock, do not expose this
apparatus to rain or moisture.
 Do not expose this apparatus to dripping or splashing and ensure that no object
filled with liquids is placed on the equipment.
 Maintain at least six inches of unobstructed air space behind the unit to allow for
proper ventilation and cooling. Air must be capable of freely moving around the
amplifier.
 This amplifier is capable of producing very high sound pressure levels which may
cause temporary or permanent hearing damage. Use care when adjusting volume
levels during use.
 Do not turn the amplifier on without a loudspeaker.
 Refer all servicing and maintenance to qualified service personnel including
replacement of fuses and vacuum tubes. Changes and modifications not expressly
approved by EHX can void the warranty.
 DO NOT attempt to remove the amplifier chassis. There are no serviceable parts.
 DO NOT use this apparatus near water.
 Servicing is required when the apparatus has been damaged in any way, such as
power-supply cord or plug is damaged, liquid has been spilled or objects have
fallen into the apparatus, the apparatus has been exposed to rain or moisture,
does not operate normally, or has been dropped.
 The ventilation should not be impeded by covering the ventilation openings with
items, such as newspapers, tablecloths, curtains, etc.
 No naked flame sources, such as lighted candles, should be placed on the
apparatus.
 Apparatus is not for use in tropical climates.
 Only use attachments/accessories specified by the manufacturer.
 The appliance coupler shall remain readily operable.

The lightning flash with arrowhead symbol within an equilateral triangle, is intended to alert the
user to the presence of uninsulated “dangerous voltage” within the product’s enclosure that
may be of sufficient magnitude to constitute a risk of electric shock to persons.
The exclamation point within an equilateral triangle is intended to alert the user to the presence
of important operation and maintenance (servicing) instructions in the literature accompanying
the product.
GETTING STARTED
BEFORE PLUGGING POWER INTO YOUR MIG-50 AMP MAKE SURE:
1. Both the POWER and STANDBY toggle switches are off, set to their DOWN
position.
2. The AC voltage marked on the rear panel matches the wall voltage for your
region or the AC voltage powering your amp.
3. The LOUDSPEAKERS output on the rear panel should be connected via a properly
rated speaker cable to a speaker cabinet with the correct impedance (a 16Ω
cabinet to the 16Ω jack or an 8Ω cabinet to the 8Ω jack, etc.). WARNING: Only
connect one speaker output at a time! Running the amp into a speaker cabinet
with mismatched impedances or with no cabinet at all could severely damage the
MIG-50 and void your warranty. Be sure to select a cabinet that can handle the
full rated 50W
RMS
power rating for your amp.

Summary

Important Safety Instructions

Getting Started

Front Panel Controls and Inputs

Input I Jack

1/4" audio input for the normal channel with 1MΩ impedance.

Input II Jack

1/4" audio input for the bright channel with 1MΩ impedance.

Volume I Knob

Controls the overall loudness of channel I (normal channel).

Volume II Knob

Controls the overall loudness of channel II (bright channel).

Tone Knobs

Adjusts frequency response (Treble, Middle, Bass, Presence).

Power Indicator Lamp

Lights when the POWER switch is on; uses Dial Lamp #47.

Rear Panel Connections and Fuses

AC Inlet

Standard IEC power cable connection point.

Main Fuse Holder

Contains the main fuse for the amplifier's power supply.

Valve Fuse Holder

Contains a fuse protecting the audio circuitry in case of overload.

Loudspeaker Outputs

Output jacks for 4Ω, 8Ω, or 16Ω loudspeaker connections.

Bias Adjust Trim Pot

Allows adjustment of power tube bias without exposing user to high voltages.

Bias Fuse Holder

Contains a fuse that blows if a power tube fails.

How to Adjust Power Tube Bias

Warranty Information

Product Registration and Service

Details on registering the product and procedures for warranty service.

Contact Information

Contact details for EHX Customer Service in the US, Canada, and Europe.

Overview

1. Function Description
2. Important Technical Specifications
3. Usage Features
4. Maintenance Features

The Electro-Harmonix MIG-50 is a 50W all-tube guitar amplifier head, designed as a faithful reissue of the Sovtek MIG-50, incorporating modern enhancements to both its electronic and mechanical design. It comes equipped with three 12AX7 preamp tubes and two 5881 power tubes.

Function Description:

The MIG-50 serves as a powerful and versatile amplifier for guitarists, offering two distinct channels: a normal channel and a bright channel. Each channel has its own volume control (VOL I for normal, VOL II for bright), allowing for independent level adjustments. The amplifier also features a comprehensive tone stack with TREBLE, MIDDLE, BASS, and PRESENCE controls, enabling users to sculpt the amplifier's frequency response to their desired taste. The MIG-50 is designed to deliver high sound pressure levels suitable for various musical applications.

Important Technical Specifications:

• Power Output: 50W RMS
• Tube Complement: Three 12AX7 preamp tubes, two 5881 power tubes
• Input Impedance: 1MΩ for both INPUT I (normal channel) and INPUT II (bright channel)
• Speaker Outputs: 4Ω, 8Ω, or 16Ω loudspeaker connections (only one output should be connected at a time)
• Mains Fuses:
  • 100VAC (Japan): 3A / 250V slow-blow 5x20mm fuse
  • 117VAC (US/Canada): 3A / 250V slow-blow 5x20mm fuse
  • 230VAC (EU/Australia): 1.6A / 250V slow-blow 5x20mm fuse
• Valve Fuse: 1A fast-blow 5x20mm fuse (protects audio circuitry)
• Bias Fuse: 800mA fast-blow 5x20mm fuse (blows if a power tube fails)
• Dial Lamp: #47, T-3-4, 6.3V, 0.15A, bayonet base
• Recommended Power Tubes: 6L6/5881 style tubes (EL34 style tubes are not compatible and will damage the amp)
• Bias Adjustment Range (for 6L6/5881): 58-64mV (setting higher than 70mV may damage tubes and amp)

Usage Features:

• Two Channels: Offers both a normal and a bright channel for diverse tonal options.
• Independent Volume Controls: VOL I and VOL II knobs allow for separate volume adjustments for each channel.
• Comprehensive Tone Controls: TREBLE, MIDDLE, BASS, and PRESENCE knobs provide extensive frequency shaping capabilities.
• Power-Up Procedure: To power on, first flip the STANDBY switch to ON, then the POWER switch to ON. The lamp will light, indicating power. The STANDBY switch should be flipped on FIRST to increase reliability and longevity.
• Speaker Connection: Connect a properly rated speaker cable from the LOUDSPEAKERS output to a speaker cabinet with the correct impedance (e.g., 16Ω cabinet to 16Ω jack). Only one speaker output should be connected at a time. Running the amp without a cabinet or with mismatched impedances can severely damage the amplifier and void the warranty. Ensure the cabinet can handle the full 50W RMS power rating.
• Input Jacks: INPUT I (1/4" jack) for the normal channel, INPUT II (1/4" jack) for the bright channel.
• AC Inlet: Standard IEC power cable connection.

Maintenance Features:

• Fuse Access:
  • Mains Fuse: Located within the AC inlet jack. Use a small flathead screwdriver to slide the fuse holder out.
  • Valve Fuse: Access by turning the fuse holder 180° with a small flathead screwdriver.
  • Bias Fuse: Access by turning the fuse holder 180° with a small flathead screwdriver.
• Power Tube Bias Adjustment:
  • Requires a digital multimeter capable of reading DC millivolts and a small flathead screwdriver.
  • Ensure no instrument is plugged in, and all controls are at minimum.
  • Power on the amp (STANDBY first, then POWER).
  • Set multimeter to DC millivolts. Insert black probe into negative test point (-) and red probe into positive test point (+).
  • Turn the ADJUST trim pot with a flathead screwdriver to set the bias between 58-64mV for 6L6/5881 tubes.
  • Allow the amp to warm up for 5-10 minutes and readjust if necessary.
  • Only use 6L6/5881 style tubes; EL34 tubes will cause damage and void the warranty.
  • Power tubes get very hot; allow 5-10 minutes to cool before removal.
• Cleaning: Clean only with a dry cloth.
• Ventilation: Maintain at least six inches of unobstructed air space behind the unit for proper ventilation and cooling. Do not block ventilation openings with items like newspapers or curtains.
• Servicing: Refer all servicing and maintenance (including fuse and vacuum tube replacement) to qualified service personnel. Do not attempt to remove the amplifier chassis as there are no user-serviceable parts inside. Unauthorized changes or modifications will void the warranty.
• Warranty: Register online at http://www.ehx.com/product-registration. The warranty covers defects in materials or workmanship for one year from the date of purchase for original purchasers from authorized retailers. For service, obtain a Return Authorization Number (RA#) from EHX Customer Service and include a written description of the problem, contact information, RA#, and a copy of the receipt.

Electro-Harmonix MIG-50 Specifications

General

Brand	Electro-Harmonix
Model	MIG-50
Category	Musical Instrument Amplifier
Language	English