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.


  • 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.




  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 50WRMS power rating for your amp.


  1. Flip the STANDBY switch to the ON position first.
  2. Flip the POWER switch to the ON position. The lamp should light.
  3. As soon as the tubes warm up, you are ready to ROCK & ROLL!

NOTE: Contrary to popular wisdom, the STANDBY switch can actually do more harm than good in some cases, such as is the case in the MIG-50. To increase the reliability and longevity of your MIG-50, flip the STANDBY switch on FIRST.


INPUT I Jack – This ¼” jack is the audio input for the normal channel. The input impedance is 1MΩ.

INPUT II Jack – This ¼” jack is the audio input for the bright channel. The input impedance is 1MΩ.

VOL I Knob – Controls the overall loudness of channel I, the normal channel.

VOL II Knob – Controls the overall loudness of channel II, the bright channel.

TONE Knobs – TREBLE, MIDDLE, BASS and PRESENCE controls are used to alter the amplifier’s frequency response. Adjust to taste and experiment with different settings.

Lamp – Lights when the POWER switch is on. Replacement part: Dial Lamp #47, T3-¼, 6.3V, 0.15A, bayonet base


AC INLET – Plug the standard IEC power cable into this jack.
FUSE (MAINS) – Within the AC inlet jack is the fuse holder. To access the fuse, use a small flathead screwdriver to carefully slide the fuse holder out.

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

WARNING: The AC voltage rating is marked on the amplifier

’s chassis.Failure to use the appropriate fuse could damage the amplifier., ?s chassis.Failure to use the appropriate fuse could damage the amplifier.


FUSE (VALVE) – This 1A fast-blow 5x20mm fuse’s purpose is to protect the audio circuitry in case of overload. To access the fuse, use a small flathead screwdriver to turn the fuse holder 180°. Hold your free hand out to catch the fuse in case it falls.

LOUDSPEAKERS – These output jacks are for 4Ω, 8Ω, or 16Ω loudspeaker connections only.

WARNING: Only connect one loudspeaker output at a time. A loudspeaker must always be connected while the amp is powered up and there is signal present at the input. Failure to do so may damage your amp and void the warranty.

BIAS ADJUST – This trim pot allows you to bias your power tubes without needing to expose yourself to the dangerously high voltages contained within the amp or take your amp to a technician just to replace some tubes. See HOW TO ADJUST POWER
TUBE BIAS section below for more instructions on using this control.

FUSE (BIAS) – This 800mA fast-blow 5x20mm fuse should blow if a power tube fails. To access the fuse, use a small flathead screwdriver to turn the fuse holder 180°. Hold your free hand out to catch the fuse in case it falls.


In order to adjust the bias of your tubes, you will first need a digital multimeter capable of reading DC millivolts and a small flathead screwdriver. If you are uncomfortable with using these types of tools or do not understand what power tube bias is, please refer to a professional technician. We also encourage you to research the subject yourself as there are plenty of resources written online and books published by the likes of Randall Aiken, Rob Robinette, and Merlin Blencowe, to name only a few.

WARNINGS: 1) Power tubes get very HOT! Allow the tubes to cool for at least 5-10 minutes before trying to remove them. 2) Only use 6L6/5881 style tubes. Do not use EL34 style tubes or you will damage your tubes and the amp and void your warranty.

After installing your new 6L6/5881 style tubes…

  1. Make sure there is nothing plugged into either input on the amp. Turn all of the controls down to their minimum positions (zero). Turn the amp on by flipping the POWER switch to its ON position. Wait 30 seconds and flip the STANDBY switch to its ON position.

  2. Set your multimeter to read DC millivolts. Insert the black test probe into the negative test point marked (-). Insert the red test probe into the positive test point marked (+).

  3. Use your flathead screwdriver to turn the ADJUST trim pot while viewing the reading on your multimeter. For 6L6/5881 style tubes, set the adjustment between 58-64mV. From the factory the power tubes were biased to around the middle setting of 62mV. WARNING: Setting the bias higher than 70mV may destroy your tubes and your amp and will void your warranty.

  4. Allow the amp to warm up for at least 5-10 minutes and readjust the bias to the desired setting.

  5. Plug an instrument in and play through the MIG-50. Adjust the bias to taste, if necessary.


Please register online at or complete and return the enclosed warranty card within 10 days of purchase. Electro-Harmonix will repair or replace, at its discretion, a product that fails to operate due to defects in materials or workmanship for a period of one year from date of purchase. This applies only to original purchasers who have bought their product from an authorized Electro-Harmonix retailer. Repaired or replaced units will then be warranted for the unexpired portion of the original warranty term.
If you should need to return your unit for service within the warranty period, please contact the appropriate office listed below. Customers outside the regions listed below, please contact EHX Customer Service for information on warranty repairs at or +1-718-937-8300. USA and Canadian customers: please obtain a Return Authorization Number (RA#) from EHX Customer Service before returning your product. Include with your returned unit: a written description of the problem as well as your name, address, telephone number, e-mail address, and RA#; and a copy of your receipt clearly showing the purchase date.

United States & Canada
47-50 33RD STREET
Tel: 718-937-8300

Tel: +44 179 247 3258

ce.pngThe CE logo indicates that this product has been tested and shown to conform with all applicable European Conformity directives.
wee.pngThe WEEE or “trashcan” logo indicates that this product is made up of electronic components that should not be trashed alongside household waste but instead should be recycled by a proper electrical waste facility.
Note: This User's Manual is adapted from the official manual created by Electro-Harmonix in PDF format, without modification of the content. We just rewrite the PDF, into responsive mobile friendly pages.So, you can read this document anytime and anywhere.

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