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 50WRMS power rating for your amp.

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 50WRMS power rating for your amp.

HOW TO POWER YOUR MIG-50 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.
FRONT PANEL
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, T-
3-¼, 6.3V, 0.15A, bayonet base
REAR PANEL
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.
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.
HOW TO ADJUST POWER TUBE BIAS
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 (+).

HOW TO POWER YOUR MIG-50 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.
FRONT PANEL
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, T-
3-¼, 6.3V, 0.15A, bayonet base
REAR PANEL
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.
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.
HOW TO ADJUST POWER TUBE BIAS
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.
WARRANTY INFORMATION
Please register online at http://www.ehx.com/product-registration 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
[email protected] or [phone]. 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, RA# and a copy of
your receipt clearly showing the purchase date.
United States & Canada Europe
EHX CUSTOMER SERVICE JOHN WILLIAMS
ELECTRO-HARMONIX ELECTRO-HARMONIX UK
c/o NEW SENSOR CORP. 13 CWMDONKIN TERRACE
47-50 33RD STREET SWANSEA SA2 0RQ
LONG ISLAND CITY, NY 11101 UNITED KINGDOM
Tel: [phone] Tel: [phone]
Email: [e-mail] Email: [e-mail]
The CE logo indicates that this product has been tested and shown to
conform with all applicable European Conformity directives.
The 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.

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.
WARRANTY INFORMATION
Please register online at http://www.ehx.com/product-registration 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
[email protected] or [phone]. 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, RA# and a copy of
your receipt clearly showing the purchase date.
United States & Canada Europe
EHX CUSTOMER SERVICE JOHN WILLIAMS
ELECTRO-HARMONIX ELECTRO-HARMONIX UK
c/o NEW SENSOR CORP. 13 CWMDONKIN TERRACE
47-50 33RD STREET SWANSEA SA2 0RQ
LONG ISLAND CITY, NY 11101 UNITED KINGDOM
Tel: [phone] Tel: [phone]
Email: [e-mail] Email: [e-mail]
The CE logo indicates that this product has been tested and shown to
conform with all applicable European Conformity directives.
The 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.