# Vacuum Tube - 5881 / 6L6WGC, Sovtek

The 5881 is a very reliable tube that is widely used in many current production tube amplifiers. It has a warm tone with good 'bite.' This modern version is able to tolerate higher voltages than its 5881 / 6L6 cousins. The Sovtek 5881 delivers a warm, round tone that "sweetens" any vintage or modern guitar amp design. Built to rigid military standards, the 5881 will tolerate higher voltages than any other 6L6. In fact, they're frequently used as replacements for the old 7027 model in vintage Ampegs. Extremely consistent from piece to piece. The Sovtek 5881 has a heater voltage of 6.3 volts at 0.88 amperes. Maximum plate voltage is 250 volts while maximum plate current is 73 mA. The 5881 has a Transconductance rating of 6000 micromhos and a maximum output power of 5.8 watts.

### Accessory Items:

Single or Matched | Our Part Number | UPC/EAN |
---|---|---|

Apex Matched Pair | T-5881-SOVT-MP | 609722124010 |

Apex Matched Quad | T-5881-SOVT-MQ | 609722124027 |

Single | T-5881-SOVT | 683274021294 |

Capacitance, Cathode to Heater | 11 pF | |

Capacitance, Transfer | 1.0 pF | |

Capacitance, input | 11 pF | |

Capacitance, output | 6.7 pF | |

Cathode to Heater Insulation Resistance | 4 MΩ | |

Filament Current (I_{f}) | 840 - 920 mA | |

Grid 1 Insulation Resistance | 200 MΩ | |

Grid 1 Inverse Current | 0.5 mA | |

Grid 2 Current | 6 mA | |

Height, base to top | 3.25 in. | |

Internal Resistance (R_{i}) | 18 kΩ - 75 kΩ | |

Non-linear Harmonic Distortion | 15 % | |

Output Power (P_{Out}) | 5.8 W | |

Plate Current (I_{a}) | 60 mA - 86 mA | |

Readiness Time | 50 s | |

Transconductance (S) | 5.2 mA/V - 6.8 mA/V |

Packaging Dimensions | Apex Matched Pair version | T-5881-SOVT-MP | 5.1 in. × 3.5 in. × 1.8 in. |

Apex Matched Quad version | T-5881-SOVT-MQ | 5.1 in. × 3.5 in. × 3.5 in. | |

Single version | T-5881-SOVT | 1.5 in. × 1.5 in. × 4 in. | |

Weight (Packaging) | Apex Matched Pair version | T-5881-SOVT-MP | 0.294 lbs. |

Apex Matched Quad version | T-5881-SOVT-MQ | 0.588 lbs. | |

Single version | T-5881-SOVT | 0.147 lbs. |

T-5881-SOVT-MP - Apex Matched Pair version | Capacitance, Cathode to Heater | 11 pF |

Capacitance, Transfer | 1.0 pF | |

Capacitance, input | 11 pF | |

Capacitance, output | 6.7 pF | |

Cathode to Heater Insulation Resistance | 4 MΩ | |

Filament Current (I_{f}) | 840 - 920 mA | |

Grid 1 Insulation Resistance | 200 MΩ | |

Grid 1 Inverse Current | 0.5 mA | |

Grid 2 Current | 6 mA | |

Height, base to top | 3.25 in. | |

Internal Resistance (R_{i}) | 18 kΩ - 75 kΩ | |

Non-linear Harmonic Distortion | 15 % | |

Output Power (P_{Out}) | 5.8 W | |

Plate Current (I_{a}) | 60 mA - 86 mA | |

Readiness Time | 50 s | |

Transconductance (S) | 5.2 mA/V - 6.8 mA/V | |

T-5881-SOVT-MQ - Apex Matched Quad version | Capacitance, Cathode to Heater | 11 pF |

Capacitance, Transfer | 1.0 pF | |

Capacitance, input | 11 pF | |

Capacitance, output | 6.7 pF | |

Cathode to Heater Insulation Resistance | 4 MΩ | |

Filament Current (I_{f}) | 840 - 920 mA | |

Grid 1 Insulation Resistance | 200 MΩ | |

Grid 1 Inverse Current | 0.5 mA | |

Grid 2 Current | 6 mA | |

Height, base to top | 3.25 in. | |

Internal Resistance (R_{i}) | 18 kΩ - 75 kΩ | |

Non-linear Harmonic Distortion | 15 % | |

Output Power (P_{Out}) | 5.8 W | |

Plate Current (I_{a}) | 60 mA - 86 mA | |

Readiness Time | 50 s | |

Transconductance (S) | 5.2 mA/V - 6.8 mA/V | |

T-5881-SOVT - Single version | Capacitance, Cathode to Heater | 11 pF |

Capacitance, Transfer | 1.0 pF | |

Capacitance, input | 11 pF | |

Capacitance, output | 6.7 pF | |

Cathode to Heater Insulation Resistance | 4 MΩ | |

Filament Current (I_{f}) | 840 - 920 mA | |

Grid 1 Insulation Resistance | 200 MΩ | |

Grid 1 Inverse Current | 0.5 mA | |

Grid 2 Current | 6 mA | |

Height, base to top | 3.25 in. | |

Internal Resistance (R_{i}) | 18 kΩ - 75 kΩ | |

Non-linear Harmonic Distortion | 15 % | |

Output Power (P_{Out}) | 5.8 W | |

Plate Current (I_{a}) | 60 mA - 86 mA | |

Readiness Time | 50 s | |

Transconductance (S) | 5.2 mA/V - 6.8 mA/V |

Specification Sheet | All Models |

## My Project Lists

## Specifications, Files, and Documents

## Questions and Answers

*Anonymous*on November 19th, 2015.

*Anonymous*on February 23rd, 2018.

*Anonymous*on March 10th, 2020.

## Substitute Products

The following items can be substituted for this product. While not necessarily exactly the same, they will function as replacement items in your project.

## Product Reviews

Recently received 4 of these supposedly matched. They don't appear to me that they are. Is this Apex Matching for real? I have my doubts, or someone made a mistake boxing them up. At a constant plate V of 495VDC, there is a difference of 10 to 12mA plate to cathode current between each tube. The amo is a SLO100. The problem is not the amp as this difference in plate current follows each tube no matter where they are placed in the amp's power section. Otherwise, they sound fine biased @ 25 to 35mA (this is the spread between all 4 tubes in the SLO100). I've never got a bad tube ever from Antique Electronic Supply, so I'll hang onto them, and see how long these hold up where I have them set. Which according to my figures is just under 70% of max rating.

I bought matching quartet to replace my older Sovtek 5881`s...almost one full year one of these failed.Went full purple with HUGE hum from speakers.I removed the tubes and put the old pones back in...way better.They do not make tubes worth a crap anymore.I had exact same issue with RUBY...brand new,one failed in about 2 months.So far the MULLARD EL34`s are holding up.

These Sovtek 5881 tubes are perfect for my 1966 Supro Thunderbolt. This amp runs the tubes hot and they just seem to like it that way. Nice crunch when pushed hard.

These things sound RAD! Tight, nice compression.

Very pleased with the "sound" of these Sovteks. Smooth midrange and high end with solid bass. I like these better than some of the more expensive 6L6's

Good basic power tubes