Sovtek 5881WXT Power Vacuum Tube (Matched)

7 Reviews

Availability: Usually ships within 24 hours.

USD $‎43.95

Need matched power tubes? Don't worry! Price includes matching in any quantity you need for no extra charge. Need a matched pair? Just order "2" tubes. For a matched quad order "4" tubes. Matched sextets and octets are available as well.

The Sovtek 5881WXT vacuum tube is a reliable beam tetrode delivering a warm, round tone that "sweetens" any vintage or modern guitar tube amp design. Built to rigid military standards, the Sovtek 5881WXT power tube will tolerate higher voltages than most other 6L6 tubes. This tube is commonly found relabeled by Fender and Groove Tubes to GT-6L6B. Mesa Boogie relabels them STR425.

From our review of the Sovtek 5881-WXT tube: "Solid construction and good performance. While not outstanding, the 5881WXT is probably the most commonly used tube of its type. Many amp manufacturers have been using these reliable workhorses as original equipment components. A good choice for general purpose use but not as rich in harmonic content as other tubes in this class. If you like to run your guitar straight into the amp, there are better choices. If you prefer to run through a bunch of rack equipment or like major crunch and overdrive sounds then this tube will work well."

Other Sovtek tubes6L6 Tube Types

Additional Information and Downloads

6L6 Tube Review

Tube Matching Information:
Power Tube Matching FAQ
Perfect Pair System

Sovtek 5881WXT Datasheet (PDF)

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Warranty Information and Return Policy

Warranty Period: 3 months

All our tubes are guaranteed for 3 months from the date of purchase. (Any exceptions will be noted on that tube's Warranty tab)

If you receive a tube that does not perform to the manufacturer's specifications, please do the following:

- contact us to get a return authorization
- return it via regular mail within 90 days from when we shipped it, and we will provide an exchange or refund of the full purchase price of the tube.

Returns not related to warranty or defect will be considered at our discretion, and are subject to a 15% restocking fee.

We can not accept returns that don't have an authorization, are past 3 month, or are returned improperly.

These guidelines may be updated without notice.

Good, cheap, working to last long NOS tubes


Hi, with all respects, I replaced old Sovtek 6l6s 30W versions for these, but Groove Tubes versions 1 year used and pulled from Fender tube combo (not sure what model they put them in) in my Guyatone Bassman 1100-DB and they perform great, everyone should know these are russian NOS tubes and when perfectly matched, they last longer than any other 6l6s I know. My tech measured 124 Watts on the output with matched quad so Its really strong tube we are talking about. I would say they open their sound best when they are adjusted on the hot side rather than cold. These old Fender silverface/blackface amps are tube eaters and these Sovteks are great for them if you want your tubes last. I can recommend them and make sure you have good 12at7 at PI, like I did (NOS Mullard) and good 12ax7s in other stages. Because not only power tubes make your amp sound good but I hear preamp tubes making much bigger difference. That is my opinion after couple years of playing through a tube amplifiers.

Noiseless and predictable clarity


I’ve got them in my fender De Ville 2 12 and they sound great in any channel, no noise at all or popping and the clarity is very predictable depending on your tone selection . I will experiment with others later with jj’s and EH’s but for if it doesn’t hiss or pop, why change anything when you’re happy with them, I give them a 5 rating for sure!

ice pick highs


these tubes really frustrated me. I put them in a VHT along with trying different tubes, speakers ect... after going piece by piece on why my amp sounded terrible I found these where the culprit. do not buy these if you are serious about your tone.

Great Tube


The owner of a repair shop recommended these for my 5150 head. Great sound and performance. I used JJs for over 10 years but I prefer these tubes.

Heater-cathode short?


I used 5881WXTs in my Sherwood C300 mono integrated amp. The amp developed a strange problem - intermittent hum. I would turn it on and it would be fine for 5-10 minutes. Next I would hear a click or pop, then hum. Everything worked; it just hummed. I had recapped the unit. However, I rechecked every cap anyway with an ESR tester (all good). I started thinking about H-K (heater-cathode) shorts. I replaced every tube in sequence (two 5y3's, followed by 12at7s and 12au7s). No change; still started humming after a 'pop'. Then I replaced my six month old 5881s with a pair of Sovtek 6L6WGCs. After two hours of continuous play, no more 'pop' and no more hum. Looks like at least one of my 5881s had an H-K short. Odd that this did not show up on my Eico 667 or Mighty Mite testers. I guess the only way to be sure is through substitution. Conclusions? Great sounding tube. Failed after 6 month's casual use. Out of warranty of course.