The Sovtek 5881WXT 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 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."
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.
By Mike Stamper from Windsor, CT
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.
By Frank from Toronto, Canada
Good tube for a good price
I use them with my Traynor amps, good performance for a good price. A good middle-of-the-road tube when you don't want to spend too much yet still want some quality. When they start "popping" you know it's time to replace them.
By Bill from Ohio
This tube sounds ok, and has held up great over 5 years. The amp has seen some heavy bumps and bruises, but these Sovteks hold up. Reliable indeed... They were the stock tubes in my amp, and they keep going back in when others fail.. I can count on these to work.