Sovtek 5881 WXT Tube Guide PDF

Sovtek 6l6GB, 6L6WXT+, Electro Harmonix 6L6GC, 6L6WXT, 6Π3C-E, 6Π3C, 6P3S-E, 6N3C-e, 6Π3C,   Mesa Boogie STR425,  Fender GT-6L6B or 6L6R Groove Tubes GT-6L6B  or GT-6L6R, Ruby Tubes 6L6R Fender 6L6 Precision Matched Tubes are just some of the names for just a few different Russian tubes. 
Russian Tubes?

Why not buy American?

Unfortunately we can’t. They no longer make tubes in the United States, England, or Western Europe. By all accounts they were the best but now supplies of them are running out and they have gotten very expensive and are harder to find. 
Several online stores sell NOS (New Old Stock) tubes. These are tubes produced long ago that have been sitting in a warehouse for years unused. You can still find them if you have the cash, but buy them from a reliable dealer. I buy new production Russian tubes, so I have no experience with dealers who I could recommend. New tubes are made in Russia, China, and Slovakia. The most common one is a Russian variant of the 6L6. It comes in many names and it is sold at many (often outrageous) prices. But we'll need a little background in tube codes first.

The letter codes unraveled:

Russia uses the Cyrillic Alphabet:

С- Cyrillic Capital letter es (equivalent to an ‘S’, but looks like a ‘C’)
Π – Cyrillic Capital letter pe (equivalent to a ‘P’, but looks like an ‘N)’
Е- Cyrillic Capital letter ie- (Same as our ‘E’) A  -E Designates a Russian military spec tube

U.S. Tube Codes:

6L6GC- 30 watt power tube (used by most Fender, Soldano, many Mesa, and a few Marshall Amps)
6L6GB- 23 watt earlier version of the 6L6GC
5881- Short Plate Military Version of the 6L6GB, glass part is smaller than most other 6L6GBs or GCs)
W- Indicates a military spec version of a tube (Equivalent to Russian –E code)
JAN- Indicates the tube was produced under contract for the U.S. Military (Tube almost always has a W in its name) It Stands for ‘Joint Army Navy’

Famous/Infamous Cold war era tubes:

6Π3C-E- (Really 6P3S-E, but often mistakenly translated 6N3C-e) Servo Tube for Soviet (Now Russian Federation) Mig Jet Fighters
6Π3C- Russian ‘consumer’ version of the military tube
JAN 5881WGB- Servo tube for American B-52 Bombers

Sovtek Tube Codes:

6l6GB- 6Π3C Tube. Sometimes rebranded 6L6GC out of ignorance or dishonesty. Most Fenders will eat this for breakfast.
5881 WXT- 6Π3C-E Tube With a regular U.S. size base.
5881/6L6 WGC- 6Π3C-E Tube With its original small disc base.
6L6 WXT- New longer plate Sovtek 6L6 design with 20% more power
6L6 WXT+- New name for the 6L6WXT, to avoid confusion with earlier models
Electro Harmonix 6L6GC- Brand name for the 6L6WXT+

 

The Sovtek 6L6-GB (AKA 6Π3C) Vacuum Tube

The Sovtek 6L6GB has a very smooth warm and round tone (and can be had super cheap). It is used in some low wattage boutique amps (Traynor for instance). Unless you own a boutique amp that has these recommended for it, DO NOT BUY IT FOR A 6L6 AMP!
I have heard that these tubes have been discontinued, but that there is still a massive supply of them. If you really like these tubes and they are appropriate for your amplifier, now would be the time to get them! Once supplies drop, people will start wanting them. Even if they hate them now.

The Sovtek 5881 WXT or 5881/6L6 WGC (AKA 6Π3C-E)

 The 5881WXT or 5881/6L6 WGC (same tube different base) is used as the OEM power tube for almost all amps calling for 6L6GCs by Fender, Mesa, Marshall. It is a reliable, low cost replacement, and it’s probably what you have in there now.
They have about 20% lower output than a true 6L6GC. However they will handle any amp you probably have (rated for 500 plate volts with 2 tubes).
Some folks don’t like the tone. But they are near indestructible and long lasting. They have a mean, crunchy tone with an upper midrange spike.
Highly recommended if you play loud in a band with a 50-100 watt head these things sound great, punch you through the mix, and survive tours and drunken roadies.
Not recommended if you play small boutique amps and are looking for a smooth warm tone for solo playing or home recording.
Why is it called a 5881 if it can handle going into a 6L6GC (30 watts per tube) amp, a 5881 is 6L6GB (23 watts)? Remember it’s really neither; it’s really a 6Π3C-E. When choosing a name for the American market the JAN 5881WGB had similar function (Servo tube for military aircraft, compact size and plate structure, and lower output than a true 6L6GC).

Fender 6L6 Precision Matched Tubes (5881WXT)
Fender GT-6L6B or 6L6R  (5881WXT)
Groove Tubes GT-6L6B  or GT-6L6R   (5881WXT)
Marshall 5881  (5881/6L6 WGC)
Mesa Boogie STR425 (5881/6L6 WGC)
Ruby Tubes 6L6R (5881/6L6 WGC)
Sovtek  5881/6L6 WGC
Sovtek  5881WXT

They have been rebranded by various companies EITHER to:

A) Maker it easier to know it’s the proper tube for a specific amp.
 Or more cynically:
B) Really just to extract more money from you.

Remember the 5881 WXT or 5881/6L6 WGC is a different tube than the 6L6WXT, 6L6WXT+, & Electro Harmonix 6L6GC (which are all the same as each other).