Vacuum Tubes for Audio, Music and Radio from BOI AudioWorks

6L6 Guide

Power Tubes wear out

Output power tubes generate a lot of heat, and this causes it to wear out. If your amp starts to sound a bit flat and thin after some use, it's time to replace the output tubes.

Not all 6L6 are same

Just some of our 6L6 offerings! There are several 6L6 tube types, and some amp manufacturers used one type over another for cost and/or power considerations. When you replace 6L6, you should make sure that you replace with the right type.

The main variations of 6L6 are:

  • 6L6GC
  • 6L6GB / 5881
  • KT66
Each are covered in sections below.

Original Brands at much less

Are you looking for Groove Tubes 6L6? GT-6L6B is relabeled Sovtek 5881WXT. GT-6L6S is JJ 6L6GC respectively. We carry the same tubes with original brand that cost less.

You can make quick price comparison by clicking Quick Lookup in our 6L6 Category.

Enjoy 6L6 Choices

There is a large number of 6L6 tubes on the market today, and we carry over a dozen best sellers. Whether you have '65 Fender Deluxe Reverb or Mcintosh MC-240, we have the right 6L6 in stock for replacement or upgrade.


6L6GC is the higher rated 6L6. It takes 500V on the plate and can dissipate 30W.

In the past, NOS 6L6GC provided great tone, but the price has gone through the roof in recent years.

Workhorse 6L6GC

6L6GC tubes from BOI AudioWorks Fortunately, current production 6L6GC workhorses are all rugged and excellent sounding. These tubes all sound great, and are ideal as upgrade to replace factory installed 6L6 tubes in your amp:

Boutique 6L6GC

We also carry boutique 6L6GC tubes with tone and looks that combine NOS and new. These are just as rugged as other 6L6GC, and are ideal for those looking to experiment and establish your own tone:

Value 6L6GC

For those looking for direct replacements of factory installed 6L6, we carry the originals without the re-branding, keeping the price down.

Whether you are re-tubing worn 6L6s or upgrading for better tone, any of the above will sound great and do well in any amps calling for 6L6.

Remember, all our power tube sets include free burn-in for maximum stability.


TungSol 5881 Re-Issue has excellent tones 5881/6L6GB is the smaller brother to 6L6GC. They are smaller sized than 6L6GC, and rated up to 23W.

Use Tung-Sol 5881 Re-Issue if you are looking for that great 5881 tone, but make sure your amp calls for 5881/6L6GB and not 6L6GC.

If you are after that Tung-Sol 5881 tone in higher powered amp, try TungSol 6L6GC-STR.

Again these tubes can replace lower powered 6L6G, 6L6GB, 6L6WGB and 5881 types, but will not work in amps calling for 6L6GC.


Great KT66 selection at BOI AudioWorks KT66 was originally developed as European counterpart to 6L6GC. KT stands for Kinkless Tetrode.

KT66 has higher filament draw than a 6L6, and can handle more power. In audio application, KT66 are smoother sounding with great texture. In a guitar amp, KT66 gives more agressive voicing as demonstrated by Marshall JTM45 Bluesbreaker.

  • Genalex Gold Lion KT66 Beautifully constructed, with the looks of original GEC KT66. This is our favorite KT66.

  • JJ KT66 Heavy duty KT66 in KT88 form. This is a very rugged tube that can be pushed hard.

  • Tung-Sol KT66 Another KT66 in KT88 form factor. It sounds more like 6L6 than any of the KT66.

  • Chinese KT66 Faithful replication of original GEC KT66, and gets great reviews used in audio applications.

  • Groove Tubes KT66HP Out of production, but KT66 Gold Lion makes an excellent replacement.


350B Tubes at BOI AudioWorks 350B deserves a special mention. Original 350B was a 6L6 derivative made by Western Electric.

There is now a very good Chinese reproduction Valve Art 350B with great original looks and excellent sonics. This tube is very popular with HiFi and DIY enthusiasts.

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