Direct Replacements For Mesa Engineering Tubes

Posted: January 30, 2016 in Ideas To Be Developed, Mesa Boogie Dual Rectifier, Tube Amps, tubes
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(Note: During the initial 5 year period of warranty, using tubes other than those branded by Mesa will void the warranty of your amp.  This article is meant for people who have amps which are not under warranty.)

Mesa’s 6L6GC STR tubes are manufactured in China for Ruby Tubes.  It is a reproduction of the classic Sylvania 6L6GC STR.  Mesa buys a big batch from Ruby, tests them, keeps the tubes that meet their requirements, and sends back the tubes which fall out of range.  Ruby’s matched version of this same tube is the 6L6GCMSTR.  It costs considerably less than Mesa’s tubes.

Many people equate Chinese with “cheap” or “flimsy”, but the construction of this tube is very durable.  The glass is thick, the metal parts are good, and the look is classy.  Compared to some of the Chinese off-brands I’ve seen/held, they are superior.  My tubes just lasted almost 4 years, with 2 years of very loud and long periods of use.  I got close to 1500 hours with my Dual Rectifier before the tone began to fade.

It is really difficult to find information about the tests each company does to their tubes and how to cross reference them.  After a lot of reading and e-mails, I can say I know the range Mesa uses for their tubes and can make a good guess about the grades of tubes according the the PC on Ruby’s tubes and also how that translates to the GT ratings.

I was told by a dealer that Ruby tubes from 33ma to 52ma are equivalent to the grades of tubes Mesa uses.  Mesa used to use 6 color grades to separate the distortion characteristics of their tubes.  To separate them, I’m going to average it out with math.

  • 52ma-33ma=19ma
  • 19ma+1ma=20ma (spread)
  • 20ma/6=3.333ma (groupings)
  • 33ma+10ma=43ma (middle of spread)

We have to add the first number into the difference to have all the numbers for the spread.  The division of groups will be 3ma to 4ma.  I erred on the side of caution and put the 4ma groups in the middle ranges.

It would look something like this:

Ruby Tubes to Mesa GTI want to make clear that this is an estimate, but an educated one.  I also want to make clear that the transconductance (TR#) is not taken into account.  A higher TR# will amplify more easily and changes the characteristics of the tube.  What the table is demonstrating is that this range of tubes will not blow up a Recto, especially if a person stays well inside of the range (36 to 49 overall, or, 39 to 46 for the middle).

GT Is A Different Beast

I included GT, because they are popular tubes and Mesa has excluded the above GT numbers from their policy of voiding a warranty when a person uses non-Mesa branded tubes.  Their 6L6GC is a SovtekWXT, which is the tube produced for EHX.  It is a totally different 6L6GC and is included for demonstration of safe ranges, not for comparison of tone.

Save Your Money

A quad of Ruby 6L6GCMSTR can be bought for $50 to $80.  A person can ask for a certain range when they buy the set, or, at a store, look for the exact number they want.  Compared to the prices of quads of Mesa (about $100) or GT ($107), the Ruby brand is a very good deal, is practically the same as the Mesa brand, and is safe to use when correctly chosen.  The 38ma Ruby tubes I was using were freaking awesome and I can’t wait to get another set in that range.

  1. […] perform to their specifications.  Putting Ruby tubes in a Dual Rectifier requires a person to purchase a set of tubes with plate currents between 33ma and 52ma.  Whether Mesa considers any other variables, such as […]


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