Tech Tip - Groove Tubes scale vs. Mesa Boogie scale

[myles_rose]

This was an article on tube manufacturers and how the "Groove Tubes" 1-10 scale could be used for tubes that were desired for a Mesa Boogie amp which has a fixed bias.

 

Tech Tip 021402 - Groove Tubes vs. Mesa Boogie Tubes

 

Many people do not realize that there are not all that many vacuum tube factories in the world.

 

Mesa Boogie does not make tubes.

 

Groove Tubes does not make tubes (with the exception of their new 6L6GE which will be coming out in the next few months, which is in BETA test now in a few cases.

 

Ruby does not make tubes.

 

The major factories are:

 

Reflector in Moscow .... makers of Sovtek and Electro Harmonix tubes.

 

Svetlana in St. Petersburg ... makers of Svetlana

 

JJ / Tesla in Prague .... makers of Tesla, and they were the OEM in the past for Siemens, Mullard, and Telefunken in many cases.

 

Sino in China ... which is a group of a number of tube factories in China.

 

There has always been talk that the Chinese tubes were bad, but in the last year, the money that they have put into new tooling has paid off. They are on their 3rd newest generation of the 12AX7, and it looks as though it will be found to be a pretty good tube.

 

In any case, Mesa and Groove tubes both sell all these tubes. In the case of Groove Tubes, they use a rating scale of 1-10. Mesa Boogie uses a color code system. Here is the cross reference to use the same "grade" of tube if you switch from one vendor to the other:

 

Mesa vs Groove Tubes scale

Red 4

Yellow 4

Green 5

Gray 5

Blue 6

White 6

 

The reason for Mesa's narrow range, is that their amplifiers do not have an adjustable bias. This way if you have one of their amps, you can use any of their tubes safely.

 

For amplifiers without an adjustable bias, if you want more headroom and/or power as an example ... and you amp had a #5 or Mesa "Green" tube in it .... and had an idle dissapation of about 50%, you would just go to a "White", "Blue" or a Groove Tubes #6. You will see your idle dissapation go up to maybe 55%. This is a way to fine tune your amp.

 

Regards,

[signal1000]

What do the grading scales stand for? Is a "1" a tube that tested better than a "10" or vice versa?

 

I have some GT E34Ls that say "S2" on them. The salesman said that stood for "soft two" which meant the tube would break up faster. He had some that said "H10" and he said those were "hard tens" that wouldn't break up as soon as the "S" ones. Any truth to that?

 

Thanks.

[Big Al]

That salesman told you the truth.

 

The numbers reflect how soon the tube breaks up or goes into "overdrive" The lower numbers breakup earlier than the later ones. It seems that the softer Vacum tubes breakup earlier and the tighter vacum tubes have much more headroom.

 

A S2 would be a very soft tube indeed.

[Chip McDonald]

Excellent rundown, Myles...

[signal1000]

Originally posted by Big Al:

That salesman told you the truth.

 

The numbers reflect how soon the tube breaks up or goes into "overdrive" The lower numbers breakup earlier than the later ones. It seems that the softer Vacum tubes breakup earlier and the tighter vacum tubes have much more headroom.

 

A S2 would be a very soft tube indeed.

Interesting. Thanks.

 

I love these tubes in my Marshall Jubilee - they really made that amp come alive.

[myles_rose]

Originally posted by signal1000:

What do the grading scales stand for? Is a "1" a tube that tested better than a "10" or vice versa?

 

I have some GT E34Ls that say "S2" on them. The salesman said that stood for "soft two" which meant the tube would break up faster. He had some that said "H10" and he said those were "hard tens" that wouldn't break up as soon as the "S" ones. Any truth to that?

 

Thanks.

signal1000,

 

Generally, tube from Europe and China have "S" ratings for soft, and those from the USA have "H" ratings for hard. This refers to the vacuum inside the tube.

 

The EL-34 generally has an S rating, although the USA version (6CA7) will carry an H rating.

 

If you go to my website, and on to the Groove Tubes link, there is a chart that shows the difference in actual wattage between a "1" and a "10" on a different tube. Basically, the difference in wattage is not all that great, it is just that the lower numbers will distort quicker. In the case of your tubes, E34L's, they are from the JJ factory, and are very strong tubes, stronger than any of the other EL-34 tubes including the Svetlana, Siemens, Mullard, Sovtek, or EH tubes.

 

Regards,

[signal1000]

Thanks Myles.

[myles_rose]

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[myles_rose]

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