Mesa power tube color coding - Anyone know the key?

Hi,

I posted this question in the Tubes section too but thought those with the same question/concern/knowledge might lurk more in the LS forum given the recent posts about bias mods.

Does anyone know the order (as in coldest to warmest) of Mesa’s power tube color coding system? For example is red the coldest and yellow the warmest? I’m specifically interested in 6L6 info for my LSC. Any color code information on any Mesa power tubes would be appreciated especially if you know the actual mv.

Not sure I want to try the bias mod just yet as the amp is under warranty but might go down that road eventually.

Thanks!

Hey:

I don't know the Mesa Color-Coding key...at least not in it's entirety...but I can tell you the following.

In a Lonestar Classic set at 50 watts, silicone diodes...

'Yellows' read somewhere in the mid 30's range...(34-38mv). It varies a few mv from pair-to-pair.
'Greys' read in high 20's to low 30's (28 to 33mv)

ALL other colors I tried were COLDER...and in my estimate...totally useless in a Lonestar. One pair (can't recall the color now) read 16mv!

Keep in mind that setting the amp at 100-watts will drop the reading on the outside pair of tubes approximately 2mv from what they read at 50-watts. The inner pair (if they are 'perfect' matches to the outer pair) will be another 2mv cooler than the outer pair at 100-watts.

Using either the Tube-Rectifier setting...or...the 'spongy' power setting will also drop the readings.

For these reasons; if I were not willing to go through with the 'bias-mod'; I would only buy the 'Yellow'-coded tubes.

The 'bias-mod' would allow you to set all the tubes higher...and make the Tube-rectifier and 'spongy' power setting more useful.

Charles

Thanks Charles. It's helpful to know at least yellows should be good. Next time I call I'll try and get more information out of Mesa.

http://www.guitaramplifierblueprinting.com/Rating.html

I just found this link of the Groove Tubes website, which contains a very helpful chart:

Mesa scale Groove Tubes scale
Red 4
Yellow 4
Green 5
Gray 5
Blue 6
White 6

However, my question concerns the supporting text below -

The text goes on to say that “Lower numbers will start to distort at lower volume settings on your amp, and have more dynamic touch and feel.”

And then:

“High number will have to be driven at higher volume levels to begin to reach output stage distortion. These are liked by some Jazz players that want a very clean sound. They are also preferred by some heavy metal folks, who want very clean high headroom. These folks like to get most of their distortion from front end effects, pedals, or by running their preamp levels very high.”

Followed by:

“In a amp with a given bias, a higher GT rated tube will have a higher idle dissipation if no adjustments are made. This aspect can be used to fine tune amps such as older tweed era Fender amps, Mesa Boogie Amps, Hiwatt, Orange, etc. If you find as an example that a #5 tube has an idle of 26mA and you wish something closer to 30mA you may want to try a #7 rating.”

I had always thought that the warmer an amp was biased the earlier it broke up. My understanding is that an amp biased to 38ma would break up earlier and have a warmer sound than an amp biased to 28mA. The above text says the opposite and also is not consistent with Charles’ findings with the yellow tubes (the table would be consistent however).

Any thoughts? Is the text a misprint?

In the current intellectual environment, where everyone is entitled to not only their own opinion, but even their own facts, It's become nearly useless to convince anyone of anything.
Fact: Mesa uses their color code to match tubes in pairs. They have never claimed or published anywhere at any time that these codes have any effect on tone. They have stated that it's OK to use Groove tubes between 4 and 6 (used to be 7).
My opinion?
I have 6L6s and EL-34s, reds, yellows, greens, greys, blues. I've tested them in a Mark III Simul I've owned and gigged with for over twenty years, at the same settings, at loud and soft volumes. There are larger sonic differences between manufacturers than there are between any Mesa color. The STR-442, STR-447, STR-430, STR-440, etc., each have their own sound. But RED 442s don't sound a heckuva lot different from BLUE 442s. Your mileage may vary.

Charles Reeder said:

Hey:

I don't know the Mesa Color-Coding key...at least not in it's entirety...but I can tell you the following.

In a Lonestar Classic set at 50 watts, silicone diodes...

'Yellows' read somewhere in the mid 30's range...(34-38mv). It varies a few mv from pair-to-pair.
'Greys' read in high 20's to low 30's (28 to 33mv)

ALL other colors I tried were COLDER...and in my estimate...totally useless in a Lonestar. One pair (can't recall the color now) read 16mv!

Keep in mind that setting the amp at 100-watts will drop the reading on the outside pair of tubes approximately 2mv from what they read at 50-watts. The inner pair (if they are 'perfect' matches to the outer pair) will be another 2mv cooler than the outer pair at 100-watts.

Using either the Tube-Rectifier setting...or...the 'spongy' power setting will also drop the readings.

For these reasons; if I were not willing to go through with the 'bias-mod'; I would only buy the 'Yellow'-coded tubes.

The 'bias-mod' would allow you to set all the tubes higher...and make the Tube-rectifier and 'spongy' power setting more useful.

Charles

Click to expand...

Charles

Any idea what happens to readings in 10W mode, and which tubes are in play?

Chester:

I wish I could help you with an answer to your quite reasonable question...but both my Lonestars are the 50/100-watt versions and I've never even played on one with the 10-watt option.

Perhaps...John Mansfield of Mansfield Guitars could give you an intelligent answer. I believe he has received schematics for all the Lonestar variants by now...if so, he could perhaps tell you.

I don't know his email address (offhand) ; but it is posted in several places in the threads pertaining to 'bias-kits' for the Lonestar and Stiletto. You should be able to find it without too much trouible.

PS. In regards to another posting about changies in tubes and Mesa color-coding NOT affecting tone , etc.,etc.. My 'mileage' varies...greatly.

Regards: Charles