What's Up With This? (Mesa about their coloring system)

[Octavarius]

Ok, so the negative voltages are:

Inner sockets: -46V
Outer sockets: -37V

So when the export tranny puts out only 450-460 volts and 430 - 440 volts under load to the plates, what will that be? I have no idea how to calculate this. :shock:

Let me know when you've measured the current draw under load. After all, that's when my tube shorted.

Ok, if you have a minute, please put me on the right track about bias calculations, etc. I only know bits and pieces... Ok, what elements are there and how do you calculate them together? :?

I figure somewhere there is a ratio of how much you should move the bias voltage versus the plate voltage to achieve the same (in theory) current draw at the tube. But I don't know what it is. On a good note, one of my friends just came up with an export simul C+. When I can get my bias rite hooked up to his amp, I will test the same tubes as I did with my amp and post the results.

Oh, that's really great, man. Thanks! Can't wait to see the results.

 

[123thefirst]

Just curious: do any of you still have a problem with what Mesa wrote? It seems that all they were saying is that they don't consider their color rating system as being based on variations in tone of the tubes. They only use their system as a means to facilitate the matching of pairs or quads.

Are you reading something more into that?

 

[HipKitty]

Just curious: do any of you still have a problem with what Mesa wrote? It seems that all they were saying is that they don't consider their color rating system as being based on variations in tone of the tubes. They only use their system as a means to facilitate the matching of pairs or quads.

Are you reading something more into that?

Absolutely Yes!

 

[Octavarius]

Ok, so the negative voltages are:

Inner sockets: -46V
Outer sockets: -37V

So when the export tranny puts out only 450-460 volts and 430 - 440 volts under load to the plates, what will that be? I have no idea how to calculate this. :shock:

Let me know when you've measured the current draw under load. After all, that's when my tube shorted.

Ok, if you have a minute, please put me on the right track about bias calculations, etc. I only know bits and pieces... Ok, what elements are there and how do you calculate them together? :?

I figure somewhere there is a ratio of how much you should move the bias voltage versus the plate voltage to achieve the same (in theory) current draw at the tube. But I don't know what it is. On a good note, one of my friends just came up with an export simul C+. When I can get my bias rite hooked up to his amp, I will test the same tubes as I did with my amp and post the results.

Any results, yet?

 

[JOEY B.]

His amp went out to California for a checkup and I have not been able to get him over to my house for a test session yet. I did test a 60/100 "105" C+ today and had a very different current draw than my simul (inner sockets) with the same tubes. We did a complete bias check on his amp, and it is all in spec. Hopefully I'll have some results on the export very soon.

Food for thought. A matched quad of winged "C" 6L6's that all measured very close to 25 mA in the inner sockets of my simul C+, drew around 45 mA in the 60/100 C+. Both have the 105 PT with 480+ plate voltage, and the bias voltage was correct on both amps. Very interesting. Would a 4V difference in bias make the current change that much? I guess it will vary by the tubes that are used.

 

[JOEY B.]

Finally tested the export simul today. The inner sockets had about 7mA more current draw than my 105 with the same 6L6's. The outer sockets had about 15 mA more current than my 105 with the same EL-34's. Some of this extra current draw is offset by the lower (450 plate) voltage. I will conclude that if one has an export simul C+, and wants to use current MESA branded tubes, it would be best to use:

Red, Yellow, or Green STR-440's in the inner sockets.
Red or Yellow STR-447's in the outer sockets,

Or, if you want an all 6L6 lineup:

Red, Yellow, or Green STR-440's in the inner sockets.
ONLY Red STR-440's in the outer sockets.

 

[Octavarius]

Great! Thank you! I really appreciate it. Did you test the outer EL-34's in Class A? Was there any big difference in the current draw?

 

[JOEY B.]

Did you test the outer EL-34's in Class A? Was there any big difference in the current draw?

Maybe 1-2 mA difference with the amp switched to Class-A. Not enough difference to cause any issues. This was at idle. When pushed hard in Class-A, there might be a strain on the tubes under heavy load. So if you want to crank it, switch to Simulclass for a safety net.

 

[igfraso]

I apologize in advance if I am saying something stupid. If so, please correct me.

If I remember correctly, Mesa says that the color code is useful just for matching purposes but the tone is always the same no matter the color code.
However, I think I also remember that red code tubes are a little bit be stiffer and distort a little tiny bit less than yellow, green, etc, tubes. White code tubes are just the polar opposite.

Red 4
Yellow 4
Green 5
Gray 5
Blue 6
White 6

Regards

 

[MrMarkIII]

So, Mesa is masterminding this vast conspiracy to actively prevent their huge army of customers from achieving better tone because they would rather you bought the *WRONG* tubes and get crappy tone because...?
What are you people smoking? :lol:

 

[igfraso]

Conspiracy? Smoking? :shock: :roll:
At least, I apologized in advance if I was saying something stupid.

Just in case, my British pronuntiation was too strong and I went misunderstood, Mesa says that the differences are negligible... and they surely are between reds and yellows, or yellows and greens, or greens and grays, etc. Certainly there is a tiny little difference between red and green and white.

When you buy tubes from Mesa, you can specify whatever color code you want.

 

[JOEY B.]

What are you people smoking? :lol:

Definately not what you guys in California are trying to legalize. :wink: The 105 PT amps as well as the Coliseum Mark series are really the only ones that might have any issues pushing some of the current MESA branded power tubes past their mA limits. I do not think that the tone would vary much, if any, between the color codes. The redplating is a different issue, altogether. :shock: