mesa boogie color codes for 6l6 help

[billboogie]

Hello
I just bought a matched set of mesa 6l6 440str-grey. Are these OK in my DC5? I don't have the original set and I have been everywhere to find out which is the proper color code to get but have found nothing. From what I read there is a voltage difference and the wrong color code may make my amp "redplate". Any help would be greatly appreciated. Thank you in advance

 

[kekam35]

You have been highly misinformed. Color codes don't mean anything other than grey are matched
w/grey, green w/green and so on.In other words, any grey will work w/each other as a matched set.
It has nothing to do with tone or gain. Any matched set of mesa tubes will be within proper operating
range for your amp.

 

[edward]

You have been highly misinformed. Color codes don't mean anything other than grey are matched
w/grey, green w/green and so on.In other words, any grey will work w/each other as a matched set.
It has nothing to do with tone or gain. Any matched set of mesa tubes will be within proper operating
range for your amp.

Correct. You have been told one of those oft-repeated bugaboos that is completely wrong. The color code is simply there so you can match (approximately) between pairs of tubes. Like if one of your "Grays" go bad, you replace with another gray and not with a different color as that would result in a mismatched pair. Or if your amp runs 4 tubes that you match the two pairs. That's it.

Sidenote: try a pair of SED "Winged-C" 6L6 tubes (the real ones, not re-issues) ...very nice-sounding tubes, and an improvement over the Mesa ones, IMHO. But that's just my take on the tone

Edward

 

[billboogie]

Thank you both for the information. The "redplate" warning I had read on this board in the Mark Series index. I searched for a couple of days for more info and have been coming up empty. I'm sure Mesa would have some sort of info on this if there was a chance of damaging your amp. BTW,Edward, What differences do you notice between the Mesa and the SED tubes. I have been experiementing with dif. preamp tubes as suggested here on the board.
I bought a JAN NOS 5751 and couple of dif. lower gain tubes. I do notce the suttle dif. when changing from an "X" to a "T". I find I like 5751 the best in p4 and a "T" in the PI slot. Thanks again.

 

[dodger916]

Color codes don't mean anything other than grey are matched
w/grey, green w/green and so on.In other words, any grey will work w/each other as a matched set.
It has nothing to do with tone or gain. Any matched set of mesa tubes will be within proper operating
range for your amp.

I believe board member JOEY B measured the current draw for the different colors and found the range from low draw to high was Red and Yellow having the lowest current draw, Blue and Green in the middle, and White and Blue having the highest. So while tone differences may or may not be perceptible, it seems the colors might designate relative current draw.

 

[Monsta-Tone]

Correct. You have been told one of those oft-repeated bugaboos that is completely wrong. The color code is simply there so you can match (approximately) between pairs of tubes. Like if one of your "Grays" go bad, you replace with another gray and not with a different color as that would result in a mismatched pair. Or if your amp runs 4 tubes that you match the two pairs. That's it.

Believe it or not, even a little change in bias point can change the way the amp sounds, depending on gain settings, etc.

I've done a lot of experimenting on this (not necessarily Mesa tubes, but the concept is the same).
If your amp is baised a little cold, it will be slightly more quiet (noise wise), have a more focused feel (not get really mushy very easily).
If the amp is biased a little hot, it will have a much more dynamic feel, more harmonics, and get mushier sooner due to power tube breakup.

But....if the amp is biased somewhere in the middle of the acceptable range, which is a 70% ratio between Plate Voltage and Bias Current, then it is the best of both worlds.

I really think that most Mesa amps are biased so cold because they want the tubes to last longer, the amp to have more headroom, and to lower the noise floor on the higher gain amps like the Rectos.
And....They really make a lot of money on tube sales, so they create a myth that their amps run better on their tubes!


Now, if we look at Mesa's statement about matching color to color, they are defeating their own argument. If a Red is not a good match to a Grey, then that means that they draw different amounts of current.
I've always looked at it like Groove Tubes' matching system. If you look at Joey B's findings, it sort of supports this theory.
Red tubes overdrive more easily than the Whites.

 

[dodger916]

Correct. You have been told one of those oft-repeated bugaboos that is completely wrong. The color code is simply there so you can match (approximately) between pairs of tubes. Like if one of your "Grays" go bad, you replace with another gray and not with a different color as that would result in a mismatched pair. Or if your amp runs 4 tubes that you match the two pairs. That's it.

Believe it or not, even a little change in bias point can change the way the amp sounds, depending on gain settings, etc.

I've done a lot of experimenting on this (not necessarily Mesa tubes, but the concept is the same).
If your amp is baised a little cold, it will be slightly more quiet (noise wise), have a more focused feel (not get really mushy very easily).
If the amp is biased a little hot, it will have a much more dynamic feel, more harmonics, and get mushier sooner due to power tube breakup.

But....if the amp is biased somewhere in the middle of the acceptable range, which is a 70% ratio between Plate Voltage and Bias Current, then it is the best of both worlds.

I really think that most Mesa amps are biased so cold because they want the tubes to last longer, the amp to have more headroom, and to lower the noise floor on the higher gain amps like the Rectos.
And....They really make a lot of money on tube sales, so they create a myth that their amps run better on their tubes!


Now, if we look at Mesa's statement about matching color to color, they are defeating their own argument. If a Red is not a good match to a Grey, then that means that they draw different amounts of current.
I've always looked at it like Groove Tubes' matching system. If you look at Joey B's findings, it sort of supports this theory.
Red tubes overdrive more easily than the Whites.

That's what I thought too Andy, but Joey B's comments on this thread controvert that: . http://forum.grailtone.com/viewtopic.php?f=33&t=39067. In the last post on Page 1, he's saying Red has MORE headroom and White the least. A Mesa tech said the same thing. I was trying to get my head around what Joey was saying, but I didn't fully digest it mentally. Can you comment?

 

[billboogie]

I have been playing with the amp now for about 8-10 hours on the new tubes. The last set that were in were Red 420's. The new ones are Grey 440's. This is what I notice and hear so far. tempeture-wise The amp is running hotter than before. The back plate has never felt this hot, though I am not worried yet, I will keep an eye on it and install a fan if need be. I will do a tube comparrison and try to obtain tempeture readings from both sets. The amp has less headroom. My main channel is the clean with gain on 10 (no pull boost). I have since brought gain down to 7-8 to be where I was before. The amp sounds brighter but I think that is because the old 6l6's were OLD. When I do the comparrison I will post the results. I will say I love the way the amp sounds right now, wish I had changed them sooner but I was'nt using the amp at gigs lately so the cash went to other things.

 

[Monsta-Tone]

Oops! Sorry about that. I meant to say that if the Reds draw less current, they should have more headroom since the amp will be biased a little colder.
Gotta stop trying to make sense before I have my coffee!!!!!




As for the 440 vs. the 420, that might be a whole different argument.
They are completely different tubes, so it's kind of like 'Apples to Oranges.'

I don't have anymore 420's, so I may be wrong about this, but I seem to remember them having less headroom than the 440's.
I really liked my old Dual Recto with the 420's, but when I put 440's in it, it seemed to be lacking in the power tube saturation department.
It simply had much more headroom than it did with the 420's. I never knew if this was due to the 420's being old and worn out, or if the 440's had more headroom.

 

[billboogie]

Is it possible I am getting better saturation with fresher tubes? The old ones were pretty old but I never had the need to crank it up at gigs where it mostly played. (we miked everything).
So I never drove the tubes really hard and they always sounded fine to me.

 

[Monsta-Tone]

Tubes are funny! They are so unpredictable, kind of like my wife! :lol:

Anything is possible. But, like I said, comparing 2 different brands (Mesa doesn't actually make their own tubes) of power tubes is like comparing watermellons to cantelopes. It could be the new tubes have more compression, or that they simply bring out something in your amp that may have been missing or not as prevalent with the old tubes.

If the old tubes were still working when you changed them, I would definitely save them for a backup set. You never know what will happen at a gig!

 

[igfraso]

I have to confess that I am totally confused.
I thought that red tubes were breaking up earlier than white tubes.

A couple of times, when I sent some 15-year-old amps (Simul-Class) to Mike Bendinelli for the usual check up/clean up/cap job, he put some red or yellow code tubes in the outer sockets and green or grey in the inner sockets.
I understood it was done in order to have a sweeter distortion in the 15 W Class A position and a litttle more headroom on the 75 W SimulClass position.

But maybe, it was just the opposite? :shock:

 

[billboogie]

Alright, I found something last night that may clear some things up regarding the headroom conversation. When I bought the 440's I also bought 2 preamp tubes as well. One was an ec83 (spare) and the other an ec81 (experiment). After changing the pwr tubes I swapped out my 5751 to what was suppose to be an ec81 (according to the box!) from P4. The tube inside the box was an ec83!. I was'nt very happy about this and a return trip to GC is happening today after work.
Now I can't trust GC, even for small stuff. I assume this would explain the loss of headroom.
Sorry for the confusion I will be bitching at the manager for all of us :lol: BTW Yes I will save the old tubes for spares, gd suggestion, thank you.

 

[elvis]

There is a lot of controversy about the relative performance of tubes, including gain, current draw, matching, etc. While the various colors probably are rated for idle current, they are also rated for other parameters (at least according to Mesa), including gain match.

Remember that tubes vary pretty wildly in performance, so Mesa likely throws out the extreme low and extreme high bias current ones. The rest are probably in a reasonable operation range, so I can't imagine it's that easy to tell the difference. I would guess the gain is what affects the tone, and gain doesn't change that much with idle current (2X current gives about 40% more gain). I doubt the idle current varies that much.

One important thing to remember is that tube wear is a physical phenomenon. The tubes change physically during operation, so gain, idle current, etc are changing as you use them. A few hours of use, and the carefully matched tubes are not so matched any more. It is my opinion (though highly disputed) that there is a large range of tube characteristics over which the tone is acceptable. Otherwise we'd be changing tubes every month.

It's also interesting to me that people are so concerned about bias current. Even with constant rebiasing, the gain of the tubes is changing. The gain at a chosen idle current varies from tube to tube, and changes over time. Biasing is generally done with the guidance of a tube datasheet. Those are typical values only, and usually can change by a lot. I think that in order to keep decent control over tone, you would have to measure gain vs. bias every so often, and keep rebiasing for constant gain, not constant idle current. Or constant bandwidth, or whatever parameter you think is important to tone.

 

[ryjan]

oft-repeated bugaboos

This should be the title of a stickyed thread. :lol: