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

[Octavarius]

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TUBE TIPS....Tone is Colorful!

Mesa/Boogie has always built the versatility and tonal potential into the tone controls and features of the amp, leaving the finicky variation of different tube types aside.

Mesa/Boogie amplifiers employ a preset bias to allow even the least technically oriented player to change tubes themselves and maintain the original brilliant and dynamic response from the amp. The preset bias also means that Mesa will accept a much narrower range of tubes at much closer matching tolerances, considering the window provided by the preset bias. Other manufacturers and distributors accept tubes of much more extreme current draw and match variation under the guise of bias adjustability, claiming that tubes of different current-draw offer different response.

Tubes of similar type can vary slightly in response, but variations are more dependent on the bias adjustment.( For more in depth bias discussion, see Randall Smith's article on biasing in previous Amplitudes newsletters and on our webpage at www.mesaboogie.com). In the end, for any amplifier, Mesa tubes are more stringently tested, more closely matched, and from the most consistent and reliable of tube production ranges... the middle. Our tubes don't run hot or cold...They run RIGHT! We test and match the tubes for you, which is less time spent trying to tweak the amps circuitry, and more time playing and searching for tones with the amps tone controls and features.

Mesa/Boogie tubes have a three letter color code at the base of the tube used to group the tubes into matched pairs. These color codes do not apply to different tonal variation (the number and two letter codes with the color code are Production Batch #'s and Tester's initials respectively).

Any Mesa tested tube is guaranteed to perform tonefully and reliably within the preset bias of the amp, as long as matched pairs are in the appropriate sockets. No fuss, no muss! Just plug and play when it is time to re-tube. Maintain the TONE! Use Genuine MESA Tubes!

Tien Lawrence
Boogie Customer Support

Does anyone know why do they say that when the coloring is really used to match with the (sometimes different) fixed bias in their amps? :? Weird. :shock:

 

[tetsubin]

They say that because you're wrong.

 

[Murphy Slaw]

This topic is boring me. And hey, I'm just sitting here drinking beer.

Mesa's will work. Groove tubes will work. JJ's will work. NOS will work.

Plug and play. Let your ears decide.

Best of luck.

 

[Octavarius]

Nah, come on, guys. Everybody here knows that a Red colored Mesa tube idles differently than a Blue colored one. That's what the system is about. I even talked with a guy from CS that suggested a COOLER running tube, for example YELLOW (I was using grey).

It's not about tonal variations, by the way. It's the way the tube idles. Groove Tubes also uses this type of scale, mostly to match with fixed bias amps, like Mesa Boogie.

 

[HipKitty]

Here's some info that contradicts the Mesa claim. This comes from Myles Rose..considered to be an expert in the tube field (think Groove Tubes and Guitar Amplifier Blueprinting).


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 Scale crossed to 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 dissipation of about 50%, you would just go to a "White", "Blue" or a Groove Tubes #6. You will see your idle dissipation go up to maybe 55%. This is a way to fine tune your amp.


I know that I had a personal conversation approximately 10 years ago regarding this from Boogie themselves and again at a NAMM approximately 6 years ago regarding all things tubes. Both of those conversations included their testing and the color coding on the tubes. I clearly recall the fact that the different color codes were tight in spec with each other. Now, maybe things have changed over the years, but I believe that this board would have gotten wind of it somehow.

 

[HipKitty]

And hey, I'm just sitting here drinking beer.

OK, you've got MY attention

 

[Octavarius]

Here's some info that contradicts the Mesa claim. This comes from Myles Rose..considered to be an expert in the tube field (think Groove Tubes and Guitar Amplifier Blueprinting).


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 Scale crossed to 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 dissipation of about 50%, you would just go to a "White", "Blue" or a Groove Tubes #6. You will see your idle dissipation go up to maybe 55%. This is a way to fine tune your amp.


I know that I had a personal conversation approximately 10 years ago regarding this from Boogie themselves and again at a NAMM approximately 6 years ago regarding all things tubes. Both of those conversations included their testing and the color coding on the tubes. I clearly recall the fact that the different color codes were tight in spec with each other. Now, maybe things have changed over the years, but I believe that this board would have gotten wind of it somehow.

Well, I believe that different color coded Mesa tubes are still tonally identical. It's just that, at least as I understood the highlighted (bold) part in the article I posted, they say that they only use the colors to group them into pairs, and nothing is said about the scale system that's in the article that you posted, for instance. And we all know that it's correct, and that's why I started wondering why Mesa gave out "wrong" or misleading info about their coloring system. :?

 

[Murphy Slaw]

I ordered a quad of EL84's, and a Duet of 6V6's last Thursday, 8-16-07, and Chris told me they do NOT have different rated tubes, as I WANTED a harder tube (less breakup, longer life).

It's Thursday 8-23-07, and I haven't gotten them yet because they weren't gonna ship out till Monday, but will let you you all know if they are colored, ahem...., I mean...... you know what I mean.

Best of luck.

 

[Murphy Slaw]

Okay folks. Here's what I got.
4:EL84's in seperate boxes. No codes, no colors, no numbers.
A pair of 6V6's in a box that look EXACTLY like the Fenders I bought a while back. They have a Mesa sticker that says yellow.

Go figure.

But......

I also got my BOOGIE badge for my Blue Angel.

Life is good.

Best ya.

 

[Octavarius]

Okay folks. Here's what I got.
4:EL84's in seperate boxes. No codes, no colors, no numbers.
A pair of 6V6's in a box that look EXACTLY like the Fenders I bought a while back. They have a Mesa sticker that says yellow.

Go figure.

But......

I also got my BOOGIE badge for my Blue Angel.

Life is good.

Best ya.

Well, it's very possible they do not apply the ratings for EL84's and 6V6's... I don't know, but as I said, Marcus Daniel from Mesa CS recommended Red and Yellow colored tubes for my IIC+. So the color system is definitively there for EL34's and 6L6's.

However I'm still curious why they wrote that.

 

[JOEY B.]

Okay folks. Here's what I got.
4:EL84's in seperate boxes. No codes, no colors, no numbers.
A pair of 6V6's in a box that look EXACTLY like the Fenders I bought a while back. They have a Mesa sticker that says yellow.

Go figure.

But......

I also got my BOOGIE badge for my Blue Angel.

Life is good.

Best ya.

Well, it's very possible they do not apply the ratings for EL84's and 6V6's... I don't know, but as I said, Marcus Daniel from Mesa CS recommended Red and Yellow colored tubes for my IIC+. So the color system is definitively there for EL34's and 6L6's.

However I'm still curious why they wrote that.

As far as I know, the MESA EL-84's are not matched by color codes. I do know that Mike Beninelli said that the "red" 6L6 STR-440 is the only color code that they recommend for the outer sockets of a MkIIC+ Simulclass with the "105" power transformer. He even said that the original STR-415 Sylvania tubes were put to the test in the Class-A sockets of these amps. The other MESA amps may be much more forgiving to the tubes than the "105 Simuls". I have swapped the GT-6L6GE's from my MkI into the MkIIC+ during a test sequence, and you can SEE the difference between the MkI and the MkIIC+'s load on the same tubes. :shock:

 

[Octavarius]

Okay folks. Here's what I got.
4:EL84's in seperate boxes. No codes, no colors, no numbers.
A pair of 6V6's in a box that look EXACTLY like the Fenders I bought a while back. They have a Mesa sticker that says yellow.

Go figure.

But......

I also got my BOOGIE badge for my Blue Angel.

Life is good.

Best ya.

Well, it's very possible they do not apply the ratings for EL84's and 6V6's... I don't know, but as I said, Marcus Daniel from Mesa CS recommended Red and Yellow colored tubes for my IIC+. So the color system is definitively there for EL34's and 6L6's.

However I'm still curious why they wrote that.

As far as I know, the MESA EL-84's are not matched by color codes. I do know that Mike Beninelli said that the "red" 6L6 STR-440 is the only color code that they recommend for the outer sockets of a MkIIC+ Simulclass with the "105" power transformer. He even said that the original STR-415 Sylvania tubes were put to the test in the Class-A sockets of these amps. The other MESA amps may be much more forgiving to the tubes than the "105 Simuls". I have swapped the GT-6L6GE's from my MkI into the MkIIC+ during a test sequence, and you can SEE the difference between the MkI and the MkIIC+'s load on the same tubes. :shock:

And there you have it. Now the question is why they wrote that... :? Come on, let's make this a huge theory discussion thread!!

 

[Murphy Slaw]

So I'm guessing my two 6V6's, rated yellow are softer? Oh well, compaired to the Groove tubes 1-10, it's very little difference.

The EL84's didn't have any colors. Those tubes won't go in the amp for awhile anyhow, as it sounds great with the 7 year old stock tubes.

But I swear, 8/9 years ago I was using a Peavey Classic 50, 2;12 combo some when my Marshall JCM900 (4100) 1/2 stack was too much for smaller clubs, I replaced the EL84's from Groove tube 3's with Groove Tube 10's, because I wanted the clean channel to remain clean at the insane volumes that band played. Never had it biased, used it a lot, and sold it.

So I am surprised the EL84's aren't colored, numbered or whatever, but like I said, the stock ones sound great, I'm sure these will.

Best of luck.

 

[JOEY B.]

It looks as if the MESA EL-84's are only available as singles, therefore negating the use of color matching. The GT EL-84's are available as singles, a duet, or a quad with the standard GT number rating system. When my Weber Bias-Rite gets here, I will be doing some investigating of these color codes with 6L6 and EL-34 MESA tubes in the simul C+ combo.

 

[JOEY B.]

I did some testing with the "bias-rite" hooked to a simul C+, and came to these conclusions:

The Mesa tubes that I tested, demonstrated these readings with 480 volts on the plates.

STR-440 6l6 "red" - 17 mA inner sockets
- 44 mA Class-A sockets

STR-440 6l6 "green" - 20mA inner sockets
- 50 mA Class-A sockets

STR-447 EL-34 "green" - 17 mA Class-A sockets

STR-447 EL-34 "grey" - 23 mA Class-A sockets

The color codes are assigned to pair the tubes by the amount of idle current draw. There may be other factors as well, but this is most certainly part of it. The grouping is going to be very tight with maybe only about 15 mA difference of current draw from "red" to "whte"color codes, at the most.
I now understand why the "red" STR-440 6L6 is the only color that is safe to use in the Class-A sockets of a simul C+. Its 44mA idle current draw is at the 70% plate dissipation point. Any higher idle current would be risky. The EL-34's look to be a much cooler running tube in the outer sockets, but they are capable of only 25 watts of plate dissipation. This means that their safe idle current limit is around 36mA. I have seen a very slight orange glow in the center of the plates of the STR-447's when they are pushed hard in Class-A mode that goes away when the amp is switched into Simul-Class. Because of this issue, I think that Sylvania 6CA7's or GT 6CA7-GE's would be the best tube for the Class-A sockets of the C+, if one wanted that EL-34 flavor.


I found this great webpage for bias and wattage calculations

http://www.webervst.com/tubes/calcbias.htm

 

[Octavarius]

I did some testing with the "bias-rite" hooked to a simul C+, and came to these conclusions:

The Mesa tubes that I tested, demonstrated these readings with 480 volts on the plates.

STR-440 6l6 "red" - 17 mA inner sockets
- 44 mA Class-A sockets

STR-440 6l6 "green" - 20mA inner sockets
- 50 mA Class-A sockets

STR-447 EL-34 "green" - 17 mA Class-A sockets

STR-447 EL-34 "grey" - 23 mA Class-A sockets

The color codes are assigned to pair the tubes by the amount of idle current draw. There may be other factors as well, but this is most certainly part of it. The grouping is going to be very tight with maybe only about 15 mA difference of current draw from "red" to "whte"color codes, at the most.
I now understand why the "red" STR-440 6L6 is the only color that is safe to use in the Class-A sockets of a simul C+. Its 44mA idle current draw is at the 70% plate dissipation point. Any higher idle current would be risky. The EL-34's look to be a much cooler running tube in the outer sockets, but they are capable of only 25 watts of plate dissipation. This means that their safe idle current limit is around 36mA. I have seen a very slight orange glow in the center of the plates of the STR-447's when they are pushed hard in Class-A mode that goes away when the amp is switched into Simul-Class. Because of this issue, I think that Sylvania 6CA7's or GT 6CA7-GE's would be the best tube for the Class-A sockets of the C+, if one wanted that EL-34 flavor.


I found this great webpage for bias and wattage calculations

http://www.webervst.com/tubes/calcbias.htm

That's great. Did you do calculations on the EL-34's in Simul-Class and in Class A? Or only in one of them? They're supposed to draw more in Class A, I've heard.

Another thing... Do you know what differences the power tranny would pose here? As said, one of my Grey EL-34's went mad in Class A when I pushed it. Technically, by your calculations, the Grey tubes should be fine, but then I have the export tranny. And I remember that BB posted something about the plate voltages being different... Wait a sec., I'll find it.

When you look at the export transformer, it is basically from the IIB era and only puts 450-460 volts to the plates. The negative voltage is higher as the plate voltage is much lower than the 105. The lower plate voltage, the higher the negative voltage appears to bias the tube to the same level. Under load, the X-101 may only put 430-440 volts to the plates. Even if it had a stout tybe with a strong natural current draw, red plating an STR-447 may have more to do with it's design and internal shorts. The 105 is just a headroom beast and under a 35ma load still hold 483 volts to the plates.
In audible terms, the X-101 would provide a different harmonic spread than the 105 due to the lower plate voltage. The 105, however has superb attack, headroom and may be deemed less forgiving as it does not blur notes like lower voltage power sections. Now, since all of my Euro friends seem to have a monopoly on the export model, especiialy Swedes, Norwegians and cheeky Brits, I will have to be really nice to you guys and hope one is bequeathed to me in on of your wills. Octavarius's superb example has cost me a few nights of sleep.

Ah, here we go. From what he writes, it should bias the tube to the same level. But I'm still a newbie about biasing and such, so I don't get much of this. It would be very nice if you could help me out a bit here on calculating this.
:lol:

 

[JOEY B.]

That's great. Did you do calculations on the EL-34's in Simul-Class and in Class A? Or only in one of them? They're supposed to draw more in Class A, I've heard.

Another thing... Do you know what differences the power tranny would pose here? As said, one of my Grey EL-34's went mad in Class A when I pushed it. Technically, by your calculations, the Grey tubes should be fine, but then I have the export tranny. And I remember that BB posted something about the plate voltages being different... Wait a sec., I'll find it.

When you look at the export transformer, it is basically from the IIB era and only puts 450-460 volts to the plates. The negative voltage is higher as the plate voltage is much lower than the 105. The lower plate voltage, the higher the negative voltage appears to bias the tube to the same level. Under load, the X-101 may only put 430-440 volts to the plates. Even if it had a stout tybe with a strong natural current draw, red plating an STR-447 may have more to do with it's design and internal shorts. The 105 is just a headroom beast and under a 35ma load still hold 483 volts to the plates.
In audible terms, the X-101 would provide a different harmonic spread than the 105 due to the lower plate voltage. The 105, however has superb attack, headroom and may be deemed less forgiving as it does not blur notes like lower voltage power sections. Now, since all of my Euro friends seem to have a monopoly on the export model, especiialy Swedes, Norwegians and cheeky Brits, I will have to be really nice to you guys and hope one is bequeathed to me in on of your wills. Octavarius's superb example has cost me a few nights of sleep.

Ah, here we go. From what he writes, it should bias the tube to the same level. But I'm still a newbie about biasing and such, so I don't get much of this. It would be very nice if you could help me out a bit here on calculating this.
:lol:

From what I can get from his post, is that the lowering of the plate voltage (pin #3) along with the higher negative (less negative) bias voltage (pin #5) should keep the tube near the same current draw at idle. If one of the voltages is moved without moving the other in the right direction, the current draw will be greatly affected.

When testing my amp with the bias-rite, I tried flipping the Class-A switch to see if there was a noticable difference in idle current draw. I did not see any big jumps in the meter. I don't think it is a true Class-A circuit, and do not know about the current draw under load, yet .

Check page 4 of the MkIIC users manual for the correct negative voltages (pin #5) for your export simul.

 

[lesterpaul]

"true class A circuit.."-that is what I have wondered as well

 

[Octavarius]

From what I can get from his post, is that the lowering of the plate voltage (pin #3) along with the higher negative (less negative) bias voltage (pin #5) should keep the tube near the same current draw at idle. If one of the voltages is moved without moving the other in the right direction, the current draw will be greatly affected.

When testing my amp with the bias-rite, I tried flipping the Class-A switch to see if there was a noticable difference in idle current draw. I did not see any big jumps in the meter. I don't think it is a true Class-A circuit, and do not know about the current draw under load, yet .

Check page 4 of the MkIIC users manual for the correct negative voltages (pin #5) for your export simul.

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? :?

 

[JOEY B.]

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.