This is going to sound like a stupid question but it would be more stupid to experiment without knowing the risks involved. I have a 1984 Mesa Boogie Mk 2c+. I had my amp serviced last year and I was very pleased with the work. The technician replaced all the pre amp tubes, Mesa 12ax7's, with the same brand tubes and the two power tubes, Ruby 6L6's, were traded for Tungsol 6L6GC STR's. The Ruby's that were in the amp were not defective, I had them replaced since all the pre amp tubes had been; I held on to the Ruby's.
Earlier today I decided to swap out the Tungsol's with the Ruby's to see (hear) what, if any, discernible difference there might be. I did hear a difference, one that I don't care for. The Ruby's are significantly "brighter" ...I prefer a "warmer" mellower tone. I also noticed that I got feedback with a lot less volume; for what this is worth, I'm a harp player. (oooo I can already hear the collective cringe! ...it's about tone not volume.) So that's good to know and that was the good news, the bad news is I broke one of the Tungsol's pulling it out of the socket! :/ So the Ruby's are back in whether I want them or not but I will be replacing them soon.
Now I'll expose my ignorance, naivete and general lack of knowledge about such things. I know from previous study that tubes have to be "matched" for something, not sure what or even what gets matched but I followed instructions and buy my power tubes in "matched" pairs. But now I'm very curious about what would happen if I paired up the Ruby and the Tungsol?! I've been a "tone chaser" well before I even knew there was a name for it. However, this curiosity is not going to kill the cat or my Boogie and is one "tone experiment" I will not personally be conducting! So wizards, please and thank you, what's the skinny on mismatched tubes. thanks again
Earlier today I decided to swap out the Tungsol's with the Ruby's to see (hear) what, if any, discernible difference there might be. I did hear a difference, one that I don't care for. The Ruby's are significantly "brighter" ...I prefer a "warmer" mellower tone. I also noticed that I got feedback with a lot less volume; for what this is worth, I'm a harp player. (oooo I can already hear the collective cringe! ...it's about tone not volume.) So that's good to know and that was the good news, the bad news is I broke one of the Tungsol's pulling it out of the socket! :/ So the Ruby's are back in whether I want them or not but I will be replacing them soon.
Now I'll expose my ignorance, naivete and general lack of knowledge about such things. I know from previous study that tubes have to be "matched" for something, not sure what or even what gets matched but I followed instructions and buy my power tubes in "matched" pairs. But now I'm very curious about what would happen if I paired up the Ruby and the Tungsol?! I've been a "tone chaser" well before I even knew there was a name for it. However, this curiosity is not going to kill the cat or my Boogie and is one "tone experiment" I will not personally be conducting! So wizards, please and thank you, what's the skinny on mismatched tubes. thanks again
Matching is used so the valves take the same amount of current.
This is more important for output pairs than singles.
You wouldn't want one valve to take most the current and the other one a smaller amount. It could end in reduced life of the over stressed valve.
Some designers cheat and just use one cathode resistor on a pair of tubes.
If the tubes aren't matched one valve will take most of the current.
I always use separate cathode resistors in my designs.
This is more important for output pairs than singles.
You wouldn't want one valve to take most the current and the other one a smaller amount. It could end in reduced life of the over stressed valve.
Some designers cheat and just use one cathode resistor on a pair of tubes.
If the tubes aren't matched one valve will take most of the current.
I always use separate cathode resistors in my designs.
First, this is a guitar amp, the thread belongs down in the instrument amp section.
This amp has fixed bias, just FYI.
Fender, Marshall, Peavey, and yes, even Mesa, are not using matched tubes, they build them on a line, and when it comes time to install a pair of tubes, they reach into the bulk box and pick two (or four).
We like matched pairs because they are best at cancelling out power stage ripple. Having both sides of a push pull the same is a great goal, but for that to maximize fidelity or anything else, it assumes all the rest of the power amp is similarly balanced. The phase inversion, the grid resistors, the screen resistors, etc. They rarely are.
The output transformers are robust, and really won't care if there is some small imbalance in tube current. When it comes to signal, the push and the pull really can't tell if they themselves are imbalanced or if the signal waveform itself is not symmetrical.
I respectfully point out that these output tubes are not in parallel, so there is no current hogging.
Ruby sells a number of 6L6 tubes, so there is not one Ruby 6L6. They sell their 6L6GCMSTR, which I have found to be a sturdy reliable tube in guitar amps. But they also sell JJs and Sovteks and others labeled as Ruby.
If you put a Ruby and a Tung Sol in the amp as a pair, the amp will work. You may or may not notice some tonal differences, just as you already did comparing the two brands. Keep in mind your comparison was between new Tung Sols and old Rubys. But regardless, it will not harm the amp to mix them.
When you bias the amp (And if I recall, the Mark 2C+ is not adjustable anyway) you are setting the idle DC tube current. ANother good goal, but not all output transformers have the same DC resistance between CT and plates. That affects idle current. Tubes that may misbalance that way still may process the signal symmetrically.
This amp has fixed bias, just FYI.
Fender, Marshall, Peavey, and yes, even Mesa, are not using matched tubes, they build them on a line, and when it comes time to install a pair of tubes, they reach into the bulk box and pick two (or four).
We like matched pairs because they are best at cancelling out power stage ripple. Having both sides of a push pull the same is a great goal, but for that to maximize fidelity or anything else, it assumes all the rest of the power amp is similarly balanced. The phase inversion, the grid resistors, the screen resistors, etc. They rarely are.
The output transformers are robust, and really won't care if there is some small imbalance in tube current. When it comes to signal, the push and the pull really can't tell if they themselves are imbalanced or if the signal waveform itself is not symmetrical.
I respectfully point out that these output tubes are not in parallel, so there is no current hogging.
Ruby sells a number of 6L6 tubes, so there is not one Ruby 6L6. They sell their 6L6GCMSTR, which I have found to be a sturdy reliable tube in guitar amps. But they also sell JJs and Sovteks and others labeled as Ruby.
If you put a Ruby and a Tung Sol in the amp as a pair, the amp will work. You may or may not notice some tonal differences, just as you already did comparing the two brands. Keep in mind your comparison was between new Tung Sols and old Rubys. But regardless, it will not harm the amp to mix them.
When you bias the amp (And if I recall, the Mark 2C+ is not adjustable anyway) you are setting the idle DC tube current. ANother good goal, but not all output transformers have the same DC resistance between CT and plates. That affects idle current. Tubes that may misbalance that way still may process the signal symmetrically.
First, thank you so much for clearly explaining the why and the wherefore of "matched" power tubes. Thank you more for taking the extra time to educate me about the other factors involved, this is most helpful. Second, it felt like a tube question to me and this seemed the appropriate place. I added info about the amp based on my standard belief that the more info one can provide, the more helpful the helpER can be, but I understand. I should not be brand new to what you've told me given how many years I've been using this amp but despite being brand new to this site I should have been more attentive to the set up and various categories provided; I apologize and will be careful not to repeat that error.
Yes, you are correct and I am aware that the Meas Boogie has a fixed bias and no adjustment is either required or available. I assumed :/ or rather trusted that all manufacturers of tube amps were faithful to using matched tubes as a matter of course, this too, good to know. Also, very good point regarding the age of the tubes, I hadn't considered that. For the record, the Ruby's I have are the 6L6GCMSTRs and I was pleased with them before getting to compare them with the Tungsol's. I guess I'll never know really, to what degree the "age" factor plays but regardless, I liked the Tungsol's better so I'll be going back to those. I'll let you know if I notice any tonal difference using the mixed brands but that won't be before having a new set of Tungsol's ready to install. Hopefully I won't make the same mistake or a new one, which lead me here in the first place. It seemed logical that using the different brands would not cause damage but as I am so ignorant about so much of how the whole amp works, it seemed smart to ask if I had the opportunity. I found that opportunity here and your response was/is really helpful, so again, thank you very much for your time and advice, it is most appreciated.
Yes, you are correct and I am aware that the Meas Boogie has a fixed bias and no adjustment is either required or available. I assumed :/ or rather trusted that all manufacturers of tube amps were faithful to using matched tubes as a matter of course, this too, good to know. Also, very good point regarding the age of the tubes, I hadn't considered that. For the record, the Ruby's I have are the 6L6GCMSTRs and I was pleased with them before getting to compare them with the Tungsol's. I guess I'll never know really, to what degree the "age" factor plays but regardless, I liked the Tungsol's better so I'll be going back to those. I'll let you know if I notice any tonal difference using the mixed brands but that won't be before having a new set of Tungsol's ready to install. Hopefully I won't make the same mistake or a new one, which lead me here in the first place. It seemed logical that using the different brands would not cause damage but as I am so ignorant about so much of how the whole amp works, it seemed smart to ask if I had the opportunity. I found that opportunity here and your response was/is really helpful, so again, thank you very much for your time and advice, it is most appreciated.
mmmm Harp Tone
that Elusive tone we're all looking for (fellow harp player and amp builder). Darker the better sounds good and less feed back.
so long as the tubes are same voltage specs I.e 2x6l6 about all that's really going to happen is a bit more hum. as for tube life, if your giging around the bumps and knocks will do more damage than a miss matched tube.
my "big red" 50 watt combo sounds just they way I want. but it has a 60 year old brimar 6sn7 as v1 not a nos, used for about 25 years (it does change the tone) butiful cleans all the way to grundgey blues when over driven, when it finally goes pop I will problly cry🙁 lol😀
that Elusive tone we're all looking for (fellow harp player and amp builder). Darker the better sounds good and less feed back.
so long as the tubes are same voltage specs I.e 2x6l6 about all that's really going to happen is a bit more hum. as for tube life, if your giging around the bumps and knocks will do more damage than a miss matched tube.
my "big red" 50 watt combo sounds just they way I want. but it has a 60 year old brimar 6sn7 as v1 not a nos, used for about 25 years (it does change the tone) butiful cleans all the way to grundgey blues when over driven, when it finally goes pop I will problly cry🙁 lol😀
Hey Arctic Breeze; growing up in northern Maine I can relate to that "breeze" ...thank you for your response. Re the mixed tubes; I'll mixed 'em up just to hear what it sounds like, I just needed to be sure that wouldn't 'cause me any trouble. But I will be putting in a matched set of something within the week. So far that "something" is the Tungsol 6L6's. That said however, I was just reading about Tungsol 6v6's that reportedly give a darker sound; do you know anything about that tube? I can dial in all kinds of bright and shimmery if I think the sound is too dark but I don't have much room the other way... dark gets muddy very quickly. Also if you are aware of another brand tube known for dark, I'd be pleased to hear about that. Thank you again for your response! peace
p.s. hoping for no tears for several years
p.s. hoping for no tears for several years
interesting I personally have never herd 6v6's that were darker than 6l6's, I am running JJ 6l6's in Big red and a set of real old rca 6l6's in my 5e3 based amp, I changed the cathode resistor to match only get 20watts but quite dark and brakes up nice as plate voltage is lower than for a 6l6.(this amp is all Chicago honk @ the moment will not do a clean sound due to an over driven preamp)
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