Do Mesa amps really need Mesa tubes?

Discussion in 'Ampage Area' started by Groutsch, Oct 20, 2019.

  1. Groutsch

    Groutsch Gretschie

    Jun 9, 2018
    Maryland, US
    I just got my first Mesa amp, the Mesa Boogie Express 5:50 (not the newer Plus version). The manual says the amp is designed to use Mesa tubes, so I don't need to worry my little head about tube specs or biasing. But if, hypothetically, I wanted to buy tubes from a company other than Mesa, should I specify anything besides the tube types, or adjust anything on the amp? I assume that the amp isn't too finicky about the 12AX7 preamp tubes, but I want to be careful about the 6L6 power tubes.
  2. Bertotti

    Bertotti Friend of Fred

    Jul 20, 2017
    South Dakota
    Funny I have been a lot pickier lately about my pre tubes than my power tubes. I do not have a mesa I just bias an amp after I put tubes in I want. If the mesa is capable of being biased I see no reason you couldn't use whatever brand trips your trigger. So can the amp be biased? A friend of mine has that amp I do not believe he has ever worried about the brand of 6l6 tubes he uses. His is in a rack mount road case. Sounds great!
  3. thunder58

    thunder58 Super Moderator Staff Member

    Dec 23, 2010
    tappan ny
    Admin Post
    I once went to a Mesa / Boogie Demo Night at a local music store . Mesa was giving tubes away ( 1 per person ) as door prizes to 3 lucky winner . The rep was talking way over the crowds head as you could tell most of the crowd was local High School kids or people who just didn't understand electronics at all . I picked up on a few things as I studied electronics for 2 years back in high school myself in the late 70's . Just found it to be an odd night / demo . Nice amps tho , seemed well built and loud too .
    FWIW - I'd rather have seen them give away T-shirts that night ( just sayin' )
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  4. Waxhead

    Waxhead Country Gent

    Aug 30, 2014
    No I have swapped tubes on both my Express 5:50 and Mark V.
    So have millions of other Mesa owners.

    The Manual is BS on that subject.
    They're just trying to convince people to buy their over priced chinese tubes is all

    Mesa don't make tubes and on the Express they put in cheap chinese tubes.
    As long as you use the same tubes types (not brands) there's no problem.

    Your Express 5:50 has 6L6 power tubes and 12ax preamp tubes.
    They'll be chinese tubes stamped by Mesa after they test them.

    You can swap in better quality Russian or Slovak tubes and it'll improve the tone quality on your 5:50 and reduce the hiss on the burn channel. And tubes from dougs tubes are better quality and less than half the price of Mesa stamped tubes.

    The Manual says that Mesa stamped tubes are tested and matched to each other. Yeah so what - every reputable tube seller does that.

    One great thing about Mesa though is the power tube sections in their amps don't need re-biasing when you put in new power tubes. You just slot them all in and play :)

    Dougs tubes also has recommended tube sets for Mesa Boogie amps - see here

    You can email Doug and he'll recommend a tube set specifically for your 5:50.
    I used his 5:50 tube set and they made a fantastic amp even better :)
    Last edited: Oct 20, 2019
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  5. loudnlousy

    loudnlousy Gretschified

    Oct 18, 2015
    Mesas have a fixed bias. So you cannot tinker with that. That said, you should use pairs of output-tubes that are matched to each other.
    You don´t neccessarily have to use Mesa tubes. There are other quality brands offering matched pairs.
    Remember that there are only a handful of manufacturers left building vacuum tubes (Russia, China). So you will basically buy the same tube just with another brand logo on it.
    The difference is the tolerances that are accepted by the different brands.
    Mesa can affort to reject hundreds of tubes just to keep a vew dozends that they will sell under their logo.

    From my experience Mesa tubes work great and sound great. I use them in two of my amps.
    wabash slim likes this.
  6. Waxhead

    Waxhead Country Gent

    Aug 30, 2014
    It not that simple actually.
    Look at the Dougs Tubes site and you'll find he stocks 15 different brands making power, preamp and rectifier tubes.

    Most of those companies make a few different models of 6L6, 6V6, EL34, EL84 and preamp tubes. The different brands and types have different tonal characteristics.
    Look at what Sovtek make for example

    You can get low gain, mid gain, high gain, low noise etc.
    Doug gives a description for most of them.

    Swapping in high quality tubes specifically to suit your amp and your personal tonal desires can make a big difference to any tube amp. They last longer also. I've done it on 12 different tube amps I've owned.

    Some people experiment with tubes like speakers and different guitars.
    Last edited: Oct 20, 2019
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  7. Bertotti

    Bertotti Friend of Fred

    Jul 20, 2017
    South Dakota
    Tubes and trying different ones is kind of addictive. I tried so many EL84 and would up with a military tube from Russia something like 6n1p or such. It has more ambient noise when sitting idle but the minute you pluck a string the harmonics are incredible. I have not tried as many 6L6 but recently switched from some so two I loved to something else that sounds even better to me! Give tubes a shot and rad descriptions first it can make quite a difference like changing speakers in an amp!
    Last edited: Oct 20, 2019
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  8. Synchro

    Synchro The artist formerly known as: Synchro Staff Member

    Jun 2, 2008
    Admin Post
    If these are fixed bias amps without and adjustment, then you have to match the characteristics of whichever tubes it came with, but there’s no reason to stay with Mesa’s branded tubes.
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  9. Robbie

    Robbie Friend of Fred

    Jun 17, 2013
    Sarnia Ontario Canada
    IMHO you do not need Mesa Tubes. On the base of the Mesa labelled 6L6’s there should be a small label showing they have gone through QC. There will, or at least should, be a color code as well. For example Green would be GRN. When you order the replacements and I’d suggest a Tube Depot, Doug’s or similar tell them you are replacing in a Mesa and model, and what the color code is. They will know immediately what other brand names match up to them.
    Last edited: Oct 20, 2019
    new6659 likes this.
  10. Bertotti

    Bertotti Friend of Fred

    Jul 20, 2017
    South Dakota
    Tue to a degree there is a range that will work if genuinely fixed bias, perhaps it is self-biasing? Like always a fixed bias amp can be made to an adjustable bias amp depending on how the circuit is laid out.
  11. Henry

    Henry I Bleed Orange

    Apr 9, 2014
    What @Waxhead said. I do suggest getting matched tubes from a reputable reseller (Doug's, euro). I like Doug's tubes. They have replacement packages ready and he is always available to answer questions.
    pmac11 likes this.
  12. markeebee

    markeebee Country Gent

    You don't have to use Mesa tubes, but whichever power tubes you use have to have a plate current that falls within a particular bandwidth, otherwise they might not bias properly and might sound icky. Ifs, buts, maybes, and quite probably marketing hype.

    Most reputable tube suppliers can give you tubes that meet the requirements, but they need to test them to be sure. There's a cost for that, and often it means that they'll end up being more expensive than the Mesa branded ones.

    As others have said, Mesa tubes are just tubes from a variety of different manufacturers with MESA printed on them. Having said that, I think it's fair to say that they generally source relatively decent quality tubes, they're not just the real cheapo ones.

    Unless you're really strapped for cash, or have a real objection to buying Mesa, or are a tube connoisseur that absolutely craves a certain brand, I'd suggest the hassle-free option might be to pony up the extra few pennies and get the Mesa branded ones.
    hcsterg likes this.
  13. markeebee

    markeebee Country Gent

    Just to be clear, if its possible to be clear.....

    In the arcane world of amplifier design, 'Fixed Bias' generally refers to a power amp topology where the bias voltage can be varied with a pot, it's not actually fixed. Generally speaking, more powerful amps go this route.

    Amps where you can just plug the tubes in without any tweaking are generally referred to as 'Cathode Bias' or sometimes 'Self Biasing'. These use a self-governing circuit which automatically sets the bias voltage according to the current draw of the tube. Usually, this is found on amps below 30 Watts-ish.

    Seems weird, I know. 'Fixed Bias' amps are actually the ones with a pot to vary the bias voltage.

    Mesa use a slightly different approach. Many of their amps use a 'Fixed Bias' circuit, which would normally mean you'd wiggle a bias pot in order to set the bias voltage to suit the tubes you're using. However, instead of a variable pot, they set the bias voltage with a specific fixed resistor. This means that you can't vary the bias voltage, and hence have to select tubes that will work properly at the bias voltage pre-determined by Mesa.

    Clear as beer :)
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  14. Bertotti

    Bertotti Friend of Fred

    Jul 20, 2017
    South Dakota
    very clear and I would be changing that resistor to a pot and adding a couple test points. Oh and you just reminded me I only
    Have two bottles of Guinness left!
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  15. swivel

    swivel Country Gent

    May 13, 2018
    "Fixed bias" amps are bias adjustable. Most Blond, BF, SF Fender amps are "fixed bias". The "Fixed Bias" mean it's not self biasing like a Cathode bias amp etc. You adjust it and it's "Fixed". You just either need to change a resistor or adjust a potentiometer to adjust bias.
    Evidently Mesa selects their tubes to fit in a range that works for their factory settings.
  16. stevo

    stevo Friend of Fred

    May 1, 2012
    Nope. Not as big a deal as he makes out. That being said, he selects tubes that are ideal for his settings. For instance, there is no biasing with preamp tubes - ever. So you can use any. But he does spec out lower microphonic preamp tubes so that you have less problem in the V1 position.

    For power tubes, it's more of a "thing", but not a big deal. I can say that My Mesas didn't sound any different when I used different tubes. Even NOS tubes didn't sound any more glorious.
  17. Hammerhands

    Hammerhands Country Gent

    Aug 26, 2011
    Last edited: Oct 20, 2019
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  18. stevo

    stevo Friend of Fred

    May 1, 2012
    The 5:50 has a fixed bias, but I'm pretty sure the LoneStar Special with EL84 has cathode bias.
  19. Synchro

    Synchro The artist formerly known as: Synchro Staff Member

    Jun 2, 2008
    Admin Post
    In the world of vacuum tubes, matching and labeling can become a business in its own right. Basically, that’s all that Mesa is doing.

    I agree with the poster that said people change tubes too often. Preamp tubes are all but immortal and power tubes can last a long time. I replaced the power tubes in my Twin, not because they were bad, but because the factory tubes were poorly matched. I bought a set of Groove Tube 6L6s which were, supposedly, made on the same tooling as RCA used. The set was beautifully matched and they are all biased nicely. The amp sounds great.

    You could find tubes for your Mesa that worked with the current bias built into the amp. You’d probably need access to a tube tester to be able to match a set. In every community, there is an eccentric that has a tube tester, and usually these, poor, crazy people are more than happy to break it out and do their thing. I know this, because in my local community, I’m the eccentric that has a tube tester.

    Every morning, at sunrise, I go out to the road and hold up a crude sign that says “Vacuum Tube Testing” waiting for someone to stop. A few weeks ago, some kids in an old pickup truck threw a rotten apple at me as they drove by, so business is picking up. :)
  20. Bertotti

    Bertotti Friend of Fred

    Jul 20, 2017
    South Dakota
    I change my tubes when they stop working. One day I turned on my xxx half stack hit a chord and halfway through the chord, silence. My voice, not so much. 4 6L6 aren't cheap but I was more than happy it didn't take put the power transformer that may not be common but it has happened.
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