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New Mesa D-180! Many questions!

Discussion in 'Amps and Cabs [BG]' started by slacker, Apr 15, 2003.

  1. slacker


    Nov 27, 2001
    Portland Oregon
    I just purchased a Mesa Boogie D-180. It is a very cool amp! The more I use it, the more I realize how very little I know about it.

    My first question: Will it take the same power tubes as my 400+? I know it takes 6L6 tubes, I mean will I be able to swap tubes back and forth between the two. I am using Svetlana 6L6's from Lord Valve in the 400+, The 180 has twenty year old Mesa 6L6's that are going microphonic.

    Question two: Exactly how does the "Master" volume work. I know you must turn the "Master" up to ten when playing bass through the 180 for headroom. What does Mesa mean by variable current limiter, which is how they describe the "Master" in the D-180 manual? How is this different? The crazy thing is, when tapping the 6L6's to test for microphonic tubes, four out of six give a loud "WHOOOM", but only when "Master" is set lower than ten. When turned up all the way, the amp does not exhibit any (or very little) of the "WHOOOM " sound. Why would this cause the microphonic sound to disappear when the amp is cranked?

    Question three: Which preamp tube/tubes is/are responsible for the heavy distortion when using "Input 1". I suspect it to be the 12AT7, which appears to have a tiny little transformer all to itself. Does anyone have any recommendations as to what tubes to use in the preamp? I am looking to "voice" the amp. I need a little more bass.

    Question four: Am I correct in assuming the power tubes to be at fault? The "WHOOOM" sound is generally associated with power tubes, yes? It is a little hard to tell, as the panel that holds the tubes is a little "springy" and makes it difficult to isolate a single tube.

    Could I swap in six Svetlana's from the 400+ for just a short period (10 minutes) to bench test?

    Thank in advance!

  2. stevekim


    Feb 11, 2000
    los angeles, ca
    hi pete,

    congratulations! i've got the same amp not too long ago. i'm sorry i can't answer all your questions but i do know that the tubes from the 400+ will work in the d180. i have mesa preamp tubes and mesa str-454 tubes in my d180 and i think it sounds great. i never had a problem with the power tubes being microphonic, but i always have the master on 10. when you get a chance, i would love to hear a comparision between the 400+ and the d180!


  3. slacker


    Nov 27, 2001
    Portland Oregon
    Hey, Steve!

    Yup, we got us a D-180 mini-cult goin' on here! Don't a few other TB'ers have 'em too? I know notduane used to own one, also. If anyone else is looking, I may be able to find more. Basstriaxis, looking in your diection;)

    My initial findings: This is *the* head for overdrive fans. It can be much dirtier than either the 400 or 400+. At low gain (3-4 in input 2) it sounds almost exactly like my 400+. Turn the gain up though, and it has a lot of overdrive. Much more than my 400+. Plug into input 1 and hold on to something solid. It sounds a little like my Z. Vex Mammoth. FUZZ BASS!!!

    The 400+ has a little more in the low-end department. The 180 tone stack seems to be a little more harsh at some settings, but not in a bad way.

    400+: Deeper, fatter, slightly overdriven, bell-like quality.

    D-180: Honkier, slightly leaner, overdrive all day long. I hate to bring it up, but this will give any old SVT a run for the money. Not that they sound alike, but rather it fills the same "sonic space" as an SVT would, if that makes sense.

    A much overlooked piece of gear.

    I am still waiting to try it in a band setting. It is 100% overkill for the home office it now sits in.

    Honestly, I think this will become my main amp, and the 400+ will be back-up.
  4. stevekim


    Feb 11, 2000
    los angeles, ca
    caca de kick and mthoople have one too, i believe. i agree with you about the d180's sound. i can't tell you how many overdrive boxes i've bought trying to get this sound the mesa d180 gets. once i got the mesa i promptly sold all of my overdrive pedals. i like the master on 10 and volume 2 on 5 or 6 - clean when you want it but gritty when you dig in.
  5. slacker


    Nov 27, 2001
    Portland Oregon
    One of the things I really appreciate about the D-180 is distortions touch sensitive nature. This is lacking in many of the pedals I have also.
  6. Caca de Kick

    Caca de Kick Supporting Member

    Nov 18, 2002
    Seattle / Tacoma
    A D180 cult...? I love it!

    I've had mine for 10yrs now and I just can never see getting rid of it. It serves me reliably and oozes tone forever.

    But to answer your question; yes they take the same 6L6 tube as your plus.
    On mine, I always use channel 2 only, and my master knob is always up at 10.
  7. notduane


    Nov 24, 2000
    juhh? :confused:

    I still got mine.

    Whaddya' think, I got married or sumpin? :D
  8. I bought one new in 85' and sold it in 2000,wish I had not done that now.But the new owner lives close to me and I may approch him about buying it back from him someday.:(

    murdockbass likes this.
  9. brianrost

    brianrost Gold Supporting Member

    Apr 26, 2000
    Boston, Taxachusetts
    The master works funny if you have the wrong preamp tubes in there.

    When I got my D-180 someone had four 12AX7s in there (one should be an AT7). On mine the tube sockets were marked with Dymo labels :rolleyes:
  10. Benjamin Strange

    Benjamin Strange Commercial User

    Dec 25, 2002
    New Orleans, LA
    Owner / Tech: Strange Guitarworks
    D-180 cult? :bawl: Secret handshakes, code words, midnight virgin sacrafices? Sounds like fun; I wish I could join. Perhaps I can have an honorary membership until I score one? Let's see how I can further the cause of the D-180 clan:

    #1. I would change every tube in that sucker. I second stevekim's suggestion of Mesa's STR 454's (Svetlanas). I have them in my Coliseum 300 and they sound much better than the 430's that were in there before. Much punchier, more headroom, and better bass.

    #2. The way I understand it, your master almost acts like a gain when you turn it down; you lower the headroom on the power section, which overdrives the tubes, thus you hear the "WHOOM" when you tap on them. If they are 20 years old, do yourself a favor and change them.

    #3. Usually preamp tubes serve double duty; they have two sides, and each side works for a different function. I believe that V1 is the tube for your input 1 stage (Usually the tubes are in order left to right if you are looking at the front of the amp, but don't hold me to that.). My Buster is supposed to be very similar to the D-180, so take a look at the tube chart for that if that helps. 12AT7s and 12AX7s can be used interchangably, so I would use what sounds best in that spot. 12AX7s have more will break up easier than a 12AT7 (12AT7s are usually used to drive reverbs and FX loops); I'm not sure what Boogie used in those originally, sorry!

    #4. Yeah, I think the "WHOOM" is your power tubes. You can swap them back and forth as a bench test, but if they are 20 years old, it would probably be just a waste of time. Just change them.

    Great amp, Pete! Just a little love on your part could go a long way to make that amp shine! Make sure you guys save some virgins for me; I'll be joining the cult soon enough![​IMG]
  11. Since he said the amp has the original Philips 7581's in there, Svet's would be a step DOWN in quality, power, and headroom. There is NO reason to replace the preamp tubes, either. The "whoom" is related to the way the master volume works and is not a sign of bad tubes. Mesa doesn't need the money and I seriously doubt those tubes need swapping.

    There are several different ways of implementing a master volume in a tube amp. To my knowledge, only one, Kevin O'Connor's power scaling, actually limits the amount of current the power supply delivers to the output devices. Besides, lower B+ actually makes it HARDER, not easier, for the tubes to be overdriven. You're not going to find better tubes than the power tubes that are already in there. The Philips 7581 is THE standard that all 6L6GC's are judged against.

    A 12AT7 is slightly lower in gain than a 12AX7 and can handle more plate current. They're used as reverb and FX drivers because they can handle the already preamplified signal without distorting.

    Ummm, :rolleyes: NO! Those are good tubes and while dying tubes can often exhibit current outrushes, the fact that they only occur when the master volume is set less than "10" indicates a problem with the amp, not the tubes.

    The ONLY time to worry over changing tubes is when their performance affects actual usage of the amp. ALL power tubes will "whoom" to some degree when tapped while in operation. You're helping to "knock" electrons off the cathode which momentarily spikes the plate current. Unless you're hearing that noise while you play, don't trash good tubes!!!

    If you really belive there is some problem with the amp, let a tech put it on the bench. If he finds a problem, you can head it off before it becomes more serious. If not, then he can explain what exactly is going on and give you some peace of mind.
  12. Benjamin Strange

    Benjamin Strange Commercial User

    Dec 25, 2002
    New Orleans, LA
    Owner / Tech: Strange Guitarworks
    Hmmm, I notice better performance when I change my old tubes, just like I notice better tone when I change my old strings. I would think after 20 years those tubes could do to be changed....:meh:
  13. That's almost a straight quote from Groove Tubes adversting bull$hit. I know you're not pushing GT or anything, but suffice it to say, it's a misleading statement designed more to sell tubes than offer any actual help to an amp owner.

    The reason you noticed better performance when you changed your Mesa tubes is that you have newer Mesa equipment which come standard with Chinese trash. Early Mesa products USED to only feature top quality US and European tubes (the Philips 7581 was made in what is now the Ei plant in Serbia) , but as the costs went up in the early 90's they switched to imported junk while continuing to preach the virtues of "their" tubes. The whole "testing system" is a crock designed to help Mesa sell tubes, not improve reliability among them.

    I had a BRAND NEW Mesa 6550 short out dead in the tester. There is NO way that tube was screened in any way shape, form or fashion. In order to cause a tube to short you have to shock it with vibration strong enough to cause the internal parts to come in contact with each other and usually only happens when the tube is operating and the parts are more mobile due to heat expansion. If that tube had ever been fired up by Mesa prior to my receiving it, it would have done the exact same thing in "their" tester. It was bad from its factory.

    How often do you "retransistor" your s/s power amps? You'd figure they need it too, since tubes and transistors have equivalent service lives. Good tubes last decades.
  14. slacker


    Nov 27, 2001
    Portland Oregon
    Thanks for all of the input, fellow cultists.

    Questions and clarifications:

    1) While tapping, ever so lightly on the tubes, two began to glow bright red. This only happend once, with the master and both gains on ten and no signal running into the amp. This has never happened while playing.

    2) Shall I assume other D-180s make the "WHOOM" sound when tapped? Even when the case is tapped?

    3) Just for peace of mind, will it be okay if I swap in the fairly new Svetlalas from my 400+, just to see if there is any difference in tone or function? This is my primary question at this point, hence the bold! I know Mesa has a (supposedly) tight spec for tubes to be used in their bass amps (a fixed bias issue), should I assume they are 100% interchangable?

    4) PBG? Do you have direct experience with this amp or are these generalizations? It is an odd bird, not evactly like the 400 or 400+. Just curious. No offense meant. I would be happy to shoot you a schematic if I ever get one. BTW, I don't plan on changing anything unless it fails 100% wich has happend a grand total of once in almost twenty years of playing with all tube gear.

    5) I did change the power tubes in my 400 after about the first four or five years. I did notice a change in tone. More defined, less mush. The difference was pretty slight, however. Might not have been worth the $$$!

    6) I live in a college town, I don't think there is a virgin over the age of thirteen. Maybe we can sacrifice goats!

    7) This amp has benn babied. I purchased it from the original owner. It has sat in his garage for well over half of its life. The pots and eq sliders still feel stiff as new. I did have to replace the fuse holder, it was broken in shipping. I had it gone over be a tech when it recieved it. Had him look for broken/cold solders etc. Unless he missed something, I doubt there is anything wrong with the amp.
  15. slacker


    Nov 27, 2001
    Portland Oregon
    Hey, Basstriaxis!!!

    I have a line on a couple of D-180s! One with eq, one without. Are you intersted? Contact me off-line!
  16. I suspected this. You're pushing the tubes off their axis enough to interrupt the flow of bias current through the grid pins when you tap them. The "whoom' you hear is the tube momentarily going into runaway. Clean your sockets and check that the socker solder connections are good. That might be your whole problem.

    It's not a fault of the amp's design. It's a maintainence issue.

    No! Even with their crap, BS rating system, they do at least spec tubes according to current draw and just because they're both bass amps doesn't mean that they are even remotely similar in draw!!! You can NOT do what you are asking unless you have the ability to verify that they have the same current draw. If the Svet's from your 400+ require more bias current than the 7581's, you will toast your amp.

    There's only so many ways you can build a push/pull output stage.(AB, AB1, AB2) The differences in tone come from the preamp. The way output tubes behave is a function of output topology and there is nothing weird that would work at all, especially in a production amp. It doesn't matter whether it's this amp, a Bassman, a 400+, or an SVT, the trouble you are experiencing would be the same in all of them.

    I'd appreciate a skit. Might try the preamp on the front of UL Bassman and see how it sounds.

    Was the amp rebiased for the change? It sounds like the second set of tubes bias current draw more closely matched what the amp fed them. If you still have the original tubes, I'll bet they're still 100% on tester. That is precisely why Mesa's "ratings sytem" is crock; there was enough difference between the two sets for you to be able to hear it. The change had to do with amp not being set up for the tubes, not the quality of the tubes themselves.
  17. slacker


    Nov 27, 2001
    Portland Oregon
    I also plan to ask Lord Valve if they are interchangeable. He has a pretty good track record as far as Mesa tube swaps are concerned. The Svetlanas in my 400+ were purchased from him by the previous owner. He knew immediatly which current draw/tubes would/would not work in the circuit. His rating system seems to be 1000% more thourough than that of Mesa's. Since he sold the tubes, and they work flawlessly, I figure he has a decent idea about their current draw. He is cheaper than most tube suppliers out there also!

    The amp was not re-biased. As you know (and I think you do) Mesa bass amps have a fixed bias. Changing the bias would require a mod of either a resistor or adding a pot, so bias could be adjusted for any tubes. I have spoken with a tech about this before.

    Once again, much of this discussion is theoretical. Barring any major malfunction, I will not be playing around with the D-180.

    Thanks for the "heads up".


    P.S. Have you guys recorded anything else lately?
  18. Benjamin Strange

    Benjamin Strange Commercial User

    Dec 25, 2002
    New Orleans, LA
    Owner / Tech: Strange Guitarworks
    It seems odd to me that a company as respected as Boogie would use bogus information to push tubes. They are not primarily a tube seller; they make amps. Why would they risk their entire reputation of a fine amp manufacturer by lying to the public about tubes. I don't get it. It almost makes me want to get a degree in engineering just so I can get to the bottom of it. Any suggestions on some unbiased books I can read on the subject?

    By the way, Boogie used to use Chinese 6L6s until they deemed them unreliable. Everythin now comes stock with STR430s, which are Russian Sovtek tubes.
  19. Boogie, like a lot of companies, knows that advertising can build up more of a rep than quality ever could. Look at Wayne Jones, awesome cabs, but the guy's struggling to stay in business. Groove Tubes and Boogie hedge their bets and don't outright 'lie.' They give information that implies A=B and then say B=C, leaving you to fill in the gap that A=C, when in fact they don't. Here's what I mean:


    As far as books: the RCA Receiving Tube manual from years 1970 - on, any of Kevin O'Connor's books, and Navy and Air Force radio repair guides form the 50's are good places to start.

    The old band is pretty much finished for a number of reasons. I go tonight to audition for a signed band.
  20. slacker


    Nov 27, 2001
    Portland Oregon
    Sucks, I kinda dug the stuff you had on MP3.com. Good luck tonight!