Mesa 400+ Question

Discussion in 'Amps and Cabs [BG]' started by jugdish, Sep 6, 2000.

  1. jugdish


    May 25, 2000
    Orange County
    I just got this amp and in the directions they mention running the A/B box for switching between inputs. Can this be done with an active bass? Thanks a lot.
  2. timv

    timv Supporting Member

    Jun 7, 2000
    Chandler, AZ
    Yeah, that will work fine. They say that channel 1 is more for active basses cause it has slightly less gain than channel two but both will work fine. Just don't turn the preamp volume up to the point of distortion and you'll be fine. Is this a new one? I have an 89' model that has a 6 band eq instead of the 7 band and have had for 4 years or so now. It is a really nice head, costs a bit to retube and to recap but if yours is new you won't have to worry about the caps for a while. Have fun.
  3. jugdish


    May 25, 2000
    Orange County
    Yah I got it new but so far I love it. Just the instructions are a little vague. Thanks for the help.
  4. Well the A/B-ing can not be done by tha bass.. you need an A/B box for it, but as timv said you can run your bass in either input 1 or 2, if you try them out you will find that they have different sounds. I run my Sterling (active) in input 1 since I like the cleaner sound of that one. And it is ok to gain it up so it distorts.. after all it is a tube amp right? Add some dirt to your sound :) So just play it and enjoy all sound possibilities it can offer. Those are quite a few, by the way Les Claypool plays one of those. How much did you pay and where (in the world) was it? Just curious.. Because here in Sweden they are VERY expensive, but I got mine used for almost half the price of it new.

    By the way while you are on your amp could you do me a favour? I was wondering if you play it and turn up the effects blend knob on the back with no effects attached, does the amp distort the sound? (gain up to just under distortion and eq engaged) Mine does and I dunno why?

    Oh well dont forget to turn it back after you tried that if you try it.

    Anyway enjoy your amp, seeya!

    [Edited by Mesa Man on 09-06-2000 at 02:01 PM]
  5. timv

    timv Supporting Member

    Jun 7, 2000
    Chandler, AZ
    You can use just the power amp of the head by doing exactly what you said but running a preamp into the effects return jack. I'm guessing w/ out anything running into it you are just creating distortion by overdriving the signal. I'm not sure how exactly cause i don't have the schematic in front of me. Maybe messing up the bias on the tube following it or something like that. Yeah, it is a tube head but when i turn up the preamp gain on mine at least, the distortion doesn't sound very good. It is preamp distortion which usually isn't as pleasing. I guess mine may sound different w/ different tubes in the preamp. I got mine for a good price used also. It was $500. Any more questions i can try to help.
  6. Well 500$ is cheaper than what I payed for mine, but nevermind. :) The reason why I asked if the amp distorted when you just turn up the blend knob without effects attached, was to see if the distortion comes from the amp. The blend knob doesnt do anything else but adjusting the amout of signal coming back to the amp from the send jack. That is not supposed to distort, I think. I mean there is no amplification whatsoever since I have no effects attached right? This is my problem. So now if I got to hear from another owner how his works, it would be of great help.

    Oh did mention that it distorts with effects too? This is why I want to know if anyone else has this problem. And since it distorts wothout effects, its freaking me out. But if i turn blend down to 0 its just fine without distortion.

    But I run the effects in front of the amp instead, going to the inputs as usual. (no looping, even if I want to..)

    What tubes you got in it (pre and power) I run 5881's for power, but the newer ones run 6L6's. 12AX7 for pre I think.

    Ok see ya!
  7. timv

    timv Supporting Member

    Jun 7, 2000
    Chandler, AZ
    Mine has the 6l6's i think. It has a mixture of the mesa power tubes that came with it when i got it and a couple sovtek. i need to retube it cause they are mismatched and old. I heard that svetlana 6l6's sound great in this amp and hold up to the high plate voltage that it has. They aren't too horrible as far as price either. I think 12 will be like $180. I'm going to add adjustable bias to each half of tubes also so i can adjust the bias for the push and pull seperately. I'm not sure when i'll do that though cause i'm not using it much right now. Don't have a band and i'm using my SVT now. My wife plays violin through the mesa though. That doesn't sound right that it distorts with effects though it either. Are they stomp box effect, or effects units? Some effects loops don't like floor effects boxes cause of mismatch levels. Maybe i'll try that on mine and let you know. Maybe tonight if i can.
  8. Well I would NOT go with anything but Mesa tested tubes in my amp! I mean you dont go buy some ****ty low price budget LADA parts to put in your BMW right? Plus there is a point in not having adjustable bias, you can check it out at: I know that most tubes are made at the same place, but the ones tested by mesa can stand up to their quality standrads.. see it as if they care about you as a customer. But still it is up to you, I just dont see the point.

    Now back to the effects problem.. I dont think that level mismatch is the issue here, since it distorts even when I dont have any effects attached to the loop and turn up the blend knob, this is how I figured out that it couldnt be mismatching.

    Violin, welll that should work just fine! My advice put back Mesa original tubes in it and you will be amazed once more. I have heard from Mesa's customer service that the STR 425-5881's sound better. But really dont know. I like mine.. oh well see ya!
  9. timv

    timv Supporting Member

    Jun 7, 2000
    Chandler, AZ
    Actually, they don't put adjustable bias on their amps so people don't fool around with it when they don't know what their doing and they bias it to run slightly cooler to make sure the tubes don't fail right away. They also do that to fool you into just buying their tubes which are way too overpriced but if you want to buy the mesa tubes, go right ahead. They buy all the same tubes that other suppliers do and put their name on them and put them through their testing to match them. Most other suppliers do the same but charge less. Lord Valve is one person who sells tubes and matches them and even offers to match them to mesas specs so you can put them right in your mesa amp. To get the most out of your tubes and amp it is best to rebias your amp every time though. Mesa is basically the same as groove tubes and they charge a little too much for their average tubes. I'm not trying to piss you off at all and if i did i am sorry. I am just stating the facts. I'm not a mesa basher, i love my 400+ too but i've had mine longer and had to fix things in it so I know their are certain mechanical things that could be built better. The circuit boards are fairly thin and the traces and barrels through the board rip out very easily. I work at an electronics manufacturing place and see circuit boards every day so i have an idea of what a good circuit board looks like. But, too each his own. Just throwing out the other view of their tubes and amps.
  10. killer B

    killer B

    Apr 18, 2000
    Phoenix, AZ USA
    I also have a bass 400+ and I don't get any distortion from the effects blend, unless I'm overloading my FX unit. I don't see why you would turn up the blend if you don't have any FX attached, but I tried this last night and I got no distortion, so something must be wrong.

    As for MESA tubes I just re-tubed mine a little while ago and it now sounds better than ever. I don't really buy all this MESA/Boogie use cheap tubes crap. I mean I've never gotten better support or service from an amp company. So it just doesn't make sense that they'd skimp on the tubes. Their gear is near indestructable and always sounds great. But what ever works I guess.

    Any of you Bass 400+ owners ever try using both inputs at the same time, like from the stereo out of a chorus pedal? You can get some pretty interesting sounds that way.
  11. timv

    timv Supporting Member

    Jun 7, 2000
    Chandler, AZ
    I'm not saying that mesa doesn't build nice sounding amps and that their tubes are complete crap, just that they aren't as good as they make them out to be. Here's a link to some more mesa tube talk.
    It probably sounds better cause the old tubes were old. My head has blown fuses and tubes a few times and I had to repair an internal broken wire. Also, mine is and 89' model and i haven't seen any newer ones internally so i may be going on about some issues that are only in my particular amp since it is older. So maybe i'm just being biased w/ my limited experience w/ just my head. So, i apologize is it sounds like i am saying your amps and tubes are crap when i don't believe they are.
  12. No timv, Im not offended at all. And of course they charge more for their tested tubes, why wouldnt they? I mean this is not the world of charity we are in. My point was, to keep your amp running with the mesa specs, just use their tubes. But its really up to the user what to use. Do as you wish, I just have this Lada versus BMW comparison in mind. They might aswell be using the same parts just that the BMWs are tested. As a matter of fact, there is a brand of motorcycles in Ukraine named Dnepr, which are exact BMW copies.. but they are not BMW's. Did that make any sense? Oh well do as you like. Ill stick to the Mesa tubes for a while.
    Killer B: The reason I turned up the blend knob without effects was to see if the distortion was there even without effects in the loop. Sort of A/B.

    And I will try that use of both inputs at the same time today with my chorus pedal.

    [Edited by Mesa Man on 09-12-2000 at 02:09 AM]
  13. I owned a 400+ for 6 years and loved the hell out of it. I ended up upgrading(?!) to the newer mosfet M-2000 because the 400+ was too much like carrying a big TV set around with all that glass in there. I think the 400+ was probably the better amp as it was very EZ to get a great sound from it. I've had the M-2000 for a year now and I'm still tweaking it. The BEST sound that I got from the 400+ was by running most of the knobs flat (5) with both shifts pulled out (bass+treble.) I used the graphic only for room acoustics, mostly avoiding it if possible. Now here is the trick; ALWAYS play through both preamps at the same time! I had the PUNCHIEST,PHATTEST most incredibly present and alive tone by doing this. It is also very convenient if you are running any FX at all as you can split your signal and always have a dry and effected blend. I usually had octaver and mutron through both and split it B4 any distortion so I could blend to taste. Mesa's customer support is second to none (maybe Alembic's too,) but you better make sure some good freinds are there to help you at load-out as the equipment has the nasty ability to gain alot of weight by 3 am. 5881's sounded way better, by the way. Hope this helps.

    [Edited by Mad Subwoofer on 09-12-2000 at 07:08 PM]
  14. Ok, my friend if I'm not going to buy Mesa tubes which do you recommend? I mean we all know that there are only a few producers of tubes left in the world today. So pretty much every tube has to be manufactured by them, right? I know that Mesa tubes are chinese, it is just this testing thing that I like, but I admit that they are expensive. But I guess it costs to have someone sitting there all day testing tubes. BTW dont they have a 6 months guarantee in case of tube failure? But if you can tell me a good brand that wont fry my amp I am willing to try. And dont say Marshall tubes or something, as I said, they are all manufactured at the same plant. :) Fortunately tubes dont have to be replace once a month.

    Oh well, see ya!
  15. biscuit


    Mar 6, 2000
    Virginia, USA
    Sovtek makes good tubes and they are fairly ubiquitous and inexpensive.
  16. hey PBM, havent seen you in for awhile.

    oh, Sovtek tubes are some of the best, i got 6 new ones in my traynor, it kicks ass like a 1971 tube amp should
  17. timv

    timv Supporting Member

    Jun 7, 2000
    Chandler, AZ
    I've read various places that the only sovtek tube you can use in the 400+ is the 5881WXT because it can stand the higher plate voltages that the 400+ has. The other sovtek varieties cannot. The svetlana 6L6GC is supposed to be able to and sound great as well. You can get 12 of the sovtek ones for around $130 and 12 of the svetlana for $180. When i replace mine i am going to go with the svetlana's. I've added 2 bias pots to adjust the push and pulls and resistors to measure the current for each so i can bias it as i want.
  18. Im not offended, not at all. on the contrary im flattered that someone wants to discuss it with me.

    Hmm, well I can only talk from my side of the show, and the tubes currently in my 400+ are mesa 5881's and working fine. Whats the worst scenario if I put other tubes in it? Will I fry a transformer? When I talked to Tommy Folkesson, a real tube guru, he stated that (power)tubes nowadays dont run out gradually, they just blow. So Ill take it from him that I WILL notice when the tubes need replacement. But the time will sure come and when it does I will think it over what brand of tubes i will use. I really like the punch of the Mesa tubes. So if I want that,what russian tubes do you recommend? And what are the risks and what are the odds for them to happen? I cant say that there are that many mfg's of tubes today, many of the one on that page make high end hifi tubes, not in my league. For musical use there are not more than a few. Thanks for the info anyway, useful in the future!

    Ok thats all for now, see yall!

  19. Hello again!

    Yes that thing you said that tubes nowadays blow before they degrade badly (soundwise) is what he meant I guess. By the way do you have any tech experience wioth this amp, I havent taken a closer look under the covers of it. Perhaps someone already installed the bias-adjuster.. what should I look for? Biasing is really not that hard is it? -52V, it shouldnt be that hard really?! How much is extreme bias mismatch anyway? 2-3V?

    I couldnt get that quoting thing right, but you said that there are several better tube manufacturers out there, do you mean that their tubes last longer, or is it the sound quality? When my tubes decide to blow, then I will take a good thought on trying other tubes out. Tesla by the way are made in Czech republic, I think.. or was it Slovakia?

    Well I could alway try other tubes, I mean I do have a fuse (3A, 230V) that will blow before the tranny, right?

    I really appreciate the info and comments to all my questions and stuff! Thanks!

    By the way on the Sovtek site, they state that Mesa use Sovtek tubes check at:

    Well until then,

    [Edited by Mesa Man on 09-17-2000 at 10:24 AM]
  20. timv

    timv Supporting Member

    Jun 7, 2000
    Chandler, AZ
    Mesa Man, I tried the experiment w/ my 400+ and do not get any distortion at all, just lower volume. Thought i would let you know. You may want to have that checked out if you want to use the effects loop.