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taming an MTD-535

Discussion in 'Basses [BG]' started by nonsqtr, Jun 19, 2004.


  1. nonsqtr

    nonsqtr The emperor has no clothes!

    Aug 29, 2003
    Burbank CA USA
    I'm in love with my new MTD-535. It's super responsive, and it does exactly what I want it to do, "all the time". But, there's a problem in our relationship. The pickups/electronics are so darn powerful, that it's overloading my speakers and my amp. Has anyone else had this experience with a 535?

    The amp: a Walter Woods Ultra. 1200 watts of crankin' power. With any other bass (F bass, Roscoe, Alembic, J, various others) I can crank the amp all the way up, and the worst that happens is my speakers start complaining a little. With the MTD, when I turn up the volume control, it sounds like a limiter is kicking in on the highs. Typically it happens when I pluck the G string. I actually looked at the output on a spectrum analyzer. Good God. I'm getting stuff way up in the 60 kHz range. I think this is overloading the power amp section, that's the only explanation I can come up with. You don't have to max out the amp to get the symptom, it happens even with the master volume at "7". On the other hand, I've determined that it's not the preamp section, 'cause I can crank the preamp all the way up, and as long as I leave the master at "3" everything's fine. So it has to be the power amp section that's complaining.

    The speakers: four BagEnd mini-stacks, with S-15's on the bottom and S-12's on top. Total power handling is supposed to be 200 watts RMS per speaker, which is 1600 watts total, in other words more than the amp puts out. The problem is, the fundamental on the low B is so strong that it's causing all the 15's to bark. It's creating a gnarly distorted sound that would actually be kinda cool if the speaker cones weren't trying to jump out of their frames at the same time.

    The question is: how am I supposed to tame this bass?

    As far as I can tell, it's the extreme highs and extreme lows that are causing problems. I can turn down the treble and bass controls, but it only helps "a little", in other words, the extreme highs and lows are so prevalent in the signal that even turning down the tone controls doesn't fully tame them. The only solution I can think of at the moment is a pair of 24 dB/octave Linkwitz-Riley filters at 31 Hz and 15 kHz, which would basically eliminate all the subsonic and supersonic components. Don't know whether this would take care of the problem though. Seems like the strong lows and strong highs would still be present in that situation.

    Don't get me wrong, I love this bass, and I love the sound. I don't want to change the sound "at all". I'd rather get a whole new rig. But it took me a long time to find a rig that will work in all the various gigging situations, and I'm guessing it would be next to impossible to find a rig that can handle this bass at concert volumes. Or if I could, it would be so huge that it would be impossible to move around. The only other thing I can think of is to painfully and laboriously experiment with a graphic equalizer, till I find exactly the right frequencies to start cutting, so the bass retains at least "most" of its sonic character.

    Please help meee...... aiiiieee....

    Is this what people call "quality problems"? :)
     
  2. todd 4ta

    todd 4ta

    Apr 3, 2003
    Indiana
    You have already checked to make sure that the preamp gain control is turned all the way down, right? That is how Mike recommends it be set, all the way down. (this is the little blue trim pot in the control cavity)

    I've had three 535's and two 435's, played through several different types of amps and cabs (not WW though) and never had anything other than tonal perfection.

    I found my favorite fingerstyle tone with the pickups panned slightly toward the neck, treble flat or slightly rolled off, bass slightly boosted and mids switched to low and boosted to taste.

    Have you tried different strings?
     
  3. nonsqtr

    nonsqtr The emperor has no clothes!

    Aug 29, 2003
    Burbank CA USA
    Hi todd 4ta, no I haven't checked the trim pot. Would changing this affect the tone though? See, the problem is that the tone is just fine throughout most of the audio spectrum, except at the extreme low end and the extreme high end. It sounds like the edges of the spectrum are getting boosted (don't know if there's an actual booster in the electronics, but that's what it sounds like). The extreme highs and lows are so powerful that when I get the desired volume for the major portion of the spectrum, the edges are just way too powerful. I'm guessing that backing off on the volume control wouldn't address this problem, but don't know enough about the electronics in these basses to be sure. It's a standard Bartolini preamp, isn't it? Or is it?

    And, excellent point about the strings. I'm using MTD strings at the moment, which are definitely "different". On the other hand, I have the same strings on an F bass and it doesn't have this problem "at all". The output has some of the same sonic characteristics in the audible portion of the spectrum, in other words I can tell that the strings are definitely contributing to the sound, but there's no problem with the extreme highs and lows on the F bass. I can crank that one as loud as I want, and the rig is fine, it doesn't complain at all.
     
  4. dhuffguitars

    dhuffguitars Luthier/Bass Wanker depending on your opinion

    Sep 18, 2001
    SPOKANE WA
    I will second the trim pot suggestion. It won't change the tone per se, just the overall output. Basically it's like another volume pot inside the control cavity.
     
  5. Halftooth

    Halftooth Supporting Member

    Nov 24, 2002
    Tri-Valley, NorCal
    FWIW, I turn the internal trim pot volume all the way down on all of my basses, especially on the Barts preamps. For whatever reason, the Bart has the tendancy to overdrive when the bass is fully boosted. When the internal trim pot is adjusted all the way down however, it's not a problem, plus, I get to turn my amp up to a higher level.
     
  6. nonsqtr

    nonsqtr The emperor has no clothes!

    Aug 29, 2003
    Burbank CA USA
    Thanks guys, I'll check the trim pot tonight and keep you posted with the results. I sent Mike an e-mail with the same info, so let's see what he comes back with.
     
  7. Fuzzbass

    Fuzzbass P5 with overdrive Supporting Member

    I minimized the pot on my 535. Still sounds great. As mentioned above, that should solve your problem.
     
  8. todd 4ta

    todd 4ta

    Apr 3, 2003
    Indiana
    Another thing to keep in mind is that the 535 has 'active' Bartolini pickups not 'passive'. I've always thought the active Barts are a very large part of the overall tonal power of the bass (especially for slap playing with the treble cranked - YOWZA!! :eek: )

    My understanding is that the active pickups are the standard, I've seen a couple people mention they had passive pickups.

     
  9. geshel

    geshel

    Oct 2, 2001
    Seattle
    This would really surprise me. I'm not even sure if Bartolini sell any active pickups anymore. At leats, not many.
     
  10. Ari

    Ari

    Dec 6, 2001
    I also think that Bartolini Soapbars in the MTD are active pickups, but I may be wrong!
     
  11. dhuffguitars

    dhuffguitars Luthier/Bass Wanker depending on your opinion

    Sep 18, 2001
    SPOKANE WA
    They are all passive pickups using an active preamp. Very few companies make active pickups. Best example is EMG, where without an active preamp the pickup still needs a battery to operate. That is because the EMG pickup has a small preamp built into the pickup casing.
     
  12. gfab333

    gfab333

    Mar 22, 2000
    Honolulu, Hawaii
    When I first bought my 535 (new), the internal volume trim pot was set at maybe 80-90%. I noted that thumping on the B would make the clip light on my GK 1001rb come on although the I couldn't hear any distortion. The B also had a very heavy preponderent bottom, relative to the tonality of the other strings. I did the following things in an effort to address the problem:

    I reduced the gain setting on the internal trim pot so that the 535's volume, when maxed, is only slightly louder than a passive Fender bass, when its volume is maxed, all other factors constant. I'm guessing that its set at about 65-75%.

    I lowered the height of the neck pickup until I was able to achieve a tone that was suitable to my ears, and the amp's clip light would not be activated when thumping on the B string.

    This has been my workaround for the past few years and appears to have solved the problem. I've played through many backline rigs and the stuff listed in my profile and haven't had any problem except one time... and this incident appears to mirror your experience...

    I went to an open mic jam session with my 535 a couple year's ago and the house band's rig was a high powered WW and a Epifani 3-10. I was jamming a funk tune and the rig sounded fine. As the jam progressed I noticed that I got a very compressed tone and volume response everytime I popped the G string. I looked over at the rig for an outboard compressor and there wasn't one to be seen. When I got off stage, I mentioned my experience to the owner of the rig and he confirmed that he wasn't using a compressor, and kind of shrugged his shoulders as to what I was hearing. Neither of us could figure it out. It was definitely a result of the combination of my 535 and the rig, because no one else had the same problem. Thus, you may have a trim pot gain issue to resolve, but there may also be another separate issue which is the result of running the MTD USA through certain rigs - a mysterious compression phenomenon. It's still a mystery to me. I'm still loving the MTD by the way! Enjoy that baby!

    :bassist: :meh: :bassist:
     
  13. nonsqtr

    nonsqtr The emperor has no clothes!

    Aug 29, 2003
    Burbank CA USA
    Hi gfab333, thanks for your input. I'm very relieved that someone else was able to independently confirm the symptom that I'm experiencing with the combination of the MTD and the WW amp. I thought I was going nuts for a while there... :)
     
  14. nonsqtr

    nonsqtr The emperor has no clothes!

    Aug 29, 2003
    Burbank CA USA
    Michael Tobias confirms that the dynamic range of his custom pickups is greater than most. Signal peaks considerably in excess of one volt. Oy. Okay so, I successfully tamed this behavior using a 3 dB/octave low-pass filter with a 12 kHz cutoff frequency. This prevents the Walter Woods from going nuts, and kicking in the limiter (or whatever it's doing, I haven't heard back from Walter yet so I can't say for sure). The MTD-535 sounds awesome through a tube amp "as-is", I've been feeding into a B-15 and a Twin Reverb and they both sound pretty good. The extra high end edge adds a nice grainy character to the sound. The WW is very precise though, it's trying to reproduce peaks in the signal that are taking it over 1200 watts of instantaneous output, and once those peaks are removed, everything's fine.