Onboard preamp upgrade suggestion

Discussion in 'Pickups & Electronics [BG]' started by Luka, Aug 1, 2020.

  1. Luka


    Jul 25, 2018
    Hello, I've got yamaha trbx305 and I really love it's comfy neck and feel, but the problem is that I don't really love it's sound, especially low end isn't punchy but a little muddy. Also, if I play metal, I really love to dig in hard to maintain consistant, ballsy tone, but as soon as I strike lower and lower notes, it gets more and more distorted, (gear : hartke ha3500, hartke transporter 410) and also B string doesn't have any clarity at all. So I was wondering if it's common issue on this basses or not? And also, I think to try to replace onboard preamp with tone monster sbk 3ad(1stacked pot). Will it solve my problem or do I need to upgrade pups as well?
  2. Bob_Ross

    Bob_Ross Gold Supporting Member

    Dec 29, 2012
    I think I see your problem. It ain't the preamp. :(
  3. Luka


    Jul 25, 2018
    Nah, happens on other cabs too
    Bob_Ross likes this.
  4. Zooberwerx

    Zooberwerx Gold Supporting Member

    Dec 21, 2002
    Virginia Beach, VA
    Rule-out the simple stuff:

    *All EQ knobs at center detent, bass & amp.

    *Replace 9v alkaline battery if not already done.

    *Drop pickup height(s)

    Replacing pups and/or preamp is a bit of a crap-shoot...I won't even begin to predict outcomes. I have my particular favorites but I'll save that for later. Don't go throwing money into mods / upgrades (?)...yet.

    Luka and MonetBass like this.
  5. Teck_Instructor


    Dec 19, 2018
    Many, (and IMO, most), bass cabs are tuned too high for making the B string sound good. My current cab was tuned to 55 Hz. On paper that means that it can only handle the low B fundamental up to about 130 watts even through the cab is rated like 700 or 800 watts. The B used to sound pretty bad even at 100 watts. I lowered the tuning to 37, and it now can handle a B at about 750 watts on paper. I buried the the volume on my 550 watt amp. The B string sounded a lot tighter / less muddy, and it was LOUD. I own a TRBX304, and I have 305 on order, so I had to test with a friends 5 string.

    I would suggest you use a pair of headphones that you know can do a low B well on more than one amp to see if it is the bass. The TRBX305 is considered to have a very good preamp and some of the very best pickups for a bass under $400. I really hope you don't have an issue with yours.

    I also found an old thread on TB where someone else was having trouble with a trbx305. A respondent posted a sound sample from his own 305. In it he goes pretty deep on some notes. He is obviously using a DI, but it should give you an idea of what the B string should sound like on the TRBX305.

    Last edited: Aug 3, 2020
    Luka likes this.
  6. Teck_Instructor


    Dec 19, 2018
  7. rojo412

    rojo412 Sit down, Danny... Supporting Member

    Feb 26, 2000
    Cleveland, OH.
    I've had similar issues with Yamahas and similar basses over the years. I'm pretty sure a lot of them use the same basic preamps (G&B, if I'm not mistaken) and they don't really excite me, personally.
    One thing you may want to try, if you're handy with a soldering gun, is to bypass the preamp and see how the pickups sound on their own. By doing that, you could find out if the preamp is choking off the pickups or if the preamp isn't getting enough useful info from the pickups.

    Depending on the design of the preamp, you may find that the pickups are being blended passively and can redirect the signal that goes into the preamp, sending it out to the jack directly. That would be enough to tell you what is actually going into the preamp itself.

    Another issue may be the preamp's lack of headroom, as evidenced by the distortion, lack of B signal and clarity, and muddiness. You could try upping the voltage by using 18v and see if that fixes that. Not sure how it takes batteries, but it's a relatively easy thing to try. And while I'm not 100% sure it wouldn't screw up the existing preamp, if you're already thinking of replacing it, killing it would make it a necessity at that point.
    (I know, sounds harsh, but sometimes, I fly by the seat of my pants, so take what I say with a grain of salt and assess my advice with your own personal beliefs and abilities. I'm just here, trying to help however I can)

    Also - and I feel like a broken record here, because I've posted this advice a number of times last week - if you are thinking about a preamp change, I've been very impressed with Tone Monster preamps. They have a number of configurations available, they are inexpensive, and they have a gain control built into the board. I installed one in an Ibanez which was kinda blah, low-output. It immediately was punching the input of the amp MUCH harder and allowed for much more effective control. In my own projects/builds, I use Nordy preamps and they are amazing, but have been shocked by how good the Tone Monsters are for the price.
    Luka likes this.
  8. Kinky Afro

    Kinky Afro

    May 24, 2012
    I just upgraded my preamp with a John East Uni-Pre and it rocks. My last preamp was a bit muddy but the uni-pre has internal adjustable treble and bass freqs aswell as variable mids. I don't know if its what your after but it was awesome for me.
    Luka likes this.