Markbass noise

Discussion in 'Amps and Cabs [BG]' started by rtz, Mar 21, 2020.

  1. rtz


    Jan 1, 2008
    Okay, I'm going to describe this the best I can. I have a Markbass LMT800. When the head is plugged into my cab I get occasional shots of static/white noise. It comes and goes and it does it without my bass being plugged in. I've used 2 different cabs, same issue. I also have a Markbass TTE500 that is doing the same thing. I've run them at different outlets with a furman power conditioner, same issue. This does not happen when I run my cabs thru my Carvin BX1500. I also get the noise running my MB's using the DI into my studio monitors. Again,no issue using my Carvin direct. Sometimes the noise is like a bit of white noise for about 3 seconds, other times there are single quick pops. Any ideas? I don't believe its dirty power because of the Furman,that should clean it up. I also don't believe its a house power issue because my Carvin runs without issue. Does MB have picky power supply issue? Both units doing it seems very odd?? Help,please!
  2. BogeyBass

    BogeyBass Inactive

    Sep 14, 2010
    possible Tube issue

    over the years ive had random tube preamps make random sizzles and crakles or slow crawling white noise then stop.
    usually a sign of a tube starting to go bad.

    I also had a Fender blues reissue that was notorious for bad socket solder connections. and also had 2 large 5 watt resistors for the low voltage power supply that would get very hot. on this board the hot resistors would cause a set of small signal diodes for channel switching to desolder
    and is also known for more making random crakles and white noise bursts

    why im i telling you

    i checked the sockets. 3 bad connections confirmed and fixed. Checked diodes confirmed bad connections and raised the large hot resistors away from the board.....conclusion

    the amp still made random noises crackles and soft white noise burst every few hours or even days. very random

    i finally got a hard metallic ping from playing, and that is for sure a microphonic tube. preamp 12ax7 made a ping like crazy and was changed.

    after i changed that pre tube. the random soft crakles and white noise went away
    i played the amp everyday for hours as usual and it was a pre tube making those sounds and was fixed with my favorite tube of all time
    Sovtec 12AX7 LPS

    low noise large plate tube, with low noise spiral wound heater.
    it fixed my amp. and the sound improved alot.
    i knew the amp well, i played it daily at high volume and low volume
  3. AlexanderB


    Feb 25, 2007
    There are separate boards inside the amp, connected via flat, wide multi conductor cables. The cables join the connector pins on the boards through moulded plastic connectors. Open the lid on the top, pull off one such connector at the time, give the pins a SMALL squirt of oil free electronics cleaner, wiggle the connector as you re-seat it. Rinse and repeat on all connectors. With the lid off, spray a LITTLE in the effects return jack, too. Put lid back on, coonect the power cable and see if it works.
  4. rtz


    Jan 1, 2008
    Thanks guys. Cleaned both amps. My LMT800 so far is good. Can't change the tube in that one. The TTE5000 is still giving me issues. Tubes were already new. Changed each one out with a known good tube, no change. Cleaned every connection of the board and power supply. Not sure where to go fromhere?
  5. agedhorse

    agedhorse Supporting Member Commercial User

    Feb 12, 2006
    Davis, CA (USA)
    Development Engineer-Mesa, Product Support-Genz Benz
    Try it in a different location (building) because while you THINK the power is ok, in actuality you have no idea. Power conditioners often do nothing to improve noise and can make it worse too.

    Does it make the noise with nothing plugged into the amp except the speaker?

    Is the ground pin intact on the power cable?

    It might be time for a QUALIFIED service center (i.e. the factory designated service representative) to look at it, after ruling out external causes.
    Matty Koff likes this.
  6. Matty Koff

    Matty Koff

    Aug 21, 2014
    Since you mentioned the xlr out, you have flipped the ground/lift switches right? (I'd assume you have tried it but just in case)

    Also.. with your TTE500 since it's still noisy through the cabinet.. do any of the knobs crackle when you turn them? If so.. a short shot of contact cleaner into the pot followed by moving the knob to the extremities might help.

    the MoMark I just replaced was doing something very similar to what you're describing.. and over the years the input gain knob started to crackle really bad anytime I would move it. For what should've been a simple fix.. pulling out the module there's just no way to get contact cleaner in there much less examine/replace the single tube without physically breaking the module open.

    Sometime after August of last year I did manage to spray some compressed air inside and watched a dustball fly out of it, and for awhile I was free of any static while playing but the input gain knob was still crackly when I would turn it. Then static while playing appeared again later down the road..wiggling the input gain knob got rid of it. Last time I turned it on no amount of moving the knob cured the symptom and I said screw it and bought a new amp rather than hoping a used pre-amp module would solve my woes.

    Other food for thought - My Markbass Compressore pedal was making some similar noises.. took it apart and found the grounding ring secured to the footswitch was loose.. tightening the nut fixed it. Frankly, beyond replacing the tube in that pedal.. there's not much the end user can do to service the thing. I still use that pedal all the time and love what it does.. but seeing the design, along with the flop that was MoMark.. I've personally decided to steer clear of the Italian Stallions from here on out lol. The relevance, being that a grounding issue could make said noises.

    Not to bash their other just goes to help me appreciate the way my new amp was put together. If it came down to it.. and for some reason I couldn't get someone who works with agedhorse to fix it.. I'd still at least be able to attempt servicing my own amp.

    If it's not a dirty pot or it's too dirty for contact cleaner to even help.. I'd say contacting Markbass is your best bet even if you have to pay a service charge and live without it for a time.
    Last edited: Mar 23, 2020
  7. BassmanPaul

    BassmanPaul Inactive

    Try plugging the unit straight into the wall without the Furman to see what happens.
    AlexanderB, wcriley and agedhorse like this.
  8. rtz


    Jan 1, 2008
    UPDATE - Plugged into the wall without the power conditioner, no change.
    Took the whole unit over to my sons house,no change, same popping and noise issue.
    CHecked all the ground connections when I had it apart cleaning all the ribbon cable connections. I also cleaned all the disconnected on the board for the power supply. Knobs turn free nd easy without noise.
    Could it be a faulty power supply??
  9. agedhorse

    agedhorse Supporting Member Commercial User

    Feb 12, 2006
    Davis, CA (USA)
    Development Engineer-Mesa, Product Support-Genz Benz
    Possibly, but due to the cost and complexity of the power supply I sure would want to verify this via noise figure measurements before replacing it on a hunch or a whim because it's maybe 20% likely. Not good enough odds for me.
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