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Drop in volume from solid state head.

Discussion in 'Amps and Cabs [BG]' started by Ron Johnson, Jun 22, 2016.


  1. Ron Johnson

    Ron Johnson

    Nov 19, 2014
    Chicago, IL
    I have a Behringer BXD3000H amp head. For the last month, it's been randomly failing me, and now it's gotten to the point where it is no longer usable. Upon first startup, it works fine. After a random period of time at rehearsal, I will suddenly not be able to hear myself. I check it out with nobody else in the band making noise, and there is sound coming from it, but barely any. I have to turn the volume up nearly all the way in order to faintly hear myself play, and the amp normally rumbles the walls turned up halfway when it works.
    I have done all the troubleshooting I could think of, and I am positive the amp head is the problem, and not my bass, cab, cables, or pedals. I have swapped basses, swapped speaker cables, swapped instrument cables, removed the pedals from the loop and plugged straight into the amp. I have also tried my drummer's old Crate B150 head, and it works, so my 410 cab seems out of the equation as well. I am also led to believe this is a poweramp issue, and not a preamp issue because I played through the head without a cab and with headphones for nearly 4 hours straight and the issue did not arise then.

    So for some reason the amp randomly drops in volume to nearly inaudible levels, and it has to happen at the exact same time my warranty runs out... Sometimes this problem is temporarily fixed by quickly turning the amp off and on, but it only works for a few minutes at most after that. I also take a whiff behind the fan every here and then and I do not smell anything burning.

    Is there anything I'm missing here? I haven't treated the head bad at all in the time that I've owned it. I even built my own rack case for it when I got it (with proper ventilation). All of the troubleshooting I've done has been out of the case as well. I know it's a cheap head, but the reviews I found on it were great. Does this problem sound familiar to anyone? And can it be fixed, or do I need a new head?
     
  2. Yes it can be fixed. Yes you need a new head because fixing it will cost more than another used one.
     
    cfsporn likes this.
  3. Ron Johnson

    Ron Johnson

    Nov 19, 2014
    Chicago, IL
    Could you humor me and talk about what it would take to fix this on my own. I know that paying someone else to fix it would be less cost efficient than buying another amp. But if there's a way to fix it, it's worth a try to me. Thanks
     
  4. basscooker

    basscooker Commercial User

    Apr 11, 2010
    cincy ky
    Owner, Chopshopamps.com
    So many possibilities. You'd need some experience troubleshooting a circuit, the schematic, and the equipment and tools. Maybe even a source for any proprietary components if there are any. It could be as simple as a fried IC, cap, or other simple component; but then just replacing it only fixes the symptom. What caused it to cook in the first place?
     
  5. If you have a pedal loop cable around or a spare instrument cable use that cable to connect the effects send to the effects return on the back of the amp. It sounds alot like the effects return internal contacts have fretted (comes from non-use also).
     
    ErnieD, Lobster11 and wave rider like this.
  6. A tip for the future.
    Do not turn anything up louder then you would normally, even if it is not very loud now. Because if it dose come back on and you are at full or almost full volume, you will probably kill your speakers.
     
    Cirk and Lobster11 like this.
  7. seamonkey

    seamonkey

    Aug 6, 2004
    It's probably some connector, or even the effects loop, it gets a little warm and metal expands and you get a loose connection.
    Give it a big wack on the side to see if it's some look internal connector.
    Plug and unplug a cable into the effects loop several times to clean any switching contacts.
    Put it in the freezer for a bit, and see if it last longer.
    Take it apart and reseat any ribbon cable, look for loose connections.
    Poke around with a chopstick to see if you can find a loose connector inside - normally with the amp on, but be careful.
    Get one of those infrared thermometers and point it around inside to see what's getting hot.
    Get a can of air and spray it on what's getting hot to isolate it.
     
  8. BogeyBass

    BogeyBass

    Sep 14, 2010
    if the amp works at start-up Then fades out then it wouldn't be the effects loop I'd assume. bad contacts just make it not work. sounds like a component going out and when heating up with use gets worse. just need a factory schematic with voltage readings and start checking voltage levels and find and replace faulty components
     
  9. IME bad electrical connections do as they please.
     
  10. Ron Johnson

    Ron Johnson

    Nov 19, 2014
    Chicago, IL
    I'm likely going to do that if I find a schematic. But I have been frequently feeling behind the fan and it's just room temperature. Unless said component doesn't heat up enough to have a significant change on the overall exhaust temperature, I don't know what it could be.
     
  11. Peavey and GK, being so commonplace, are often reported with intermittent faults that turn out to be the fx loop interrupts, as mentioned.

    Putting a fx patch or guitar cable into the loop is a great diagnostic. Sometimes you see amps just left like that.
     
    ErnieD likes this.
  12. I just want to drop in and say that I had a very similar symptom with a combo amp of mine (a guitar amp, actually). I stumbled across this thread and several others on the webs that said to troubleshoot by putting a patch cable in the effects loop. I didn't see how or why this would make a difference, but I tried it anyway.

    Sure enough, the symptom disappears if I leave the cable plugged into the loop and it comes back if I remove the cable.

    Good enough for me. Thanks!
     
  13. Pilgrim

    Pilgrim Supporting Member

    For this solid state head, if a simple work-around like the effects loop doesn't work, you probably would have to go to a tech - and I agree, it would cost as much to fix it as to get a replacement.

    I personally like the Behringer 4500 (had one), but my advice is to move on and look for a used Genz-Benz Shuttle 6.0. It weighs 4 pounds and will blow your Behringer out of the water.

    I'd go after this Shuttle 3.0 on Ebay and run like a bandit. You will NEVER buy a better amp for less money.

    Genz-Benz Shuttle 3.0 bass amp head with bag | eBay
     
  14. BassFishingInAmerica

    BassFishingInAmerica

    Jul 24, 2014
    This method of trouble shooting is highly underrated.