I hate to ask again...

Discussion in 'Amps and Cabs [BG]' started by Michael Jewels, Oct 31, 2001.

  1. The hummig is back! At least part of the time. Not to drag this out, I'll try to be quick.

    I bought a new amp, an Ampeg B100R and love it.
    If you recall my post of about two weeks ago, I had a humming in my Fender Bassman 60 amp, and it's coming from my Ampeg sometimes.

    I got the Ampeg a week ago, plugged it in, and it was dead silent, until I tried using my NE-1 EQ. As soon as I hooked it up - HUMMING! It then hummed every time I turned on the amp for the next two days, after that, it was gone.

    Now, Monday night and last night (Tuesday) no humming at all. Then after playing for about an hour last night, I turned down the gain and master volume all the way, plugged in my Zoom 506II effect, and, you guessed it - HUM!

    Could these effects be doing something to the pre-amp? If it is, could the hum go away after the amp discharges? BTW, how long does this take? The few times I turned the amp on and off last night resulted in nothing new; it was still humming. Also, a strange thing happens when it hums: My Yamaha bass is extremely quiet, but when the amp hums, the B,E and A string send a noticeably weaker signal to the preamp (this amp has an indicator light) but only from the neck pickup, the bridge pup is fine. I know this sounds insane, but, these things are really happening.

    Help if you can.
    Mike J.:confused:
  2. seamus


    Feb 8, 2001
    Not to sound like a wise guy, but are you always using the same outlet in the wall? The reason I ask is I ran into a hum problem once that turned out to be a problem with the wall outlet.

    I plug everything into a furman, and then plug the furman into a wall outlet. Well, it turns out the wall outlet was not maintaining proper contact with the grounding prong on the plug. Once I plugged the furman into a sturdier outlet, the hum went away.
  3. Seamus, no, I moved it from a two pronged outlet to a proper three prong outlet a few weeks ago. The thing that gets me is: It only does it sometimes. If something were broken, I could under stand, but, this is a brand new amp. And the only times it has done this is right after I plug in an effect. Also, why would just one pup of my Yamaha malfunction? I know this sounds crazy, but, there has to be a logical answer. I wonder if this could be some kind of polarity problem with the juice in my house? The amp doesn't have a polarity switch on it.

    This is gonna drive me nuts.

    Mike J.
  4. jvtwin

    jvtwin What it needs is a little more cowbell

    Jan 26, 2001
    LA Calif.
    Man - these things are always a pain in the a$$! Here's my two cents worth -

    1) try a different bass (still hums?)
    2) Check cords and connectors or try using new ones if possible (still hums?)
    3) Check effects being used - old batteries, funky AC adapters, etc. (Still hums?)
    4) Take pre amp to quilified and trusted repair guy for inspection. (Still hums?)
    5) Take whole rig to local clergyman and have it exorsized!:p

    Good luck!
  5. Sounds like a ground loop. Are the effects running on AC or battery? If they are running AC and can run on batteries, see if batteries make any difference. See if the documentation for the effects discusses ground loop problems. Check the placement of the units. Do the cabinets conduct electricity (are they metal). Are the EFFECTS sometimes touching a metal part of the amp (perhaps screws on top). Does the problem change if there is (or is not) contact between the units.

    You may need a ground lift on the connections to the effects units. This effectively breaks the ground connection on the cables connecting the effects units. You can buy ground lift connections. You can also cut the shield on one side of the cable.

    Aside: By the way, you are using shielded patch cables aren't you. If you are connecting with speaker cables, that is the problem. As a matter of fact, that would explain why it would be intermittent.

    Back to flow: I test the ground loop situation by using phono cables with phone plug adapters and pull the phono cable from the adapter until the ground is no longer connected. This way I know where the problem is before buying ground lifts or cutting cable shields.
  6. seamus


    Feb 8, 2001
    The last two posts cover a lot, hopefully you'll be able to experiment using some of those suggestions MJ. Hum is a terrible thing, especially when there's a few things going on in the signal chain. It's a pain in the butt trying to isolate that one thing that's usually causing it.
  7. Brad Johnson

    Brad Johnson Commercial User

    Mar 8, 2000
    Gaithersburg, Md
    Boom Bass Cabinets, DR strings
    Is a TV on nearby?
    Do you have dimmable lights on the same circuit as you amp?
    Is there a computer nearby?
  8. Your guitar cables are flaky, in a bad way. Not like a flaky pie crust. More like a flaky skin condition.

    Hopefully that got the point across. Get some new cables, decent ones with actual metal screw-on covers. Not the crappy molded plastic stuff. You'll be set.

  9. I'm going to try everything you guys suggested. I still can't figure out why this just started happening recently. My guitar cable is a DiMarzio, so it's a decent one. It isn't crackling or buzzing the way cables do when they start to go. The main thing to remember is that this is a brand new amp. Oh well, I think I'll go to the Halloween Parade. Thanks everyone, I'll keep you posted.

    Happy Halloween all.

    Mike J.:cool:
  10. I tried everything. I think I narrowed it down to the bass. It's got two pups, Jazz style. I don't know for sure if they're humbuckers, but, when both pups are on full, this is one of the quietest basses there is. Now, all of a sudden the neck pup is going screwy. It's a 5 string, and, I think the pups are P-Bass style split types. Compared to the B, E, and A strings, the D and G are a lot louder, and I can tell their signal isn't as strong because the amp has a gain light on it. Could some connection have come loose? It doesn't happen with the bridge pickup, however. Two of my other basses are single coils, and have always had that directional hum. Sit at 90 degrees to the speaker, and no hum. The Casady is a humbucker, and seems O.K. I guess I'll post something in the pickup thread. I'm seriously thinking of going broke and just buying a Stingray 5.

    I hate it when machines don't perform as they should.:mad:

    Later guys,
    Mike J.