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Distortion problem with amp

Discussion in 'Amps and Cabs [BG]' started by drd07, Jun 17, 2003.


  1. drd07

    drd07

    Jan 19, 2003
    Hi all,
    I need some advice from all you tube amp users. I play through a fender bassman 300. I've always gotten a killer tone from it. Really easy to use. However, lately, no matter what channel or setting, it seems to have this distorted tone/color to the sound. I've messed with all the settings, but can't seem to dial up a good sound.

    I checked all of my wires and cables and they were fine. Last Sat at a show while setting up, the sound guy came by and told me my sound was a little distorted. I made it through the show fine, but I'm still a little freaked about it.

    I've tested my bass, pedals, wires through another amp and they were all sounded fine. At another show about 2 weeks ago though, this guy was helping me carry my amp off stage and he placed it down sideways on top of my cabs. Could that possibly damaged something? Does the preamp tube need to be replaced? This is a fairly new amp, about 3-4 months old. The power tubes seem fine. Each pair is wired to it's own fuse and none of the fuses are blown. What is happening with my amp? AAAAAAAAAARRRRRRGGGGGGHHHH
     
  2. rllefebv

    rllefebv

    Oct 17, 2000
    Newberg, Oregon
    This is going to sound really lame, but hopefully it will illustrate that sometimes it is the simplest things...

    A couple of weeks ago, I subbed with my old band... My rig consists of a Carvin R600 and two homemade 1X15 cabs... The head has been a workhorse for nearly 5 years needing only minimal care and feeding. At the start of the gig, I would hear a very nasty clipping-type distortion whenever I hit the octave A on the D string... I switched cables, basses, ran it full range from both sides, bridged, everything I could think of and it still kept doing it. About 2/3 of the way through the second set, it chilled out and ran great the rest of the night... no problems the second night either. Last week at a blues jam it did the same thing and also had some heavy distortion throughout... I switched to a backup that we keep at the jam, (my old Eden), and finished out the night...

    When I got the Carvin on the bench, I was able to recreate all of the bad symptoms... I noticed that a few of the pots were scratchy, so I went through and cleaned all of the pots with quick-drying contact cleaner, sprayed some on an old 1/4" plug and worked it in and out of each jack on the amp... First thing I noticed was that the knobs turned so much smoother and cables went in like butter. Best of all, no clipping, distortion, or scratchy pots... A good cleaning fixed it. Maybe something to consider??

    -robert
     
  3. drd07

    drd07

    Jan 19, 2003
    That sounds like a good idea. However, I don't have much experience fixing up tube amps or cleaning them out. Is it hard to do? I know that if I messed with certain things that I could possibly electricute myself. Don't want to do that...

    Do you think that it could be that dirty after 3-4 months?
     
  4. Could possibly be preamp tube going bad. I've had some of the newer 12AX7A tubes go to full distortion from "gassing-up".

    Best part of this is, you can swap in a new 12AX7 by yourself before taking it to a tech. If that is the problem, you'll be able to hear the difference. Don't try swapping any 6550's around since they need to be biased when swapped, but the 12AX7's are set up to autobias so you can plug and play. Just make sure the amp is off when you change the tubes, and do it 1 at a time. If it doesn't change anything when you plug the new tube into a spot, then power down and put the old one back in, move to next tube. Try swapping them all out 1 at a time to see if this fixes it. If not, could be tech time.

    Chris
     
  5. I'm assuming it's still under warranty, and I'd take advantage of that fact by getting a tech to take a look at it. Can't hurt if it's free.
     
  6. Mike Money

    Mike Money Banned

    Mar 18, 2003
    Bakersfield California
    Avatar Speakers Endorsing Hooligan
    I highly suggest that you kick it. And if that fails, take it to a tech.
     
  7. drd07

    drd07

    Jan 19, 2003
    I don't know if I will kick it. It did cost me close to a grand! LOL I don't know how to even replace the preamp tube. I have to recheck the warrenty. However, I have to also find a fender service in my area (Chicago) in time for a gig in a week and a half. Yikes! That's cutting it very close...If I had to take it in to a non fender service repair, how much is expected to replace the preamp tube?
     
  8. Stu L.

    Stu L. Supporting Member

    Nov 27, 2001
    Corsicana, Texas
    I second the motion...:D
     
  9. no, drop kick it.