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Walkabout problems

Discussion in 'Amps and Cabs [BG]' started by Dave, Jul 24, 2005.

  1. I recently acquired a Mesa Walkabout head from Guitar Center that had been there for about a year, so I got a god deal on it. Played it at the store, sounded great. Played it at home and I got a weird distortion, sounded like I was running through a cheap distortion pedal or something in combination with a kind of rattle. I turned it off and played it again later and it had none of the distortion in it, so I take it to my gig the next night. I get there and the mysterious distortion is back. I open up the head and re-seat the tubes and then it was fine. I checked all the wires, nothing seems to be loose, coming unsoldered, etc.

    Last night (about 3 weeks after getting the Mesa), I get to church to play and the distortin is back. Thinking, hey, Ill just re-seat the tubes again and itll be gone, but nope, still there.

    Now, not really knowing the history of this head, does this sound like The pre tubes just need to be replaced or what?

    Checked bass battery, it was fine.

    BTW, the levels were quite low, about 9 o'clock on both gain and master volume.

    Anyone have any ideas? Im kinda new to having tube in my amps, especially ones that have had some use, so Im just wondering if this is easily remedied with a tube swap or if its something more serious.

  2. billfitzmaurice

    billfitzmaurice Commercial User

    Sep 15, 2004
    New Hampshire
    Owner, Bill Fitzmaurice Loudspeaker Design
    A rattle is a sign of a tube that's microphonic, so I'd swap that out first.
  3. Does it sound EXACTLY like a rattle? The noise is like a cross between crappy distortion and rattle.

    Would the "distortion/rattle" come and go if it was microphonic?
  4. I got one mine same way as you. Deal at gc with minor shop wear, but beaten tubes. First thing on it is always allow your tubes to warm a bit. It takes my WalkAbout 10-30 seconds to warm the preamps just to get sound out. So I wait 45 - 75 seconds before any playing. Even though they are preamp tubes they still need to warm up. And I give it 1 - 2 minutes with out play to allow the tubes to cool down. My shut down goes first I set my electronics on the guitar to flat. (I always do so I know where they are evertime I pick it up) Of course I shut the volume all they way down. Then I turn off my compressor pedal. Turn down the master volume. And let it sit for a little while.

    Another thing on that amp the tube in the #1 position takes 85% of the abuse and #2 takes 15% so I have been told. Both the tubes are the same. I switched mine around and got rid of all the microphonics. That crackling, pop, Cheapo distrotion sound you spoke of. Now it sounds sweeter than before. If your interested do a search of WalkAbout in this forum. There's allot of input on tubes for it here. Actually the reason I joined.
  5. cheezewiz

    cheezewiz Supporting Member

    Mar 27, 2002
    Your amp takes two 12AX7 preamp tubes. You can replace the Mesa tubes with MUCH higher quality tubes for $20-$30 total. It's a small price to pay and it will more than likely solve your problem.
  6. KJung

    KJung Supporting Member

  7. All righty, thanks very much for your help.

    Yeah, the tubes are the standard, original Mesa tubes.

    Ill do a search, but if anyone feels like it, whats a good replacement to get nice thick, clean sound.

  8. cheezewiz

    cheezewiz Supporting Member

    Mar 27, 2002
    If you wanna spend a few bucks, check ebay or online tube dealers for some NOS Telefunkens or Mullards. Alot of different tubes will work fine though. JJ's seem to be well regarded and reasonably priced.