another 7pro down....

Discussion in 'Amps [BG]' started by nubs, Dec 19, 2012.


  1. nubs

    nubs

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    turned amp on this afternoon, and it made a sound like i was plugging in the instrument cable with the amp on, then i guess i would call it a little "pop". out put level is very very weak. if i turn the compression up at all i pretty much loose all out put, and the thresh light comes on.....i am no tech head at all. anyone know what this could be? i have a authorized ampeg tech to take it to, but wont be able to get it looked at for a couple days at least in Wisconsin we are supposed to be in for a Snowmageddon the next couple days...i am bummin'! any input would be cool..
  2. hdracer

    hdracer Supporting Member

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    About all you can do is get it to your tech and rent a amp.
    Or you could go to GC and buy a amp and return it when yours gets back from being repaired.
    If your live with that.....
  3. JimmyM

    JimmyM Supporting Member

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    Did you try replacing the tube yet?
  4. nubs

    nubs

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    no, you feel it may be the preamp tube?
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  6. nubs

    nubs

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    can an electrical dummy do something that complex, remember i dont know nothin! :meh:
  7. will33

    will33

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    It's certainly worth a shot. As well as running a patch cord from effects send to return.

    Go another amp of any kind? See if you can get a good sound either out of the pre or into the power, again using the effects loops.
  8. JimmyM

    JimmyM Supporting Member

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    An electrical dummy can easily replace the tube. Unbolt the lid, open it up, pop the old tube out, po the new one in, replace lid. Try Will's idea first, though...it's free.
  9. will33

    will33

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    If you can both operate a screwdriver and change a lighbulb.....you can do it!
  10. nubs

    nubs

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    so i should try and run a patch cord from return to send? and if this gives me a proper signal then its the preamp tube? am i understanding this correctly, i dont have another amp here now, but i do have one i can get from the rehearsal joint. thanks for the help guys
  11. JimmyM

    JimmyM Supporting Member

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    Correct, except there's a chance it's the preamp tube, not a for-sure thing. But in a hybrid, the second thing behind corrosion in the effects loop that you should suspect is the tube. 12ax7a, in case you don't know the tube number.
  12. nubs

    nubs

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    okay tried it, and it doesnt improve on anything.
  13. Downunderwonder

    Downunderwonder

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    The patch cord thing is to check out the condition of the loop jacks, some amps put the loop out of play when nothing is plugged in but get corroded, so you get noise or nothing.

    If it cleans up with something in the loop then it isn't the tube! If the noise is still there then it is more likely it could be the tube,
  14. nubs

    nubs

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    no, i have some output i would say about 25% of its actually power. patching the effects loop, everything pretty much is the same.
  15. will33

    will33

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    If the patch cord makes it work again, it means those jacks need to be cleaned. If it doesn't, then try a new tube, they're onoy $10-$15. Preamp tubes usually last for years or decades, but, quality/consistency nowdays isn't what it was back when militaries depended on them and it's possible you have a bad one.

    If neither of those help anything, it's probably tech time.
  16. nubs

    nubs

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    again thanks, i guess its time to try a tube, the patch cord and effects loop had no noticable improvement.
  17. JimmyM

    JimmyM Supporting Member

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    Don't know if you have any tubes laying around, but if you don't, I have to recommend trying a different brand besides JJ. I know Ampeg puts them in there as stock tubes, but I've yet to ever buy a JJ that lasted me longer than a few months. I had one that lasted a year. Other than that one, they have all gone belly up for me within a few months, and I just bought a set of JJ 6L6's for my Super Reverb that were microphonic out of the box.
  18. nubs

    nubs

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    any suggestions then sovtek, groove tube, mullard, mesa boogie thanks in advance
  19. B-string

    B-string Supporting Member

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    EH, Shuguang , TAD, Tung Sol, Ruby, Peavey re-brands, Fender re-brands, Genalex are some others.
  20. JimmyM

    JimmyM Supporting Member

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    A NOS Mullard sounded really hot in Johnk's 7 Pro, but I don't think you need to spend $100 on good tone ;) I prefer the decent not too expensive NOS tubes like RCA, Sylvania, etc., but I've also had pretty good luck with Sovteks. And I know they're rebrands but I've never gotten a bad Groove Tube. They apparently have some sort of weeding out process that actually works.
  21. nubs

    nubs

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    so as long as the number is 12ax7a, i should be good to go? i see allot of tubes with the 12ax7 number but with different letters at the end, C, r, S, WA just double checking.....do i have to find the 12ax7a's?? sure as heck dont wanna buy the wrong stuff...

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