Problem with Aguilar DB659 pre amp

Discussion in 'Amps and Cabs [BG]' started by Larry99, Feb 20, 2006.

  1. Larry99

    Larry99 Supporting Member

    Aug 17, 2005
    Philadelphia, PA
    Help! tell me whats wrong…. When I plug in and play, quite often (not all the time), the dB level is initially not as loud as it should be. I’d say the volume/dB level is only about 65-70% what it should be. After about 10 mins, the dB level will increase instantaneously. I’ve found that volume levels will come up if I toggle the bright boost switch on the pre-amp. I can position the switch back and the levels will stay up. This does not work when I toggle the low boost switch or the ground switch in the back. Occasionally, the level will drop back down again after about 10-15 mins of playing but not so often when the amp is warmed up. Obviously this is annoying, especially at a gig in the middle of the first set.

    I opened the unit up and checked for loose connections, inspected the tubes, etc. I really don’t think it’s a tube issue ‘cause the tubes looked ok and I swapped the two 12AX7s in case the one was causing the problem but I still get the same thing. I noticed there is a small capacitor in the bright boost switch circuit. I’m thinking it might be this cap… ??
    What do you think?
  2. jokerjkny


    Jan 19, 2002
    NY / NJ / PA
    hmm... could be bad power in the wall... have you tried another outlet?
  3. ajb


    Mar 20, 2005
    I recently sent my DB 359 back to Aguilar for repairs due to a cut-out problem I had that eventually morphed into the problem you're describing.

    Give them a call. They're good guys who take their jobs very seriously and will take care of you.

    BTW Joker, how'd you manage the gig?
  4. Larry99

    Larry99 Supporting Member

    Aug 17, 2005
    Philadelphia, PA
    I wanted to avoid having to ship it out but I guess that's probably what I'll have to do.

    ...and no, the problem happens no matter where it is plugged in.
  5. westland


    Oct 8, 2004
    Hong Kong
    Before shipping this out, why don't you replace both tubes with new ones. If one has problems, it will have problems in both the V1 or V2 socket, so try to swap out both ... even for a cheap tube.
  6. jokerjkny


    Jan 19, 2002
    NY / NJ / PA
    which one?
  7. Larry99

    Larry99 Supporting Member

    Aug 17, 2005
    Philadelphia, PA
    I think I will definitely try this out.

    Also, what are the symptoms of bad tubes? I was playing again the other day and thought I heard some static just before the levels dropped out. It almost sounded like a dirty cord or pot but it was definitely somthing in the amp. Maybe I just have some bad tubes?
  8. Larry99

    Larry99 Supporting Member

    Aug 17, 2005
    Philadelphia, PA
    I wanted to resolve this thread and let everyone know how great Aguilar customer service is. Problem turned out to be as simple as cleaning the leaf switch contacts in passive input jack.

    Appearently, when nothing is plugged into the jack, there is contact closure in a leaf switch. Plugging into the jack opens the switch. So as I plug into the Active jack, the passive switch contacts were dirty and not making good contact which resulted in the intermittant dB/vol level change.

    anyway, Geof at Aguilar walked me through the process via email and all is now fine. His instant replies over 4 or 5 emails answering all my questions helped me fix it in a day!

    Bravo Aguilar!
  9. tombowlus

    tombowlus If it sounds good, it is good Gold Supporting Member

    Apr 3, 2003
    North central Ohio
    Editor-in-Chief, Bass Gear Magazine
    Great to hear that you had a happy ending! That 659 is one of my favorite preamps. :)
  10. BuffaloBob4343

    BuffaloBob4343 Supporting Member

    Jul 3, 2005
    Buffalo, NY
    Mine too, Tom!

    Larry, when you get a chance, can you PM me and tell me what they told you. I've been noticing that static sound myself on rare occasion.

  11. remo


    Jan 15, 2005
    gotta love the feeling of a DIY fix!!!