Need help diagnosing Aguilar DB 728

Discussion in 'Amps and Cabs [BG]' started by bryansells, Dec 2, 2004.

  1. bryansells


    Dec 30, 2003
    Hi, I have an Aguilar DB728 that keeps blowing fuses on one tube, and sometimes on others as well. In case you're not familiar each power tube is individually fused. Some of the tubes have 250V 1/4A fuses, and others have 250V 1/2A fuses. The first time I went into the amp I replaced five blown fuses. After replacing the fuses, the amp will sound good for a little while, say 10-20 minutes. Then the sound will lose shape, get muddy at the bottom, introduce a buzzy distortion etc. The last time this happened, I looked into the front of the amp and one tube was glowing MUCH brighter than the rest. I immediately turned the amp off. I've no doubt that a fuse is blown in there but I haven't pulled it out yet.

    The amp was purchased secondhand and did not come with a manual, and I can't find anything about it on the 'net. I can't even be sure that the fuse values that the amp came with are the correct values.

    Anyone with a DB728 willing to pull the bottom plate and tell me what values their fuses are, or have a manual?

    Anyone familiar with this sort of failure who could give me a direction to look?

    Thanks for your help
  2. Ralphdaddy

    Ralphdaddy Supporting Member

    Nov 6, 2003
    Chicago, Illinois
    You could try calling/emailing Aguilar, also they have a presence on these boards, I think Dave Boonshoft himself to tell the truth.... Try PMing him and see what they come with, no one will know better than him.
  3. vanselus


    Sep 20, 2000
    Boulder, CO
    Aguilar has great tech support. Email Geof at

    Did you bias it? I never had a fuse blow in my DB728, but for the record, Geof told me that it's normal for the tubes to glow differently. How differently I don't know. In either regard, Geof will know.

    Here's the manual:

    And it says the fuses....

    1 external 12 amp for 100 – 120 VAC operation.
    (6 amp for 220 – 230 VAC operation)
    1 internal redundant per above
    8 internal .250 Fast-Blo. One per tube.
    1 internal 15 amp Slo-Blo.
    1 internal 2 amp Fast-Blo.

    Hope that helps.