1. Please take 30 seconds to register your free account to remove most ads, post topics, make friends, earn reward points at our store, and more!  

Demeter HBP-1 Tube Problem

Discussion in 'Amps and Cabs [BG]' started by SpreadinButter, Mar 23, 2009.


  1. SpreadinButter

    SpreadinButter

    Jan 26, 2009
    Hey everyone heres what happened...

    I was getting levels set for a new recording I was working on and my drummer jacked my Demeter HBP-1 preamp volume to about 3 o'clock after I had him turn it down. I kept playing in about 15 minutes I started hearing a very odd crackling noise through the headphones on any note sustain for a period of time... especially when it was a lower freq. Anyways I turned the level to 0, put down the bass, and checked all my cables.

    To my suprise when I came back to my bass the preamp was not working at all. I checked all the cables, the power amp, as well as the speaker. Seems to be the pre-amp. The amp is only about 30 days old mind you.

    Took the chasis off of the unit and inspected it. Nothing looked weird accept when I turned it on the tubes were glowing very faintly. Now this is my first tube amp so I don't really know how much they are supposed to glow so I'm stuck.

    Anyways, my preamp gives no signal when sent DI and no signal to the power amp. I am assuming it is a defective/blown tube since it is the first "stage" of the preamp. Does anyone know how to replace one on this particular pre? I've only used solid state before and It seems too delicate for me to start messing with before I know what I'm doing.

    Thx
     
  2. uaudio

    uaudio

    Apr 11, 2008
    Arizona
    Assuming it is the tube, its a 12ax7. Easy to find, should be easy to replace.

    I'm not sure if this applies, since it seemed like they solved this problem. Were you using the XLR output straight into the board? If the board is 48v phantom powered, Demeter states this might cause damage to the pre.

    http://www.talkbass.com/forum/showthread.php?t=267952
     
  3. Pickebass

    Pickebass Supporting Member

    Jul 12, 2004
    San Antonio, TX
    I'll put money on it being the XLR was blown. That's exactly how it behaves when this happens.
     
  4. SpreadinButter

    SpreadinButter

    Jan 26, 2009
    1.) Yea the tube is a 12AX7. What do you do just pull it straight from the yellow chip? It looks to be soldered in there. (very new at this)

    2.) No I was going direct out 1/4" to an unpowered digital board. The XLR is being used to provide signal to my power amp, I've been playing with it this way since I go the pre with no problem so far.
     
  5. SpreadinButter

    SpreadinButter

    Jan 26, 2009
    Maybe, but would that damage ALL of my outputs? I am getting absolutely no signal from any of them. I was just assuming it was the tube since it is the first stage of the pre and there is no singal from either the DI or XLR.
     
  6. Zooberwerx

    Zooberwerx Gold Supporting Member

    Dec 21, 2002
    Virginia Beach, VA
    Call Mr. Demeter:

    http://demeteramps.com/contact/index.html

    You'll probably get his voice mail but he's good about returning calls.

    BTW, I saw a couple of references to "tubes". To the best of my knowledge, the HBP-1 only has one.

    Riis
     
  7. SpreadinButter

    SpreadinButter

    Jan 26, 2009
    Thx I will... Just let it run for about 10 minutes and the tube is physically warm. If it was defective would it still warm up. (Starting to get a bad feeling about the whole XLR deal)
     
  8. uaudio

    uaudio

    Apr 11, 2008
    Arizona
    I don't mind a little DIY, but on a high end Demeter preamp less than a month old...that thing is going back to the manufacturer, unless its a just a bad tube. I'd talk to Jim, see what he says.
     
  9. Zooberwerx

    Zooberwerx Gold Supporting Member

    Dec 21, 2002
    Virginia Beach, VA
    S*** happens. I did something to mine last year whereas the mute button quit working. Don't know if I inadvertantly spiked it with phantom power or what. Anyway, I shipped it to CA for repairs and its been fine ever since.

    FTR, I use the 1/4" balanced out to my amplifier and the XLR DI to the board. This kinda makes more sense as the XLR DI can be switched betweenst DI and line level modes. There's a reason for this but I can't begin to explain the rationale.

    Riis
     
  10. SpreadinButter

    SpreadinButter

    Jan 26, 2009
    Yea thats what I normally do as well but my power amp only has XLR inputs and I wanna blend the cab and DI signals. I've heard you can get pretty decent results with this pre on its own though so I'm excited to experiment.

    Just left a message with Demeter.

    How much did they charge you for repairs?

    Did you buy it straight from them or a middle man?

    Lovin that avatar btw, your work?
     
  11. Zooberwerx

    Zooberwerx Gold Supporting Member

    Dec 21, 2002
    Virginia Beach, VA
    IIRC, the repair was ~$80 but Mr. Demeter did a couple of upgrades whilst in the chassis. You'll deal straight with the man himself, no middle man.

    The avatar is a partial scan of a print (gift from wife). It kind of looks like me: big puffed-up blowhard playing a Mouradian-shaped plexi bass with a badly warped neck and wanger-shaped headstock.

    Riis
     
  12. blowinblue

    blowinblue Blue in name only. Supporting Member

    Nov 29, 2006
    SoCal USA
    Sorry to hear of your troubles, mate. This is why I bought the 'J' version of this preamp. The 'J' (Jensen transformer equipped) is supposed to be immune to 48v phantom power issues...or so I'm told. :eyebrow:

    M. M.
     
  13. Sure it's not the input jack? I had trouble with my passive one.
    Also, a nice lady at Demeter told me that the DI won't be harmed by phantom power unless it exceeds 60vdc. I learned this while asking about upgrading to the transformer DI.
    And even if it blows, the other outs should still work, according to the manual.
     
  14. SpreadinButter

    SpreadinButter

    Jan 26, 2009
    Thanks for the info everone.... just talked to Master Demeter said its prob not the XLR and to try the unbalanced 1/4" out before I send it back to him.
     

Share This Page

  1. This site uses cookies to help personalise content, tailor your experience and to keep you logged in if you register.
    By continuing to use this site, you are consenting to our use of cookies.