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bass head is really hot during practice

Discussion in 'Amps and Cabs [BG]' started by o2bass, Mar 30, 2005.


  1. o2bass

    o2bass

    Mar 30, 2005
    :help:

    Ok....help!!!

    I have a Gallien Krueger 700RB bass head and I was playing through a Hartke VX4x10 (flatulent edition) bass cabinet. Well I got tired of the cheap drivers over-distorting and dropping out and the tweeter popping on every slap so....

    I got an ampeg SVT 8x10 cabinet. It sounds wonderful. I can't say enough good things about it. But with that aside, I've noticed the GK head is getting REALLY hot during practice. No smoke yet, nothing like that but if it were any hotter you wouldn't be able to hold your finger to it. The heat is coming from the left side of the head if youre looking at it from the front end but I beleive the transformer is on the right side, which is odd. I'm worried that once we get on stage next week the additional heat from just being on stage *and* having the volume turned up even higher will be enough to push it over the edge and my whole rig will burn up. I'm also running a samson rackmount compressor and a furman power conditioner.

    Any suggestions? A bigger head? Two AC fans in the back of my cabinet?

    I'm using the output (380 watt AMP ONLY) jack thats 1/4 inch. The ampeg doesnt have speakons.
     
  2. Something isn't right. Is the fan spinning? If you're only running a single 4 ohm cabinet, it should be fine.
     
  3. o2bass

    o2bass

    Mar 30, 2005
    It doesn't have a fan. I was asking if I should install some in the back of the rack.
     
  4. bigbeefdog

    bigbeefdog Who let the dogs in?

    Jul 7, 2003
    Mandeville, LA
    More info on the 8x10... did you buy it new?

    Obviously, the concerns are:

    - if you bought it used, did someone change a driver or drivers to change the cab impedance, or

    - is there a short inside the cab that is dropping the cab impedance.

    I'd have it checked out before I use the head and cab together..... I assume it didn't do this with the Hartke?
     
  5. o2bass

    o2bass

    Mar 30, 2005
    The guy that sold it to me said he never changed the drivers and being the cab that it is, I have little reason to suspect he would.

    I could put an ohm meter on it and it should read 4 ohms.

    No it never did this with the hartke but it was only a 400 watt cabinet, quite possibly 200 watt RMS.
     
  6. Sutton

    Sutton

    Mar 3, 2005
    Plainwell, MI
    the head has no fans whatsoever? Because if that was the case, then yes, install some sort of ventilation system
     
  7. bigbeefdog

    bigbeefdog Who let the dogs in?

    Jul 7, 2003
    Mandeville, LA
    The cab rating won't matter.... unless you're saying that you never pushed the head with the Hartke for fear of blowing the drivers. Then it matters.

    BTW, a DC resistance test for the 8x10 would probably show something more on the order of 2.5 - 3.0 ohms for a 4-ohm cab. See if you get that. If you're lower, it probably suggests a wiring short inside the cab.
     
  8. o2bass

    o2bass

    Mar 30, 2005
    I could do that, no problem.

    Ampeg says this cab has an RMS handling of 800 watts. Are the speakers pulling too much power from the cab? Is that even a possible scenario? Or would the cab just put out what it has (380 watts).

    I know a little about electronics and I know one thing. If you put a 500ma DC transformer into a device that draws 3000ma, the transformer will overheat and burn up. Is that whats happening here? Kind of?
     
  9. A 700RB does have a fan on the top. Is this head in a rack? If there isn't any clearance above the top of the head, that would explain why it's getting hot.
     
  10. o2bass

    o2bass

    Mar 30, 2005
    Why would the ohm reading be anything less than 4 ohms?

    Im not doubting you, I just want to know why.
     
  11. bigbeefdog

    bigbeefdog Who let the dogs in?

    Jul 7, 2003
    Mandeville, LA
    Absolutely not. The speakers can't "pull" power from the head.

    Only two things to focus on - a fan issue (it's MISSING? :eek: ) or a connected load lower than 4 ohms.
     
  12. o2bass

    o2bass

    Mar 30, 2005
    Daniel, thou hath enlightened me. I never knew the thing had a fan.

    http://www.zzounds.com/item--GKR700RB

    Thats my head ^^. The area getting hot is the ventalation area which is covered up by the compressor. Thats a really quiet fan!

    Thank you for saving me from destroying my equipment. haha!
     
  13. bigbeefdog

    bigbeefdog Who let the dogs in?

    Jul 7, 2003
    Mandeville, LA
    Because cab impedance is not quite the same thing as DC resistance.

    Impedance is a little more complex, and includes capacitance and inductance as contributing factors. When you run a DC resistance test, you'll get something a little lower - generally about 65% - 70%.
     
  14. also check the resisters i remember in my ampeg head i had a problem like that it turned out someone put in the wrong resister. that caused it to overheat.