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Discussion in 'Amps and Cabs [BG]' started by DaS HaaS, Jun 12, 2004.

  1. DaS HaaS

    DaS HaaS

    Feb 11, 2004
    Sunrise, Florida
    Endorsing Artist - Ampeg, Ernie Ball
    I am in need of some help. Im desperate. I have a GK 400RB-III head that I use with a Hartke 410TP cabinet My bass of choice is a Cort Curbow5 I have a decent sized pedal board with about7 pedals. I have been using this rig for a bout 2 years and have never had a problem with it. last week I tried to add a second cabinet to my rig and about 25 min into practice the "power/protect light on my amp went from green to red and i had no sound, The clipping light was also solid red ( I have never seen the4 clipping light on in 2 years) I looked to see if anything was disconnected or anything of that nature and all seemd well. I turned of the amp and used another amp and continued playing. About 10 min later i turned on my GK head and the light was green again. I then tried to play again using my original setup with the 410tp cab and about 10 min into playing it happened again. I eventually left it off and continued practicing with the amp that was in the studio. When I got home I took the head out of the SKB case and smelled the inside just to see if it was fried, but all seemed well Today I went to practice with the normal setup I have been using for 2 years and about 45 min into practice it whappened again. sometimes the clipping light goes on in addition to the "power/protect" light going red, and sometimes it does not go on, just the "power/protect" is read and no sound. i tried diff cables and nothing still happens after x amount of minutes. i dont understand why this is happening after i rteverted back to my normal setup. Is my amp fried? shoudl I try to get it repaired? PLEASE HELP IM DESPERATE!
  2. mikezimmerman

    mikezimmerman Supporting Member

    Apr 29, 2001
    Omaha, Nebraska
    You didn't say what the second speaker cabinet was, but if it was a 4-ohm cabinet, you may have fried something. The minimum impedence for the RB400 is 4 ohms, and an 8 and 4 ohm speaker combined give you 2.66 ohms.

    Alternatively, you may have a short in either your speaker cabinet or your cable. I'd start by replacing the cable, and if you continue to have the problem, contact GK.

  3. DaS HaaS

    DaS HaaS

    Feb 11, 2004
    Sunrise, Florida
    Endorsing Artist - Ampeg, Ernie Ball
    The hartke cab specs on the hartke site say 8 ohms. The speaker that I have on the second cab is a Carvin PS15 speaker According to the specs it is 8 ohm as well. I also did some research on the GK website and I dont think the fan in my amp is working. The site said that when the fan takes a dump the amp will go into protect mode after a certain temperature is reached. Last night I had the amp on for about 2 hours and the light was green. so I am stumped. Any advice would be greatly appreciated
  4. notanaggie

    notanaggie Guest

    Sep 30, 2003
    I think you have it.....sounds like a classic thermal problem. Fan is a good place to start if yours isn't working.

    Stands to reason the amp might be OK at 8 ohms, but the extra dissipation at 4 ohms load might easily be too much with no fan. Replace the fan and it may be as happy as a clam in the mud.