GK-NEO 700rb bi-amp no sound from tweeters

Discussion in 'Amps and Cabs [BG]' started by acmeseed, Dec 26, 2013.

  1. Hello,

    I have a GK 700rb head and 3 NEO cabinets, 112,115 & 410. I connect them with speakon cables and have the cabinet's switch set to bi-amp mode.

    I don't get much sound out of the tweeters, I can turn down the woofer level all the way down and crank the tweeter all the way up, I barely hear any sound.

    I wonder if I am missing anything about how this is supposed to work or if my amp head may need to be repaired.

    Thanks in advance for your feedback.
  2. How bright is your bass, what are your eq settings? Flats, half rounds or round wounds. The crossover point is 5 KHz, you may not have a lot of information up there from your setup.
  3. My first guess is that you're running one too many cabinets. The head runs down to 4 ohms. You're somewhere around 2 ohms now if those are 8 ohm cabinets. Remove one cabinet.
  4. DWBass

    DWBass The Funkfather

    Are you using GK cables or proper Bi-amp Speakon cables? And yeah, don't run that head under 4ohms!
  5. Cirk


    Jan 16, 2011
    Pittsburgh, PA
    Do the crossovers on your cabs have fuses? Have you checked them? Sometimes they're just a light bulb. Look for any toasted components.
  6. With the cab in "Biamp" mode the horn is directly connected to the 2+,2- on the speakon cable :cool:
  7. BassmanPaul

    BassmanPaul Gold Supporting Member

    Aug 25, 2007
    Toronto Ontario Canada
    You are using a Speakon cable with four cores?

    If all of the cabinets are 8Ω then, as Kedo opines, you are below the minimum for your amp and damage will result. Running your 4x10 with either of your other two cabinet will cause the larger cones to fail. They simply cannot keep up with a 4x10. Please do a search on the subject of mixing driver sizes. Even if your amp could accept al three this simply means that both larger canes will be subject to failure.
  8. BassmanPaul

    BassmanPaul Gold Supporting Member

    Aug 25, 2007
    Toronto Ontario Canada
    So they bypass the high frequency components of the Xover? Interesting, I would have thought they'd leave them in to offer some high pass protection. Even with the bi-amp Xover, there will be the possibility of low frequency noise coming off the mains into the high amp.
  9. Only if the electronic crossover fails in the amp head, if it did fail (utilizing TL072 opamps) it's really doubtful it would pass anything to the "horn amp". :)
  10. Thanks Paul and everyone else.

    I left out important information, I do not run more than 2 cabs at a time, the 3 cabs are 8 ohm. I was trying to say that I hear the same results with either cab which points to either a non-issue or an issue with the head. I am just not familiar enough with bi-amped cabs to know what to expect.

    Paul, from your message I gather that you think even running the 410 with another cab would damage the other cab's cones?

    I am using the cables that came with the cabs, I have 4 cables, all of them display the same low output out of the tweeters.

    I am using 2 Fender basses, 1 P-Bass and 1 Jazz-Bass both with Chromes flatwound.

    I am trying to figure out if there is a problem so that I can get GK involved in case the head needs service.

    Thanks again for all your responses.
  11. Flatwounds you are not sending much up that high, mostly fret and pick noise. Try fretting close to the neck pickup on your G string.