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Power Amp settings...HELP!!

Discussion in 'Amps and Cabs [BG]' started by Mr_Sore_Fingerz, Mar 13, 2009.


  1. So I have a Sansamp RPM going into a Behringer EP1500 power amp and supposed to go into two 8 ohm GK cabs (later two Markbass cabs).

    I am posting this because i have not the foggiest how to set all this up and the guy i bought it from used it as a PA power amp, so he was no help. Also, how do I know when im pushing the speakers too hard. This thing puts out 700w per channel so should i just use common sense math (12'clock = 350w?).

    Tips, experiences or any advice is greatly appreciated! :help:
     
  2. MIJ-VI

    MIJ-VI Banned Supporting Member

    Jan 12, 2009
    Amps FAQ *** Now with info on OHMS, PORTABLE RIGS, & Over/Underpowering Cabs & DIY!
     
  3. smogg

    smogg

    Mar 27, 2007
    NPR, Florida
    I'm not crazy, I'm just a little unwell
    Your sansamp is your pre, use a 1/4" to dual 1/4" LINE cable from the "out" of the sansamp to the 2 "ins" of the power amp. Run SPEAKER cables from the left out to one cab and the right out to the other cab and use the two volume controls on the power amp as your master volumes. Just turn them up a little at a time till you hit the volume you need.
    note: with both volumes at 12 o'clock it will probably be very very loud. have fun.
     
  4. no real rhyme or reason to figuring out how many watts im putting into my cabs? I don't care TOO much about the GK's cuz they are cheap, but I'd like to be a bit more careful with the Markbass ones. Any utilities I could use to tell how many watts are going into them?
     
  5. 3506string

    3506string

    Nov 18, 2004
    Lawton, OK
    The red peak light will let you know if your pushing the cabs too hard. The volume knobs don't necessarily negate wattage but the gain of the signal. And the EP1500 only puts 260 watts at 8 ohms per channel. You can bridge the amp and run the cabinets in parallel to get 1400 watts. And you don't need to run two cables into the power amp there should be white switches on the back of the amp that will allow you to run the inputs parallel.
     
  6. smogg

    smogg

    Mar 27, 2007
    NPR, Florida
    I'm not crazy, I'm just a little unwell
    +1 If the amp has a built in parallel switch one (1) LINE cable will suffice to connect pre to power amp.

    To original OP: It is really important that you use the correct cables. DO NOT use a speaker cable to connect the pre to the power amp. Use a shielded LINE cable only (like the cable that runs between your bass & amp) the shorter the better and recommend nothing lighter than 16 gauge speaker cable.

    P.S. if you don't have the manual for the power amp go to the manufacturers web site and download it. ;)
     
  7. Thank you for the tip on the cable, I haven't cranked it up because my cabs only use 1/4" and the amp only does speakon, but that will change soon with markbass cabs I'm hopefully getting.

    As far as the bridged mode and stuff like that...waaay over my head. I'll check out the online manual but if anyone could point me in the direction of a tutorial or walkthrough for that I'd be very appreciative.
     
  8. Are there any Y-Cables or something I could use to hook up 1 output on the power amp to my 8-ohm cabs and get a 4 ohm load on it?
     
  9. David1234

    David1234

    Jun 1, 2004
    Sydney, Australia
    Endorsing Artist: SWR Amplifiers
    Your cabs probably have two connectors, so run a cable out from one cab to the other.
     
  10. David1234

    David1234

    Jun 1, 2004
    Sydney, Australia
    Endorsing Artist: SWR Amplifiers
    Also note these amps are pretty decent but can sound worse in bridge mode. If you can order your markbass cabs in 4 ohm and run the rig in stereo you might have more fun.

    The EP1500 has some speaker protection circuitry that you ought to use. A clip limiter and a selectable HPF. Definitely use the limiter, it doesn't kick in too early but can protect your speaker. .

    Depending on your cabs and whether you're going to play 5 string or not, you can choose the 30Hz or 50Hz setting on the highpass filter, or you could leave it off if you don't like the changes it makes to the sound (you probably won't hear the difference, and having it on means you're not wasting power amplifying anything you can't hear)

    Enjoy!
     

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