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Question on frequency splitting two cabs (biamp question?)

Discussion in 'Amps and Cabs [BG]' started by Meatbass, May 3, 2010.


  1. Meatbass

    Meatbass

    Apr 30, 2010
    Frazier Park, CA
    I have a mono head (B1500) and two cabs (one 18, and four 10's).

    I was talking to someone about bi-amping (since I don't know anything about it) and he seemed pretty knowledgeable. He told me about crossovers and how to work them, but then I asked him if there was any way I could split my hi's to my 10's and low's to my 18 without bi-amping. He explained that I can go from my power amp into my two channel EQ (one channel for each cab) and then back out to the cabs.

    Correct me if I'm wrong, but this wouldn't this mess something up due to power running through the EQ?
    I don't want to put anything in between my power amp and my cabs. That in itself just seems like bad news waiting to happen.

    B1500 Amp
    My EQ

    Thanks in advance for all of the input!
     
  2. Rick Auricchio

    Rick Auricchio Registered Bass Offender

    1. You can't run power through an EQ designed for line levels. Not more than once, if you like smoke. With a mono head, you're out of luck there. You need two power amps.

    2. Tens and an 18 cover a lot of the same frequency range. So you're wasting your time and effort lugging 10s to cover the upper freqs. You'd do much better with a midrange driver, like an 8 or 6.

    Bottom line, it isn't worth spending any time trying to make this work with your present equipment.
     
  3. craig.p

    craig.p

    Sep 28, 2008
    New Hampshire
    Yeah, something definitely got jammed up there. The only things the power section of an amp should see are a crossover or a speaker -- plus maybe a voltage divider in certain cases, to knock the signal down to line level for a board feed.

    Only way I know to create separate frequency ranges post-power-amp is with a passive crossover. But maybe I'm missing something.
     
  4. Queg

    Queg

    Nov 20, 2009
    SF Bay Area
    I'm not expert but it doesn't sound kosher to me. I don't think you should try it. Most eq components are line-level, and aren't intended to handle all the gain of a power amp.

    Also, but doing this seems like you would be tremendously under-utilizing your 4x10 cab. It's more capable of handling low end then you're giving it credit for...

    EDIT: Wow, fast fingers before me as I was typing this!
     
  5. Meatbass

    Meatbass

    Apr 30, 2010
    Frazier Park, CA
    Thanks for the reply. I figured something was off with what he was describing.
    The 18's frequency response is 24Hz-2kHz while the 10's are 26Hz-22kHz.

    I also have a Carvin DCM2000 power amp. Would bi-amping then be possible?

    ...Are there any good threads on explaining exactly how bi-amping works? It seems it's still a gray area.

    I usually only use one cab or the other. They are both great! I just figure I have two cabs that are sitting next to each other, why not dedicate them to their own frequencies. *shrug*
     
  6. babebambi

    babebambi

    Jan 7, 2008
    YTZ
    yup, you are right

    if you want to avoid bi-amping, you can use a passive cross-over.
     
  7. Rick Auricchio

    Rick Auricchio Registered Bass Offender

    The Carvin power amp has two channels, which puts you closer to the solution.

    But a passive crossover would suck down so much power, it would have to be very expensive and large, and you'd have to design and build it yourself. An active crossover runs at line level on the amp's inputs.

    And there's still a huge overlap in the cabs' frequency response. Both are meant to cover the entire bass guitar range. Not sensible to try biamping with those cabs. Why yank around a 410 when you could get the desired result with two 8s? You wouldn't be using any of the low-freq power of the 410 cab, so lugging it around is silly.
     
  8. IvanMike

    IvanMike Player Characters fear me... Supporting Member

    Nov 10, 2002
    Middletown CT, USA
    in general biamping without cabs specifically designed for the frequencies involved is a waste of time in bass rigs. furthermore, one ten alone would be fine for handling the high end while one or two 18 cabs would do the lows. run them both full range. there may be some phase response anomalies, but maybe they will sound ok (check the faq sticky for that topic)

    and no, running speaker level outputs into an eq will not be pretty.
     
  9. billfitzmaurice

    billfitzmaurice Commercial User

    Sep 15, 2004
    New Hampshire
    Owner, Bill Fitzmaurice Loudspeaker Design
    +100.
     
  10. uhdinator

    uhdinator

    Apr 20, 2010
    Maine
    Here is how it would work providing you have the equip:

    effects send on your amp (controlled by Drive volume/pre-amp) to input full range on a rack mount crossover (only need to use one channel of a stereo 2 way crossover)
    set Xover freq at about 100-120hz. Send LOW out of x over to input on channel 1 of a stereo amp. connect the 118 cab to the speaker jack of channel 1 on amp.
    send HI out of Xover to channel 2 on stereo amp. Connect 410 to channel 2 speaker jack of amp. Use volume knobs on amp to adjust balance of high and low. (amp volumes become your MASTER volumes.

    Turn master volume on B1500 off.....(no return signal is going back into bass head).
    Set your drive level on head and leave it. I usually set the drive or pre amp by thumping the bass pretty hard and turn up pre amp until I see a little clip lite flicker and back it off a little from the point where the lite just starts to flicker to have some headroom. If you turn drive up too much you will just overdrive the stereo amp.

    set all input and output levels in the Xover at zero to start and tweek a little if necessary. Also you could run either the HI or LOW out of the Xover back to the return input of your head if you wanted, then the master on your bass head would be the volume for that freq range and you would only use one side of the stereo amp for the other freq.

    One reason where this would apply is say if your head is 700W at 8 ohm and your other stereo amp is only say 300W. If your 118 cab can take it then run the LOWs back into the B1500 head (to put the power to the low end as low freq needs more power than HI) and run the low freq off the amp in the head and run the HI out of Xover to the other amp. Hope that makes sense..

    Just don't run speaker jacks into line level inputs on EQ's or Xovers.
    (one way to avoid that is always use Speakon equipped speaker cables and you CAN't make a mistake). Oh and your crossover would need to have 1/4" input jack to connect the line out/send of your bass head. (some Xovers may only have XLR)

    I noticed the SEND on your rig is POST EQ so what ever you adjust on your tone controls would be going out the send and work normally.
    I run a bi amped rig but my head has 2 amps in it with Xover built in. Like it better bi amped and only use 115 and 210 cab
     
  11. Rick Auricchio

    Rick Auricchio Registered Bass Offender

    Except on the Fourth of July.
     

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