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Cabs, Ohms & Power

Discussion in 'Amps [BG]' started by Woheelo, Nov 30, 2012.


  1. Woheelo

    Woheelo

    Joined:
    Nov 30, 2012
    I recently purchased a Carvin BX1500 amp head to run 2 Ampeg cabs. One cab is a 15" woofer in an 8 ohm cab, the other is a 4x10 in a 4 ohm cab. In reading the specs for the Carvin it appears that the best and safest way to use the amp with these cabs is not bridged, but using the bi-amp mode and 2 outputs from the Carvin. Does anyone have experience with this, any comments or suggestions?
     
  2. makohund

    makohund

    Joined:
    Dec 12, 2002
    No, don't bridge into those. Poof.

    Biamp mode generally refers to using the crossover, which would be pointless here... leave the crossover turned off.

    But it is still two amps with separate controls. Plug one cab into ch1, the other into ch2. Adjust volumes to match. Done.

    If running a 4x10 & 1x15 mix, that's the right way to do it, too. (On two separately controllable amps.)
     
  3. john m

    john m Supporting Member

    Joined:
    Jan 15, 2006
    4-10's and 1-15 is a bad combo to start.

    The 4-10 being 4ohms vs the 8 ohm 15 makes it worse.

    You'll hardly hear the 15 unless you have a way to turn down the 4-10.
     
  4. BassmanPaul

    BassmanPaul Gold Supporting Member

    Joined:
    Aug 25, 2007
    Location:
    Toronto Ontario Canada
    While I am completely against the dreaded 4x10 plus 1x15 pairing it can work to some extent if run from separate amplifier channels. The BX1500 is fine for this purpose. What you WILL have to be aware of is that the 15 cannot keep up with the 4x10 in volume. If you try to get equal volume from each cabinet you'll end up killing your 15.
     
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  6. xUptheIronsx

    xUptheIronsx Conform or Be Cast Out.... Gold Supporting Member

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    C-ville, Col, Ohio
    is this the same for a 4x10 and 2x15 combo as well?
     
  7. HolmeBass

    HolmeBass Supporting Member

    Joined:
    Jan 18, 2007
    Location:
    Charlottesville, VA
    No, not at all. A 2x15 cabinet is plenty loud and can probably keep up with a 4x10 for the most part, and you actually will get a different low-end / sub quality to your sound with that combination.

    You do still have to properly match the impedance of your cabinets to your amp- so if the 4x10 and 2x15 are both 4 ohm cabinets, you need to either have two 4 ohm stable amps, or a single 2 ohm stable amp to run them in parallel (parallel being the 'stock' way cabinets connect together when daisy chaining or running from two outputs of a single amp. For series connections you usually need some sort of a special cable.)
     
  8. CL400Peavey

    CL400Peavey Supporting Member

    Joined:
    Nov 7, 2011
    Location:
    Grand Rapids Michigan
    The best pairing for any cab, is an identical one.

    :scowl:

    Nope. Speaker size has nothing to do with frequency response. Its about the design of the speaker and the cab around it. While a 215 and 410 might be more closely matched in output, you will still have more consistent results matching identical cabs.
     
  9. ThisBass

    ThisBass

    Joined:
    Aug 29, 2012
    Location:
    Germany
    So can one 110 keep up with 310 in volume the answer will be no.
    If you try to get equal volume from each you'll end up killing the 110.

    So can one 110 keep up with 210 in volume the answer will be no.
    If you try to get equal volume from each you'll end up killing the 110.

    So can one 110 keep up with 110 in volume the answer will be YES
     
  10. ThisBass

    ThisBass

    Joined:
    Aug 29, 2012
    Location:
    Germany
    But impacts efficiency as well (which is SPL).
     
  11. two fingers

    two fingers You tahkin 'uh me? Yeah, you. You tahkin 'uh me? Supporting Member

    Joined:
    Feb 7, 2005
    Location:
    Eastern NC USA
    If I were you I would pick the cab I like the most. Sell the other one and buy one to match the one you kept. Mismatched drivers ind impedance is a bad stew. It's just not worth trying to get them to play nicely together.
     
  12. BassmanPaul

    BassmanPaul Gold Supporting Member

    Joined:
    Aug 25, 2007
    Location:
    Toronto Ontario Canada
    Forgive me but I fail to see the point of your post. It's completely meaningless.
     
  13. bassmeknik

    bassmeknik

    Joined:
    Nov 6, 2009
    Location:
    Fair Haven, MI
    wow. just wow. The entertainment factor of TB just keeps growing and growing. Such excitement.


    I will never cease to be amazed how many people on TB try and sell their version of sliced bread (I am referring to mixing driver sizes) to the rest of us who are way ahead of them. I used a mixed driver rig several years ago. Dumped it once I heard myself out front and never really liked my sound. The power balance issue was another thing entirely making the whole rig monstrous. Today my cab has all the same size drivers in it and this whole subject on TB is really quite amusing.
     
  14. two fingers

    two fingers You tahkin 'uh me? Yeah, you. You tahkin 'uh me? Supporting Member

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    Feb 7, 2005
    Location:
    Eastern NC USA
    Si, I guess we should, from now on, just tell everybody that everything is a GREAT idea. Mix and match drivers and ohms. It's a free for all! Woohoo! No more rules! :rollno:
     
  15. BogeyBass

    BogeyBass

    Joined:
    Sep 14, 2010
    Woheelo

    as you can tell mixed driver setups are greatly discouraged.
    but the one thing that can make mixed drivers work, and does make mixed drivers work is a crossover. lucky you the carvin amp has a active one...yay

    But yes your correct you should use biamp mode with your cabinets.

    The low output would go to your 1x15 and the high output would go to your 4x10

    so yes the output of a 1x15 is much lower than a 4x10.

    this is why carvin is smart and put a level control for each output. so you can balance the system.

    [​IMG]

    start with the level turned up on just the 1x15, then bring up the level on the 4x10 to match.
    once the system is balanced use the master volume to control the overall level.
    Keep in mind at lower volumes the levels on the high/ lo might be different, than using higher master volume settings. So when you increase the master volume you might have to re balance the hi lo levels on the crossover.

    the 4x10 can handle a good deal of bass so you should be able to use a lower crossover point, even down to 200hz

    this means everything above 200hz will go to the 4x10 and everything below 200hz will go to the 1x15.
    of course this is adjustable so you can sweep the crossover point till it sounds good to your ears.

    start slightly below the midpoint around 700hz and then lower it to 600, 400 ,300 till it sounds right to you.

    again as said the weak point is the 1x15, you can balance the system but when you need to get louder and the 15 starts to distort, then that is max volume of the balanced system.

    most likely as stated the 4x10 should be able to go louder, but you wont be able to go any higher than this if you want to without adding another 1x15. Or just running a matched system without the crossover and just run 2 fullrange 4x10's or 2 fullrange 1x15's

    also you could try just running the 4x10 without the 1x15 and see if that gets you more volume than using the balanced pair.
    if you find the balanced system not loud enough in your band situation.

    also if you just listen to just the 4x10 on the crossover and sweep the crossover point higher say 600hz to 700 to 800 to 1000hz
    you will notice that it will be reducing the amount of bass content going to the 4x10 since it is a highpass filter (only high frequency pass through)
    reducing the bass will also reduce the overall level since most bass guitar is below 700hz. by using a higher crossover point it can help reduce the level of the 4x10 if you need more adjustment between the High low adjustments.

    so say the lo crossover is way up to get the 1x15 right and then the high is turned way down to get the 4x10 to balance right. Raise the crossover point to help further reduce the level of the 4x10.

    most likely since the 4x10 can handle alot of bass the crossover point will be around 200hz. but then again there is a limit to the system since now most of the bass content is being reproduced by the 15, and again as mentioned the balanced system can only go so high because the 15 will distort first.
     
  16. bassmeknik

    bassmeknik

    Joined:
    Nov 6, 2009
    Location:
    Fair Haven, MI
    just to be clear I was using an electronic crossover set at about 150hz. My mixed driver rig was 1 or 2 18"s and a 4-8" top box, sealed top box/vented 18"s. sucked IMO... 810's rule.
     
  17. Growly Lytes

    Growly Lytes

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    Dec 4, 2009
    Location:
    Downunder Oz
    Disclosures:
    Bass player
    Man ive been doing it for years.
    I just needed to get a stereo poweramp which i did.
    Im using 2 different 4x10 cabs.One on each channel.I also have a 15` that i tried & worked well with a 410.
    Top cab gets more top-end sound & the bottom cab gets low, low-mids but by nature the cabs are voiced,made that way.Im sure you can get it to work but the ohms worry my a little.Try to find cabs that are the same ohms.I think an 8ohm & 4ohm together makes a load of 2.6 ohms or somewhere there abouts im not 100%.Make sure your amp can handle this !
    Im not using a crossover & am still getting a good result by adjusting db levels & eq.
    so im in the boat that says yeah anythings possible.
    Good Luck.
     
  18. B-string

    B-string Gold Supporting Member

    Joined:
    Nov 21, 2008
    Location:
    Lake Havasu City, Az USA
    Yes a 8 ohm and 4 ohm cab in parallel is 2.667 ohms.
     
  19. ThisBass

    ThisBass

    Joined:
    Aug 29, 2012
    Location:
    Germany
    So can one 115 keep up with 410 in volume the answer will be no.
    If you try to get equal volume from each you'll end up killing the 115.

    So can one 110 keep up with 410 in volume the answer will be no.
    If you try to get equal volume from each you'll end up killing the 110.


    So can one 210 keep up with 410 in volume the answer will be no.
    If you try to get equal volume from each you'll end up killing the 210.
    But this would be a problematic if you consider a 610 cab.
    So a chainsaw may solve this problem. :D
     
  20. ThisBass

    ThisBass

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    Aug 29, 2012
    Location:
    Germany
    math is correct but I'd say appro 2.7 Ohm
     
  21. dincz

    dincz

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    Sep 25, 2010
    Location:
    Czech Republic
    Three decimal places for nominal impedance is unnecessary. In fact let's call it 3 ohms :)
     

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