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What to listen for with mismatched cabs (out of phase, one cab over-powered, etc)?

Discussion in 'Amps and Cabs [BG]' started by Phlipper, Mar 10, 2013.

  1. Phlipper


    Feb 5, 2013
    Fayetteville, NC
    Endorsing Artist: Old SS Peavey Lead Sleds and Peavey tube amps
    I'm making the switch fulltime from guitar to bass and trying to read all I can about cabs and amps. I'm a typical tube snob guitarist who sometimes fretted over minute details on amps, tube combinations, booteek pedals, etc., but the bass side is new to me. Lots to learn.

    I'm still a bit perplexed by cab mismatches and what I would be hearing (or should be listening for) if the match is bad, especially phase issues or overpowering one cab in a rig.

    1. If I have a 4 ohm 2x12 rated at 1200 watts on top of a 4 ohm 1x15 rated at 600, and I'm pushing 700 watts thru it with the gain/volume up enough for my circuit protection light to blink constantly ... what will the 15 cab likely sound like, or what characteristics tell me it is maxed out while the 2x12 isn't breaking a sweat? Will the 15 start farting or breaking up? That's what I'd hear on a guitar amp pushed to the max, are bass cabs the same, does it just start farting and sputtering when it's maxed?

    2. If I have a 4 ohm 2x12 rated at 1200 watts underneath a 4 ohm 2x10 rated at 700, and I'm pushing 700 watts thru it with the gain/volume way up there on an outdoor gig ... if the cabs are 'out of phase' or just not synching up somehow, what sound or characteristic am I going to be hearing that tells me specifically it is a phase issue? I have heard speakers within a single cab that were wired incorrectly and was told they were 'out of phase' and it just sounded not quite right.

    From some of the posts it seems a phase issue or power handling mismatch is glaringly obvious, something more than just "I don't sound so good!". Gimme a hint.
  2. JonnyAngle

    JonnyAngle Dropping Acid Pedal Etching .com Supporting Member Commercial User

    Nov 24, 2008
    Maple Grove, MN
    I may get flamed your saying this but Watts are less important for bass amps.

    First off, make sure your head can handle a 2 ohm load.

    Second, if your cabs have the same impedance, divide the power by 2 to get the power that each cab will receive. Then take into consideration the number of drivers in each cab.

    So each cab gets gets half of the amps power. Therefore a115 will get 350 Watts and each 12 in your 212 will get 175. The 115 will be working much harder than the 12s.

    Phase issues are something I cannot help with
  3. jellymax

    jellymax Don't fry any wooden fish

    Nov 29, 2006
    SF CA
    if 1 box is wired out-of-phase then running both cabs will produce less bass than 1
    box alone, more so if the boxes are identical

    here is my take on mismatching speakers. i had a good 410 eden box & a good 15"
    box. together they produced a midrangy sound i did not like. seperately they were
    good, although each requires different eq.

    here is a tip; you dont need to 15" boxes for lows anymore. you can get
    all the bass you need with modern 8, 10, 12, 15" speakers. find a box that
    sounds good to you, then buy 2 of them.

    if you are running 2 4 ohm boxes thats a 2 ohm load for the peavy--you will
    overheat that amp & fry it!
  4. The "phase" issue that is talked about when using mixed drivers in full range is NOT the reverse polarity phase issue.

    It is about the frequency responses of the different drivers causing additive and destructive frequencies that will cause boom in certain areas of the spectrum, and cut outs of other parts of the spectrum around the room (depending where you stand in the room, your sound could be overbearingly boomy, and if you move to another area you may hear no bass at all).
  5. Mr. Foxen

    Mr. Foxen Commercial User

    Jul 24, 2009
    Bristol, UK
    Amp tinkerer at Ampstack
    Ugly sound is pretty much it.
  6. DigitalMan

    DigitalMan Wikipedia often mistakes my opinions for fact Supporting Member

    Nov 30, 2011
    Bay Area, CA
    Here is a thought on the phase issue.

    First, it's totally unlike wiring two cabinets with reverse polarity. That'll be obvious and sound very weak and thin.

    Instead, two cabinets with different phase response profiles will possibly have one or more frequencies where there is more cancellation than reinforcement. My own analogy is that it would be like a sound engineer applying a notch filter or two (or three) at random frequencies into your signal path and not telling you about it. The frequencies would not be based on any judgment as to whether it improves or harms the sound. The only thing that would be somewhat predictable is that the frequencies where this happened would have some order of spacing between them.

    So how do you listen for that? Probably the same way you play a bass up and down the neck to listen for dead spots. The problems are more likely to be pronounced in the lower frequencies, although they are certainly possible across the whole spectrum.

    Note that this phase issue is caused by wave with the same frequencies having a different absolute start time from either speaker. In other words, all speakers lag at producing sounds at various frequencies. This lag differs up and down the frequency spectrum, but is also different from one model speaker to the next.

    There are other positional factors not related to mixing drivers that people will sometimes throw into the conversation. Those factors are real as well. They just don't relate to response-time induced phase issues, although they could certainly compound them (or mitigate them) if you set your enclosures any significant distance apart.
  7. SirMjac28

    SirMjac28 Patiently Waiting For The Next British Invasion

    Aug 25, 2010
    The Great Midwest
    I just called the fire dept for this thread it's going to get hot very soon.
    jwindham likes this.
  8. subbasshz


    Aug 11, 2012
    phoenix az
    Im addicted to punishing volume.
  9. BawanaRik


    Mar 6, 2012
    New Jersey
    It's happened before. There are many ways to skin a cat, or to get a desirable tone.

    I would postulate that the physical placement of speakers could have as much effect as how well matched they are.

  10. BAce


    Jul 31, 2012
    First off, congrats on graduating to bass from guitar. You are now the backbone of the band and with great power comes great responsibility.
    Keep in mind that the two cabs in question may also have different sensitivities. One of them may be rated at 94 db and the other at 100 db. The 100 db cab will be considerably louder when connected in parallel to the 94 db cab.
  11. DigitalMan

    DigitalMan Wikipedia often mistakes my opinions for fact Supporting Member

    Nov 30, 2011
    Bay Area, CA
    The beauty of screwing things up with poor placement is that it's predictable. Unfortunately the person placing the cabinets (for example on either side of the drummer) hasn't the (knowledge) tools to make the prediction.
  12. Jaco who?

    Jaco who?

    May 20, 2008
    If you can EQ your amp to where both cabs sound clear and articulate at the same time without unwanted boomyness, (not a real word but I don't know how else to describe it) you're probably not experiencing phase differences between the two cabs, and you shouldn't worry about it.

    You also shouldn't take cab wattage ratings too seriously - even the all hallowed fEarfull 212 probably can't handle 1200 watts.
  13. Jaco who?

    Jaco who?

    May 20, 2008
    No need to worry, the old FireBass 700 will run all day long @ 2Ω and barely break a sweat, I know, I've done it.
  14. BawanaRik


    Mar 6, 2012
    New Jersey
    Back in the day (BITD) Peavey was pretty much the only major running 2 ohm loads. When ever I hear the word Peavey I think of the term Work Horse.

    In many ways Hartley Peavey was the next gen Leo. When ever I feel to old I check the want ads for used motor cycles and think about Peaveys. The T40

  15. makohund


    Dec 12, 2002
    +1 to most of that.

    Though you might be suprised at what that all hallowed cab can handle. Mine gobbles up 1500W without issue or worry. Sure if I compressed the snot out of everything and actually tried to blow it up I probably could... but that'd be dumb. :D
  16. will33


    May 22, 2006
    It's most easily heard when carrying smaller places with your rig. As you get out where your audience is and move around the room, you will find places where the low frequencies are very strong...to the point of muddying up the mix and other places where the LF almost goes away and the bass can almost disappear in the mix or sound very thin.

    The phasing thing can also be heard further up in the mids where depending on how well the speakers mix or not, the mids can sound "smeared" or less clear than matched speakers.

    Between boundry reflections, room reverberance, or lack of it, mic bleed and whatever else, there's enough going on already that could stand in the way of getting a balanced sound. Taking the mixed speakers out of the equation makes it easier to get a consistant sound out to a greater portion of the audience.

    On a big stage, where your rig is a monitor, it's not as big a deal provided you're not running loud enough to interfere with FOH much past rhe front few rows, though the more consistant, widely dispersed speaker system can still help get a better sound to the rest of the band members across the stage.
  17. When two cabs individually sound nice and clear but when together become simply loud and lose clarity you got misphasing.

    Big +1 to Will33.
  18. Phlipper


    Feb 5, 2013
    Fayetteville, NC
    Endorsing Artist: Old SS Peavey Lead Sleds and Peavey tube amps
    Kool. Thanks for the info, guys. Much appreciated. :)

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