1 Sealed, 1 Ported Cabinet Together?

Discussion in 'Amps [BG]' started by spitfirees20, Jan 7, 2014.


  1. spitfirees20

    spitfirees20

    Joined:
    Dec 20, 2013
    Hello All,


    Looking for some experience here. Right now I have 1 cabinet, an custom 2.25 ft^3 sealed enclosure with an Eminence CA154. I really like it because I like the sound of a sealed cabinet, it's super portable (30 lbs and easy to cary with one handle), and reasonably loud. However, I have two problems. One, I need a little more volume. Two, I feel like it doesn't go low enough. Modeled in WinISD the -3db rolloff is at 80 Hz, and the -6db rolloff occurs at around 60 Hz. When I hit the low E, I can tell it's missing something as the fundamental occurs at 41 Hz. It's most noticeable when hit an E and then an A after for comparison; you can clearly hear the strong fundamental of the A.

    What I want to do is add a second cabinet. I could add another identical custom sealed enclosure, but I was thinking about a ported 1x15 or 1x18 for some extra low end extension. I know that mixing two different types of cabinets is usually seen as a bad idea, but I was wondering if anyone has heard this combo in person? Ideally if you've heard 1x15 sealed and 1x15 or 1x18 ported at the same time that would be cool, but if not, any combo of ported / sealed I would be interested to hear about.

    If it matters at all, I'm running my bass through a sansamp vt bass di into a carvin poweramp. I was also thinking about doing something crazy, like maybe running just the vt bass into one side of the poweramp for that ampeg distortion into the sealed 15, and then one side into a cleaner preamp to go into the ported 15 or 18. Would that work, or would I be introducing some other weird phase issues?

    Thanks in advance!
     
  2. christw

    christw Get low!

    Joined:
    May 11, 2008
    Location:
    Dayton OH
    Disclosures:
    Endorsing: J Worrell Bass
    Clean/dirty rigs are certainly a normal thing and people doing that don't usually worry about phasing. If it sounds good...awesome! :D

    [del]It could work. Have you tried a bass boost around 4-6 dB at 50 Hz to compensate or would that drive your 12 too hard?[/del]

    In retrospect, that's not the best idea. ^
     
  3. spitfirees20

    spitfirees20

    Joined:
    Dec 20, 2013
    It's actually a 15, and I haven't yet because the only graphic eq I have is for guitar and it stops at 100 Hz. I can probably find an EQ pedal meant for bass and give it a try though!
     
  4. Downunderwonder

    Downunderwonder

    Joined:
    Aug 26, 2009
    Location:
    New Zealand
    Boosting E fundamental in sealed cab will only eat up power, heating your driver.

    Try boosting 80hz. It's not like svt 8x10 has much response down below 80hz, yet that tight sound you think you like, you don't?
     
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  6. Bassmec

    Bassmec

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    May 9, 2008
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    Ipswich UK
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    Proprietor Springvale Studios
    The phase anomaly between the ported and non ported cab is only in the area of the overall frequency response that the port is extending the low frequency, therefore as the sealed enclosure rolls off quite steeply, the ported cab will just take over and extend the low frequency response without having much in the way of phase cancellation, as there is little or nothing coming from the sealed enclosure to fight with, phase wise, at that frequency.:bassist:
    [​IMG]
    This is not just the usual music tech student theory vis a vis phase anomaly dogma (that abounds this board like a plague), this is from actual tested experimentation with 12" drivers and cabinets measuring the results with Waves software.
     
  7. wcriley

    wcriley

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    Apr 5, 2010
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    Western PA
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    Uncompensated endorsing user: fEARful
    ????????
     
  8. bgavin

    bgavin Supporting Member

    Joined:
    May 3, 2001
    Location:
    Orangevale, CA 95662
    JBL K2 Project with IET

    JBL did something similar in their no-holds-barred design of the K2.
    In a nutshell, they use two of the same bass driver, but in two different vented alignments.

    The Bessel (0.577) offers the tightest transient response and minimal phase shift, where the Butterworth (0.707) offers the flattest response.
    These Q values are normally associated with sealed boxes, but they do have vented equivalents: SBB4 and Flat.

    JBL's objective was reducing the "vented box" sound inherent in reflex cabinets.
    In a reflex design, vent radiation is 90-degrees, or more, out of phase with the cone.
    Sealed boxes do not have this, and sound "tighter" or "faster".

    Opinion: IET has no value for live electric bass in a mix.
    This is for the critical audiophile.

    For the OP, mixing different drivers over the same operating range is a recipe for merde.
    If this had merit, the pros (Meyer Sound, et al) would do it, and they do not.
     
  9. spitfirees20

    spitfirees20

    Joined:
    Dec 20, 2013
    Thanks for all of your well thought out and informative replies, everyone! Basically, after reading all of these and doing some more independent research, I've realized it's an awful idea, unless I want to get a larger ported cab and set it up with some sort of crossover, so that I use the ported cab for the lows and the 15 for the highs, which I'm not really interested in.


    What I'm going to do is:
    - Get another identical cab
    - Try a boost around 100 Hz


    Thanks again for the help!
     
  10. Downunderwonder

    Downunderwonder

    Joined:
    Aug 26, 2009
    Location:
    New Zealand
    First you should learn what frequencies you actually want to hear. The low A you hear presently isn't 55hz, it's 110hz overtone. This is "tight" bass. Your sealed cab rolls off too much 80hz so E pales.

    EQ and two cabs may get you over the line. A couple of tl606 type cabs might be better. They don't do fundamental E either.
     

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