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Front ported vs. rear ported cabs?

Discussion in 'Amps and Cabs [BG]' started by gmanbass, Mar 7, 2008.


  1. gmanbass

    gmanbass

    May 16, 2007
    Which type of enclosure do you guys think is best for clubs (small to medium sized) rather than large venues or outdoor gigs?
     
  2. alexclaber

    alexclaber Commercial User

    Jun 19, 2001
    Brighton, UK
    Director - Barefaced Ltd
    It makes absolutely ZERO difference. Nothing, nada, null.

    Alex
     
  3. I agree, the porting simply regulates the tuning and low frequency drop off of the cab (or something like that :))
     
  4. Eric Moesle

    Eric Moesle Supporting Member

    Sep 21, 2001
    Columbus OH
    Agreed, rear porting makes no difference EXCEPT for times if you place the cab right against a back wall so the port is blocked and can't do its job and breathe. Keep your cab 2" from the wall and you won't have a problem.
     
    zon6c-f likes this.
  5. billfitzmaurice

    billfitzmaurice Commercial User

    Sep 15, 2004
    New Hampshire
    Owner, Bill Fitzmaurice Loudspeaker Design
    +1. Markbass makes larger and smaller versions of most of their offerings, the smaller ones are rear ported only because there's not enough room to put them on the front. The output from a port is totally omni-directional.
     
  6. Peter Murray

    Peter Murray Commercial User

    Dec 13, 2005
    Toronto, Ontario, Canada
    Artist Relations and Social Media Manager, Pigtronix and Supro
    Ok, I've heard this argument before. In theory, with ALL OTHER FACTORS BEING EQUAL, it makes no difference. In reality, the cabinets DO sound different, and maybe that's simply because the front ported cabinets are larger and double-ported (the rear-ported cabs have one port on the bottom). But the important fact here is that the cabinets do sound different. And that's what's relevant to our customers.

    I've gigged many times with most of our cabinets and I can tell you from practical experience that there's a difference. Why would we make front and rear-ported cabinets if there was no difference in sound? We'd just go with rear-ported because they're smaller, lighter, and cheaper to ship!

    All science aside, the front-ported cabinets we make provide fuller, deeper bottom end, and the rear-ported ones sound tighter in the low end. Bassists tend to have a preference one way or the other when they compare. Marcus Miller, for example, tried both and preferred the rear-ported. Tell him there's no difference in sound between the front-ported and rear-ported cabs!

    Cheers,
    Peter
     
    1960jbass likes this.
  7. alexclaber

    alexclaber Commercial User

    Jun 19, 2001
    Brighton, UK
    Director - Barefaced Ltd
    Peter, it is nothing to do with the ports being at the front or rear, or to do with 'double ports'. It is simply that the front-ported cabs are larger in internal volume than (and possibly have a different tuning frequency to) the rear-ported cabs.

    From a marketing perspective it is easier to explain the difference in sound to the layman as 'the bigger double ports add low end' but the reality is just that the bigger cabs have more low end. The smaller cabs are too small to fit the ports on the front so they go on the rear. So Markbass may have two product lines, one front-ported, one rear-ported, but actually they really have two product lines, one larger volume and deeper and bigger sounding, one smaller volume and tighter and quicker sounding. The port positioning has no bearing on the sound.

    Make a rear-ported cab of equal volume and tuning to your front-ported cab and they will sound identical.

    That is it. The end!

    Alex
     
    TrevorR likes this.
  8. RickC

    RickC Gold Supporting Member

    Jun 9, 2005
    Okay, naive question. I admit I don't exactly how porting works. Does any sound come out of the port?

    /rick
     
  9. billfitzmaurice

    billfitzmaurice Commercial User

    Sep 15, 2004
    New Hampshire
    Owner, Bill Fitzmaurice Loudspeaker Design
    Of course, because the rear ported cabs are smaller/front ported are larger. The tonal difference is there, but it's the result of cabinet volume and tuning, not the port location. Not to scold you Peter, but it is in order. :rollno:

    Yes. But the sound coming from the port is at low frequencies only, assuming the cab is properly constructed, and radiates equally in all directions.
     
  10. gmanbass

    gmanbass

    May 16, 2007
    Thanks guys. I thought the front / rear port thing might make a difference in "projection" into the room or venue.
     
  11. nysbob

    nysbob

    Sep 14, 2003
    Cincinnati OH
    Here's what I don't like about rear ports -

    sometimes you play with a carpeted back wall, sometimes a hard one (like glass), sometimes you're out in the middle of a parking lot. The rear ported cab sounds different in each environment.

    Front ports don't seem to be affected the same way or to the same degree.
     
  12. Blues Cat

    Blues Cat Payson Fanned Bass Strings Owner Commercial User

    May 28, 2005
    Katy, Tx
    Payson Fanned Bass Strings Owner
    +1. Very well stated. :bag:

    I find a rear ported cab with no boundary behind it will sound thin. You will over compensate by turning up the bass, eating headroom and giving FOH a headache if you're running direct from the amp. My experience has been with an SWR GoliathII 410 and an Ampeg 115 combo. Same problems I've found regardless of speaker size.


    The experts will disagree all day long. We've had this discussion about a year + ago. Just copy and paste the thread here to save time.:)
     
  13. I sure did notice this on my Bag End SD15's. It seemed that there was a lot of DIRECTIONAL sound coming from that big hole cut in back of the little cab. When playing with that particular cab outside, you really noticed a drastic change in the tone. I did not notice this at all with my Acme cabs (also rear ported), so I always attributed it to the cab tuning, where the very high roll-off Bag's seemed to actually behave somewhat like an open backed guitar cab (i.e., you could hear clear, wide-range tone coming out of the back of that cab), whereas the Acme rear ports seemed to behave more in the manner that the experts are describing... a more sub-bass omnidirectional type thing.

    Who knows though!
     
  14. BassJunkie730

    BassJunkie730

    Feb 3, 2005
    Brooklyn
    Perhaps it has something to do with smaller more mid oriented cabs bien in different environments? Since our ears are much more sensitive to midrange than true bass is it not possible that when you take your bag end outside you are hearing the cab in an "anechoic" environment - or at least with considerably less reflection than when in a room? which would have a very different effect on the presence of midrange?

    Your acme wouldn't do this because of all the differences Right?

    different cabinet volume, different drivers (and different driver components) possibly even a different amp?
     

  15. All the above might be true. However, when you stood behind those things, it was like standing behind a Twin Reverb... you heard very distinct, directional sound cranking out of that port. Since I used a variety of different cabs, most voiced to the mids (like small EV 112 cabs, etc.) at the time, all with the same head, there did seem to be something going on that, to my ear, was an interaction between the tuning of the cab and the design and placement of the port.

    I could be wrong on this though, and since those are the only cabs I've experienced having this issue (i.e., my rear ported Aguilar DB112's don't have this issue at all), something seems funny with that particular cab and that particular port design.
     
  16. billfitzmaurice

    billfitzmaurice Commercial User

    Sep 15, 2004
    New Hampshire
    Owner, Bill Fitzmaurice Loudspeaker Design
    If that was the case it was a sign of poor construction methods. A properly built cab is fully lined with absorbent material, so that internal reflections can't go back to the cone or escape through the port, as that will result in rough response. In the case of a rear-vented cab internal baffles must be employed so that there is no direct path from the cone to the port, for the same reason.
     
  17. bassbrock

    bassbrock

    Feb 20, 2007
    Callahan, FL
    +1,000,000 - End of discussion.

    Amen to that Alex!

    You can make a cab with IDENTICAL dimensions and simply move the port to the front, rear, top, side, wherever and it will sound the same regardless of port placement.
     
  18. B String

    B String Supporting Member

    Apr 11, 2002
    Los Angeles

    One of the things I like about my Mini 112P combo, is that as
    a VERY small, rear ported box, it gives me quick response
    for my upright bass without too much extended low end.
    When I use that same amp for electric bass, if I put it a
    foot or so in front of a wall or corner, I can get a frightning
    amount of lows for such a small combo. I like having the options.
     
  19. jgsbass

    jgsbass

    May 28, 2003
    Floral Park, NY
    There is a huge volume of air coming out of the slot port on the front of my Avatar SB112. Enough to flap my trousers.
    On a side ( or back) note: do the jacks on a Polytone Minibrute constitute ports? They sure move air like a port
     
  20. +1... I was not saying it was a good thing... it was a very bad thing IMO. Those cabs sounded GREAT in many situations, but did seem to interact with what was behind them MUCH more than any of the other cabs I've owned. Something not quite right there.

    However, per all the other comments, I think this is specific to this one cab (at least it is the only rear ported cabinet that I've owned or played that seems to behave this way), and not obviously indicative of port placement in general.
     

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