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ported and sealed cabs

Discussion in 'Amps and Cabs [BG]' started by jjl5590, Nov 7, 2008.

  1. jjl5590

    jjl5590 Banned

    Mar 28, 2008
    London, UK

    does anyone know what the difference is between these? does a ported cab have more low end?

    and can you use one ported cab, and one sealed cab, together in a rig?

    thanks alot
  2. I could blather a lay person's generic response, but I really hope Bill Fitzmaurice is out there and will provide more his more technically correct insight.

    Bluesy Soul :cool:
  3. mattq


    May 23, 2006
    Santa Cruz, CA
    sounds like a cue to me.

    supposedly a sealed cab works better with all tube amps. i have yet to understand why, but i've tried it myself and am willing to agree with that overly generalized statement. ported cabs typically have an extended range of low frequencies, and, since they usually have tweeters or horns installed as well, they also have an extended range of highs. once again, i have no idea why exactly, but can't help but agree with it out of experience. now, let's all hope for mr. fitzmaurice to chime in so we have a better understanding
  4. Gentlemen,
    No offense, IMHO this has not been proven. The Sunn 200S and 2000S rolled outta da factory with 2 15" D-140f's in a Bass Reflex Cabinet. I have owned both. Both are 6550 platform tube amps. I currently own a Sunn Model T, 4 x 6550 tubes. This I play thru 2 SWR Goliath III 4 x 10" with horns or my Sunn 200S bass reflex Cabinet with D-140f's. They sounded great to me. I also owned a 1968 Fender Dual Showman with 2 D-140f's in the issue DEAD BOX infinite baffle big Showman cabinet. There are subtle differences in the 2 designs no doubt. I also have an Acoustic 370 and 2 301 cabinets each with a Cerwin Vega 18". I prefer ported cabinets. I do believe a speaker driven to the brink has a HIGHER survival rate due to excessive BTU's being vented outta da port! Each to his own. My Buddy has a Bergantino NV610, it is a fine cabinet, loud, clean and well, DEAD just like an over-rated MAGNAVOX SVT 8 X 10". So if you like an unresponsive dead box and believe that TUBE amps can't power ported cabinets then buy non-ported. Damping factors are affected by ports. Big Dog amps all have several attributes in common: Big power supplies and can run day and night at 2 ohms, this my bass peers DOES affect damping factors. Only 3 big dog amps, SVT, Acoustic 370, Sunn Coliseum. ABILITY TO RUN AT 2 OHMS IS CRUCIAL. Read some technical manuals such as the RCA Receiving tube manual and this will dispell some myths.
  5. newbold


    Sep 21, 2008
    ports allow air to move with the speaker and provide less resistance on the speaker. this means the speaker wastes less energy pushing against air - it moves more freely

    there's a reason most bass speakers are ported.

    I haven't played through open back bass rigs. Do they exist?
  6. seamonkey


    Aug 6, 2004
  7. jjl5590

    jjl5590 Banned

    Mar 28, 2008
    London, UK
    is mixing a ported cab with a sealed cab kinda the same as mixing neo speakers with ceramic speakers (i.e. not done)?

  8. Yep. Good thing most tube bass amps have more than enough negative feedback that output stage impedance is very low. ;)

    BTW, when are you going to stop trying to use an advertisement as credible scientific study?
  9. There's no reason not to. Most modern bass cabs are ported and sealed cabs (8x10's) are big enough to be standalone, so it usually doesn't come up, but it won't hurt matters to mix them.
  10. billfitzmaurice

    billfitzmaurice Commercial User

    Sep 15, 2004
    New Hampshire
    Owner, Bill Fitzmaurice Loudspeaker Design
    For the most part, yes. But not inevitably.

    Yes, although the results of so doing are unpredictable.
  11. jjl5590

    jjl5590 Banned

    Mar 28, 2008
    London, UK
    oh right, do you run the risk of blowing one cab because it was being pushed harder than the other one?

  12. billfitzmaurice

    billfitzmaurice Commercial User

    Sep 15, 2004
    New Hampshire
    Owner, Bill Fitzmaurice Loudspeaker Design
    That would be a possibility with an impedance/power mismatch. Mixing different cabs will always have an unpredictable result as their phase responses will be different, so they will both augment and detract from each other across the frequency bandwidth.
  13. Other than the normal reasons for not mixing drivers, why specifically not mix neo & ceramic?:confused:
  14. OliverH


    Aug 2, 2008
    OK, to throw something else into the mix:

    How about the difference between:
    - Ported cab
    - Non-ported cab with a passive driver
  15. fdeck

    fdeck Supporting Member Commercial User

    Mar 20, 2004
    Madison WI
    HPF Technology LLC
    A passive radiator works pretty much like a port.
  16. Mystic Michael

    Mystic Michael Hip No Ties

    Apr 1, 2004
    New York, NY
    Right. For this reason, ported cabs generally have a more open and airy sound with extended frequency range, while sealed cabs generally sound more compressed...some would say more focused.



    Nov 24, 2001
    New York,NY
    ...ohhh boy...guess everyones been wrong ALL this time about those "DEAD" Berg NV6x10's...hate to see what you think of a NV215 or a new NV4x12...LMAO...gotta love it...

  18. fishtx


    Mar 30, 2007
    Dallas, TX
    Endorsing Artist: Spector Basses/Genz Benz - RIP/Mojo Hand FX
    Is there a list anywhere of sealed and ported cabs?
  19. billfitzmaurice

    billfitzmaurice Commercial User

    Sep 15, 2004
    New Hampshire
    Owner, Bill Fitzmaurice Loudspeaker Design
    Venting a cab allows it to be tuned to a lower resonant frequency than if the cab is sealed, and that accounts for the added low end. It has nothing to do with how freely the cone is able to move.
  20. Rear output from the speaker is also "added" to the front in a ported cab so the ported cab is more efficient, the "sealed" cab has a smoother response.