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Sealed Cabs = Solution to Boomy Rooms?

Discussion in 'Amps and Cabs [BG]' started by jokerjkny, Dec 9, 2005.


  1. jokerjkny

    jokerjkny

    Jan 19, 2002
    NY / NJ / PA
    i've heard this, but havent gone into depth about learning. anyone care to share?
     
  2. Sealed cabs are down -3dB from vented cabs. They are down even more in the bottom octave.

    This can be done with EQ on a vented cab, then undone when you need your vented cab outdoors.
     
  3. jokerjkny

    jokerjkny

    Jan 19, 2002
    NY / NJ / PA
    english man, english! :p
     
  4. He's saying "use your EQ" to get the same effect with a vented cab. Sealed cabs don't have the same bass response at the bottom end. Then, when you're not in a boomy room, put the EQ back to normal. Now you have the advantages of both.


    - Andrew
     
  5. billfitzmaurice

    billfitzmaurice Commercial User

    Sep 15, 2004
    New Hampshire
    Owner, Bill Fitzmaurice Loudspeaker Design
    The key words here are boomy rooms. It's the room that causes the boom, not the speaker. There are entire forums devoted just to room acoustics and how to fix them; that's where you should be looking for answers. Unfortunately, if it's not your room to fix you'll just have to deal with it.
     
  6. Doug Parent

    Doug Parent Supporting Member

    May 31, 2004
    San Diego, Ca.
    Dealer Nordstrand Pickups.
    Say Bill, stupid question here: I assume "plugging a port" in an attempt to achieve the desired solution to answer this thread's point is a "bad idea" ?
     
  7. billfitzmaurice

    billfitzmaurice Commercial User

    Sep 15, 2004
    New Hampshire
    Owner, Bill Fitzmaurice Loudspeaker Design
    Not necessarily. Plugging the port raises the tuning frequency of your cabinet and if that helps improve response in certain rooms then do it. But it won't be effective in every room, as every room has different response modes. The reason I mentioned forums dedicated to room acoustics and how to deal with them is that you can do a lot to alter response via placement and room treatments; the topic is far more complicated than space here allows for an in-depth discussion.
     
  8. dancinDaveNY

    dancinDaveNY

    Sep 27, 2001
    Western NY
    So Bruce and Bill, you're more or less saying, owning the ported cab is better because, with good EQ you'll have the best of both worlds? That's what I get from your replies anyways? I've also been thinking of switching to sealed cabs for the same "boomy" reason. Maybe I'll see what I get next gig with some bass rolled off and the treb and mids boosted just a bit. Running flat with ported cabs, I'm booming! (DB750 to Eden XLTs)
    <smiles> dD
     
  9. I don't know about "better", but most most drivers are designed for vented cabinets. I'm one for running a given driver where it is designed to run.

    Plugging ports depends on the driver, and the cabinet volume it lives in.

    A sealed box with Qtc = 0.7 is the compromise tradeoff between bass extension and transient handling. If your vented cabinet happens to be the same size, then plugging your ports gives you this sealed alignment.

    If your cabinet volume is already too small for a correct vented alignment, then plugging the ports will probably give you a much higher Qtc, say 1.0 or higher. As Bill points out, this raises the system resonance point, and will give you a big hump/boom in the mid-bass. The unwashed here this as big bass, and the industry considers this "saleable."

    If your cabinet is large, such as an SBB4 vented alignment, then plugging the ports will get you very close to a D2 sealed alignment, which is the optimum for tight transients. I have yet to see this in a commercial cab. Typically they are too small, not too large.

    In the end, use EQ to get around boomy rooms, and spend more time practicing the bass instead of plugging ports.
     
  10. I'm not surprised.

    The D410-XLT I had on the bench has the pronounced Eden honk, which is a boom in the mid bass. The upper resonance in this vented box is quite strong. It always reminds me of Mr. Limpet doing his thrum. This is a classic response from a box that is too small for its drivers.

    Use EQ to cut the boom band.
     
  11. DEVILMAN

    DEVILMAN

    Nov 24, 2001
    New York,NY
    ...well, tonight I'm going to pair my BergNV215 & PV 2x15(Eminence drivers) together(sealed + ported), might sound good, might suck, we'll see/hear...

    ~S~

    PS: I've tried it at home & it sounded great, live is the true test...
     
  12. billfitzmaurice

    billfitzmaurice Commercial User

    Sep 15, 2004
    New Hampshire
    Owner, Bill Fitzmaurice Loudspeaker Design
    What Bruce touches on here but doesn't say in so many words is that sealed vs ported isn't the reason for boom, it's how the cabinet is tuned. A vented box that's tuned with an exaggerated response bump from 100-160 Hz will sound louder and will seem to have more bass response than one tuned lower. This helps to sell speakers, as when auditioned in a store one has a tendancy to go for the speaker that is louder. But louder doesn't necessarily mean better, which you find out when you get the cab out of the store and into the nearest Elks Lodge. Real bass is down below 100 Hz, and it doesn't boom. 'Faux bass' is above 100 Hz and does boom. A properly tuned reflex won't boom, an improperly tuned reflex will boom. A sealed box generally won't boom, but it won't reach below 100 Hz either.
     
  13. dancinDaveNY

    dancinDaveNY

    Sep 27, 2001
    Western NY
    I hope I'm not stealing the thread on you joker, I don't mean to...
    So Bruce, in your opinion, the XLT boxes are too small for the Eden drivers? and that's where the boominess comes from? Yet 'they' say the Eden D410XLT is "the standard of the industry". hmmm...

    After reading Bill's last response, it's making a whole lot more sense. So, how do you find a properly tuned reflex cabinet? Word of mouth? Some times that's even deceptive, as in what's above. ^ It sure would be nice to have one really efficient, tuned cabinet to haul around. THEN spend the rest of the time practicing the bass like I need to be doing.
    dD
     
  14. The Clap

    The Clap

    Jan 5, 2004
    Scottsdale, AZ
    All of this doesn't mean you should work from a mathematical vantage point when choosing commercial cabs. Most of this theory applies to building your own cabinets which, if you're really interested in flat frequency response, can be the way to go. For commercial cabs, just trust your ears, because what sounds good live IS good

    The EdenXLTs for example, sound really good in certain live settings, and the fact that they aren't in a certain alignment doesn't diminish that. It's good to know the difference between real bass and excessive midbass though.
     
  15. jokerjkny

    jokerjkny

    Jan 19, 2002
    NY / NJ / PA
    ok, you mathematical acoustical denizens of TB,

    my solution to cure "bad rooms" is to take my Demeter HBP-1, reduce the Q to the narrowest of bands, cut about -6dB, and spin the frequency knob until all is much better onstage.

    am i doing the right thing that should help my sound into the room?
     
  16. billfitzmaurice

    billfitzmaurice Commercial User

    Sep 15, 2004
    New Hampshire
    Owner, Bill Fitzmaurice Loudspeaker Design
    That's what I do with the parametric EQ on my 01v to get rid of room boom with my PA. Works perfectly.
     
  17. jokerjkny

    jokerjkny

    Jan 19, 2002
    NY / NJ / PA
    always good to have some validation. :)
     
  18. jokerjkny

    jokerjkny

    Jan 19, 2002
    NY / NJ / PA
    if i may,

    the Eden cabs are interesting. onstage the cut and punch like a mofo, but because of that inherent aggressive voicing, they're really hard to dial in for particularly bad smaller rooms where your rig may well feed the room.

    thus, that drives much of the reason why i use more neutral sounding cabs like Acme, Accugroove, and EA. gives you that blank canvas to build your sound upon.

    SO, i can actually dial in that aggro lower middy punch, and yet w/ my parametric EQ, pinpoint that one or few annoying frequencies, and do away w/ them.

    again, cabs are one thing, but if a bassist thinks like a soundman (as bill so eloquently stated), you can find a killer sound no matter the room.
     
  19. fdeck

    fdeck Supporting Member Commercial User

    Mar 20, 2004
    Madison WI
    HPF Technology LLC
    Short of curing the room, attenuating the lowest frequencies does seem to help in boomy rooms. It can be achieved in a number of ways:

    1. Starting with a cab that has less low end, i.e., typical sealed boxes.

    2. On some cabs, plugging the port does the trick. YMMV on this one, and it may affect the power handling by forcing the cone to do more of the work at the lowest freq's.

    3. Getting your speaker away from floors, walls, and corners. The first thing I do when I arrive at a gig is look for a chair to put my speaker on.

    4. The magic "low cut" button on my GK MB150E combo.

    5. The whole band turning down the volume. I think this changes how you hear yourself. A friend once told me that you can't drown out a bad room.
     
  20. emjazz

    emjazz Supporting Member

    Feb 23, 2003
    Boston, MA
    I've had the opportunity to try a lot of Jim Bergantino's cabs, including ones that never became products he's sold. He's been doing something very interesting with his newer lines where he's been slimming the depth of the cabs. I've personally found that it creates more cut and I would imagine that to work really well in a live situation. I know that my 112 Bergs with their smaller design always allows my sound to be heard through the biggest of bands in any size room. I think that there's something to this. His new IP212 and IP310 have been redesigned to be less deep and the difference is noticable from the older cabs.