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How speaker cone movement should you see in a cab?

Discussion in 'Amps and Cabs [BG]' started by Da LadY In Red, Jul 21, 2008.

  1. alexclaber

    alexclaber Commercial User

    Jun 19, 2001
    Brighton, UK
    Director - Barefaced Ltd
    You're also more likely to see excursion in a ported cab when you're driving it below its tuning frequency. With typical basses and amps this isn't terribly likely due to relatively brief low fundamental content from the bass and preshaped preamp EQ that rolls off the lowest frequencies but I noticed a lot of movement when driving one of my new 15"s with an Avalon U5 and PLX 3002 with the filters turned off (which I don't normally do but I'd switched them off when breaking in the woofer) with a 36" scale RIM Custom 5 with Q-Tuner pickups - response almost down to DC!

    It was only after the gig it dawned on me that I'd had the highpass filter switched off. Next gig I was using a slightly smaller 15" cab without PA support, used the Avalon to give about 6dB of bass boost and had the 50Hz filter engaged on the PLX. Very little visible movement and a gloriously loud fat clear sound.

  2. Bill,

    I didn't consider that. It does make more sense now.
  3. They were for various apps and were mated with the below Bass Guiar Cabs. They have been discontinued BUT they were bass cabs


    John Patitucci used them when he was in the Electric Band

  4. billfitzmaurice

    billfitzmaurice Commercial User

    Sep 15, 2004
    New Hampshire
    Owner, Bill Fitzmaurice Loudspeaker Design
    What usage they were appropriate for I can't say without seeing the driver specs. What I can say is that a driver well suited for use in an ELF system would not be well suited for use in a non-ELF system, and vis-versa.
  5. Petebass


    Dec 22, 2002
    QLD Australia
    Bills already picked you up on this one, so I won't go on about it too much other than to say my DIY sealed cab experiments proved Bills version to be correct. In fact my DIY home theatre subs are sealed and sound great. Yep they're high excursion drivers.........
  6. iammr2


    Jun 10, 2002
  7. KPAX

    KPAX Banned

    Mar 22, 2005
    This is a very serious question that is not asked nearly enough. First, you should obtain an interferometer (every bassist should have one) for maiking these crucially important measurements. A low E should move the cone exactly 0.1967943 inches at the dome. 0.1322675 for open A, 0.0994563 for D and 0.0698875 for open G.
    If your measurements differ from these, you and your bandmates are in serious danger and should STOP DROP AND ROLL immediately.
  8. Pretty much all SS power amps do this. It caused by the amp settling into its operational mode. Most decent amps have a turn on delay before connecting the speakers to allow this to happen silently. Doing what you re doing is fine as long as you are connecting the amp end last.

  9. billfitzmaurice

    billfitzmaurice Commercial User

    Sep 15, 2004
    New Hampshire
    Owner, Bill Fitzmaurice Loudspeaker Design
    Not if he has 1/4" plugs, which can short the amp output when inserted and removed. :eek:
  10. ShaunMatthew


    Apr 2, 2018
    I’m seeing a lot of movement in my my Epifani DIST 410 speakers. It’s paired with a Mesa M-Pulse 600 at 4ohms being played with a Fender Marcus Miller MIM. I am using the active preamp but usually roll off the low end. When I do bring the low in I notice a lot of movement. The only reason I started noticing it was because I noticed a slight change in voicing the other day.

    The cabs continuous rating is 1000watts. The Mesa can only produce 600 plus or minus at 4ohms.

    Any ideas or opinions people? Should I be concerned about the speakers jumping around?
  11. Rick James

    Rick James

    Feb 24, 2007
    New Jersey
    When you boost the lows you increase the voltage input to the drivers. 6dB of bass boost doubles the voltage input, which doubles cone excursion. The cab rating is thermal, what the voice coils are rated for before burning up. That doesn't mean they'll take 1000 watts before excessive excursion can cause physical damage to the drivers. Most cabs have mechanical limits around half their thermal limits.
  12. BadExample


    Jan 21, 2016
    McFarlin likes this.
  13. ShaunMatthew


    Apr 2, 2018
    I’ve never seen that rating on any cab or speaker before. Where would I find that information on these speakers?
  14. Rick James

    Rick James

    Feb 24, 2007
    New Jersey
    Sorry, that's Top Secret information, because you can't handle the truth. Or it's an inconvenience to the marketing department. You can try asking Epifani, but all you'll hear is crickets.

    Eminence isn't nearly so secretive. You can see how most of their drivers work in various size cabs in the designs links listed on the driver catalog pages. One example is http://www.eminence.com/pdf/Legend_CA10_8_cab.pdf
    It recommends, for instance, the maximum power of a 410 loaded with CA10 drivers to be limited to 250 watts, based on the driver excursion, even though the thermal limit, Pe, is 800 watts.

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