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Question For The Speaker Gurus Among Us

Discussion in 'Amps and Cabs [BG]' started by BloozBass, Oct 17, 2009.


  1. BloozBass

    BloozBass

    Oct 29, 2008
    Charlotte, NC
    Couldn't find anything close to this with a search, so I thought I'd throw this out there for those of you who know a whole bunch more about this than I do.

    I have an Ampeg B15T which doesn't see nearly as much use as it used to since I picked up the Micro VR head and 210 cab. However, I'd love to use this as an extension cab with the Micro on larger gigs. The problem is that the speaker is 4 ohm, and I need an 8 to keep the Micro within range.

    My understanding is that the original speaker was made by Eminence for Ampeg, so I fired off an email to them to see if an identical speaker in 8 ohm was available. The replied very quickly that no, there wasn't an 8 ohm model of that exact speaker, but the Delta Pro 15A had very similar characteristics.

    Here's the question - why would a pro audio speaker be a closer match than a bass driver such as the Legend CB15, or something comparable from a different manufacturer? I'm not tech-savvy enough to compare the specs and decide what is or is not important, but to my limited knowledge I would think that a bass speaker would be a better choice than a pro audio speaker.

    Thanks in advance for your help with this one!!!!!


    Blooz :bassist:
     
  2. billfitzmaurice

    billfitzmaurice Commercial User

    Sep 15, 2004
    New Hampshire
    Owner, Bill Fitzmaurice Loudspeaker Design
    Because when you compare drivers you use their T/S specs.
    http://www.eminence.com/resources/data.asp

    As for classifying a driver 'pro-audio' versus 'electric bass', it's an arbitrary distinction, there's no major difference.
     
  3. unclejane

    unclejane Guest

    Jul 23, 2008
    Speaking of the TS params, speakers designed for musical instrument duty often do differ from those designed for hi-fi/subwoofer duty and this is usually reflected in the TS params. The main differences I've tended to see:

    - MI/bass amp speakers tend to have less compliant suspensions. This is usually a strength thing since you need a strong suspension for the higher volumes (i.e. large cone motions) needed for bass amp use. So the (free air) resonance freq (Fs) tends to be higher and suspension compliance (Vas) figures are usually smaller.

    - bass amp drivers usually have lighter cones. This is in the interest of efficiency and transient response, this also raises the resonance and affects other things like suspension compliance and Q, etc.

    - often bass amp speakers have intentional peaks and dips in their freq. response to achieve a particular voicing. Hi-fi speakers usually tend to try to achieve as flat (i.e. hi-fi) a freq. response as possible.

    So when sort of browsing through different drivers to get ballpark ideas of how they differ I usually look at free air resonance (Fs), compliance (Vas), total Q (Qts) and freq. response graphs if there are any.

    If two of them match fairly closely in these figures they're usually pretty decent substitutes for each other plus or minus.....

    LS
     
  4. JimmyM

    JimmyM Supporting Member

    Apr 11, 2005
    Apopka, FL
    Endorsing: Ampeg Amps, EMG Pickups
    I've got Delta 15a's in my B-15 extension cabs. Don't get hung up on labels. They're the go-to B-15 replacement speaker, along with the Beta 15. The Beta 15 handles less power but sounds similar and costs less. In a B-15, you can get 200w clear with a Beta, but if you want to be on the safe side, you can put 300w into a Delta in a B-15 cab.
     
  5. billfitzmaurice

    billfitzmaurice Commercial User

    Sep 15, 2004
    New Hampshire
    Owner, Bill Fitzmaurice Loudspeaker Design
    They're completely different from those intended for hi-fi subwoofer duty. They are indistinguishable from what the OP asked about, pro-sound woofers.
     
  6. unclejane

    unclejane Guest

    Jul 23, 2008
    Not quite sure I understand your comment - what is indistinguishable from... ...pro-sound woofers?

    Otherwise, yeah good hi-fi speakers usually make pretty lousy bass amp drivers and the other way around too. Tho if I were really going for the reggae or very extended range thing I'd do a pair of JBL 2226's (or even a single 2242) for the very low end in a heartbeat... and if I had a roadie to carry the cab around ;)

    LS
     
  7. BloozBass

    BloozBass

    Oct 29, 2008
    Charlotte, NC
    As usual, the folks with the information have chimed in to help those of us lost in the woods. I can't thank you enough for your participation in this thread. I understand what the T/S parameters are as a group, but individually they mean nothing to me. I certainly appreciate the help of those who know what they are talking about. Thanks again.


    Blooz :bassist:
     

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