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Replacement Speaker(s) for Acoustic Control 406 2x15 Cab?

Discussion in 'Amps and Cabs [BG]' started by donalddemon, Aug 27, 2016.


  1. donalddemon

    donalddemon

    Feb 26, 2010
    Asbury, NJ
    Disclaimer: I'm not a (real) bassist. My bassist has been using my Acoustic 220 amp & 406 cab at my basement studio for practices and has managed to blow the bottom speaker, as he is known to do. I'm looking for a decent but inexpensive replacement. Maybe something with more wattage so he doesn't blow them? I'm thinking an Eminence Delta 15a?

    So I took the offending speaker out to measure the ohmage, it's an Eminence Beta 15. Someone wrote "350 watts, 8 ohms" on it in magic marker. When I measured the ohms with my DMM it read around 4. Is that because the wires are still hooked up to the other speaker? The ohm reading for the speaker cable coming out of the jack is about 14 ohms so I am confused. It should be two 8 ohm speakers in series for 16 ohms, I guess. I thought the cab was supposed to be 8 ohms.

    Which ohm rating should I get for the new speaker?
     
  2. Normally you would see two 8 ohm speakers in parrallel,
    for a 4 ohm total.
    Since the DC resistance you are reading is less than the
    nominal impedence rating, expect an 8 ohm speaker to read
    lower, perhaps 5 to 7 ohms.
    The easiest thing to do would be to just get another Beta 15
    to match the one that survived.

    If you want to upgrade, plan to change both speakers.
    I believe I have heard that JBL K140s work quite well in those.
     
    Bassmec likes this.
  3. Bassmec

    Bassmec

    May 9, 2008
    Ipswich UK
    Proprietor Springvale Studios
    +1 The old D/K/orE140 is a great replacement if you can pick a pair of them up.
     
  4. donalddemon

    donalddemon

    Feb 26, 2010
    Asbury, NJ
    Any ideas on newer speakers that are readily available?

    So I was getting some very weird readings on the DMM and came to the conclusion that the input jack is no good. I think I'll start with replacing that first, maybe the speakers are even fine, could be the crackling I'm getting. I would think those speakers wouldn't blow seeing that they are rated for 300 watts and the head is only 150 watts.
     
  5. Bassmec

    Bassmec

    May 9, 2008
    Ipswich UK
    Proprietor Springvale Studios
    Well I have no experience of any other speakers than the original drivers and the JBL K140 in a 406 cab but they do say that the Fital PR400 is a good replacement for a JBL K140 but I haven't tried that.
    By all means sort the wiring out first, testing the drivers individually outside the cab is the best way to listen for non cab associated rattles, voice coil scrapes etc.:)X
     
  6. donalddemon

    donalddemon

    Feb 26, 2010
    Asbury, NJ
    Good idea, I haven't tried each one outside the cab yet. I've never heard of voice coil scrapes, is that when there is dirt or debris in the coil? I'll have to look that up. Thanks.
     
  7. The VC can rub from debris or damage such as getting deformed from hitting the
    magnet, from being overextended or ending up out of round from overheating.
    It's also possible to have the spider and/or surround get stretched or otherwise
    damaged causing the cone to be out of alignment.

    Testing the speakers individually, out of the cabinet will rule out things like
    bad glue joints or loose mounting screws, but be very careful not to drive them hard
    when they are out of the cabinet.
    If one of them works, but sounds scratchy, it could have VC rub.

    If you think the input jack may be bad, the traditional correct fix is a new Switchcraft jack.
    If it needs replacing and you want to go modern, there is a Speakon with 1/4 inch input
    in the center that will cover both old and new speaker cables.
     
  8. donalddemon

    donalddemon

    Feb 26, 2010
    Asbury, NJ
    Good to know, thanks. I was looking at getting a locking 1/4" jack but not sure what to get. Looks like there is closed circuit and open? No need for a speakon really, the cab never leaves the basement.
     

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