Dismiss Notice

Psst... Ready to join TalkBass and start posting, make new friends, sell your gear, and more?  Register your free account in 30 seconds.

Blown speaker in a BA-115

Discussion in 'Amps and Cabs [BG]' started by denton57, Jan 13, 2006.


  1. denton57

    denton57 Supporting Member

    Nov 1, 2005
    Ok. I have a Ba-115 that has a blown speaker. It came with a 4ohm 15 wired with a tweeter. I disconnected the tweeter, and am looking at a cheap 8ohm 15 to replace it with. Will volume decrease significantly with the 8ohm? Does the tweeter when hooked up affect ohms? What ohms does the head operate at? I basically want to fix it as cheap as possible so I can sell it.
     
  2. luknfur

    luknfur

    Jan 14, 2004
    DIXIE
    FWIW:

    Here's some input. How worthy is debateable at the least, cuase I don't know myself. Maybe somebody that knows will chime in second round.

    Comparatively, the efficiency of Ampegs speakers I've run across as a group is definitely on the low side. Like low 90's. If that's the case with your speaker it's likely to be louder than anything with replacement if it were 4 ohm. How much louder would depend on the efficiency of the replacement. The fact it's 8 ohm will cut into that. Someone probably knows that exact breakdown all esle equal. I don't. I ran an 8ohm Altec in a 4 ohm Poly and volume didn't seem any less to me but the Altec I now had an spl of 98, don't know what the stock was. I also know an Engineer that ran a JBL E140 in an old 4 ohm Poly. So it's not something that's unacceptably out of the question.

    How it will sound may be a totally different matter. May even sound better to you though. You know when it's done.

    I was asking my speaker guy about tweeters the other day and he said a tweeter either has a coil or a diaphragm, can't remember which and those may be the same thing when it comes to tweeters (looks like a coil anyway) and a piezo doesn't. Seems most the combos have piezo's not tweeters and a piezo doesn't require a crossover and apparently takes no significant load if any (maybe tied in with the speaker circuit). So basically if it just looks like a formed piece of plastic and nothing of substance, it's probably a piezo and it shouldn't fit into the equation.

    If a post like this doesn't bring additional input, I don't what would.

    I would throw out a caution that you know before you do. A blown speaker is one thing. An amp meltdown is a totally different ballpark. You can go larger in ohm rating with the speaker itself with SS and not worry about damaging the amp. The tweeter factor, I don't know about.
     
  3. denton57

    denton57 Supporting Member

    Nov 1, 2005
    Hmmm....very interesting. I didnt even think about the efficiency of the speaker in it. If the Ampeg speaker rates that low, then maybe a higher efficiency 8 ohm would bring it back to normal??? Im gonna leave the tweet out of the mix.
     
  4. Jerrold Tiers

    Jerrold Tiers

    Nov 14, 2003
    St Louis
    The BA115HP (I assume that's what you have) has a Foster tweeter, so the diaphragm only can be replaced. Probably cheaper than replacing the whole thing, but with cheapo chinese everything available, who knows. Frankly, lots of things will fit the hole.

    As far as the 15.... the 15 goes with the cabinet. Tuning, and all that..... Another speaker chosen for the fact that i's cheap and fits in the cabinet may sound like dung....

    That particular 15 is not too bad on efficency, so I suspect that an efficient 8 ohm would about match it, maybe not quite get there. Probably not noticeably louder in any case.

    it takes about 6 dB to sound twice as loud, which is about the minimum definitely detectable when playing....

    If your speaker were as much as 5 dB more efficient, which I doubt, you will lose 3 in the higher impedance, leaving it 2 dB louder.... which I would bet nobody could hear.

    But, of course, it may sound like crap in the cabinet.... The actual speaker from service isn't bad.... I think it costs about $40 or so, might be worth a check.
     
  5. Using same speaker but in 8 ohm you will notice a slight drop in overall sound level. As stated above, get an efficient speaker and it may even be louder.

    Since the tweeter is typically blocked by a capacitor it has only a small effect on impedance and is not figured in the total impedance of the cab.
     
  6. McHack

    McHack

    Jul 29, 2003
    Central Ohio!
    Hey Jerrold,

    You should pass this along to the designers.

    But, I've been a little frustrated, that the BA115's & 220's didnt come w/ an speaker defeating, external cabinet output plug...
     
  7. luknfur

    luknfur

    Jan 14, 2004
    DIXIE
    FWIW:

    personally I would be shocked if this is the case, but undeniably the way to go no questions asked if accurate.

    I would figure more like $140. Even 10" Ampegs usually go for roughly a $100 on ebay. Reconing is roughly $75 for a 15" Eminence and it's about $50 just to have a surround thrown on a 10" JBL. Shipping alone would probably be 15-$20 depending.
     
  8. Metal Mitch

    Metal Mitch

    Jul 14, 2003
    NJ
    At that price, I'd go with Jerry's recommendation for the Ampeg part. But whatever you do, be sure to use a 4 ohm driver to replace the 4 ohm driver.

    All this efficiency blah blah blah doesn't address the fact the amp will put out less power at 8 ohms. The original driver most likely blew due to underpowering for what you're trying to do. Installing an 8 ohm driver will guarantee an even faster blowout of the replacement driver.