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Fixing up my first ever bass cab

Discussion in 'Amps and Cabs [BG]' started by Petebass, Oct 14, 2003.


  1. Petebass

    Petebass

    Dec 22, 2002
    QLD Australia
    The poor thing is sitting in the garage looking very sad and lonely. I should have sold it years ago but being my first ever cab, I can't bring mysef to do it.

    It's a Fender BXR 115 with a single 15 in it. But the speaker doesn't work, which is a good thing because I didn't really like the sound. It was originally an EOM Eminence driver of some sort. The cab is huge, 173 litres (6.1 cu feet)

    so.........

    I'm thinking about replacing the 15, plus adding a 5" driver for midrange, + a horn. Ideally I'd like a final nominal impedance of 4 ohms and I'd use this as a stand-alone cab.

    At this stage I'm looking at the Delta Pro 15 which comes in at 8 ohms. I have absolutely no idea how to approach the midrange 5. I've spotted a couple of locally made drivers that have a Fs of 550Hz and recommend a 12db crossover at 800Hz. They're 8 ohm speakers so my first instinct is to wire it to the 15 in parallel to get a 4 ohm load. But I'm not sure if midrange drivers are treated like horns in that they don't affect the overall nominal impedance?

    Also has anyone got any suggestions for a 5" midrange driver?
     
  2. flacko

    flacko

    Dec 6, 2001
    Surrey , UK
    You could use an Eminence 10" Legend B102 for your top end. I have this paired with a 15" and it works well.
     
  3. Petebass

    Petebass

    Dec 22, 2002
    QLD Australia
    It won't fit. With the 15 in it's current position, there is space for a 5" driver, even a 6" at a tight fit.

    The only way to fit in a 10 is to remove the whole baffle and replace it with the 15 in a different position. That's more work than I wanted to do on this cab.
     
  4. flacko

    flacko

    Dec 6, 2001
    Surrey , UK
    You could maybe put the smaller driver in a seperate box. As its going to be a sealed box it would not be too difficult to make. I'm guessing that you will need to build a box round it if you mount it onto the existing baffle to give it some pressure to work against .

    A seperate box would open up the choice of drivers you could use.
     
  5. Petebass

    Petebass

    Dec 22, 2002
    QLD Australia
    Thats kinda what I've got going on right now. I've got several cabs (5 to be precise) that work well in two's, but nothing that works well as a stand-alone.

    yep that's the plan. Even better would be to get a sealed back midrange driver.

    Out of curiosity Flacko. Which 15 have you used to pair up with the Ledgend B102?
     
  6. flacko

    flacko

    Dec 6, 2001
    Surrey , UK
    I used an Eminence Kappa 15LF. I made the mistake of putting the B102 in a sealed sub-enclosure within the 15" ported cab. This bumps up the weight of the cab. Wish I had made a seperate enclosure for the 10".

    I use the bi-ap facility in my amp : so I didn't get involved in external crossovers.
     
  7. NeedMoreBass

    NeedMoreBass unregistered

    Feb 14, 2003
  8. BruceWane

    BruceWane

    Oct 31, 2002
    Houston, TX
    As long as you're using a crossover, the individual drivers only affect the impededance in the frequency range that they are being given. So yes, the mid driver will act like a horn in terms of impedance. You'll need to use a true crossover though, unlike the typical practice of adding a tweeter with a capacitor to roll off lows while running the woofer full-range and letting the highs roll off by the natural frequency response of the woofer. That's not really a crossover, it's just a low-cut filter on the tweeter. You have to cut the high frequency response of the woofer so that it doesn't overlap the midrange, otherwise you'll get an impedance curve that goes to 4 ohms in the overlapping frequency range, along with a bump in response.

    Eminence makes a 6" mid driver (Alpha 6), but I haven't used one so I can't attest to it's sound quality.

    Don't know if you'd be interested, but if you're not going for high SPL with this thing, you might consider using an Adire Audio Tempest for the 15". Specs are here....

    .......and they have a distributor in Australia here....

    Not real efficient, but it goes seriously LOW in a 6ft cab, and they're pretty cheap, too - $150 US (direct from Adire, so your price there will probably be a bit higher).
     
  9. Petebass

    Petebass

    Dec 22, 2002
    QLD Australia
    Thanks Bruce, that's exactly what I needed to know. Call me crazy but I think I would prefer the 4 ohm load with the extra midrange.

    As you can probably tell from my comment above, I'm not a fan of "flat to 30Hz" type bass cabs. I play in loudish bands and need that midrange kick to cut through the mix. I leave the really low stuff to the PA. My "deepest" speaker at present is a JBL 15 that is -3dB at 55Hz, and that's too deep. I often cut everything from 75Hz down with the EQ when I'm using that speaker.

    I prefer something with a sensitivity in the mid-to-high 90's. The localy made midrange driver I mentioned has a sensitivity of 96dB so ideally the 15 will be similar.

    Having said that, the speaker you suggested would be a beauty for a home theatre or Hi-Fi Sub! I've been know to build those occasionaly for friends and relatives and I think this driver just made it onto my list of favoured subs for someone with a biggish lounge room - thanks.