Replace tweeter with mid driver-Avatar SB112

Discussion in 'Amps [BG]' started by wraub, Nov 29, 2012.


  1. wraub

    wraub

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    Hey all.
    So, I really like my Avatar cab, but lately have been thinking of getting "more" out of it. I know it's not a perfect cab, but for me, most of the time, it's great.

    That said, the tweeter seems superfluous at times, and comically unnecessary at other times. I usually run it just above off.
    Having read of the various fEARFUL and nearful designs, I was wondering about how well this idea might work.

    Find a suitable mid driver, alter the crossover (or get a new one), throw some batting into the cab and make some noise.

    Suggestions/criticisms/advice, please?

    Thanks to all.

    wraub
     
  2. selassie1

    selassie1 Supporting Member

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    I've been researching the same mod and there are threads here that discuss this topic thoroughly. From my research, it seems like the "Burdizzo mod" outlined on Harmony Central is the simplest but it's a few years old. I'm wondering if there are more recent recommendations that will yield better results.
     
  3. topcat2069

    topcat2069 Supporting Member

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    I would much rather have a 5" or 6" mid driver than a tweeter in any cab.... subscribed.
     
  4. wraub

    wraub

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    I agree, I think i'd also prefer a mid driver in this box.
    Some research online seems to indicate that a 500 Hz crossover would be about right for this, apparently there's an Eminence one but they don't really look all that hard to build.
    Still digging, though, not completely sure yet...

    And, btw, searching for "Burdizzo mod" also yields some, um, interesting non-audio related hits.
    Yecch. Seriously.

    wraub
     
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  6. Bmorefoozler

    Bmorefoozler

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    It seems that a closed back midrange and an off the shelf Eminence x-over would be a pretty simple swap for an 8 ohm cab. Whether you go 5oo or 800hz may depend on the mid driver of choice.
    It also seems that a 3012LF wouldn't be too unhappy in that box if you wish to take it a step further, and also that a large country crock butter tub doubled up and glued inside the box and stuffed is a satisfactory subchamber.

    There is lots of talk of the potential in the fearful threads, but I can't remember seing toomany people actually see it to fruition.

    The extended x-max deltalite that can spec'd int hat box isn't a terrible candidate for a 2(with mid)-3 way woofer as it sits.
     
  7. will33

    will33

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    There's a couple guys here who've done exactly this, though I can't remember user names to find the threads. As it turned out, the closedback eminence la6cbmr with their 800hz 2-way, "board only" crossover was a good solution and shouldn't run more than about $100, doesn't require a subchamber and will fit in the Avatar cab. Don't go lower than the 800hz with the crossover as the drivers fs is around 500. This would be for an 8ohm woofer in the Avatar cab.
     
  8. 4Mal

    4Mal Supporting Member

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    I did this years go with the 212. It's pretty easy. The mid i used back then was a glaxay audio 5. Today, I would use an Alpha 6, open back and a CBG fearful crossover kit from Leland @ Speaker hardware.

    Remove woofer, tweeter.
    Place the speaker face down on the cab, centered on the hole. Make pilot holes for the screws. Take a piece of scrap 1 by 2 or three, locate it under the tweeter hole. Drive a couple of scews into it through the pilot holes. Use a screw with a much smaller dia than those that will hold your mid driver in place.

    Mark the center of the hole.

    Get a hole saw of the appropriate size. Cut out the baffle locating the mandrel on the center mark.

    Take a plastic tub about 7 in diameter and say 4 to 6 on depth. Somethink like a 'Shedds ' imitation butter container... Make a hole in the bottom center. Take some string, tie it around a nail, piece of dowel, pencil, something... String through the hole in the bottom of the tub and up towards the top, open side, pencil or whatever outside.

    Get a piece of scrap that will span the sides of the cab.

    Glue on the rim of the tub.tub and string inside the cab, straddling the hole for the mid. Tie off the string using it to 'clamp' the tub to the inside of the baffle. When the glue sets, you have a nice, low tech but workable mid chamber... You'll use hot glue to seal the wire for the mid driver and poly fill to stuff.

    Cross over should be built and tested. I mounted mine to some scrap masonite and made standoffs for cooling. Probably overkill for my situation but there you go...

    The whole mod is pretty straight forward an in the B212 it was a huge improvement.

    On my B212's the x-over was mounted to the jack plate. I had to pull that, disconnect and wire jack to the new x-over directly. On one, I left the epriginal x-over intact, you could barely hear the mid... Which didn't sound bad actually as the stock Avatar x-over was at 3.5 k iirc. I don't use a lot of hi end, though more now than I used to... Today the CbG i expect would be perfect.
     
  9. selassie1

    selassie1 Supporting Member

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    I have two sb112s with the extended xmax neos so I'm going to try this on one as see how I like it. I plan to build my own 800hz crossover.

    Which mid speaker would sound crisper in the highs? Eminence LA6-CBMR or the Alpha 6a?

    Or maybe I should keep the foster horn and L pad and use a 800/5000hz 3 - way crossover...

    Thoughts?
     
  10. bobcruz

    bobcruz

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    Does anyone have a link to a frequency response and impedance graph for the Foster tweeter in these cabs? I'm wondering if a simpler improvement would be to cross the tweeter in at a lower frequency, say, 2.5 KHz with a 24 dB per octave slope, better wave guide and beefier l-pad. Not as good for dispersion, of course, when running the woofer up that high, but it could deal with the "hole in the mids" between the woofer and tweeter. Just thinking out loud here.
     
  11. wraub

    wraub

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    Thanks to all who posted so far.
    The cab in question for my mod is a non-Neo, 4 Ohm, typically standard SB112.

    Not sure how that'd affect mid driver and crossover choices. Still digging around the 'net.

    Ideas and suggestions definitely welcomed.

    wraub
     
  12. Bmorefoozler

    Bmorefoozler

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    it would take off the shelf x-overs out of the question, unless someone besides eminence builds them for 4 ohm loads.

    Unless you want to buy a 3012LF, Alphalite 6a and buy a CBG from speaker hardware and re-use yoru box and "almost" have a fearful.
     
  13. 4Mal

    4Mal Supporting Member

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    CBG for a 1212/6. Would be 4 ohm on the botton, 8 on top. I think the crossover point (between 600 amd 800) is really good for the Alpha 6a.

    I also think the foster horn is more annoying than useful...

    I'm a long ways parted from my SB112. If I still had it, I would for certain be trying a 3012lF in it and thinking about some retrofit bracing...
     
  14. selassie1

    selassie1 Supporting Member

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    Hey OP,

    I finished modding my sb112 last weekend. I chose the EMINENCE ALPHA-6CBMRA 6-1/2" sealed back speaker and made my own "Solon split" crossover at about 800hz. I reused the tweeter attenuator on the mid driver.

    I've been A/B ing the modded cab with my other stock sb112 and here are my thoughts so far:

    1. Modded cab is much much louder and more articulate in the highs and mid. I'm glad I used the attenuator. That little 6.5 driver can really knock you over when cranked.
    2. The high end sounds a lot better to me than the original horn. I can hear a lot better off-axis as well.
    3. I lost some low end volume compared to the stock cab. I think it's due to the inductor I used but I'm not sure.
    4. Using both cabs together sounds great!

    So far so good.
     
  15. topcat2069

    topcat2069 Supporting Member

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