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A small subwoofer

Discussion in 'Amps and Cabs [BG]' started by ACB0015, Aug 16, 2012.

  1. ACB0015


    Oct 27, 2010
    Portland, Maine
    Hello physicians!
    I have a 1x10" Eden box, the CX110, that I would like to put to work as a small subwoofer. The external dimensions are 15.25"w x 16"h x 14.5"d and the port is about 2" diameter x 8" long. Box is made with .75" plywood. I think it is supposedly tuned to 38Hz. Any recommendations for a 10" woofer? Does not need to be neodymium, but could be. I can tune the crossover point anywhere from 31.5Hz to 3.15kHz via an Ashly BP41 preamp, which also has a LF-HF balance control. Box might sometimes be used full-range, but I want to try it as a sub under my EA VL110. Right now the Eden box has an Eminence Beta 10 in it.
    Thank you in advance for any responses!
  2. will33


    May 22, 2006
    Well....subwoofer and small don't really go together, but, based on your cab description, stick an Eminence BP-102 in it. Will reach deep. Not incredibly loud, but doesn't have to be uber loud. Still easily audible when it's putting out stuff the other speakers can't.

    Should preface that by asking what is the situation/intended use, etc.
  3. fokof

    fokof One day ,I'll be in the future

    Mar 16, 2007
  4. Using your numbers with a 2" inside diameter vent, I get different results.

    The gross internal volume is approximately 1.46 cubic feet, assuming a driver displacement of 0.04 cubic feet (typical).
    Subtract another 0.018 cubic feet for the nominal vent displacement, and you have a net 1.44 cubic feet for the driver.

    A 2" ID vent with 8" long duct and 0.732 end correction factor tunes to 25 Hz. Much too low.
    At 55 watts, this gives a Mach of 0.503%. Much too high.
    This is a non-problem because this box won't be generating 25 Hz, so the vent will never chuff.
    As it stands now, this box is poorly executed.

    Beta 10a wants 2.36 to 4.0 cubic feet to reach its potential.
    BP102-8 wants 2.7 to 4.0 cubic feet for its full potential.
    Neither driver will achieve its bottom end in a box this small.

    Deltalite 2510-II in BB4 tuning is a perfect match for 1.48 cubic feet.
    This is hardly a subwoofer, as the F3 is 56 Hz, and the Xmax is quite modest.

    Another choice would be the Dayton (Parts Express) 295-412 Titanic sub.
    This is a sealed box driver with a very close match for the D2 sealed (0.577 Bessel) alignment.
    D2 gives the tightest bass response of all, but with a higher rolloff point.
    F3 is right at 40 Hz. SPL is quite low at 85, but usable for a small box.

    Your electronics provide biamping with independent level control.
    You will need this to balance a true sub with your existing top box.
    The Dayton would be my choice for a low volume rig, easy installation (plug the vent), and a straight drop in.
    Make sure the hole cutouts are capable before buying any replacement driver.
  5. ACB0015


    Oct 27, 2010
    Portland, Maine
    Thank you for these well considered replies. Correction on the port tube dimensions in the Eden box -- it is 3" diameter by 9" long. That oughta change things. I often do very small footprint jobs in theater pits so that's why the small size. I'm looking at a used RCF ART 800 sub too but that of course is a different animal. The VL110 is my choice as a stand-alone for the pits but I sometimes supplement it with the 1 way Eden box. I guess I'm not looking to make a true subwoofer as there will be no crossover in the box but I'm looking for something that may perform better than the Beta 10 as a one way in that box but may reach lower than the VL110 if I biamp with the tunable xover in my Ashly pre.
    Many thanks, gangmembers!
  6. will33


    May 22, 2006
    Probably scratch the bp102 if you think you might run it fullrange.

    True they want a bigger box to reach their full pptential, but that potential reaches into the 30's. If you put them in a smaller box, you lose some of that lowend extension, but they'll still reach into the 40's, which is really all you'd need, even as a subwoofer. But, spl and mid response are not good for fullrange use.

    The sealed box sub driver bgavin pointed to at parts express would be a nice fit for your box size. Simply seal off/plug the port. Don't know if the spl is enough to balance with your other cab. If you're actively biamping, you don't need crossovers in the cabs. Can balance output between the 2, at least until the low spl sub driver runs out of gas.
  7. will33


    May 22, 2006
    What do you most miss out on not using one of the optimal alignments like Bessel, etc? I rarely do in exchange for practicality/portability and the stuff still ends up sounding how I envision it.

    I ask because I recall working out a sort of Acme-ish design a few years ago using a pair of BP-102's and an Alpha6 in a 3cu.ft. box. If I remember right, it still modeled out in the low 40's and handled a lot of power. I never followed through with it due to the spl requiring me to build 2 of those cabs and take them both everywhere. And having to buy a more powerful amp to take advantage of them.
  8. The sealed D2 Bessel is the equivalent of the vented SBB4.
    Both roll off from a higher frequency than Flat, both are (usually) tuned lower than Flat.
    BB4 and SBB4 tune at the free air Fs resonance frequency.
    The D2 and SBB4 have the tightest transient response in their respective families.

    In the vented world, the different alignments heavily influence where the upper and lower Xmax points fall.
    These two peaks are the determining factors for how much power you can push.

    For linear response, the maximum usable voltage is that which pushes the driver to the Xmax limit, but not beyond.
    For high power use, it is pointless to drive a vented box below Fb because the cone severely unloads and rolls off at a 24dB/octave rate.
    This is where the driver beat its brains out and takes a one way trip to the land of Munch and becomes a Munchkin.

    Use the Definimax 4012HO as an example:
    • Flat - Fb=53 Hz, lower Xmax peak is 46 Hz
    • SBB4 - Fb=46 Hz, lower Xmax peak is 39 Hz
    If my application is a 4-string bass, I have to reduce voltage to accommodate the Xmax limitation at 41 Hz.
    For my particular project, my need is a lower limit of 50 Hz, which allows me to use a higher voltage down to 50 Hz and stay within Xmax limits.
    The alignment that provides the most area under the response curve is the natural choice.

    The OP must specify the lowest operating frequency for his 10" subwoofer.
    If he is a 5-string player, he will eventually land on low B, not want to munch his driver.
    His restated vent looks to be 1.37 cu.ft. tuned around 50 Hz with a 5% Mach.
    This is not suited for a 5-string at a higher power level.
  9. will33


    May 22, 2006
    Hey, thanks.

    Those descriptions are all the stuff I look at when modeling, but don't stick to a sort "this alignment or that alignment" approach, but rather juggle things around and just obtain whatever performance I'm looking for, but keeping in mind stuff like an overly large box, even if it may be "optimal". Size, shape, weight, portability, etc. It's why I shrank the bp-102's to 3cu.ft. It provided enough extension, even though they may've been capable of more, and kept a more manageable, ergonomic box size, etc.
  10. ACB0015


    Oct 27, 2010
    Portland, Maine
    You guys are the bomb.
    My applications will be 4 string Pbass EADG, 5 string Pbass BEADG, 4 string upright EADG.
    From my understanding when it comes to low B (is that what you mean by BB tuning?) it is most important to have the first harmonic well represented, not so much the fundamental. re: This Is Your Brain On Music
    Again, thank you!
  11. will33


    May 22, 2006
    No, the alignment labels don't have anything to do with note names. They are different approaches to optimally matching a speaker with a suitable box.

    Your 5 string and your upright will be the most taxing on your speaker system. Plan for those and the 4-string will play fine with that.

    Can do some digging around this weekend looking for small sub driver matches for your box. I take it your main speaker you're using now would be your main "fullrange" speaker and this sub box would be sort of an add-on when you need more "oomph"?

    Stacking a sub under your regular speaker will put your fullrange speaker that much closer to ear level, making it appear louder and easier to hear even if it really isn't on paper. So is this sub box an actual sort of mini-subwoofer add-on?
  12. ACB0015


    Oct 27, 2010
    Portland, Maine
    Yes, that's how I'm imagining it, will33.

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