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fEarful™ 12/6 & 15/6 enclosure designs - FREE! (Part V) On with the Madness!

Discussion in 'Amps and Cabs [BG]' started by Chef, Dec 27, 2009.


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  1. BurningSkies

    BurningSkies CRAZY BALDHEAD

    Feb 20, 2005
    Seweracuse, NY
    Hey, you should note that the image shown is 3x8ohm resistors in parallel and then 2x8ohm resistors in series. That gives values of 2.67 and 16 ohms respectively, or 3.5db of attenuation. Its slightly different values than the ones that would later show up in the GB crossover/L-Pad, but still more than in the right ballpark.

    There's no mystery to the L-pad, it's simple resistive circuit math as found here:

    http://www.webervst.com/lpad.htm

    The 8ohm value of the resistors was suggested by Charlie as it means you can use 5 of the same resistor for the layout and it streamlines things a little bit.

    The Eminence crossover has been pulled and replaced with the GB 15/6 design, in the good-and-not-cheap format with upgraded components across the board:

    [​IMG]

    And how it looks installed on the shelf:

    [​IMG]
     
  2. Yup. My bad.
     
  3. Nordskov

    Nordskov

    Apr 26, 2007
    Denmark
    Am I correct that the coil in the high pass filter that shunts low to ground carries almost no current.
    It could be replaced by a coil of 0.5-0.7 mm wire to save some cash.
     
  4. byoung

    byoung

    Mar 13, 2005
    Covington, WA
    Interceptor's soldering tutorial is up on the wiki.
     
  5. Passinwind

    Passinwind I Know Nothing Supporting Member Commercial User

    Dec 3, 2003
    Columbia River Gorge, WA.
    Owner/Designer &Toaster Tech Passinwind Electronics
    When you model that be sure to look at what happens if and when the driver fails as an open. You can make the call on treating that inductor as a fuse, or not. In all honesty, I don't really have a great feel for how much to over- or under-rate crossover component power handling. So far so good with the ones I've built though.

    With a 100 watt nominal swept sine input the SPICE model for my 12/6 crossover (not the one in the picture, mine is 3rd order) shows ~3.3A max current through that inductor. I've been meaning to try using an actual recording of my bass for signal analysis -- have to put that on my ever growing to-do list. ;)
     
  6. NickRich

    NickRich

    Oct 13, 2008
    Quebec, Canada
  7. Nordskov

    Nordskov

    Apr 26, 2007
    Denmark
    I don't know the voltage drop across the coil. How many watts do 3.3A equal?
     
  8. rpsands

    rpsands

    Jul 6, 2007
    Phoenix, AZ
    amps are watts / voltage, IIRC, so if you don't know the volts of the signal, I don't think you can know the watts from the amperage. Unless I'm missing something :)
     
  9. Passinwind

    Passinwind I Know Nothing Supporting Member Commercial User

    Dec 3, 2003
    Columbia River Gorge, WA.
    Owner/Designer &Toaster Tech Passinwind Electronics
    Around 72 watts in this case, but please don't trust or pay much attention to this model beyond realizing that substantial current flow can happen in that coil. The average power will be a lot lower, that's just the peak. That was just a semi-random example from an experimental SPICE file I happened to have kicking around for my old 12/6 design.

    I managed to make a nice sounding crossover using that model, but I have not really proofed the model to my satisfaction just yet. Give me a few days and I'll take some actual in-circuit measurements from the 1515/66 Cheap But Good crossover I'm building up at the moment. I want to see how greenboy's sims (and mine) using Crossover Designer compare to real world measurements. I'll be doing thermal testing on the attenuation network as well, with an eye to the "heat sink needed?" question.

    I just did another huge rebuild of my test bench yesterday, and all that's left is making a few new dummy loads out of parts I have on hand. The big one will be good for 2400+ watts at 4 ohms. :bassist:
     
  10. 4Mal

    4Mal Supporting Member

    Jun 2, 2002
    Columbia River Gorge

    " with great power comes great responsibility ... " Just saying, ya know... :bag: (wondering if it's safe to go outside - I'm only 3 miles away!)
     
  11. Foz

    Foz

    Jul 26, 2008
    Jax FL USA
    I will follow your posts on this topic with great interest.
     
  12. Nordskov

    Nordskov

    Apr 26, 2007
    Denmark
    That's freakin'! Even though it's peak.

    Interesting, too bad it ain't the 12/6. I have my mind set on the Codger/himppe crossover, but I could be persuated to turn around.

    That'll be good for a nice cup a tea. Boiling a kettle in a split second :cool:
     
  13. Bjazzman

    Bjazzman

    Dec 7, 2004
    Madison WI
    ok i know i've posted on here before about this but my head is spinning with all of these fearful options

    i play in a band which isn't very loud. its a 3 piece with a guitarist and computer drummer.

    i want one that can be used kind of like a monitor since i will be running synths, saxes, and other instruments into it

    i use a mesa m6 carbine as my head which can do 2 ohms

    which one will really let me FEEL the bass and allow me to use my dod fx25 to its full potential as the dub effect- think deep dub reggae a la theivery corporation

    im really wanting a one cab solution and i don't think i want the 1515/6 since i don't want to lug arround that much weight. i would do two cabs if necessary since that would probably get the most out of my head's power. But since my band doesn't play that loud, thats why im wondering if i could get away with a single cab

    any ideas for what im trying to acheive? fearb? 15/6? 15/6/1? maybe a combination of these? or maybe a 1212/6? or 1212 sub with headcase?
     
  14. rpsands

    rpsands

    Jul 6, 2007
    Phoenix, AZ
    A 15/6/1 would almost surely be plenty for you. A 1212/6/1 would be a safe bet.

    With lots of effects I'd tend to want the horn with an on/off switch.
     
  15. byoung

    byoung

    Mar 13, 2005
    Covington, WA
    A 12/6 will hit about 117 dB @ 320w, and will have a thick, deep bass response. Based on your description, it would be suitable.
     
  16. Bjazzman

    Bjazzman

    Dec 7, 2004
    Madison WI
    Just curious why you'd suggest a 12/6 over a 15/6/1 for my situation?
     
  17. Swift713

    Swift713

    Dec 4, 2006
    Florence, Ma
    With these cabs the speaker size only effects dB, not frequency response. The 15/6 is more sensitive than the 12/6 but you can't go wrong.
     
  18. pathdoc2

    pathdoc2

    Oct 16, 2002
    Allen, TX
    I'd be willing to pay anyone for a completed crossover for my fEarful 15/6. Cab is basically complete, just finishing the Duratex but the weather has been horrible in our area lately.

    Any takers? Anyone consider building a crossover and selling it to me?
     
  19. 4Mal

    4Mal Supporting Member

    Jun 2, 2002
    Columbia River Gorge

    The advantage to a 12/6 is of course - portability. The disadvantage is that it is lower efficiency and not as loud.

    Portability is a big deal to me as my stuff get's moved a lot and some times in the nastiest of weather...

    I'm going with a pair of 12/6 cubes. Only one will have the mid driver loaded though - so either a 12/6 or a modular 1212/6 makes sense to me...
     
  20. 4Mal

    4Mal Supporting Member

    Jun 2, 2002
    Columbia River Gorge
    Biscuit Jointer in 12mm material.

    Hey - this is a PITA. As it turns out, the cutter height is predetermined for .75 inch material. So you have to shim under the 12 MM work pieces and raise them up to get the cutter centered on the piece...

    So far my plan is to create a fixture. Whatta pain. Anybody else deal with this ?
     



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