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fEarful™ 12/6 & 15/6 enclosure designs - FREE! (Part II)

Discussion in 'Amps and Cabs [BG]' started by Kelly Lee, Apr 3, 2009.

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  1. This sure is a whole lot of work, expense and fiddling around for a general purpose cab.

    Build two cabs, buy two 3012LF drivers and a $135 6" driver. Expensive.
    Build a passive crossover for the one cab, and a LP filter for the 2nd. Expensive.
    Use a second amp channel as needed. Expensive.
    All this effort and expense results in two cabs that produce 100 SPL for the woofers and 102 SPL for the mid-range.

    Those wanting two cabs are better served with a modest 6" driver SPL matched to the 3012LF driver. This is the Alpha 6.
    Build the baffles in mirror image layout, so the 6's are adjacent when stacked.
    Unlike the 6ND410, the Alpha 6 can crossover at 800 Hz and not run out of linear response. PXB2:800 works just fine.
    The passive crossovers in each cab remain undisturbed with one or two cabs in use.
    No dual channels, no LP filters, just plug and play. Less expense.

    Those wanting a single cab that makes 100 SPL are better served with the 3015LF and a matching mid-range.
    I am not aware of a 6" that is an SPL match to 3015LF, unless horn loaded. That is already done, and is a proven and measured solution.
    Non-horn loaded, two Delta Pro 8B in parallel is a power and SPL match to 3015LF, and uses a standard crossover.
    Yes, the 15" box is larger.

    For this project, the second box could be retrofitted with a 6" driver unless there is a brace in the way.
    The biggest PIA is cutting the baffle.
    The sub chamber can be easily fitted through the 12" driver opening.
  2. davio


    Nov 2, 2006
    Boston, MA
    I don't see where you'd save much money. 2xAlpha 6A = $80 vs. 1x6ND410 = $135 but with the Alphas you'd need 2xPXB2:800 = $100 vs. PXB2:800 + LP filter = ~$70(?) so you only end up saving ~$25. If you're using a stereo power amp anyway and have a channel sitting unused, why not?

    All that said, I wouldn't do it. ;) :D
  3. greenboy


    Dec 18, 2000
    remote mountain cabin Montana
    greenboy designs: fEARful, bassic, dually, crazy88 etc
    I haven't had time for this thread because I've been traveling and taking care of my dad, who's given maybe until the end of the year to live.

    But Bruce: if you differ in design philosophies publish your own plans and start your own thread about your own designs rather than second-guessing mine. Stop giving advice better left to Alex or Passinwind who have actual experience here with very similar designs - and experience with the same drivers and with crossovers for those drivers. They also have a better track record of understanding what they talk about when they actually do speak, seem to do fuller research both in sim and in the physical before stating with certainty, and generally are constructive.

    Stop confusing people! It's hard enough for them to become familiar with new concepts and solutions without you further muddying the trough. I am reporting you because you making it hard for people here.
  4. Passinwind

    Passinwind I Know Nothing Supporting Member Commercial User

    Dec 3, 2003
    Columbia River Gorge, WA.
    Owner/Designer &Toaster Tech Passinwind Electronics
    FWIW, I have found a friend who will cut the panels for a 12/6 for me. I will try out a bunch of crossover configs using my Rane DSP speaker controller and biamping, then attempt to build a passive crossover to replicate whatever I like best, maybe attempting to keep the cost "reasonable" for once. That'll be a bit tough, as I'm just not wired to do things that way.

    So my question to the fEarful builder community would be: what do you consider a reasonable target number for a 2-way passive crossover for these cabs? As usual, I have no interest in building and selling anything, but I will be more than happy to share whatever I learn. Given the weather constraints here, I doubt I'll have much to report until early May or so though...;)
  5. davio


    Nov 2, 2006
    Boston, MA
    That's very generous of you! I'd venture a guess at saying ~$50 is a resonable balance point. That's the cost of the PXB2:800 and beyond that it would be up to the potential builder exactly how much more they'd be willing to spend according to how much better the DIY crossover would perform over the Eminence...and how much they'd notice the superior performance.

    Many (myself included) probably wouldn't notice the finer differences between a well-designed crossover and very well-designed crossover. That said, if it were within the same pricerange, I'd probably attempt a build if plans were readily available just because I enjoy putting things together.

    EDIT: I don't know if $50 is reasonable for parts but like I said, I ventured a guess. :)
  6. vlad335

    vlad335 Supporting Member

    Apr 14, 2003
    Latrobe, PA

    Sorry to hear that. Didn't know that was going on. Man that sucks.

    Just lost my Father In Law to Parkinson's a couple months ago. 62 years old then one day out of the blue, he is having trouble walking. Despite all the doctors and the experimental drugs he was gone in a year. I still can't believe it happened.

    Screw this thread. You do what you have to do.
  7. Passinwind

    Passinwind I Know Nothing Supporting Member Commercial User

    Dec 3, 2003
    Columbia River Gorge, WA.
    Owner/Designer &Toaster Tech Passinwind Electronics
    Thanks for your input. I think I will probably buy one of the Eminence crossovers as a benchmark, then re-sell it when I'm satisfied with whatever I come up with. Realistically, I doubt I can come up with anything that'll be an improvement for less than $100 or so. But I'll definitely try!
  8. davio


    Nov 2, 2006
    Boston, MA
    Very cool. Again, if I ever get around to building one of these cabs I might just attempt building the crossover too just because I love tinkering. Good luck with the R&D!
  9. himppe


    Feb 22, 2009
    I've tried to design a 2-way passive XO for 12/6, but at a moment it's just a sketch.

    Anyway, according to my calculations components for the 12dB/18dB XO + Zobel network would cost something around 60-70€ when quality parts (low-resistance Corobar coils and 400V capacitors) used. On this basis I think 70€ (~100$) would be nice target for the price.

    It's a bit high cost, I know, but passive XO allows one to use even the smallest one-channel amps available, Markbass for one example.
  10. GregBlach


    Mar 5, 2009
    Greenboy > So sorry to hear about your father. I lost my dad a year ago at the age of 54 to an aggressive brain cancer. All I can tell you us to spend as much time with him as you possibly can (as I am sure you already do) and tell him how much you love him every day. It's going to hurt like hell when he is no longer there, but you have time to talk things through and prepare yourself for what's coming.

    And thanks for making a clear statement! I did actually get somewhat confused with the last few posts. I needed the input from you to get back on track. I am of course sticking to your design.

    Passinwind > Even if your crossover reaches a 100$ it would still be a cool alternative to those really want to build everything themselves. And if you eventually do deside to realease the schematics I guess it would be because your are pleased with the way it performs, and who wouldn't want that.
  11. Passinwind

    Passinwind I Know Nothing Supporting Member Commercial User

    Dec 3, 2003
    Columbia River Gorge, WA.
    Owner/Designer &Toaster Tech Passinwind Electronics
    I've never heard (or even seen) the 3012LF, so I have no real preconceptions of how and where to cross it to a 6" driver. So I have no schematics to consider releasing just yet...:cool:

    By the way: nice looking job you've done there Greg.
  12. greenboy


    Dec 18, 2000
    remote mountain cabin Montana
    greenboy designs: fEARful, bassic, dually, crazy88 etc
    Finally took time to build an overlay of the 3012LF and 6ND410 charts, but due to the way the respective companies put plots on their datasheets the midrange driver response is probably a tiny bit lower (a few pixels) so the horizontal grid wouldn't be so distorted.


    Why did I do this? Anyone who's spent much time in the Excel spreadsheet-based PASSIVE CROSSOVER DESIGNER I linked awhile back has probably become aware of the relationships one can expect between graphs of derived results and the summed response, and what's on the datasheets.

    I don't have time right now to point out some of the ideas that might help one choose a crossover point or other considerations, but I will say that this overlay makes a pretty good case for padding back the 6ND410 as much as 8 dB when used with a single 3012LF since its sensitivity in the area definitely below crossover is nicely sitting at 94 dB, and the 6ND410 definitely above crossover is averaging 102 dB. So with TWO 3012LF it should be possible to pad 2 dB for on-axis parity - or if one wants an especially bright combination that looks more at the 6ND410 off-axis plot, go for no padding.

    One will also note that the 3012LF could be climbing in output in the crossover region, while the 6ND410 in the tested enclosure size has yet to come up to the 102 dB value I'm concerned with. In PASSIVE CROSSOVER DESIGNER (or other tools) this means that each driver being filtered by its half of the crossover has good potential of complimenting the others' output. Cross over too low and this can't happen because the 6ND410 has fallen off so much ... cross over too high and the 3012LF's peakiness disturbs a nice summation. 800 Hz looks pretty damned nice taking this into account, and with proper driver values plugged into PASSIVE CROSSOVER DESIGNER including impedance, a number of nice approaches using different slopes seems to be possible.

    More later, when I can.
  13. greenboy


    Dec 18, 2000
    remote mountain cabin Montana
    greenboy designs: fEARful, bassic, dually, crazy88 etc
    Some further thoughts from experience using my DSPs flexible crossover sections, and verified by Passinwind's work with passive designs: Taking into consideration the drivers, the ability with styrofoam to change the midrange driver's [closed] chamber size, and using various crossover topologies/slopes... one can of course have low pass section and high pass section overlap or underlap to fit the situation.

    That means that one not need use the same crossover frequency for both filters but may use numbers that are different for each section, overlapping or underlapping. Ferinstance, though one might be obstensively toying with classic Butterworth 2nd-order (12 dB falloff) for the woofer, and BW 3rd-order (18 dB) falloff for the midrange cone, one could if the situation warranted, overlap to make up for response dips of one or both drivers, or underlap to take the Butterworth -3dB and make a -6bB point instead where responses meet, to achieve a smoother summation, since the classic Butterworth - 3dB definition actually sums with a hot humpy response whereas a -6dB definition like Linkwitz-Reilly sums flat around the crossover point.
  14. greenboy


    Dec 18, 2000
    remote mountain cabin Montana
    greenboy designs: fEARful, bassic, dually, crazy88 etc
    Also just learned this via email - seems the gentleman who wanted to help with CNC'd cutkits has been downsized (bummer, this economy!) and no longer has access to his former shop's CNC. But he still cares about the fEarful designs, so if anyone is interested in taking over where he left off, contact me here or in PM and I will get you in touch with him so that the cutlists and ideas we had worked on for dados and such can be discussed and the current state for each plan shared.
  15. I have access to a couple independent woodshops around here in RI, so as I do my circuits I'll look in and ask if anyone's interested. Some of these guys are musicians... just a shot, FWIW. I'll post, PM any signs of promise.

    P.S. Good on you for hanging with your dad. Hope all is as well as can be.
  16. I'm not dissing your design, nor pushing any other design. I'm pointing out the obvious. Anybody who actually takes the time to measure their boxes knows when you parallel two drivers such as 3012LF together, you get a +6dB boost. This isn't rocket science, it is well known fact.

    If you get offended because the Emperor has no clothes, that is not my concern. This two-cab arrangement is very expensive, and that's a fact.
    The crossover scheme being touted here is equally touchy due to the impedance mismatch. And that's another fact.

    You don't publish charts, but your simulations show your 6" at +8dB hotter than the 3012LF. This is almost 2x the apparent loudness of the woofer, and makes for a shrill sounding combination. Adding the second cab brings this into balance, but introduces crossover impedance problems. The verbiage in your simulation chart admits this is a too-hot combination with a single driver. And that's another fact.

    Your cab is designed to take a 6" driver. I pointed out the Alpha 6 offers a more balanced solution, at less cost. It also offers the added benefit of stacking the 6's in a vertical line array. Each cab is then useful by itself without requiring the 2nd cab for balance. Each cab remains at 8 ohms and allows for the use of an inexpensive commercial crossover. The Alpha also crosses over in the linear range, not on the downslope as does the 6ND410.
  17. You know, I would really hate for this thread to degenerate into a pissing match after 1000+ posts. GB, I appreciate your contibutions-even though you dont always agree with me-and I feel for you with the situation with your dad. He'll be in my prayers.

    But I will say that everybody better go stand in a corner til they can come out and talk nice. This thread is too important to risk being shut down because we cant get along.
  18. architect


    Feb 23, 2009

    Good talk Ol'Bass'ead

    About the crossover; I think it is important to have real measurementdata, because de Thiele-Small parameters do not show peaks and dips for example. There is a program called SplTrace that can do the job from the datasheet frequencycurve.

    SplTools http://www.pvconsultants.com/audio/utility/spl.htm

    Boxsim is a nice XO design program http://www.visaton.de/downloads/boxsim104_080828.zip

    For low frequencyresponse Unibox for Excel is a nice program http://audio.claub.net/software/kougaard/ubmodel.html
  19. alexclaber

    alexclaber Commercial User

    Jun 19, 2001
    Brighton, UK
    Director - Barefaced Ltd
    Switchable L-pad allows you to use one mid with one or two woofers. A DIY crossover can be just as inexpensive as a commercial crossover, especially as you would only need one highpass section. When the mid is placed in the right enclosure size the response in the upper midrange is increased which flattens the curve. A single mid will sound clearer, especially up close, than two mids. Vertical pair works well horizontally off-axis but most bass players stand far too close to be even vaguely near on-axis vertically, hence the single driver has an advantage.

  20. greenboy


    Dec 18, 2000
    remote mountain cabin Montana
    greenboy designs: fEARful, bassic, dually, crazy88 etc
    Simulation? It's an overlay of published data. Big difference.

    That's why we have talked about padding. Many times actually. Do try and read the thread.

    Covered probably in uh, post #1 of the 1000+ post megathread that this thread is a continuation of. Somewhere very early anyway, and Named in big bold text on the drawings/plans. Talked about many times. Done to death too. I suggest you actually read the thread and retain some of it before acting if you are personally introducing the obvious because everybody else somehow missed it.

    Greg is using the 6ND410 because he wanted to, after we had a back-and-forth on it, actually. Read that too before you go spouting off on the Emporer and his duds. As is usual, you come into this with so much wrong with your post it takes too much time to go point by point, and since the fEarful thread is not a debate thread, it's a "help people building them thread", I hate to do that. It seems like you want to force that to happen. Maybe that is why you are not aware of any actual things that have been covered and so often get things wrong.

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