DIY 12/6/1 cab design

Discussion in 'Amps and Cabs [BG]' started by oerk, Mar 21, 2014.

  1. oerk


    Oct 16, 2009

    I present to you: a 3-way cab design that was inspired by the fEarful and fEarless designs.

    First, a bit of background: I've gigged a Hartke Kickback 15 for the last few years. It's defining feature is that it works exceptionally well in a gig situation, mostly due to the wedge design and the adjustable notch filter - but it's not what I would call a great sounding amp.

    So, I wanted something better. Design goals were:
    - better dispersion through separate mid driver
    - usable as a monitor, so reasonably flat response
    - 12" woofer with high Xmax
    - light
    - wedge design
    - better overall sound
    - more low end

    The end result weighs in at 15.2 kg and is better than what I tried to hope for. It's better than every cab I've tried so far. Neutral sounding in a good kind of way, not boring at all. And it works exceptionally well with upright.

    I haven't had a chance to gig with it yet. This will be resolved soon, hopefully.



    I will post build pics and measurements in this thread. More to come.
    markroman likes this.
  2. oerk


    Oct 16, 2009
    - Woofer: Monacor SP-12/500FH
    - Mid: Celestion TF-0615MR (closed back)
    - Tweeter: Monacor MHD-220N/RD

    Here's the simulation (green line):

    It's tuned to 60hz, one should use a high pass filter at 50hz for full performance, but that is true for many bass cabs.

    The dip at 110hz is not noticeable.

    It's possible to substitute the woofer with it's higher powered brother, the SP-12/700HP. Simulation looks slightly worse but that shouldn't be an issue. It has 2mm more Xmax and is slightly heavier.
  3. oerk


    Oct 16, 2009
    Crossover points are at about 1100hz and 4800hz.

    I didn't go for completely flat, I wanted the crossover to be as simple as possible.

    I can't measure anything below 300hz in my room - I have to trust the simulation. The following graphs show 300hz and up.

    Overall frequency response:
    Dispersion is pretty good; orange is 0°, blue is at 30°, purple is at 60°

    Switchable mid driver
    There are two switches at the back. One is for tweeter on/off, one switches the resistors out of the mid driver bandpass. This means that the mid is that the cab is about 5dB louder between 2 and 5kHz.

    This gives a grindier feeling when used with bass guitar with more attack. I like it very much, which is why I left the setting in.

    The mid driver has a peak at about 5 kHz, which gives the cab a bit more character. When the tweeter is switched on, this peak is more noticeable, especially with recorded music. So I have a coil in the crossover to suck out that peak only when the tweeter is switched on.

    (orange line=without coil, red line=with coil)

    Switches at the back:
    Tommy L likes this.
  4. Jim Carr

    Jim Carr Dr. Jim

    Jan 21, 2006
    Denton, TX or Kailua, HI
    fEARful Kool-Aid dispensing liberal academic card-carrying union member Musicians Local 72-147
    Very Cool! Would it be possible to tune lower with either of those 12" drivers?
  5. oerk


    Oct 16, 2009
    The cab is built from 10mm poplar plywood (less than 1/2 inch!). Poplar is extremely light, so I've braced it very well internally. I kind of went overboard, so it's not as light as I hoped it would be.

    If anyone is interested in building one of these, I will draw a plan.

    Build pictures:

    I have wood :D

    Front baffle






    I've done the 45° angles with a router bit.

    Gluing the 45° board was a major PITA:



  6. oerk


    Oct 16, 2009
    Hey Jim,

    thank you!

    I'm afraid not, 60hz is the sweet spot. These are intended for active PA systems with active EQing. Going lower means a significant dip below 200hz:

    I've yet to torture it with a five string. Four string standard and double bass sounded pretty good, I didn't miss anything.

    I personally wouldn't want it to go lower - less problematic on less-than-optimal stages.
  7. Me likey!
    I'd love to try building one. Not sure I'd be able to glue the 45° board though.
  8. oerk


    Oct 16, 2009
    Thanks! It isn't THAT hard, you just have to find a way to saw the 45° angles. For me, the easiest way was to use the router.

    Gluing itself isn't that hard if you don't use (way) too much glue like I did. It's also easier if it's the last piece, i.e. after the top is on.

    Anyway, here's the crossover, professionally done in Paint.Net ;)
  9. Arjank


    Oct 9, 2007
    Above Amsterdam
    Great stuff, this is what I expect from a German speaker builder, they have a great tradition in DIY speaker building:bassist:.
  10. In picture two (kickback mode), I can see that you've used the port opening to a attach a metal bracket which supports the amp. Very clever. You should show a detail picture of that too.
  11. oerk


    Oct 16, 2009
    Hey Arjan,

    I can assure you, if I had posted this project to a german speaker builder forum, they'd have me drawn and quartered for:
    - not posting accurate measured graphs
    - not posting waterfall diagrams etc.
    - not using a calibrated microphone
    - "sounding" the cabinet by adding a mid level switch
    - using relatively high crossover points
    - not using an absorption circuit for the 5kHz hump
    - not properly lowpassing the mid driver
    - not doing anything against the lower mid hump
    etc. etc.

    One can learn a lot from these forums, but they are - for the most part - not a pleasant place to be.

    Anyway, I'll probably do more accurate measurements and prettier graphs in the future.

    I've stolen the idea from the fEarless F110 thread. Genius.

    My version is just a prototype, so it isn't pretty. It works very well though, so I'll eventually clean it up and paint it.


    Tried my pre/power rig and the amp from the Hartke Kickback with it today. No complaints at all! (if I had neighbors, there would be...) Even better, the normally slightly sterile Hartke didn't sound sterile at all.


    One minor drawback: Because of the 60hz tuning, it isn't really suited for five strings. Drop D works though.

    Next: building a baffle for speaker protection - this is still in the planning stage
  12. OldogNewTrick


    Dec 28, 2004
    Germany, EU
    Hey Oerk, nice build ! :bassist:

    some points / questions:
    Why did you choose the Monacor woofer? For that kind of money at €190, there are plenty of choices, which would allow for a lower tuning.

    Cab weight / reinforcement - quite a bit of the weight went into the "Dachlatten", why not use beech dowel sticks for bracing? Lower weight and also available from obi/hornbach/[DEL]praktiker[/DEL]

    Anyways, no criticism intended, just wondering... :)
  13. Arjank


    Oct 9, 2007
    Above Amsterdam
    You mean
    Well, you've build a cab for bassguitar and most builders don't even do the measurements you did. The above are valid points if you wanted to go for the ultimate in " un-colored" cab design like e.g. I did with my cab. I still think you did a great job :)
  14. Arjank


    Oct 9, 2007
    Above Amsterdam
    It should be able to project the 2nd harmonic of a low B pretty well though. Maybe you can extend the shelf and lower the tuning to 50hz, but then you may have to EQ a bit.
  15. swamp_bass

    swamp_bass I love it when a groove comes together

    Nov 20, 2013
    North Cackalacky
    Nice work! That's some serious reinforcement ya got going on in there! If you invite the fat lady to sing, you don't have to wince if she sits on your cab afterward.
  16. oerk


    Oct 16, 2009
    Several reasons:
    - I had access to the Monacor program cheaply at the time
    - It was mainly intended for me :) and I don't play a 5-string live
    - 60hz is less problematic on boomy stages
    - cab size: the 3012LF doesn't work much better in the intended 50hz enclosure
    And it sounds quite good, as it turns out.

    What alternatives do you know about? The 3012LF obviously, and what else? Just curious.

    It's what I had laying around. Had I known beforehand how much reinforcment I'll make, I'd have chosen something else. You're absolutely right though.

    No offense taken!

    Yep, but it isn't the only one.

    This is most certainly the flattest bass cab I've ever heard. The Glockenklang 12" probably comes close, but it doesn't have a mid driver and therefore the usual dispersion problems.

    I was actually a bit worried that it'd sound too neutral, and not like a bass cab anymore. Not the case!

    Oh, and thanks for the kind words!

    You lose 3dB sensitivity if you lower the tuning to 50hz. Not worth it IMHO.

    Certainly not! :D
  17. OldogNewTrick


    Dec 28, 2004
    Germany, EU
    I was thinking of the Beyma 12 MW ND. (Monacor SP-12/500FH)
    FS 43Hz (45Hz)
    Qts 0,32 (0,25)
    EBP 126 (173)
    VAS 100 ltr (76 ltr)
    Xmax 7,5mm (7,25mm)

    Not too many choices for a Neo, long throw motor (xmax >7mm) and a bass reflex friendly EBP / QTS.... I thought there would be more...
  18. oerk


    Oct 16, 2009
    Thanks, I didn't know about the Beyma!

    The Beyma simulates a bit better in 50l, but not by much.

    So, there's the Eminence 3012LF, the Beyma 12MW/ND, and the two Monacor woofers (SP-12/500FH and SP-12/700HP). Not that much choice sadly.
  19. Passinwind

    Passinwind I know nothing. Commercial User

    Dec 3, 2003
    Columbia River Gorge, WA.
    Owner/Designer &Toaster Tech Passinwind Electronics
    Nice build! I dig the metal bracket too. :bassist:
  20. Arjank


    Oct 9, 2007
    Above Amsterdam
    Nope, not much choice. Oberton has nice drivers but their 12" line is designed towards high efficiency in a small enclosure so they skip the lowest octave too....