DIY Vertical 312

Discussion in 'Amps and Cabs [BG]' started by 5StringPocket, Jul 31, 2022.

  1. 5StringPocket

    5StringPocket Supporting Member

    Jan 11, 2006
    Texas
    A vertical 312 with the right drivers should have an output similar to a 410 or 215 and place the top driver close to ear level with good horizontal dispersion. The Faital 12PR320-8 weighs only 6.1 lbs, has a wide frequency response to 5.0 kHz, and models well in a compact ported enclosure.
    https://www.usspeaker.com/faital pro 12pr320-1.htm
    This one looks good to me without a tweeter, which saves about $100 and 3lbs off the build. The weight with 1/2" poplar and a 3/4" Sande ply baffle looks to be about 56 lbs. Castors and kick back handles would make for easy transport. The 2.67-ohm load would be fine with an amp stable down to 2.67 or 2 ohms. Here is the proposed construction drawing.
    Faital 12PR320x3V CabDwg.png
    This cab and tuning should reach Xmax with 900 watts at 40 Hz with a total displacement (Vd) of 1082 cc. Thats a lot of air moved. The response is 0dB at 79 Hz and +0.8dB at 100 Hz, but flattens out at +1.0 dB by 120 Hz so it should be solid but not boomy. I think an 800-to-1200-watt amp with some overdrive would really make this sing. Here is the Boxsim frequency response and max SPL graphs.
    Faital 12PR320x3V Boxsim FreqResp.PNG
    Faital 12PR320x3V Boxsim MaxSPL.PNG
     
    Last edited: Jul 31, 2022
  2. I'd love to see how this turns out. Keep the updates coming!
     
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  3. agedhorse

    agedhorse Supporting Member Commercial User

    Feb 12, 2006
    Davis, CA (USA)
    Development Engineer-Mesa Boogie, Development Engineer-Genzler (pedals), Product Support-Genz Benz
    Double the port length and remodel
     
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  4. What box frequency should he aim for?
     
  5. ThisBass

    ThisBass

    Aug 29, 2012
    Germany
    @5StringPocket

    If I was in your shoes I'd lower the net volume down to ~4 cuft and build a 212 instead.
    The benefit was some extend low end (f3 ~55Hz) versus your design, yet high powerable design that provides plenty acoustical power
     
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  6. agedhorse

    agedhorse Supporting Member Commercial User

    Feb 12, 2006
    Davis, CA (USA)
    Development Engineer-Mesa Boogie, Development Engineer-Genzler (pedals), Product Support-Genz Benz
    Not important, based on the shape of the curve, double the length and re-examine the shape of the curve.

    Optimum (at least my definition of optimum) will be between these two lengths.
     
  7. 5StringPocket

    5StringPocket Supporting Member

    Jan 11, 2006
    Texas
    I've got a good 212 and there are so many good ones available. The 12PR320-8 has a small Vas which doesn't require a large enclosure. This thread explores a simple, but effective option for a single 312 tall vertical cab which would have a very small demand niche and is not commercially available. I and a few others have expressed an interest in this form factor so I wanted to see how it might come together.
     
    Last edited: Aug 1, 2022
    musicman556 likes this.
  8. 5StringPocket

    5StringPocket Supporting Member

    Jan 11, 2006
    Texas
    In my software, with constant box volume and port area, the only adjustable handle for affecting port length is tuning frequency. I lowered tuning frequency to increase port length as suggested and do like the change. It has a bit more low-end extension and the upper end was a bit flatter, but still 0dB on the normalized response by 81 Hz and +0.7dB at 100 Hz so the upper bass should be full. I think lowering the F3 and F6 points with less peaking around 120Hz is desirable for a full sounding bass response that is more optimally damped.
    Here is a comparison of the normalized frequency response between the two models:
    1st: 2.0" port shelf, Vb=4.56ft3, Fb=52.0Hz, F0=79.0Hz, F3=59.2Hz, F6=48.7, F10=41.2Hz, +1.1dB peak
    2nd: 4.0" port shelf, Vb=4.50ft3, Fb=48.2Hz, F0=81.1Hz, F3=58.2Hz, F6=48.1, F10=39.5Hz, +0.9dB peak
    Faital 12PR320x3V CabDwg.png
     
    Last edited: Aug 1, 2022
  9. squish

    squish Nothing TOO fancy Supporting Member

    Dec 6, 2005
    Atl
    I use 3 12s on stage more than any other configuration. With lightweight cabs (212 @ 52 lbs and a 112 @ 33 lbs), it's still 85 lbs which is is not really that light anymore. My Henry 8x8 loaded with ferrite drivers doesn't seem to be that much more at 99 lbs. The proposed 75 lbs (56 lb cab plus 18.3 lb drivers) might be a good compromise. The proposed wheels and pull handle would make this heavy hitting cab very portable.
     
  10. ThisBass

    ThisBass

    Aug 29, 2012
    Germany
    For Fb=52.0 Hz:
    F3=62.2 Hz,
    F6=52 Hz,
    F10=41.2 Hz,
    +1.35 dB peak

    For Fb=48.2.0 Hz:
    F3=63 Hz,
    F6=51.7 Hz,
    F10=41.6 Hz,
    +1.13 dB peak


    212 design (reduced net volume) - Fb 50.6 Hz:
    F3=54.6 Hz,
    F6=46.8 Hz,
    F10=39.4 Hz,
    +0.93 dB peak


    At least to me it would make not much of sense to trade off low end benefits for higher efficiene in the bandwidth above 100Hz.

    For me the smallish footprint of this tall skinny 312 tower design was likely too unstable on a floppy-sloppy stage.

    If any I'd build a modular cab system 212+112
    Half the size (net volume) of the 212 for the 112.
    This modular design furthermore also would help to improve transportability.
    I'd choose roughly 24" width x 16" depth both cabs just to have a stable footprint on a sloppy stage like I did have about 4 weeks before at an outdoor event.
    I'm pretty sure your skinny (likely top heavy) 312 tower might have sucked on stability issues on this stage, and may be would have fallin' over sometime when the drum player did a solo playing...

    Here you are with the benefit of improved lowend response for a 212 where the net volume was reduced versus your tall skinny 312 design.

    upload_2022-8-1_19-8-17.png


    Max SPL (acoustical power) of the 212 design
    upload_2022-8-1_19-11-46.png
     
    Last edited: Aug 1, 2022
  11. agedhorse

    agedhorse Supporting Member Commercial User

    Feb 12, 2006
    Davis, CA (USA)
    Development Engineer-Mesa Boogie, Development Engineer-Genzler (pedals), Product Support-Genz Benz
    I would start at around 55Hz, the balancing of tradeoffs means that currently (IMO) you are leaving a fair amount of useful performance on the table. Maximally flat is NOT the ideal tuning for about 95% of applications.

    IMPORTANT NOTE: I see that there is a typo in my post #3 above that I can't edit. I meant to halve not double the port length, sorry for the confusion. You want to see peak of ~1.5dB give or take.

    For ease of construction, I also suggest centering the drivers in the box and using the same port areas for each port. In theory it helps balance out forces on the cone, but in practice it's probably more valuable for ease of construction.

    ThisBass shows similar results. A smaller box may or may not be beneficial, and as a box gets taller the footprint needs to be large enough to remain stable on a bouncy stage.
     
    ThisBass likes this.
  12. ThisBass

    ThisBass

    Aug 29, 2012
    Germany
    Here you are with SPL (1 Watt 1 Meter) consideration
    212 design vers 312 design
    The 312 design will benefit from +2dB more of SPL at 100Hz (and also +2dB in the bandwidth above 100Hz)
    upload_2022-8-1_19-51-34.png
     
  13. 5StringPocket

    5StringPocket Supporting Member

    Jan 11, 2006
    Texas
    The 56 lb weight includes the drivers. Probably need to add a couple more lbs for castors and kick back handles but the finished cab with waffle style grills (lighter and cheaper) should be under 60 lbs.
     
  14. agedhorse

    agedhorse Supporting Member Commercial User

    Feb 12, 2006
    Davis, CA (USA)
    Development Engineer-Mesa Boogie, Development Engineer-Genzler (pedals), Product Support-Genz Benz
    IMO, it would look SO much better with a full face grille...
     
  15. Gizmot

    Gizmot

    Mar 22, 2009
    Pittsburgh area
    For some people, the 5 kHz top end is just fine. For me, I'd want more (~ 10 kHz).

    I have an EV B-210 (I was part of the team that created it) which has ~8 kHz response and it's smooth, but doesn't have the very top end sparkle that I like.
     
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  16. 5StringPocket

    5StringPocket Supporting Member

    Jan 11, 2006
    Texas
    A full face grille would be nice and could be the builder's choice. It would add additional cost and weight.
     
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  17. Passinwind

    Passinwind I know nothing. Commercial User

    Dec 3, 2003
    Columbia River Gorge, WA.
    Owner/Designer &Toaster Tech Passinwind Electronics
    I just priced a new one from Reliable Hardware for one of my cabs and the price was much higher than previously. Increased shipping costs do no favors there!
     
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  18. 5StringPocket

    5StringPocket Supporting Member

    Jan 11, 2006
    Texas
    With Eminence Designer using minimal damping and Boxsim as a cross check, a tuning of 55.4Hz gave a peak of +1.5dB that was reached at 101Hz.
    3rd: 1.25" port shelf, Vb=4.58ft3, Fb=55.4Hz, F0=70.7Hz, F3=57.4Hz, F6=49.8, F10=42.0Hz, +1.5dB peak

    The box as shown has identical ports top and bottom so it should be balanced. Sorry if the representation wasn't clear. The drivers could be centered in the box with four smaller corner ports or with these two ports if the box was 19" wide instead of 18". Many commercial cabinets are about 19" wide. 24" width is a knuckle buster when going through doors and would require a more squat profile which the 312 is not. I've owned 24" wide cabs, don't like them, and wouldn't own another one. I understand the need for stability but have never had an issue with a single cab 15" deep. Using a full front grill would add an extra inch of depth. IME, I don't think a 39.5"Hx18"Wx15.5"D 60 lb cab with evenly distributed weight and a Class D head on top should be unstable.
     
    Last edited: Aug 1, 2022
    agedhorse likes this.
  19. 5StringPocket

    5StringPocket Supporting Member

    Jan 11, 2006
    Texas
    I understand, all of my cabs have a mid-driver or tweeter, even if it's dialed back. A high frequency driver and HPF could be added but this first pass is for those who don't want a tweeter and just keep it simple. This is one of the few 12" drivers I found that looks like it could actually get to 5kHz. No sparkle but with treble boost I don't think it would sound dark.
     
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  20. 5StringPocket

    5StringPocket Supporting Member

    Jan 11, 2006
    Texas
    I'd be more interested in an optimized 312 design with internal volume, porting, and tuning given. Box shape can be adjusted with a given Vb to get a stable footprint but the drivers won't quite be vertically aligned if the box is shorter. The 212 is well covered elsewhere.