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Need Simple Plans For a 212 Cab

P

Precisionb87

Dec 15, 2010
212
85
Philadelphia, PA
#1
Hello,
I want to make a 2-12" bass cab for a pair of speakers I have laying around. Anybody have any plans?
Nothing super fancy, possibly just a ported box. (no tweeter)

Here is the response/impedance curve of the drivers I am using:
curve.jpg


Thanks for the help!
 
#4
A guitar cab is just a box to hold the speakers, a bass cab is not. OP, you have any other ts specs on those? I'd be a little concerned about that 400hz dip considering the baked in voicing of a lot of bass amps but I don't know what your pre sounds like. Without at least Q or excursion, it's hard to tell if they're even worth putting in a box.
 
#6
Lets think and comment constructively guys. @ SolarMan: What makes you think so? Please offer substance to back your thoughts, I would like to hear why.

The exact speaker is this:
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Guys, I'm not trying to build the best cab to ever grace the planet earth, I just wanted to put something together to house these speaker I have laying around. I figure I need something with a res frequency of about 50hz right? (to line up with the free-air res of the drivers, and cut that impedance hump in half)

So, something for 2-12s, and a res frequency of about 50hz. Any suggestions?
 
#7
That might make a decent bass cab. At least with a set of specs people can run models on it and actually have some constructive ideas. BTW, port tuning doesn't have much to do with the free air fs of the driver. Rather tayloring lowend output and lowend response vs. ecursion limits, slope of the rolloff, etc.
 
#8
It might take a day or two, but i'm willing to run the numbers through the ol' ISD see what we might have.. However, the eyeball hunch kinda tells me these drivers are lacking way too much on the low end to do a reasonable job w/bass.. The giveaways are the high resonant frequency, and the low Qts.. This is going to favor a very small box, and (even the response graph hints at this) hardly anything under 150Hz.

A good bass cab design will show a flat response curve between 60/80 and 200Hz. You can increase the box volume to extend the LF response, but as you go larger, the SPL response of the desired frequency range will only go lower..

These drivers are labeled PA, and probably rightly so.. these are better suited to reproducing vocals, and higher pitched instruments..
 
#10
You guys are quick. Was curious how much box it would take to get low. Q isn't real high but workable.

OP, you could try shrinking it a little or raising the tuning a little but I'd stay fairly close to that model. If you start getting a bump on the lower end of the curve there it'll make that 400hz dip sound even more scooped than it is.
 
#11
I ran the #'s on Isd pro, and the curve didn't look too bad. The problem is I modeled a 2-12 vented box, and it came out 2.75 cu.ft... no way you can even mount 2 12" speakers on something that small. One would be a challenge..

However.. if you increase the volume to 4.9 cu.ft., tune it to 47, you will have something that might actually be workable.. The first harmonics will be about 2dB down, but the curve is nicely flat between 60-100 Hz.. Thats 5-string territory.. Download WinISD pro alpha and plug in the #'s..

I haven't considered porting yet, and that could pose another challenge.. Isd will calculate a round port OK, but not a shelf port. Has to be big enough not to chuff, yet small enough to fit properly in the cab. Remember to add volume back into the cab!
 

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