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Building 212 cab

#21
SimonD said:
Yeah, At first, I wanted to buil these Fearful desing ..but It's hard to me to buy all the parts required for this bulding without having custums fees ...(I'm in Canada). Also, I found these a little bit to big for me...I want something more easy to carrying. Following this, I decided to simplify my desing and use only 2 x 12" speaker and a tweeter...
Click to expand...
greenboy fEARful 1212/6 Bass guitar DIY speaker kit. Your own custom bass guitar cabinet

Eminence drivers are available in Ca, right? The hardware is generic enough so that it can be substituted for other brands or similar components, and all the xover parts, or at least the same values, should be available through Solen. I haven't run the BOM but I'd be surprised if that wasn't correct especially as the poly caps are easily found there and 1.2 and 1.5mH inductors are standard values (from the CBG xover in the .zip above).

All of the rest of the design is done for you and proven by many previous builders and users here. You have a very steep learning curve otherwise.
 
#22
18sound speakers are hard to find here... 6NM410 and tweeter XD125...
For the midrange, I could have an Eminence Alpha 6A, but I think that it is "OK" with an 12/6 but not recommended with 1212/6...2 x 3012LF push too much low end for the only 1x Alpha6A ...
For the tweeter I could have an Selenium D220Ti and wave guide DaytonH07E, a combinaison that I found in the plans of Greenboy..
But I don't know...I have no doubt about the sound of these cab, but I don't like the aesthetics of this cab..
I still love the idea to build my cab with only 2x12 and maybe a tweeter (I'm not sure of its usefulness.. :eyebrow:)

Thanks for your input guys!:smug::):bassist:
 
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#23
SimonD said:
I still love the idea to build my cab with only 2x12 and maybe a tweeter (I'm not sure of its usefulness..
Click to expand...
It can still be done, but you need to define the performance parameters from the cab. And you'll need someone to be able to design the xover for you. Generic off the shelf xovers aren't worth a pinch of poo in my experience.

For example, almost every HF driver I've ever seen on a BG cab are too small to cross over to a 12 where it would need to to maintain the DI through the crossover. The H07E loses horizontal control about an octave above where I'd use it, so it's OK above the 6 where GB used it, but not a 12. The H6512 would be better here as would the H812 for the bolt on version of the Selenium. I've used both, the H812 in a more recent PA design (actually Celestion H9040 - same flare) as well as the original JBL that the H6512 is a copy of.

Here's a more recent design by Scott Hinson demoing some of the excellent new SB Audience drivers (I have a bunch here for testing) and explains his design philosophy which I agree with by and large, and may help with your design.
SB Audience :: Compact 12 inch Two Way
 
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#24
Snert said:
It can still be done, but you need to define the performance parameters from the cab. And you'll need someone to be able to design the xover for you. Generic off the shelf xovers aren't worth a pinch of poo in my experience.

For example, almost every HF driver I've ever seen on a BG cab are too small to cross over to a 12 where it would need to to maintain the DI through the crossover. The H07E loses horizontal control about an octave above where I'd use it, so it's OK above the 6 where GB used it, but not a 12. The H6512 would be better here as would the H812 for the bolt on version of the Selenium. I've used both, the H812 in a more recent PA design (actually Celestion H9040 - same flare) as well as the original JBL that the H6512 is a copy of.

Here's a more recent design by Scott Hinson demoing some of the excellent new SB Audience drivers (I have a bunch here for testing) and explains his design philosophy which I agree with by and large, and may help with your design.
SB Audience :: Compact 12 inch Two Way
Click to expand...
I sure hope that's not being suggested as the gold standard, or even ANY standard in how to build a crossover.
 
#27
SimonD - your plan for a 2 x 3012HO cab makes sense to me, if you're willing to trade low for light and loud. That speaker seems to be happy in a small box. It's efficient, goes high for a 12, and takes a lot of power, though not so much down low. I'd build and try it before you decide if you need a tweeter... you might not.

I don't know if 115 liters/60 hz is the right target; looks like power handling would drop like a rock below 52hz. A smaller box would help that, and also be lighter.
 
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#28
Yes I try to have a box frequency as low as possible.
But, the more I go down the frequency box, the more problems I have with cone excursion. Does it always have to stay below the Xmax? My amp , GK 1001RB-II, can produce 700w @4ohms so I set the input signal at 700 watts..Of course, I never play with all the volumes at 10....but I would like to have a cab that can handle at least 700 W... When the box is tune at 60Hz, the cone excusion is good, but I lost low frequency....What remains an acceptabe risk to have the most bass? This is at 54 Hz...
upload_2023-3-18_21-44-40.png
 

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#32
SimonD said:
Thanks @agedhorse !
"verifying" do you mean build it and try it out or is there another way? (another software than WinISD?)
Click to expand...
Yes, you might find differences of between 20-50% on some performance variables.
 
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#33
For me, it's easier to see what's happening with excursion by looking at the maximum power graph. Above 100hz, it's a flat line at the thermal power limit. Below 100hz, you see the effects of the port, and speaker unloading. For some lower frequencies, maximum power is where excursion reaches xmax. Here's a 115l cab tuned to 60hz. Below 52hz, max power drops steeply as the speakers are unloaded. By 41hz (E1), max power is excursion-limited to about 162 watts (81w per speaker).
maxPower1.png


If you reduce cab volume to 80l and drop the tuning to 50hz, max power at 41hz increases to about 542w combined.
maxPower2.png


Of course, theres a tradeoff for that LF extension: lower output above 52hz, as seen in the maximum SPL graph.
maxSPL.png


The 115l/60hz cab isn't quite as bad as it looks down low, because bass guitar signals aren't sine waves; the fundamental is only a fraction of the total signal. And built-in high pass filters will help, and/or turning the bass knob down. But otherwise, you could easily be in over-excursion on an open E at full volume with a 700w amp.

WinISD critics - please note: 1) that is what the OP is using; 2) I'm not discussing port length; and 3) it's still useful for seeing the relative effects of cabinet size and port tuning on a given driver, and the tradeoffs between power handling and output.
 
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#34
I have 2x12 with tweeter on Eminence Beta 12A made by Handbox. Great cab. Small, portable, compact. For me it's enough for everything to even small-medium outdoors. I don't think that you need a lot of rumble low end anyway. Those frequencies are not so necessary. Especially on stage. FOH's when they see that I have cab are really affraid that maybe I would bleed from my amp. But never. And I hear myself crispy clear! Maybe because of this great Handbox R400 amp ;)
 
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#35
First thing first, thank you so much @1n3
I have to keep an 18" x 27" facade to be able to put two 12" speakers and possibly a tweeter.
So with a volume of 80 L (4882 in2) I only have 10 deep left. i think that is not enought, and I'm not able to configure air port properly...with these dimensions...I only keep 60% of the port length in WinISD

But I can design a cab with a 12" depth of 96L at 52Hz
This cab is close to what you proposed..and I can design air ports that have a suitable length and velocity
the difference of the "cone excursion" curves is negligible between each model...

Note: all dimensions are interior..

Green: 80L @ 50 Hz
Blue: 96L @ 52 Hz
Red: 115L@ 60 Hz
upload_2023-3-20_21-39-59.png


upload_2023-3-20_21-47-30.png


I ordered my components, we start construction this weekend !!!!
:hyper::):cool:
 
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#36
jb90 said:
I have 2x12 with tweeter on Eminence Beta 12A made by Handbox. Great cab. Small, portable, compact. For me it's enough for everything to even small-medium outdoors. I don't think that you need a lot of rumble low end anyway. Those frequencies are not so necessary. Especially on stage. FOH's when they see that I have cab are really affraid that maybe I would bleed from my amp. But never. And I hear myself crispy clear! Maybe because of this great Handbox R400 amp ;)
Click to expand...
I can't open your attachement...
 
#39
I want to keep the design easy to build (vertical!). I'll build it with a internal volume of 96L (18"W x 27"H x 12"D). Do I have to deduct the port volume from the total volume or it's negligible? I leave the sides protruding about 1" in order to insert the grill. Currently I hesitate between plywood 12mm (9 ply) or 15 mm (11 ply). The lightness is an important criterion for me... but the solidity too... obviously I will put reinforcements inside. I plan to make the joints of a dovetail joint..
 
#40
Port volume could be significant or not, if it's less than 5% of the total volume you can round the internal volume down a bit.

No need for dovetail joints unless you are into the labor of love. Also no need to over-bracethe crap out of it, just enough bracing is "just right".

I've designed cabinets out of 12mm and 15mm, since your cabinet it fairly large, I think 15mm will end up being a better choice overall.
 
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