B&C Sub designs

Re: B&C Sub designs

True, WinISD is for PC.

It is probably easier to just work in metric. I always just stay in metric when building speaker cabs.

Kip Conner said:
It looks big to me but let me show you how i got that 7" opening...

339 sq cm is equal to 133.465 sq in.

One side of the opening is 21" so I did the division 133.465" / 21"= 6.35"

Giving me a port area of 21" by 6.35"

Is this right?


All the freeware in the world is for PC... :(
Click to expand...
 
Re: B&C Sub designs

For Alan's design you might want an HPF nearly that high, but for the B&C design you would be wasting a lot of LF capability. 30 hz would be more like it.

Kip Conner said:
As far as program music goes that booty music gets played on NYE gig's so the ability to reproduce 40Hz is probably not a bad thing. My guess is that I'll end up with a 4th order 40Hz HPF on the subs anyways to act as a protectant to the drivers.
Click to expand...
 
Re: B&C Sub designs

Kip, you can make the box a variable amount of sizes I just went to 30.5 wide and it looks better yet. Fb is 42, f3 is 38. Thats why I asked if we could go bigger, another reason I go double 18 with 1 inclosure.
 
Re: B&C Sub designs

Alan Sledzieski said:
Your forgot what I for got to do, convert 6.36 cm back to inches, yielding a port opening of 2.5'' on the b + C design. So 2.5 x 21 on the b+c,12.48 deep.
Click to expand...

You're going to have better luck with a taller port, than a super deep port. At least that's what I've found from past experience.

Oh, and I'm surprised that nobody else has mentioned it... Make sure your brace the absolute shit out of your design. Any movements in the wood is lost output. You want as stiff of a box as possible! And remember, lots of bracing = lost cabinet volume, which means you need to take that into account too!


Evan
 
Last edited:
Re: B&C Sub designs

Evan Kirkendall said:
You're going to have better luck with a taller port, than a super deep port. At least that's what I've found from past experience.

Oh, and I'm surprised that nobody else has mentioned it... Make sure your brace the absolute shit out of your design. Any movements in the wood is lost output. You want as stiff of a box as possible! And remember, lots of bracing = lost cabinet volume, which means you need to take that into account too!


Evan
Click to expand...

You mean like this

002.jpg003.jpg004.jpg005.jpg
 
Re: B&C Sub designs

Evan, do you mean that you've had better luck with a port that is taller and not as wide? Port depth (length) is a function of Vb, Fb and port area as I'm sure you know.

+1 on the bracing.

Evan Kirkendall said:
You're going to have better luck with a taller port, than a super deep port. At least that's what I've found from past experience.

Oh, and I'm surprised that nobody else has mentioned it... Make sure your brace the absolute shit out of your design. Any movements in the wood is lost output. You want as stiff of a box as possible! And remember, lots of bracing = lost cabinet volume, which means you need to take that into account too!


Evan
Click to expand...
 
Re: B&C Sub designs

Ah, calculating volume is a vicious cycle! After determining that cabinet needs to be 221.75 liters with the speaker chamber, the port and speaker itself I then started calculating the bracing. As the bracing adds up the gross volume adds up and the width changes which then makes the braces longer which changes their volume...

So I settled for just over estimating once with a batten on every corner, any other cross bracing will just be a deduction i suppose.

I'm think going with a box that has internal dimensions of 22.5 x 21 x 29.5 with a port that is 2.5 x 21 x 12.5- it's going to add about 7 inches of width to the current OAP LF118 cab, most of that being an actual port, where the OAP has only a vent.


OAP LF118 Mod.jpg
 
Re: B&C Sub designs

Im sure that will be a significant improvement for you. The volume of bracing material is unlikely to be enough to make a real difference. Make sure you add enough baffle offset at the front of your design to allow room between the driver and the grill. You don't want the driver slapping the grill.

Kip Conner said:
Ah, calculating volume is a vicious cycle! After determining that cabinet needs to be 221.75 liters with the speaker chamber, the port and speaker itself I then started calculating the bracing. As the bracing adds up the gross volume adds up and the width changes which then makes the braces longer which changes their volume...

So I settled for just over estimating once with a batten on every corner, any other cross bracing will just be a deduction i suppose.

I'm think going with a box that has internal dimensions of 22.5 x 21 x 29.5 with a port that is 2.5 x 21 x 12.5- it's going to add about 7 inches of width to the current OAP LF118 cab, most of that being an actual port, where the OAP has only a vent.


View attachment 4627
Click to expand...
 
Re: B&C Sub designs

We're going to add just over an inch between the driver and grill so the sides will extrude past the speaker surround. The next thing I need to get learnin' on is insulation. How much is needed, if any.
 
Re: B&C Sub designs

Kip Conner said:
Ah, calculating volume is a vicious cycle! After determining that cabinet needs to be 221.75 liters with the speaker chamber, the port and speaker itself I then started calculating the bracing. As the bracing adds up the gross volume adds up and the width changes which then makes the braces longer which changes their volume...

So I settled for just over estimating once with a batten on every corner, any other cross bracing will just be a deduction i suppose.

I'm think going with a box that has internal dimensions of 22.5 x 21 x 29.5 with a port that is 2.5 x 21 x 12.5- it's going to add about 7 inches of width to the current OAP LF118 cab, most of that being an actual port, where the OAP has only a vent.


View attachment 4627
Click to expand...

I just plugged your numbers, its not good. Vent velocity is up there, power handling is down right where you want it not to be down, x max is over 12 mm most of the time in the sweet spot, right where its most important, dip in spl in the most important part.

I wouldn't do it.
 
Re: B&C Sub designs

Alan Sledzieski said:
I just plugged your numbers, its not good. Vent velocity is up there, power handling is down right where you want it not to be down, x max is over 12 mm most of the time in the sweet spot, right where its most important, dip in spl in the most important part.

I wouldn't do it.
Click to expand...

Hmmm, those are the exact dimensions that B&C suggested, just not the exact shape... not sure what to do about it... is the modeling program you use for a generic speaker where you just input the known data?
 
Re: B&C Sub designs

Kip Conner said:
Hmmm, those are the exact dimensions that B&C suggested, just not the exact shape... not sure what to do about it... is the modeling program you use for a generic speaker where you just input the known data?
Click to expand...


I know thats the problem, its what b+c suggested, look at post 73. You said you plan on doing a 24 db high pass at 40 hz, to protect the speakers, problem is the big problem is from 45 to 56 ish with that port design. When I wake up I'll give you a new port opening to your new box dimensions, this opening will increase spl from 44 to 56 and not exceed x max, and will handle 1500w in that area.

Yes on the program, get it you'll love it.

US Speaker - Eminence Speaker Cabinet Design Software for designing professional speaker cabinets.
 
Top Bottom