So I had a box design done by someone that seems to be a reputable designer around the car audio forums, and I have a couple of questions about it.

I have a FI BTL N2 12" D2 running on a SAZ-1500, 250amp alt, 0 ga wire throughout including big 3 and additional grounds throughout the engine compartment, XS Power d975 in the back, Optima yellow top up front.

The design he gave me has a net volume of 4 cubes. Is that too big for that one sub? I told him I wanted a daily ground pounder that can kill some lows. Well it does destroy the low notes, but it seems to be pretty weak with the majority of rap/hip-hop songs, and doesn't sound real strong on rock or metal. I know the specs call for 1.7-2.5 cubes on FI's cut sheets, but I was wanting some input on the situation. I know that too much volume can cause excessive excursion and damage the sub. By my calculations the box seems to be tuned right around 35hz.

Even with that little power 4 cubes seems a bit large. I've never modeled the 12 so I'm not speaking from expeirience.

Edited October 15, 201113 yr by ricksi30

So I had a box design done by someone that seems to be a reputable designer around the car audio forums, and I have a couple of questions about it.

I have a FI BTL N2 12" D2 running on a SAZ-1500, 250amp alt, 0 ga wire throughout including big 3 and additional grounds throughout the engine compartment, XS Power d975 in the back, Optima yellow top up front.

The design he gave me has a net volume of 4 cubes. Is that too big for that one sub? I told him I wanted a daily ground pounder that can kill some lows. Well it does destroy the low notes, but it seems to be pretty weak with the majority of rap/hip-hop songs, and doesn't sound real strong on rock or metal. I know the specs call for 1.7-2.5 cubes on FI's cut sheets, but I was wanting some input on the situation. I know that too much volume can cause excessive excursion and damage the sub. By my calculations the box seems to be tuned right around 35hz.

yeah thats to big. I would add enough bracing to bring it down to 2.5 cubes.

Ok, that's what I was thinking too. I sent him an email asking why he designed it so big, so I'm curious to see what he says. Guess it's low volume bangin for me for a bit.

So I had a box design done by someone that seems to be a reputable designer around the car audio forums, and I have a couple of questions about it.

I have a FI BTL N2 12" D2 running on a SAZ-1500, 250amp alt, 0 ga wire throughout including big 3 and additional grounds throughout the engine compartment, XS Power d975 in the back, Optima yellow top up front.

The design he gave me has a net volume of 4 cubes. Is that too big for that one sub? I told him I wanted a daily ground pounder that can kill some lows. Well it does destroy the low notes, but it seems to be pretty weak with the majority of rap/hip-hop songs, and doesn't sound real strong on rock or metal. I know the specs call for 1.7-2.5 cubes on FI's cut sheets, but I was wanting some input on the situation. I know that too much volume can cause excessive excursion and damage the sub. By my calculations the box seems to be tuned right around 35hz.

yeah thats to big. I would add enough bracing to bring it down to 2.5 cubes.

Don't do this without changing the design. If you just add bracing you will change the tuning.

the designer clearly must have chosen that size based on what you requested!

You said yourself you wanted some killer lows... that's the whole reason why this person\company chose such a size.

He could have mis-read or misunderstood and thought 2 12"s?

IMO- order a 15" recone, and cut that hole in the box a little bit bigger to make room

IMO- order a 15" recone, and cut that hole in the box a little bit bigger to make room

I think he said it was a design. Can be re-worked.

He could have mis-read or misunderstood and thought 2 12"s?

Well I had originally contacted him with the design involving two SA-12's, but then I found the FI at a good price and I wanted to try it out. I told him about the change in drivers and he acknowledged it. And the design only had one cutout for a sub in the pdf pics, so he knew I was using only one sub.

IMO- order a 15" recone, and cut that hole in the box a little bit bigger to make room

I think he said it was a design. Can be re-worked.

Yeah, but I already built the box. Don't get me wrong, I have no problem building another one, building boxes is fun to me. Its just gonna be whether or not I can get a response out of him...

IMO- order a 15" recone, and cut that hole in the box a little bit bigger to make room

I like where your heads at!

But I'm not real familiar with the recone process. Can you put a 15" recone on a 12" motor and basket? Wouldn't that be a 12" motor running a 15" cone? Does that turn out decent?

the designer clearly must have chosen that size based on what you requested!

You said yourself you wanted some killer lows... that's the whole reason why this person\company chose such a size.

Right, but wont that sub still hit some strong lows in a box that's closer to FI's recommended specs? I mean it's 1.5 cubes bigger than their high end recommendation for that sub.

when you say killer lows.. that to me would indicate an excessive amount, therefore, larger box.

Keeping the box within specs has greater potential to not lose the 40-60hz area in music like what you are experiencing.

But many people who want crazy lows only want the lows...mainly because they are decaf fanatics.

IMO- order a 15" recone, and cut that hole in the box a little bit bigger to make room

I like where your heads at!

But I'm not real familiar with the recone process. Can you put a 15" recone on a 12" motor and basket? Wouldn't that be a 12" motor running a 15" cone? Does that turn out decent?

You would just send it in to get reconed to a 15" you'd have to pay a tad extra to get a new basket for the recone.

when you say killer lows.. that to me would indicate an excessive amount, therefore, larger box.

Keeping the box within specs has greater potential to not lose the 40-60hz area in music like what you are experiencing.

But many people who want crazy lows only want the lows...mainly because they are decaf fanatics.

Maybe I was a little over zealous when I was telling him I wanted it to slam the lows...

yeah thats to big. I would add enough bracing to bring it down to 2.5 cubes.

That would considerably raise the tuning going from 4ft^3 to 2.5ft^3 and not adjusting the port any.

IMO- order a 15" recone, and cut that hole in the box a little bit bigger to make room

I like where your heads at!

But I'm not real familiar with the recone process. Can you put a 15" recone on a 12" motor and basket? Wouldn't that be a 12" motor running a 15" cone? Does that turn out decent?

You would just send it in to get reconed to a 15" you'd have to pay a tad extra to get a new basket for the recone.

$31 for the basket, for a total of $171 not including shipping.

yeah thats to big. I would add enough bracing to bring it down to 2.5 cubes.

That would considerably raise the tuning going from 4ft^3 to 2.5ft^3 and not adjusting the port any.

Yeah I think I'm just better off putting that box to the side for time being. I've never run a 15" before, so reconing the FI is actually a pretty good idea. I did also pick up a 12" Nightshade V2 last week, so I'll probably just run that in the mean time until I can get the FI reconed. Ram, any tips I should keep in mind when designing a daily ground pounder for the Nightshade?