first box build 18"FI SP4 *need advice*

[Mack187Murder]

Allright first attempt at a box. I got that winsidpro program. Make a little headway but don't know what a few abbreviations mean so it's preventing me from getting any further.

First off here's my equipment

-2x helix slx amps @1600 watt rms @1ohm each

-1x fi sp4 18" 3000 watt rms sub (dual 1 ohm vc)

-big three done

-2x xs power batteries 3300 amp each

All o gauge wiring

-140 amp alt (looking to get a 270 or 320 probably necessary no?)

Here's the subs parameters.

Here's where I've got so far with the program

-I want to make a vented box. No port

-I want to make the box 1"birch or 1.5 " walls with a 2" sub face

-now the max room I have for an outside diameter of a box is

Length-35" width-25" depth 20"

-I want the box tuned to 28 hertz

Did a few calculations and i beleuve totals 7 cuft roughly. I'm shooting for a minimum 6 cuft box after vent and bracing and sub displacement. I'm horrible with numbers. Makes my head hurt. But I really wanna make my own box. And im trying to do as much as i can on my own. Quite a big project for a first timer tho I understand that. Any help or advice u can give would be really appreciated

[Mack187Murder]

This is how the box will have to sit n the truck. I only want to take out one seat. I'm pretty sure if braced and built solid with birch it should be fine.

I may be able to move the sub down into the middle a bit to as long as it clears the seat beside it. Not sure how this will affect the vent and box tuning

[Vice03]

Props for trying to figure it all out. It takes some time to get the hang of everything and WOW you are not starting small/easy. Keep playing with the software.

[Triticum Agricolam]

Some of your specs you put into WinISD look pretty wonky. WinISD is vey picky about how you enter in the parameters. Here is the best way to do it:

The suggested procedure for entering driver parameters is following (check first that "Auto calculate unknowns" option is checked):

1. Enter Mms and Cms

This gives fs. If either is not available, then enter fs and other parameter.

2. Enter Sd, Bl and Re

Now, you should get all but Qms (and Qts), Vas. Please note that Vas may not match exactly what is specified by manufacturer, because exact value of Vas depends on environmental parameters. See FAQ.

3. Enter Rms or Qms.

Either one will do, although I tend to prefer Qms over Rms, because it can usually be measured in driver measurement procedures.

4. Enter Hc, Hg and Pe.

If Hc or Hg or either is available, then enter Xmax and optionally either Hc or Hg if available.

5. Enter number of voicecoils.

This procedure is most accurate. Also note that it also calculates true SPL (1W/1m) value. So it might not match the marketing SPL value, which is generally somewhat vague. Not in all cases, though.

6. Correct Znom, if necessary.

If there are several voicecoils, then you must be careful when entering parameters in that case, because many manufacturers give Bl in voice coils in series, because it yields double value for Bl against parallel connection. If driver manufacturer gives Qes, Bl and Cms or Mms, then you can check how Bl is specified. For that, you can enter following parameters to calculate Re: Qes, Fs, Mms or Cms and Bl. Connection mode can be changed by changing the combobox selection. The driver editor then converts Bl and Re values accordingly.

Equivalently, you can check for Bl by entering:

Qes, Fs, Mms or Cms and Re (for desired connection mode).

If you enter resistance for parallel connection and get about half of advertised Bl, then you know, that Bl was specified that way.

Like in Driver-tab in project window, you'll probably noticed the driver icon in bottom of the driver editor window. you can drag the driver object into some project by just dragging the icon.

[Joe X]

Also enter the parameters in the units provided, for example Fi provides Sd (effective radiating area) in square centimeters.

[Mack187Murder]

Lord Jesus Trit thank you for the reply. When I have some time off in the next day or two I'll go over that. I guess my next question is if fi sp4 says I need a 6-8 cube ported box. Could I just build that box and tune a port to a certain hertz and be happy.

Or is entering the sub parameters dictate? Roll off? Spl? Frequencies range etc? The correct and only procedure for building a proper enclosure

[Triticum Agricolam]

Lord Jesus Trit thank you for the reply. When I have some time off in the next day or two I'll go over that. I guess my next question is if fi sp4 says I need a 6-8 cube ported box. Could I just build that box and tune a port to a certain hertz and be happy.

Or is entering the sub parameters dictate? Roll off? Spl? Frequencies range etc? The correct and only procedure for building a proper enclosure

Yeah you could just build the box to FI's specs and you probably would be happy. Though putting the info into WinISD will let you see the difference in output between a 6 cube box and an 8 cube box. Its also handy for knowing what your port velocity will be and how tuning affects output.

[Mack187Murder]

Allright. Sounds good.nill get as far as I can on my own. do u mind if I pm you if I have any questions.

Also since If it's dual 1 ohm voice coil does that mean I run in parallel to hit 1 ohm at my amps?

[Triticum Agricolam]

Allright. Sounds good.nill get as far as I can on my own. do u mind if I pm you if I have any questions.

Also since If it's dual 1 ohm voice coil does that mean I run in parallel to hit 1 ohm at my amps?

Yeah you can PM me if you need.

If you have dual 1 ohm voice coils that mean you can wire to .5 ohm or 2 ohm final loads, you can't wire to 1 ohm.

[Mack187Murder]

OK and since I'm strapping two 1600 watt rms amps @ 1 ohm which have a master and slave switch on them does that change them from 1 ohm individually to 2 ohm combined? Or does it stay at 1.

And if so it sounds like i should order the 2 ohm dual voice coil sp4 instead of the dual 1 ohm