Look over my 4th order specs

[Charles Phillips]

Hey! I'm working on a build log for my friends box that I'm designing, and I just wanted some who's designed some of these (especially isobaric) to take a gander. 

I wrote my own 4th order calculator in Java and posted it before I figured out there already was one online (fail). The specs are as follows:

 

Enclosure type: Isobaric 4th Order Bandpass

Subwoofers: 2 SoundQubed HDS-2.110 600WRMS

F(s): 31.63 Hz

Q(ts): 0.519

V(as): 1.97 ft^3

Vf: 0.52 ft^3

Vr: 1.101 ft^3

Qbp: 0.71

S Factor: 0.7

Fb: 43.53 Hz

Desired F3(L): 26.8 Hz

Passband: 26.8 - 70.72 Hz

Gain: 0 dB

Also the port specs were kind of crazy. The minimum size was 11.24" diameter and 78.84" long. I'd like a shorter port but the only way to do that is decrease diameter which increases air speed and might cause port chuffing. 

 

Thanks a ton!!!

[Triticum Agricolam]

How much power are you going to be running?  

Why do you want to use an isobaric pair?

 

[Charles Phillips]

1300 watts. He requires an isobaric pair because he needs room for his surfboard and personal baggage. He also liked the idea that having the woofers fully enclosed in the box would protect them from being rubbed up against by stuff in the trunk. Unfortunately the ported box specs were a bit too large. Not looking for major SPL. 

[Triticum Agricolam]

40 minutes ago, Charles Phillips said:

1300 watts. He requires an isobaric pair because he needs room for his surfboard and personal baggage. He also liked the idea that having the woofers fully enclosed in the box would protect them from being rubbed up against by stuff in the trunk. Unfortunately the ported box specs were a bit too large. Not looking for major SPL. 

I admire your effort, but unfortunately the box specs you are proposing aren't going to be feasible.  Its going to be nearly impossible to tune a .52 cu ft front chamber to 43 hz and have enough port area so your friend isn't wasting most of his amp power on port compression and making port noise.  Just the general box layout with two 10" subs and a .52 cu ft port chamber is going to be extremely difficult.  Not to mention how you are going to implement the isobaric configuration.  

If your friend has room for a 1.6 cu ft total volume isobaric bandpass box, I pretty much guarantee you can fit a 2 cu ft net volume ported box in the same space.  The ported box will me MUCH simpler to design and construct and will absolutely stomp ALL OVER that bandpass box when it comes to performance.  If your friend is worried about protecting the subs, but grills over them, they are like $5 from parts express.  

If for some reason a 2 cu ft ported box still won't fit, a 1.5 cu ft sealed box is another option and it is still going to perform better than that bandpass box would.  

[Charles Phillips]

So basically a ported box is the way to go, unless at some point he decided f*** it, let's do a B-pillar wall? My assumption from looking at WinISD is that it would need to be many times larger to have a reasonable size port with good efficiency and SPL. 

[Triticum Agricolam]

6 hours ago, Charles Phillips said:

So basically a ported box is the way to go, unless at some point he decided f*** it, let's do a B-pillar wall? My assumption from looking at WinISD is that it would need to be many times larger to have a reasonable size port with good efficiency and SPL. 

You could get away with as small as a 2.0 cu ft net box.  I guess it depends on how much space your friend has available.  It will take a moderately large size port, but it should still be manageable.  Here is an example: