New Build - 2019 JL Wrangler 2 door

[DavidRam]

I'm wondering about the 91.94 Hz F3, which seems awfully high for a vented sub, and given the 33.07 Hz Fb.

Looking forward to modeling this in WinISD this evening, if only to satisfy my curiosity.

Grinder, thanks for taking a close look at it... You know me, I have no idea what that ^^^ means! Lol

I can build a box, I just don't understand it scientifically!

[Grinder]

.... Grinder, the F3 point is that high because the response has a peak above that F3 point. ....

I see now. WinISD is showing an only slightly higher corresponding "upper F3" (for lack of a better term) of 93.58 Hz, and a "lower F3" (again, for lack of a better term) of 31.35 Hz.

FWIW, it looks like vent velocity (vent compression and/or chuffing) might be an issue. Based on MFR rated 2 kW RMS and 19.69 in^2 listed vent area, WinISD is showing a peak vent velocity of 52.323 m/s at 31.57 Hz. Having no first-hand experience with slot ports, I have only my very limited experience with flared and non-flared tube ports, and the 22 m/s rule of thumb, which suggest to me that vent compression might be a factor at as little as ~500 W (based on modeled 22 m/s at 350 W). Absent proper vent flaring, audible chuffing might begin at as little as ~800 – 1000 W. At rated 2 kW (52.323 m/s), vent compression would be considerable; and perhaps even given proper vent flaring, audible chuffing might also be an issue.

"High F3"


"Low F3"


SPL at 2 Kw


Peak vent Velocity at 2 kW

[Grinder]

Grinder, thanks for taking a close look at it... You know me, I have no idea what that ^^^ means! Lol

I can build a box, I just don't understand it scientifically!

I wasn't sure whether or not you would know what that meant. There's really not much at all to it, though. I only know just barely enough to be dangerous. LOL

[JCsAudio]

Grinder, Bassbox Pro estimated vent velocity at ~ 38 m/sec @ fb and 2k watts which is a little more than ideal but David has box constraints I had to work around and after a lot of modeling and tweaking this was the best compromise I came up with. I’m willing to bet 95% of his critical listening is at much less than 2000 watts too. I’m not sure why WinISD has vent velocity so high. Something could be off with your model or maybe mine, I can check later this weekend if I get my older laptop to cooperate. I’d post up the specifics of the model but I did it two months ago and my computer with this file is currently down for repairs thanks to Windows abandoning Windows 7.

[Grinder]

Grinder, Bassbox Pro estimated vent velocity at ~ 38 m/sec @ fb and 2k watts which is a little more than ideal but David has box constraints I had to work around and after a lot of modeling and tweaking this was the best compromise I came up with. I’m willing to bet 95% of his critical listening is at much less than 2000 watts too. I’m not sure why WinISD has vent velocity so high. Something could be off with your model or maybe mine, I can check later this weekend if I get my older laptop to cooperate. I’d post up the specifics of the model but I did it two months ago and my computer with this file is currently down for repairs thanks to Windows abandoning Windows 7.

John, kudos to you for doing all this for David. I sincerely hope I'm not being a pest.

In hindsight, it does seem that my WinISD m/s values for this driver are rather high. Hopefully these corresponding impedance and driver parameter values will shed some light:



By way of comparison, here's what I got from Triticum's Port Area Calculator (I didn't think to check this last night), which also suggests that my WinISD m/s values for this driver are rather high (for example, 22 m/s at 47.25 in^2 vent area; compared to Triticum's optimal vent area of 37 in^2):


https://docs.google.com/spreadsheets...gid=1632976665

[DavidRam]

Hey guys, thanks for caring about my sub box, I really appreciate all the help I get especially in the areas where I am utterly clueless...

The good news about the new wheels and tires is that up to 50 mph there is no noise difference compared to the stock tires (whatever tire/road noise there is/was is being drowned out by the wind noise, lol). With how aggressive their tread is, this really surprised me, but many Jeep guys with these tires said that noise what not an issue at all, too...

[chithead]

Sooooo hawt. Want to touch the Jeepy

[DavidRam]

Sooooo hawt. Want to touch the Jeepy

[DavidRam]

There is just something about that clunky box on wheels that is soooooo appealing to me!! I just can't explain it... The steering wanders, it bounces around on the road with every bump, it creaks and groans when brand new, but I freakin love it!

[JCsAudio]

Grinder, I appreciate the help. We certainly do not want to steer David in the wrong direction and if my calculations are off then I would much rather catch it now then after he builds the box. Good imperial information is also hard to argue with over say anecdotal so I think this is just a matter of checking the numbers, comparing them, and hopefully learning something that we all can benefit from. Sharing information for the good of the members after all is what this Forum is about (Al correct me if I’m wrong). I will see if I can check sooner than later as now it’s going to drive me crazy not knowing for sure.