FAST PPSL+TB W4-1320SIF design study sugestions

[hajj]

Did you consider the Markaudio Pluvia 7?
Works great in a small sealed enclosure (4.5 liters), and has ample headroom in terms of x-max.
As others have already noted, matching driver efficiency is a non-issue....

 

[jirm]

Thank you so much for your sugestion hajj !!!
This driver was not in my scope. But seems clearly a win 😉 .

Next I post the sim and looks very very good. 😛

Indeed about matching efficency on both drivers, I'm starting forget that and only focus to have the best FR driver that can work well on this cab.

Again thank you for your good sugestion.

Regards !

 

[hajj]

Very interesting response! 🙂
Would you mind running the sim but with the small end closed? (sealed enclosure)

 

[Mayuri]

I found that in Transmission Line software if you split the enclosure, stuff the front part only very lightly, and the end part heavily, you get a quite good results. I have no idea if they reflect on real life measurements and performance, maybe some pro with good measurement equipment could verify this? 😀

 

[hajj]

Stuffing works at the high velocity points in the TL and does very little damping at high pressure points.
This might explain why you are noticing this effect 😉

 

[jirm]

Very interesting response! 🙂
Would you mind running the sim but with the small end closed? (sealed enclosure)

Here we go. Sealed for Marc Audio Pluvia Seven.
Same enclosure volume.

Unless I am mistaken now I see on sealed that driver roll-off at low frec I think too soon because now start to go down near 300Hz...so seems TL enclosure work very well for this purposse.

What do you think ?

Regards

 

[hajj]

Do you happen to have a driver excursion plot by any chance?

 

[jirm]

Do you happen to have a driver excursion plot by any chance?

Here it is.
But I dont know if realible is the sim. You can see that only 0,2 mm displacement in TL at 150Hz... 😕

I use this soft to sim others and compared with hornresp and some akabak and seemed rigth with Leonard...but now im little dubting if I do something wrong in this sim.

 

[jirm]

Here it is.
But I dont know if realible is the sim. You can see that only 0,2 mm displacement in TL at 150Hz... 😕

I use this soft to sim others and compared with hornresp and some akabak and seemed rigth with Leonard...but now im little dubting if I do something wrong in this sim.

So sorry I forget pushing the system to max SPL.

Now all seems rigth.

 

[jirm]

I found that in Transmission Line software if you split the enclosure, stuff the front part only very lightly, and the end part heavily, you get a quite good results. I have no idea if they reflect on real life measurements and performance, maybe some pro with good measurement equipment could verify this? 😀

Mayuri, interesting idea and I belive that if that effect are in sims, sure are some reflect on real life.
I post another sim with Markaudio driver, now with the CHR70 to see waht happend and, I aplied sttufing 0,6 and 4 spliting enclosure to a half.

Regards

 

[hajj]

I like the closed box sim for the Pluvia Seven.
Keeps excursion controlled and thus reduces distortion.

 

[jirm]

I like the closed box sim for the Pluvia Seven.
Keeps excursion controlled and thus reduces distortion.

hajj, you can see that in TL excursion only goes up to a 1,5mm max at 150Hz on full power rms continued from manufacturer specs, so seems TL have too controlled excursion lower its limits. So I think distorsion in TL will keep mostly like sealled, and we can take advantage on lower fb of the FR enclosure at least to 150Hz with enougth margin to crossover with the PPSL sub unit without so much worries.

Marcaudio CHR70 have a very very similar sim response like pluvia on that enclosure, and only shows something less sensivity.
So I think it can be another great candidate.

Now I post quick sketch with vertical manifold. I like much more aestetics in horizontal that (I confirmed) also seems have better WAF factor, but sure vertical is a rigth setup to anyone and without worries about sag on drivers.

Regards

 

[jirm]

Nobody has comments and / or any suggestions regarding the PPSL sub section ?.
Maybe will be better ask for that question on suwoofer forum section?

I would like to have any opinion of many experts prowling around here about that sims I attach on post #1 and honestly because for me seems "to much good" for those little drivers 8 "Gradient, and I am concerned because is really possible subwoofer section sims contains some severe errors that invalidate the sim results.

I post few additional needed calcs and prepossitions that I used to buiild the sims on BassBox Pro.

Enclosure Type = Vented 6th order

Fb=Fs=Faux

Fb=0,3x(Fs/Qts) = 0,3x(38/0,48)= 23,75 Hz
Vb = Qts² x 4,1xVas=(0,48)²x4,1x36,2=34,2x(2 drivers) = aprox. 70L
Faux=Fbx1,07=25,5Hz

Rounded and ajusted on sim to:
Vented Active EQ 12db/Oct
Vb= 90L (external enclosure)
QL=6,2

Filter:
Faux=27Hz
Q=2

best wishes

 

[badman]

With respect to matching dynamics, it can be an issue but I think so long as you're "in the ballpark" it's fine- a few dB this way or that won't be an issue but 10dB might.

 

[jirm]

With respect to matching dynamics, it can be an issue but I think so long as you're "in the ballpark" it's fine- a few dB this way or that won't be an issue but 10dB might.

Thanks for your reply Badman.

I'm starting forget matching dynamics to find best "sounding" FR section that fits with a better driver, but I dont know if are "in the ballpark" 6-7db FR down from sub section.

Most "common" FR drivers with 3-4inch specs seems have about 85-86db/1w/m on my TL sim enclosure and sub section is at 92db/1w/m.
And I think we must not forget the different much more power management margin that sub drivers have vs litle ones FR drivers.

So I go to select drivers without focus on mathing them in sensibity but I must confess that I'm a little concerned on final results on dynamics.

Badman do you have any comments about sub section sims I posted?

Again, so many thanks for your comments 😉

 

[badman]

The sub alignment looks fine, though I'd suggest running the vents at floor level rather than just above, and using the enclosure bottom/sides as parts of the vents. More space and material efficient that way. Also, flares on the vents are a good idea in all cases, particularly smaller vents tuned low, to avoid chuffing. I might want to up the cross sectional area a bit, through most of the vent. One can use a "mini scoop" style vent to achieve this (a smaller version of pro-style scoop cabinets), the restriction at the minimum cross sectional area will be critical to tuning so is best left adjustable until you can measure. That buys you both a flare and a little more CSA and is easy to get to the right length with a little work. I'd also add additional cross-panel bracing- the PPSL gets rid of some of the direct mass excitation from driver motion, but the acoustic energy will still excite the walls. Since you can sim ML/TLs that might be a route worth considering for the sub section with a small final termination flare for minimized vent noise. More material and potentially a slightly larger enclosure, but worth considering.