PP Slot Loaded Sub with Alpine SWR 12D2

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#284
tb46 said:
Hi lawbiding,

The diameter for the round hole is obviously larger ~ 7-3/4"Dia.

Regards,
Click to expand...

Tb46
Should I smoothed/break/round the edge of the round hole.

cp.jpg

Thanks
 
#285
tb46 said:
Hi lawbiding,

One more try at it:

Regards,
Click to expand...

From experience, I can say that you want to go easy with the stuffing below the driver or you won't get much bass. I would just put stuffing from closed end up to driver and leave rest open. If you have a removable panel you can adjust but if sealed up put stuffing in a mesh bag tied with a pull string to remove.
 
#286
Hi lawbiding,

Post #284: "Should I smoothed/break/round the edge of the round hole."

Missed that one. Acoustically I doubt it matters, but it's easier on the fingers to use at least a 1/4"Rad. to round the edges.

Did you get it build for Christmas?

Regards,
 
#290
I seem to have been on a parallel path. I just built a PPSL that looks uncannily like the design posted here. The sub is for a 2001 Subaru outback sedan(my stepson's) and is meant to play through the ski hole. It uses a pair of CerwinVega S-8 (vintage) 8" woofers, EBS alignment tuned to ~35Hz. Below is a measurement taken with the mic at the opening. There is no stuffing or lining of any kind yet, I haven't had time for tuning yet. It looks like it'll be pretty boomy in the car but that's what the kid wants. I'll measure again when I get it in the car.
 

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#292
If anyone wants to play with the Akabak code for the above PPSL speaker, here it is.

Code: 
| Push Pull Slot Loaded Subwoofer
| v6 with Alpine swR 12D2 Nov 11 2014 34x15x25 in dims
| xrk971  DIYAudio

Def_Const
{
Q=0.707;

Speaker_pos=8.0*0.0254;  | Height of centerline of exit port above floor
Width=15.0*0.0254;  | Width of cabinet external 
Height=34*0.0254; | Height of cabinet external, 24 in long chamber ea + slot
Depth=16.5*0.0254;  | Depth of cabinet 14 in deep internal
Dist_wall=5000*0.0254;  | Distance from wall

| ****

Backchamber_vol=40.0*0.001;  | 40L = 2442 in cu gives 15.125in D x 13.5in H x 12in deep per chamber

Slot_width=8.5*0.0254;  | needs to wide enough to fit driver in push-pull
Slot_height=13.5*0.025;  | height accounts for bracing reduction in CSA
Slot_length=16.25*0.0254; | length of two ducts that form slot deep enough to house 12 in driver

| *** dual rear resistance vents

Vent_width=0.90*0.0254;
Vent_height=12.00*0.0254;
Vent_length=24.0*0.0254;

Seatduct_len=12.0*0.0254;  | Seat duct length from box to rear seat backs inches

}

System 'PPSLSUB6'

Def_Driver 'Alpine SWR-12D2'  |Alpine DVC sub 12in Qts=0.44, xmax=20mm, 72mm travel(p-p), 84.7dB, 6.375in depth, Nov 11, 2014
 Sd=479cm2 
 Qms=7.1
 Qes=0.47
 fs=27Hz 
 Vas=46L
 Le=2.23mH 
 Re=3.90ohm  | 1.95+1.95


|OFF
Filter    'High Pass'  | 4th order Butterworth -24dB/oct
    fo=23.3Hz  vo=1.0
    {b4=1;  
     a4=1;  a3=2.613126;  a2=3.414214;  a1=2.613126;  a0=1;  }
|OFF     
Filter 'LowPass' |Lowpass filter - 48dB Butterworth (change 'fo=***' and refresh for changes)
fo=90Hz vo=1
{b0=1; 
a8=1; a7=5.125831; a6=13.137071; a5=21.846151; a4=25.688356; a3=21.846151; a2=13.137071; a1=5.125831; a0=1; }

|OFF 
| Speaker placed in corner with driver at Driver_pos above floor in corner
Def_Reflector  BottomCorner
Bottom={Speaker_pos}  Left=17in Right=17in
HAngle=0  VAngle=0  

OFF
| Speaker with driver at Driver_pos above floor Dist_wall away from wall 
Def_Reflector  HorizEdge
Bottom={Speaker_pos}  Top={Depth + Dist_wall}
HAngle=0  VAngle=0

Enclosure  'Back chamber 1'  Node=10
Vb={Backchamber_vol/2}  Qb/fo={Q}  Lb=10in  


Enclosure  'Back chamber 2'  Node=20
Vb={Backchamber_vol/2}  Qb/fo={Q}  Lb=10in 

Driver Def='Alpine SWR-12D2' 'Driver 1'
Node=1=0=30=10


Driver Def='Alpine SWR-12D2' 'Driver 2'  | driver 2 is reverse mounted with phase reversed
Node=1=0=30=20

Duct    'D3'  Node=31=30  | rear half of output slot
    WD={Slot_width}  HD={Slot_height}  Len={Slot_length/2}

OFF
Duct    'HR189'  Node=30=0  | Helmholtz resonator in main slot to absorb 180 Hz peak
WD=14in HD=1.0in Len=18.7in  Visc=30

Duct    'D4 Slot'  Node=30=32   | front half of output slot
    WD={Slot_width}  HD={Slot_height}  Len={Slot_length/2}

Duct    'D1 Vent'  Node=10=31   | resistance vent 1 leading to slot
    WD={Vent_width}  HD={Vent_height}  Len={Vent_length}

Duct    'D2 Vent'  Node=20=31   | resistance vent 2 leading to slot
    WD={Vent_width}  HD={Vent_height}  Len={Vent_length}

| *** Connector duct from box through flip down ski hole door in back seat ****

Duct    'D5 Seatduct'  Node=32=33   | duct from box to radiator, assume same CSA
    WD={Slot_width}  HD={Slot_height}  Len={Seatduct_len}
 
Radiator 'Vent_rad' 
Def='D5 Seatduct'
Node=33
x=0  y=0  z=0  
HAngle=0  VAngle=0 
WEdge=30in  Hedge=15in  | Assume seats are 60in wide x  30in tall
Reflection
 
#293
xrk971 said:
Awesome news! You work really fast and we are all looking forward to seeing the result of the fruits of your efforts. I think this may qualify as a unique alignment due to the asymmetry - I certainly have not seen another speaker with displacement predictions that look like this. I am curious to hear how it sounds flipped around with vent at the top and having a top speaker placed on it.

452046d1417656337-pp-slot-loaded-sub-alpine-swr-12d2-wood.jpg


For those who may have lost the bead on this rapidly evolving project, here is what it will look like courtesy Tb46.
Click to expand...
I thought this design looked promising, so I built one...Quite pleased with the results, but the tuning and impedence seem a little different from the sim. Measurement made outside, well away from any boundaries, at about 3m from the mouth, ground plane. With a 30Hz 24 dB LR high pass flat down to 35Hz, in half space, which is quite impressive in this size cab!
mcm sub data.jpg
 
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#295
I would like to build a subwoofer like the one in the OP for the trunk of my car. How do I go about modeling it in Hornresp? The drivers I want to use would be different and the dimensions would be a little different, so I would like to get the model perfect before I build anything.
 
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