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Old 22nd July 2011, 06:22 PM   #121
jdubs is offline jdubs  United States
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djk, any issue with flipping this design so that the port is on the bottom? I.e., the 32" is the height, not the width? Would imagine additional bracing would be needed in the port to accommodate the weight, but hopefully that's it?

Thanks,
Jim
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Old 22nd July 2011, 10:07 PM   #122
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Originally Posted by scameron78 View Post
check my dimensions for this PPSL i'd like to build. i currently have 4 peavey SP118X cabinets loaded 1808 SPS BWX drivers and would like to build 2 dual 18 cabinets. the box is about 10 cu/ft with out bracing. port is 4W x 21.5L x 10D.
Scameron,

21.5 x 23 x 42 are all dimensions that are not multiples of any truck box I am aware of.

What is the rational behind those dimensions?

DJK's 32x24x24 dimensions will work for wide body semis, but I'd suggest going with integers of the usual 90 inch clear box width and height of rental trucks.
Those integers would be 11.25, 15, 22.5, 30, 45.
Mixing in some integers of 98 allows for a decent truck pack in either wide body semis or regular straight trucks.

Making something that only fits a specific van or car pretty much insures a "fire sale" if you change vehicles or decide on different cabinets.

Art
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Old 22nd July 2011, 10:56 PM   #123
badman is offline badman  United States
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Hi badman,

Putting the passive radiators into the same plenum (manifold) will increase the volume of the plenum a lot, and this may reduce the effective coupling of the drivers, which is what you're really after with the PPSL.

I would keep the passives out of the front plenum, and go with djk's recommendation of keeping the plenum small. This should help in reducing the upper frequency response peak (see: Post #5 and #6).

Regards,
Thanks for your input- the increased volume of the plenum should not be an issue for coupling, in my understanding- what it WILL do is reduce any downward Fs shift due to mass loading. The coupling has to do with spacing, which will still be close together. I'm not talking about making it wider, just giving a taller height.
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Old 22nd July 2011, 11:17 PM   #124
djk is offline djk
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Peavey 1808 SPS BWX

Specifications: • 18" woofer • Impedance: 8 ohms • Power capacity: 2000 watts peak, 1000 watts program, 500 watts continuous • Sensitivity: 97.5 dB; 1W/1m • Usable freq. range: 35 Hz - 1 kHz • Cone: Kevlar® impregnated cellulose • Voice coil diameter: 4.0" / 100 mm • Voice coil material: Aluminum ribbon wire Polyimide-impregnated fiberglass former Nomex® stiffener Solderless diffusion welded OFHC copper leads • Znom: 8 ohms • Revc: 6.71 ohms • Sd: 0.1237 sq. m • BL: 16.26 T/M • Fo: 37.4 Hz • Vas: 368.0 L • Cms: 169.4 uM/N • Mms: 106.7 gm • Qms: 7.545 • Qes: 0.637 • Qts: 0.587 • Xmax: 4.60 mm • Le: 0.38 mH • SPL: 96.7 1W/1m • No: 2.94% • Vd: 69.4 cu. in./ 1138 mL • Pmax: 1000 watts pgm • Disp: 228 cu. in./3737 mL.

Put the drivers back in the SP118X cabinets and sell them. Buy better drivers, then build a box for them. I don't care for several details of your design, but when you find some better drivers we can try again.

Note:

The Eminence 15 can displace more volume than that Peavy 18, and the box will have flat frequency response. The T/S parameters are not very good on the Peavey.
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Old 25th July 2011, 01:31 AM   #125
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Originally Posted by djk View Post
Peavey 1808 SPS BWX

Specifications: • 18" woofer • Impedance: 8 ohms • Power capacity: 2000 watts peak, 1000 watts program, 500 watts continuous • Sensitivity: 97.5 dB; 1W/1m • Usable freq. range: 35 Hz - 1 kHz • Cone: Kevlar® impregnated cellulose • Voice coil diameter: 4.0" / 100 mm • Voice coil material: Aluminum ribbon wire Polyimide-impregnated fiberglass former Nomex® stiffener Solderless diffusion welded OFHC copper leads • Znom: 8 ohms • Revc: 6.71 ohms • Sd: 0.1237 sq. m • BL: 16.26 T/M • Fo: 37.4 Hz • Vas: 368.0 L • Cms: 169.4 uM/N • Mms: 106.7 gm • Qms: 7.545 • Qes: 0.637 • Qts: 0.587 • Xmax: 4.60 mm • Le: 0.38 mH • SPL: 96.7 1W/1m • No: 2.94% • Vd: 69.4 cu. in./ 1138 mL • Pmax: 1000 watts pgm • Disp: 228 cu. in./3737 mL.

Put the drivers back in the SP118X cabinets and sell them. Buy better drivers, then build a box for them. I don't care for several details of your design, but when you find some better drivers we can try again.

Note:

The Eminence 15 can displace more volume than that Peavy 18, and the box will have flat frequency response. The T/S parameters are not very good on the Peavey.
i see. i don't recall asking about how bad my drivers are; i understand they are not the greatest. i only wanted to place them in another box so i could maneuver 2 boxes instead of 4. i've beat on these speakers extremely hard in 9 cuft boxes for several years. according to simulations in bassbox they reach xmax with very minimal wattage; they should have died by now. individuals come to this site for information. i thought i would try to design something based off what i have read in this thread. i must be completely off base. selling the peaveys is not an option right now seeing how they are used weekly. when the money is there again, i will buy new drivers. till then, i guess i should keep educating myself.
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Old 25th July 2011, 02:29 AM   #126
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Old 25th July 2011, 11:10 AM   #127
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The truth hurts, do what you will.
ahahaha. i guess so.

it's about what works for an individual.

Last edited by scameron78; 25th July 2011 at 11:14 AM.
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Old 25th July 2011, 06:02 PM   #128
badman is offline badman  United States
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Originally Posted by scameron78 View Post
ahahaha. i guess so.

it's about what works for an individual.
Indeed it is. Your drivers would require a HUGE box to perform well, due to the high Qts- they'd be better off in a large, sealed enclosure, IMO, than a tuned system. Try modeling it with WinISD, you'll find what different arrangements require and look like.

My own "PPSL" styled sub is very different from what is discussed in this thread, being passive-radiator based and those living inside the manifold (though I am still considering whether to try to mount them outside the plenum)
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Old 26th July 2011, 05:25 PM   #129
jdubs is offline jdubs  United States
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djk, did you get a chance to snap any pics of your build? Would love to see them, if so.

-Jim
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Old 26th July 2011, 09:17 PM   #130
djk is offline djk
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Just finishing up.

Wisconsin had a bad storm last week and the power was out a couple of days at my brother's house. With cleanup and emergency roof repairs it put things back a bit.
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