Please help me design a PR subwoofer

**mike c** · **05-12-08, 02:52 AM**

gluing together

2.25" walls

**mike c** · **05-12-08, 02:54 AM**

i have a problem. in my zeal to brace the crap out of the box ... i ended up doubling the walls instead of bracing the walls ... now i have a net volume of 3.05 cubic feet instead of the targetted 3.5 cubes. (drivers included assuming .1 and .15 volume displacement of the two drivers)

on the weight side of things:
enclosure weight is 99lbs. + 59lbs active driver + 12lbs. PR + steel weights 44lbs.

**mike c** · **05-12-08, 03:46 AM**

never mind, opening them BACK up literally + .48 cubes back again

panels for the front - old school - drill a million holes around the circumference of the driver

**mike c** · **05-13-08, 03:30 AM**

sand and steel

sealed up

test fit

**mayhem13** · **05-13-08, 06:06 AM**

Looking good Mike!

**Canadian_Dude** · **05-13-08, 07:17 PM**

How long did it take to make those holes with the drill?

**mike c** · **05-13-08, 09:44 PM**

an hour or two per hole

np. i'm not doing the leg work.

heehee

**mike c** · **05-13-08, 10:00 PM**

ready for testing (waiting for the amp)

for scale

**mike c** · **05-14-08, 04:43 AM**

uh oh, there's air leaking out of the PR - from the sides, like the PR isn't flat to the baffle ... will try to fix it later/tomorrow

in case you guys have some ideas for:
cutout too big? too small?
or how to make a flange?

please chime in

**mike c** · **05-14-08, 05:35 AM**

found the problem ... one part of the cone is not attached properly (glue dried up?)

what kind of glue do i use? will mighty bond work? (super glue) or is that too hard?
http://www.allproducts.com/philippines/rci/p01.html

what about shoe glue?
http://www2.bostik.com.ph/products/d...px?Mode=0&ID=2
http://www2.bostik.com.ph/products/d...px?Mode=1&ID=2

**mayhem13** · **05-14-08, 06:03 AM**

I guess it would depend on what the surround is made of. Give Audiopulse a call and see what they suggest. My guess would be a weatherstripping adhesive used to attach plastic and rubber mouldings to car panels-3M makes one in black.

**mike c** · **05-14-08, 06:12 AM**

unfortunately Audiopulse is as good as gone. no one answers their phones or email anymore.

they're bankrupt.

**financethi$** · **05-17-08, 01:46 PM**

mike,
this jeff, i bought the other tc passive, hey my passive is having the same problems. nearly 40 to 50% of that surrond it lose. let me know what glue you are going to use. after i saw your post i went and checked mine and sure enough, the surround is flapping in the wind. WOW

**mike c** · **05-17-08, 06:33 PM**

super glue

**mike c** · **05-18-08, 06:21 AM**

i think im online

YouTube - DIY 13

racing weights

YouTube - DIY 13

**Ricci** · **05-18-08, 12:30 PM**

Nice vids. By the way it doesn't look like that is anything with very low frequency content being played as the PR is barely moving. Wait until you really get that PR moving around tuning. You are going to have some serious vibration going on! Those weights will fly off the top of that cab.

**mike c** · **05-18-08, 06:18 PM**

yeah, that's why i removed some of the weights off the PR ... to tune higher and give it a little bit more work.

im thinking the 3.5 cube net volume is already pretty big and perhaps the 13av isnt compressing on that volume enough to make the heavy PR move.

and then there's the way more massive cone area on the PR ... kinda like having dual 6" ports on a 13" driver

ill check what the f3 is in room, and decide if i can tune it even higher

but first i need to get two more guys to move it to the desired location

**robertcharles123** · **05-18-08, 09:38 PM**

What kind of signal are you using?

**mike c** · **05-18-08, 10:32 PM**

Quote:

robertcharles123 wrote:

What kind of signal are you using?

you mean like if its LFE or L and R? mine's LFE out with music or movies

**mayhem13** · **05-18-08, 11:34 PM**

The Pr won't be doing much of anything above 22 hz, about half the excursion of the main drive unit which your video shows. Things will really start moving around 17.5 hz. Above that, it's just allowing greater extension of the drive unit. Decreasing box volume will effectively raise the F3. If you can give this baby some really low freq's, you will get to appreciate the advantages of what you've built.

**mike c** · **05-19-08, 12:16 AM**

Quote:

mayhem13 wrote:

The Pr won't be doing much of anything above 22 hz, about half the excursion of the main drive unit which your video shows. Things will really start moving around 17.5 hz. Above that, it's just allowing greater extension of the drive unit. Decreasing box volume will effectively raise the F3. If you can give this baby some really low freq's, you will get to appreciate the advantages of what you've built.

thanks again for the info ...that video was taken with 1470 grams of weight on the PR's (tuned slightly lower than 19hz)

ill try some test tones soon

**robertcharles123** · **05-19-08, 01:23 AM**

I mean what frequency is being sent to the woofer. The passive does virtually nothing above tuning. If you are sending a nice 30 hz signal to the woofer, the passive is just hanging around saying, "I'm ready". Try sending test tones at and below tuning- It will move. The passive is not just being moved by the back pressure of the woofer, but being driven with frequencies at or below tuning. The driver will move very little at the tuning. Try different frequencies and notice cone movement of each component and when the driver moves least and passive really wails, that is the tuning frequency.

Robert

**mike c** · **05-19-08, 01:30 AM**

i tried black hawk down (famous for sub 10hz frequencies) but im thinking the SMS-1 bypass mode still filters the low end ... i actually forgot to try with no SMS-1 in the chain (or at least moving the subsonic filter to 10hz)

ill find out if the SMS-1 affects the low end when i burn the test tones to disc.

**bobgpsr** · **05-19-08, 08:28 AM**

I really like UniBox for modeling a PR subwoofer's performance. It makes it easy to see just what the contribution by the PR to the sound output is. This is what my DIY sub project showed in UniBox:

pr_response.JPG

With a 15 Hz tuning point the driver and the PR's contributed equally at 21 Hz, but the driver was 10 dB higher in output than the PR's at ~30 Hz.

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