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moparerrnocar
05-20-2012, 07:10 AM
I'm looking to get some extra vol until I can build a new box. My question is... How do R's react to being inverted? What other pros/cons are there? Also, my HU has sub phasing setting (0 or 180), is this for inverting? Any other setting I might need to change?

Also is it possible to use polyfill in a vented enclosure? If so, how do I keep it from flying out? If I staple it to the walls, will it have the same effect as being loose and fluffy? Idk how much I'd need, I heard 1 lb for every 1.5 cuft. I think my box is 2.97 after port displacment, so I'd need 2 lbs? Would more be better?

Thanks

subzero
05-20-2012, 07:18 AM
poly fill, use a wire mesh, chicken wire fencing type. Invert will give you the speaker displacment back. 180, then yes switch to 180, but listen to how it sounds bout ways. Down fall is dependant on mechanical noise exposioure

TaylorFade
05-20-2012, 07:22 AM
There's no real downside to inverting subs. Well, other than having to line them up on the baffle juuuuuust right so the surround doesn't rub on the cutout. If you can, mount them traditionally first so you can use the screw holes to line it up when you flip them.

You don't need to wire them any differently. I always hear that phase switch is to "center" the sub bass in your sound stage. But I never use it. Lol. It's a useless knob on my amps.

I always read that it's 1lb/1cf for proper damping (dampening?). You can adjust the amount until you get it right. It's usually easy enough to add or take some out. As far as using it in a ported box, just put some chicken wire across the throat of the port and you shoudl be good. You don't need to staple it or anything.

moparerrnocar
05-20-2012, 07:38 AM
poly fill, use a wire mesh, chicken wire fencing type. Invert will give you the speaker displacment back. 180, then yes switch to 180, but listen to how it sounds bout ways. Down fall is dependant on mechanical noise exposioure

Wow thanks for the quick reply... I like the chicken wire idea. How far should I keep it from the port? Its a center slot port thats 3.75 from the back wall. Should I line the entire back? Or should I leave 3" from the port and not pad the port wall all? Any idea how much vol 2 lbs will add?... I've messed w/ the phasing b4 w/ them mounted normally but didn't notice a difference. What do you mean by "dependant on mechanical noise exposioure"?

moparerrnocar
05-20-2012, 07:45 AM
There's no real downside to inverting subs. Well, other than having to line them up on the baffle juuuuuust right so the surround doesn't rub on the cutout. If you can, mount them traditionally first so you can use the screw holes to line it up when you flip them.

You don't need to wire them any differently. I always hear that phase switch is to "center" the sub bass in your sound stage. But I never use it. Lol. It's a useless knob on my amps.

I always read that it's 1lb/1cf for proper damping (dampening?). You can adjust the amount until you get it right. It's usually easy enough to add or take some out. As far as using it in a ported box, just put some chicken wire across the throat of the port and you shoudl be good. You don't need to staple it or anything.

I must have just missed your post. I see now, you just use the chicken wire as a grille/screen. At first I thought subzero meant to "matt" it down. Duh that makes sence cuz then its still fluffy.

Thanks

subzero
05-20-2012, 07:58 AM
1lb for every 1/2 cub gain.

Chad1
05-20-2012, 09:03 AM
Sorry bud, they've already been invented

moparerrnocar
05-20-2012, 09:09 AM
So 2-2.5 lbs would be good, does the box's tune matter? Idk how to figure that out and maybe it doesn't even matter. Like I said its a center slot. It measures 3x11.5x12.25 (or 4.5x11.5x12.25 O.D.) and If you or anyone else has the formula I'd be glad to "try" and figure it out if you dont feal like crunchn' numbers. Also the box measures 36x13x16. Btw what did you mean by dependant on mechanical noise exposioure. Do you meen they'll sound like crap?

moparerrnocar
05-20-2012, 09:12 AM
Sorry bud, they've already been invented

Aggh, typo... I bet I cant change it lol... Good catch :)

moparerrnocar
05-20-2012, 09:14 AM
Nope, oh well

TaylorFade
05-20-2012, 09:20 AM
So 2-2.5 lbs would be good, does the box's tune matter? Idk how to figure that out and maybe it doesn't even matter. Like I said its a center slot. It measures 3x11.5x12.25 (or 4.5x11.5x12.25 O.D.) and If you or anyone else has the formula I'd be glad to "try" and figure it out if you dont feal like crunchn' numbers. Also the box measures 36x13x16. Btw what did you mean by dependant on mechanical noise exposioure. Do you meen they'll sound like crap?



Subwoofer Enclosure Calculators, Fraction to Decimal, Parallel, Series, Port Length and Volume Calculators (http://www.the12volt.com/caraudio/boxcalcs.asp#porsq)

moparerrnocar
05-20-2012, 10:00 AM
Subwoofer Enclosure Calculators, Fraction to Decimal, Parallel, Series, Port Length and Volume Calculators (http://www.the12volt.com/caraudio/boxcalcs.asp#porsq)

Cool, all kinds of calculators. I got 40hz w/ my subs mounted normally, but Idk if the box vol they wanted was w/ or w/o port displacement. I'm guessing its w/o.

So w/ them inverted that would gain .2 ft^3 for total of 3.5, and if Subzero is correct, then 2 lbs should net me 4.5 ft^3 for a final tune of 35hz correct?

Do you got a link for the actual formula? I trust the calculator, but I'd like to know incase I cant get to the calc.

Thanks, I sure appreciate the help guys.

TaylorFade
05-20-2012, 10:25 AM
I've never actually seen a formula for how much volume you net by using polyfill. If subzero is correct, that's friggin awesome.

Dirtrider4eva
05-20-2012, 11:12 AM
I've wondered about this.. Does poly fill effectively work with ported boxes? Say I put 4 lbs in a 6 cube box, would it react similarly to a 8 cube box?

keep_hope_alive
05-20-2012, 11:39 AM
in the Loudspeaker Design Cookbook, Vance Dickason compares various fill materials. Polyfill scores the lowest. it's cheap and doesn't itch, which is why it is used. but it's absorptive qualities are poor. fiberglass is king, but working with fiberglass is a PITA. Refer to LDC 7th Edition Table 1.21.

recycled denim acoustical batt is an excellent alternative.
UltraTouch Acoustical*– Thermal Insulation for Walls & Ceilings*– Green Product (http://www.acousticalsurfaces.com/wall_insulation/ultratouch.htm?d=28)
you want to review tested/published sound absorption (ASTM tested)


From the LDC:
"Traditional enclosure damping, to suppress standing waves in a vented-box system, consists of lining one of each opposite side with 1"-2" of fiberglass. It is recommended, however, that you cover all surfaces directly behind, and adjacent to, the woofer. Colloms recommends that such damping material be placed within the volume or open area, not on the box walls.
The effects of damping can be observed by computer simulation. Using the same 12" woofer and QB3 enclosure from Section 2.50 simulation, three enclosures were built with 0%, 10%, and 50% fill of standard R19 fiberglass. The 10% was made by lining one of each opposite sides with 1" fiberglass. The 50% sample would be equivalent to lining all four sides and the rear wall with 3" thick material. The computer-generated graphs shown in Figs. 2.58-2.60 show the results. The SPL curves in Fig 2.58 show minor response changes, while the damping changes seen in the group delay in Fig 2.59 are also slight. The impedance curves in Fig. 2.60 likewise indicate only minor changes. This being the case, the primary benefit would be from decreased response changes due to box standing wave modes, making the 50% fill an attractive choice. Be sure you do not obstruct the vent with fill."

the "minor" changes are a shift lower in frequency.

keep_hope_alive
05-20-2012, 11:43 AM
as mentioned, inverting is fine, and gains extra enclosure volume. the only downside, as mentioned, is possible mechanical noise from the motor structure and airflow noise from the basket. this varies for each sub.

of course, being careful to not have the surround touching anything is key. but the Type-R gaskets keep the surround tucked-in and safe. inverting the ID in the pic below would be difficult and probably unsuccessful. The ultra is doable, but you have to be very careful. the Type-R is easy.
http://i38.photobucket.com/albums/e128/phat_funky_beats/audio%20testing/Ultra%2010/ultra10comparision005.jpg

the next challenge is protecting the magnet and wiring attractively.
i am building a cover for the ML2500
http://i38.photobucket.com/albums/e128/phat_funky_beats/2005sciontC/sciontcbox002.jpg

i had to be careful with this sub and i rounded the edges to help soften the transition. i spent hours making sure this hole was safe for the sub - made with a jig saw and sanding.
http://i38.photobucket.com/albums/e128/phat_funky_beats/2005sciontC/1014112144.jpg

http://i38.photobucket.com/albums/e128/phat_funky_beats/2005sciontC/sciontCbox_fg_pt1010.jpg

Dirtrider4eva
05-20-2012, 04:26 PM
in the Loudspeaker Design Cookbook, Vance Dickason compares various fill materials. Polyfill scores the lowest. it's cheap and doesn't itch, which is why it is used. but it's absorptive qualities are poor. fiberglass is king, but working with fiberglass is a PITA. Refer to LDC 7th Edition Table 1.21.

recycled denim acoustical batt is an excellent alternative.
UltraTouch Acoustical*– Thermal Insulation for Walls & Ceilings*– Green Product (http://www.acousticalsurfaces.com/wall_insulation/ultratouch.htm?d=28)
you want to review tested/published sound absorption (ASTM tested)


From the LDC:
"Traditional enclosure damping, to suppress standing waves in a vented-box system, consists of lining one of each opposite side with 1"-2" of fiberglass. It is recommended, however, that you cover all surfaces directly behind, and adjacent to, the woofer. Colloms recommends that such damping material be placed within the volume or open area, not on the box walls.
The effects of damping can be observed by computer simulation. Using the same 12" woofer and QB3 enclosure from Section 2.50 simulation, three enclosures were built with 0%, 10%, and 50% fill of standard R19 fiberglass. The 10% was made by lining one of each opposite sides with 1" fiberglass. The 50% sample would be equivalent to lining all four sides and the rear wall with 3" thick material. The computer-generated graphs shown in Figs. 2.58-2.60 show the results. The SPL curves in Fig 2.58 show minor response changes, while the damping changes seen in the group delay in Fig 2.59 are also slight. The impedance curves in Fig. 2.60 likewise indicate only minor changes. This being the case, the primary benefit would be from decreased response changes due to box standing wave modes, making the 50% fill an attractive choice. Be sure you do not obstruct the vent with fill."

the "minor" changes are a shift lower in frequency.
so from what i understand, damping the internal chamber of an enclosure will help with the lower frequencies, a little.
would applying Denim to 3/4 faces in the box help with Db levels, along with "mimicing" a box larger than it really is.

subzero
05-20-2012, 05:05 PM
I've never actually seen a formula for how much volume you net by using polyfill. If subzero is correct, that's friggin awesome.

Polyfill Chart (http://www.moodym.com/audio/fiber.html)

keep_hope_alive
05-20-2012, 09:57 PM
so from what i understand, damping the internal chamber of an enclosure will help with the lower frequencies, a little.
would applying Denim to 3/4 faces in the box help with Db levels, along with "mimicing" a box larger than it really is.

all it does is provide a bit more output at slightly lower frequencies. the real benefit is up in the midrange region where it helps reduce internal modes and smooths out frequency response.

Dirtrider4eva
05-20-2012, 11:07 PM
all it does is provide a bit more output at slightly lower frequencies. the real benefit is up in the midrange region where it helps reduce internal modes and smooths out frequency response.
gotcha. if damping does that, is it more beneficial than coating the internal of the box with resin?

keep_hope_alive
05-21-2012, 01:06 AM
Totally different effect.

moparerrnocar
05-22-2012, 06:04 AM
How much lower did polyfill score then denim? Cuz I plan on building a different box soon. I'm just trying to improve what I got with pennies.

I'm confused to how I should use the poly though. From what you quoted it sounds like I should line the walls. Is there a difference between lined and loose? If I line it how far should I keep it from the vent (the vent is only 3" from the back wall)? I liked the idea of chicken wire around the inside of the port, but will the fill stay in suspension or will it just get clogged and hurt the efficiency? If it stays suspended then I'd think it would increase efficiency being that it addes vol and lowers freq.

I should probably start a new thread to get more insight, cuz everyone reading the header is thinking I'm some crackhead trying to reinvent the wheel lol.

keep_hope_alive
05-22-2012, 07:27 PM
if you start a new thread, mention me so i see it.

denim scores as high as fiberglass. but it's specific acoustical insulation.

lining the walls with 3" of fiberglass or denim fill , you can glue it to the walls, you could hold it with a few runs of string stapled, you just want to avoid compressing it.

some kinds of acoustical fill come in sheets, those are easy to cut and glue.

moparerrnocar
05-23-2012, 02:10 AM
if you start a new thread, mention me so i see it.

denim scores as high as fiberglass. but it's specific acoustical insulation.

lining the walls with 3" of fiberglass or denim fill , you can glue it to the walls, you could hold it with a few runs of string stapled, you just want to avoid compressing it.

some kinds of acoustical fill come in sheets, those are easy to cut and glue.

I asked how polyester compared to denim. Fiberglass, eww, itchy and unhealthily. I'll just start a new thread titled "polyfill and vented enclosures"...