Back-wave distortion

[brazilianguy 10+ year member]

so i build a sealed enclosure for my sub, but its too thin, as that my magnet is too close to the back end of the box

now instead of building another box, is there anything i can put it in the box that will eliminate the back-wave syndrome??

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[TeoTorriatte 10+ year member]

so i build a sealed enclosure for my sub, but its too thin, as that my magnet is too close to the back end of the boxnow instead of building another box, is there anything i can put it in the box that will eliminate the back-wave syndrome??

WTF is back-wave syndrome? That's a new one...

 

[brazilianguy 10+ year member]

WTF is back-wave syndrome? That's a new one...

lol i just made that up //content.invisioncic.com/y282845/emoticons/biggrin.gif.d71a5d36fcbab170f2364c9f2e3946cb.gif

 

[helotaxi 5,000+ posts]

Seriously though, what is your concern? Not enough clearance for the pole vent or what? If there's no pole vent, you can bump the rear of thesub right against the back of the box. A pole vent only needs its diameter in clearance from the rear wall of the box.

 

[brazilianguy 10+ year member]

Seriously though, what is your concern? Not enough clearance for the pole vent or what? If there's no pole vent, you can bump the rear of thesub right against the back of the box. A pole vent only needs its diameter in clearance from the rear wall of the box.

not enough clearance on the back of the sub from the box

the sub sounds awful in this box, i'm getting a back wave that is moving the cone

i need to know some kind of material i can put it on the back wall so that it wont reflect the sound wave

 

[ultimate157 5,000+ posts]

not enough clearance on the back of the sub from the boxthe sub sounds awful in this box, i'm getting a back wave that is moving the cone

i need to know some kind of material i can put it on the back wall so that it wont reflect the sound wave

I'm going to go ahead and say you have a leak in the box.

 

[brazilianguy 10+ year member]

I'm going to go ahead and say you have a leak in the box.

i sealed everything with silicone, as well as used wood glue and screws

why? is what i'm saying about back-wave completely stupid and insane?

 

[CRXBMPN 5,000+ posts]

why not just add some polyfill

or build a different box

 

[01 S 10 10+ year member]

what kind of sub? how big of box?

 

[brazilianguy 10+ year member]

why not just add some polyfill
or build a different box

you think polyfill would do it?

what kind of sub? how big of box?

alpine type-s 12"

30x14x7 outside using 3/4mdf

 

[FoxPro5 5,000+ posts]

How high does the sub play? We'll just say it plays to 100 hz. To eliminate a back wave, you'd need to block it with something very heavy and dense (like lead) or you'd need to absorb it. To absorb a 100hz wave at a 0* incident angle (straight on) you'd need an absorptive material (ex open cell foam) that's about 34" thick (nearly 3 FEET). A 100hz wave is over 11 feet long.

Really anything thinner in absorptive material and the wave will just refract right around it. How is it that you can hear heavy bass notes from the Hummer 6 cars away??

 

[brazilianguy 10+ year member]

How high does the sub play? We'll just say it plays to 100 hz. To eliminate a back wave, you'd need to block it with something very heavy and dense (like lead) or you'd need to absorb it. To absorb a 100hz wave at a 0* incident angle (straight on) you'd need an absorptive material (ex open cell foam) that's about 34" thick (nearly 3 FEET). A 100hz wave is over 11 feet long.

i see

i guess i'll be building another box

unless someone can tell me that this back-wave thing is just my imagination, and i have another problem

 

[FoxPro5 5,000+ posts]

If it's a sealed enclosure that's built well, try adding a coat or two of liquid deadener to the inside. This will probably force the RF of the MDF below the passband of the sub.

You also need to make sure the part of the box which the sub is mounted to is strong and rigid as possible.

The correct enclosure is what makes a sub sound good, not the sub itself. Just play your sub free air and you'll get an appreciation for that. Using tricks like polyfill can help, but they should maybe come later down the road after the basics are covered.

 

[ultimate157 5,000+ posts]

Push LIGHTLY, and equally on the cone. Once its depressed, release it; If it takes a while to come back out, you have a leak. If it springs back instantly, then its sealed.

 

[brazilianguy 10+ year member]

I'll try some polyfill in there since I don't have any liquid deadener handy

I just did tryed pushing the cone in, it comes back up pretty instant, i don't feel like i have a leaky box

thanks for the help guys