sub out of tune

[acold7dusta 10+ year member]

recently i made a box for my diamond D6 sub. internal dimensions are 38.5 x 12.5 x 8.5, which brings it to 2.1 after sub displacement. i put a 3", 9.25" long tuning it to about 28 hz. this is WAY too low for this sub. I barely hear any notes besides the real low ones. put my ear up to the speaker, and it was making like a squeeking noise when its supposed to hit, but doesnt. I'd prolly do alot of damage if i continued it like this.

which bring me to my next question: i love how ported boxes sound, so can anybody tell me what tuning range this sub likes (for the most flat response), and how much to trim the port, or is there a way to seal off the box to make a small sealed box? i really dont wanna trash this box and make another one, but i guess i could if all else fails.

thanks in advanced,

kev

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[iamamp3pimp 5,000+ posts]

make a new one

its cheaper thatn ptentialy destroying your speaker.

Robin

 

[thatkidbob 10+ year member]

i need a picture of this box so i can figure out whats going on...

 

[acold7dusta 10+ year member]

minues the back plate

 

[thatkidbob 10+ year member]

wierd... i don't see any obvious construction errors... and 400 watts in 2 cubes shouldn't hurt that sub..

i'm unsure of what could cause problems like what you're describing...

does the sub sound regular outside of the box?

when you press straight down on the cone does it rub at all?

do you have access to a DMM? if so check out the voice coils...

 

[iamamp3pimp 5,000+ posts]

thats a 12, right?

that isnt very much port area imo

 

[iamamp3pimp 5,000+ posts]

espically for such a large box.

 

[acold7dusta 10+ year member]

the sub is perfectly fine, its brand new. I think since its tuned too low for it (only a 10"), so heres how im gonna describe it. When the lower drum notes that are supposed to hit, dont, the sub kinda makes a squeek/ rattling noise. when it gets to a real low note (late nite tip for example, it get amazingly low and sooo much output, enough to shake the car on higher volumes.

Playing Incubus "circles", for example , i get port noise and missing ALOT of the notes, except the real low notes. Im still scratchin my head, but im keyin in that box is not tuned properly for that sub. Diamond recomends tuning it to 35 hz @ 1.25 cu ft slot port....

 

[thatkidbob 10+ year member]

^ i've put bigger in smaller lol...

it shouldn't be making squeeking noises, and it shouldn't be as quiet as he makes it sound...

 

[thatkidbob 10+ year member]

the box is tuned fine... 7hz wouldn't make THAT much difference.

i've switched camps... the port is too small...

build something with at least 25 sq inches of port (btw, your box is about to become a LOT bigger) and chances are the probem will disappear...

 

[acold7dusta 10+ year member]

i know, the whole thing is baffling, i think iamamp3pimp and thatkidbob may be right, with the too small of a port area. it kinda sounds like the woofer is free airing, if you know what i mean. like the suspension wants to go, but its not feeding enough air?

 

[thatkidbob 10+ year member]

what are the settings on your HU and amplifier?

 

[acold7dusta 10+ year member]

+3 on the head unit (out of 15) and the amp the gains at about 3:00 right now, bass boost a lil over 1/4, the LPF is 80 hz, subsonic around 30 hz, phase 0 degrees. the more i think of it, the more it kinda reminds me of a large, leaky sealed box. if i add another 3" port, in addition the one i got, would that raise or lower my tuning, assuming the ports the same exact length

also, would it matter the length from the port in relation to the sub?

 

[thatkidbob 10+ year member]

its going to raise your tuning...

some people believe the port should be as far away from the subs as possible, but i don't know or understand the rationale behind that. If you've got a DMM laying around i'd reset the gains with it (but i doubt this is the problem), but other than that i don't see any problems with your settings.

if it isn't the amp, HU, sub, or your settings, the only thing left (by elimination) is the box. If you'd like you can add another port, but this will raise your tuning significantly. It'll be just a hair over 39hz. edit: this is also going to increase your port velocity issue...

 

[acold7dusta 10+ year member]

what if i put a baffle inside it to slow the back wave. say a board 12.5 x 5.5 (4 inches smaller than the depth) stuck a few inches away from the woofer?

ive been messing around left and right with the settings, so its def not the settings. its definately the box.