subwoofer box

[scolari]

hey guys jsut making sure because my math isn't that great if i built a box for a alpine type r 12" the box would look something like this 40cm x 50cm x 15cm also what thickness of wood should i use?
sorry forgot to mention this is for a sealed box

[Ra1d]

um i would say build the box to the volume specs for a sealed enclosure as outlined in the sub owners manual. as far as materials i would say 18mm mdf is the go

[Bz Kn33z]

yeah 15 cm doesnt sound deep enough you would put it in and it might not go in

[sganro]

^^^ agreed. 15cm sounds a bit shallow. Also 18mm mdf would be a good material to use, as mentioned

[scolari]

sorry forgot to say sub is reversed

[Ra1d]

oh...bit of an important detail there. i've never had an inverted setup before, wouldnt mind lookin into one bcoz my subs have a really nice basket. i think you comprimise a bit of sound qual tho.

[garfa]

i think you comprimise a bit of sound qual tho.

why do you think that?

[Ra1d]

why do you think that?

i cant rattle off the definitive pros and cons, but i bet you're dying to do so

[Joe Peeps]

i cant rattle off the definitive pros and cons, but i bet you're dying to do so

if you cant back up your statements, then why make them?

Can you tell the difference between an inverted sub, and a normally mounted woofer from an SQ perspective? i cant, but if you tell me you can, i'll believe you .i have a terrible ear for these kind of things

[garfa]

i cant rattle off the definitive pros and cons, but i bet you're dying to do so

no i just wanted to know if you had a basis for tat comment.
if i wanted to rattle off stuff i just do it........

scolari: how will the box be sitting? that is which way will the cone be firing?

[scolari]

rear facing boot front facing seats i'll almost done building my custom boot so i'll post pics of it soon,jsut now need to buy the amp and sub but bit low on money seeing i crashed my vz the other day =(

[Goon]

rear facing boot front facing seats i'll almost done building my custom boot so i'll post pics of it soon,jsut now need to buy the amp and sub but bit low on money seeing i crashed my vz the other day =(

dont watch tokyo drift again then lol ! j/ks!

good luck with the plans mate, i hope they work out good, i made a ruff box the other day to see if it would fit and yeah 18 is a good choice..

[scolari]

haha i wasn't drifting more like came to a stop foot slipped i was too close and barely touched the other car yet the guy goes to hospital police come i get charged and now they are looking into his medical records and and fraud and other things because they think something dodgy is going on. so much commotion over a a few scratches on the car which i would of gladly paid straight away

[Ra1d]

i was merely trying to put out there that people in the know have said that a sub will perform better mounted traditionally as opposed to inverted. i wasnt claiming to know all the technical dis/advantages, i was just repeating something i had been told expecting that someone would either validate or reject it

[garfa]

i was merely trying to put out there that people in the know have said that a sub will perform better mounted traditionally as opposed to inverted. i wasnt claiming to know all the technical dis/advantages, i was just repeating something i had been told expecting that someone would either validate or reject it

just interestede. i am here to learn as well and wanted to know a bit more.

[Ra1d]

just interestede. i am here to learn as well and wanted to know a bit more.

fair enough. i just dont like it when people (joe peeps) chime in having a go at someone for trying to contribute to a thread. ANYWAY i got the impression that cooling is one of the advantages of an inverted install, other than that its mainly for looks?

*disclaimer for joe peeps* i am not a professional and am in no way claiming to have significant knowledge in this field. i know little about this particular topic and am throwing ideas out there to spark conversation relevant to the thread. i welcome anyone to either reiterate or disagree with any statements made

scolari: sounds like the guy is looking to earn a quick buck *cough* lawsuit

[vlv8vic]

Glad that dilemma is solved. Now, no more bitching or looking for an itch to scratch. I think, however, that many people would be interested in a proper list of pros and cons if anyone knows of any...

[Joe Peeps]

Hang on, im the bad guy here???

I am also here to learn. I dont chime in and have a go at people trying to contribute. Lets look at the facts - you were the one making claims as to sound quality, and i asked if you could hear the difference, because i personally cant! i dont have trained ears so i dont hold myself out to a higher standard then the man on the street. However, i dont make statements that i wont back up with either personal experience or commonly accepted knowledge.

[Joe Peeps]

OK, I thought id be a little constructive here: Keep in mind that this is just the info that I have gathered (mostly through Mobile electronics Australia and then further research online) I encourage anyone interested to do some googling of their own.

Inverted Subs:
Pros
- can look bad ass if your sub has a nice basket
- if the enclosure needs to be/is constructed In such a way that the woofer cant be mounted normally (ie depth issues) then inverting the woofer may be necessary

Cons
- mechanical noise may be heard from an inverted sub (eg chuffing from vented pole piece )
- sub “internals” exposed to particles that may get in and cause damage

Other points to note:
- Differences in enclosure volume caused by driver displacement no longer occupying enclosure
- Phase issues. In theory the Polarity should be reversed as the cone is now moving opposite direction (assuming that the system is in phase to begin with) but its best to try both and determine what sounds best.

To understand why there is negligible difference to sound quality, we need to know how a woofer works: Have a poke around online

Howstuffworks "How Speakers Work" Note that the cone moves both backwards and forwards from its at rest position!

As such, we see that when you invert the woofer all you are doing in essence is changing the orientation of the cone (which still moves in both directions) which wont effect the non directional frequencies produced by your subwoofer (and this is why we don’t invert our mids or tweeters)

Hope this helps. please I encourage everyone to add to this post with corrections/additions cause im sure that I will have made errors/omissions

[garfa]

yeah i didn't know there was a problem till a mod came in....
who reported?

[azzfox]

As such, we see that when you invert the woofer all you are doing in essence is changing the orientation of the cone (which still moves in both directions) which wont effect the non directional frequencies produced by your subwoofer (and this is why we don’t invert our mids or tweeters)

mids can simply be inverted as long as the polarity is reversed to suit. I have seen it been done numerous times (especially in show cars). only difference is that the cone will be firing to the sides of the driver and not in a forward direction like normal. this could make or break quality in mids, but with ~100hz being non-directional it will be fine for subwoofers.

I am also not a professional in this field, just giving some input on my thoughts

[scolari]

azzfox from what ive read you dont need to reverse the polarity unless you are running another sub the normal way so that they are in sync

[azzfox]

true. but.. would you reverse the polarity on a non-inverted sub so that the cones first movement is towards the enclosure?

[Joe Peeps]

invert the sub, and then you have altered the phase (the cone is now travelling the opposite direction to what it was on any given stroke). In theory if your system was in (acoustic) phase to begin with you will need to reverse polarity to keep it that way. This applies to a single sub setup. if you have one inverted and one not, then they must be wired out of electrical phase with each other to maintain acoustic phase.

Edit: To clarify, the phase doesnt have to be altered as a matter of course (were i confused myself was that i assumed that anyone going inverted was switching from normal). As in my earlier post above, try both ways and see which way sounds better

Just because people can invert their mid woofers doesnt mean they should!. The directional nature of frequencies over 250 means that inverting becomes a bad idea.

[Ra1d]

is it true that with any type of install (inverted or not) you should try running subs out of phase to see which gives you the better results? for example which connection gives you the better sense that the bass coming from the front as opposed to obviously from the boot.

good posts from everyone, a lot of info getting thrown out