Best box for DB12 for SQ

Bryan M

Heya,

I currently have my Polks in a sealed enclosure to spec. They are running off a 400w amp (per channel) and sound pretty good.

However, I have only ever had them in a sealed enclosure, and was wondering if a ported enclosure would sound better.

My main aim is for the bass to integrate nicely with the midbass (provided by Polk Momo's, 6500's).
Is it worth trying a ported box for the woofers?

Thanks

MacLeod

A ported box would have the potential to have more output but I can almost guarantee that it will sound better in the sealed box you have it in now.

Bryan M

Heya,

I have been playing on Bassbox 6, and it seems a ported box with an Fb of around 25 gives the nicest, flattest response. Its a huge box, 100L, but on paper, it looks like a much better response than a sealed box, which drops off alot quicker.
The vented box seems to give a much flatter response from 30-100 Hz, which would be nice for SQ.

Plus, a vented box would be good for a sedan, where I can aim the woofer through the ski-hole in the rear seat, and seal if off from the boot, and push the port through the back shelf.

Sounds good on paper, not sure how good it would sound in practice though

MacLeod

Well ya can always throw one together and see how it sounds. Never know til ya try.

eloplayspolo

i could be mistaken ... but dont u want to cut off any sound above 80hz on a sub...?

Bryan M

ye, I am sure I will cross it off around there somewhere, but it still rolls off.

Anyways, I bought a new amp to run my 2 DB's, and have kept them in the same same spec sealed boxes

BTW, should I add some damping material inside, will it make a difference to the overall bass? It does sound a bit hollow atm, would the damping help?

Cheers guys,

MacLeod

eloplayspolo wrote: »

i could be mistaken ... but dont u want to cut off any sound above 80hz on a sub...?

It depends. If youre wanting your bass to image up front, you dont really want to get above 63 Hz.

If you dont care about that and want all the sub energy you can get, then 80 or even 100 would work.....it would sound like crap but it would work.

Bryan M

Thanks for the info MacLeod.

In all honesty, I am still installing my sound, and hooking up amps, so have not tuned it yet, but i will keep the 63hz in mine

Any opinions of putting fill into the sealed boxes?

Cheers,

ben62670

Loose fill in a sealed box is very good. It kills standing waves never mind other benefits. IMHO loose fill is very good.
Ben

Bryan M

Heya,

By loose fill, do you just throwing some in the box, or actually stapling / gluing it to the sides?

Thanks

ben62670

Just fill it with loose cheap stuffing like you would get at WalMart. No need to glue, or staple. One small package is enough for a pair of 12's
Ben

Jstas

Just make sure that you don't over fill otherwise pieces of the stuff can get sucked up into the motor structure of the speaker and cause lotsa problems.

In other words, don't crowd the woofer. If you lay the box on the back with the woofer hole facing up, depending on how deep the woofer is, the fill should not come up more than half way filling the box. If the woofer is deep, make sure that the majority of the fill is off to the sides.

Make sure you give the vent hole on the back of the magnet and the spider/former areas enough space to breathe. They cool themselves by the physical movement of the air. If the fill gets in the way it limits air flow around the parts and they get over heated. If pieces get in, they can hamper movement of the motor structure and cause physical failure of the driver.

MacLeod

Ive always been of the belief that if you build the box to the proper interior volume, you dont need pollyfill. Ive always considered fill to be more of a band aid for when you have to build a box that is smaller than youd like for space constraints.

Best thing to do would be listen to it for a while without fill then slap some in there and see what you think.

Bryan M

Fair enough Macleod, but even on the polk website on the box building specs, they recommend minimal fill. I have built the box to spec, so perhaps I should put some fill just to finish off the 'specs'?

Anyhoo, I will give it a go, its a relatively simple job, and it would be nice to see the comparison.

Cheers,

Kureti

MacLeod wrote: »

Ive always been of the belief that if you build the box to the proper interior volume, you dont need pollyfill. Ive always considered fill to be more of a band aid for when you have to build a box that is smaller than youd like for space constraints.

Best thing to do would be listen to it for a while without fill then slap some in there and see what you think.

I agree with you, its better to have round corners instead of sharp corners inside.

Bryan M

heya,

What possible benefit would rounded corners in a sealed box have? I understand in a ported box it may be an advantage, but would it be a benefit in a sealed box?

Thanks

MacLeod

Breaks up standing waves inside the box. But its arguable if the difference is actually audible. Still, couldnt hurt.

Jstas

MacLeod wrote: »

Breaks up standing waves inside the box. But its arguable if the difference is actually audible. Still, couldnt hurt.

I doubt it's audible. The advantage is that the standing waves cause pressure variances that can lead to distortion due to lots of things like cone flexing, uneven pressure that destroys linearity of the motor structure and can cancel out the back wave and reduce efficiency. Granted, in most usage, it's barely noticeable but at the extreme pressure levels, it can make a significant enough difference.

rdb2001

I think sealed has the best sound quality of any box. With that being said, I have never heard a sub in a sealed box hit notes that have been hit with a suib in a ported box. The ported box is a little more bassy but you can tune a port to sound very good. I have a custom 6 cubic foot enclosure for my kicker comp vr 15 in the bed of my avalanche. It is ported and I tell you that there are notes in songs I have never heard til I used this setup. So i think its all about what you want.

Jstas

rdb2001 wrote: »

I think sealed has the best sound quality of any box. With that being said, I have never heard a sub in a sealed box hit notes that have been hit with a suib in a ported box. The ported box is a little more bassy but you can tune a port to sound very good. I have a custom 6 cubic foot enclosure for my kicker comp vr 15 in the bed of my avalanche. It is ported and I tell you that there are notes in songs I have never heard til I used this setup. So i think its all about what you want.

Does somebody want to educate this tool about port resonances and frequency harmonics to explain his "never before heard notes" or do I have to do it and get told I don't know anything again?

rdb2001

I dunno who you are but my point here is that ported boxes seem to have lower freq than sealed boxes. My point with notes, switching to home theater my friend has an svs sub. I have a jbl. His sub drops deeper than mines therefore notes that I normally dont hear with my jbl are more audible when I listento the same songs with his. SVS ports are tuned to a lower freq response than the jbl I have. So why you continue to bash everything I say, please read what I wrote. You are not the sound guru you think you are.