# Downfire vs Upfire front mounted sub



## Orion525iT (Mar 6, 2011)

So, I am slowing getting my system together. I am about 1/3 of the way done with my kicks. Its all just about labor on the kicks from this point. So now I am turning my attention to the subwoofer. It will be a single 12" front mounted. I am running 2-way components in the kicks. The kicks have over .3 cubic feet of air space, so I should be able to drive the mids as low as they can handle, but I would rather leave the low frequency stress to the sub.

Read here for more details on my ideas for the front mounted sub: http://www.diymobileaudio.com/forum...am-core-composite-construction-sub-boxes.html

I am committed to the materials and location of the sub, but I am still trying to decide on position. Because of the custom work, I can fire the sub any direction I want. What I am trying to determine, is whether down firing or up firing will have a lesser chance of complications. 

It would be nice to try both with cheap MDF boxes to see what sounds the best. But due to the contours and space, it would be impossible to simulate positioning with a simple MDF box.

This will be a ported enclosure, tuned to 35-36 hz.

Anybody got some good input? I have read mention of things like "tinsel snap" and port "chuff" being more of an issue with front mount subs, which would lead me to believe that down firing might mitigate audibility of those issues. But I am not sure. I am looking for thoughts along those lines.

I will not accept "don't do it". So don't try.

Thank you ahead of time!


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## 60ndown (Feb 8, 2007)

dont do it.































definitely down fireing.


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## Aaron'z 2.5RS/WRX (Oct 24, 2007)

IMO you're tuning too low.. . You'll blend a lot better tuning near 60 and letting transfer function bring up the bottom.. 

when down firing you need to consider boundary loading..


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## jcollin76 (Oct 26, 2010)

My vote is for down firing also.
Might is well get the benefit of the boundry loading as mentioned above..


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## BowDown (Sep 24, 2009)

I ran a front 12" sub in my F350. I created a center console replacement and fired the sub off the dash. Worked great!

My current install has a 10" sub in place of the dash center console piece.. it's firing off the windshield. This too works great. It's a high eff 10" old school sub. Doesn't take much power to move it. 

Your sub choice is going to play a huge role in how much noise/artifacts you will hear from having the sub so close. 

I too vote for down firing it. This will put the sub that much farther away.


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## Orion525iT (Mar 6, 2011)

Aaron'z 2.5RS/WRX said:


> IMO you're tuning too low.. . You'll blend a lot better tuning near 60 and letting transfer function bring up the bottom..
> 
> when down firing you need to consider boundary loading..


Interesting thought. If I model the tuning that high, box size does not impact the low end at all. 2 ft3 or 1 ft3, looks about the same up to the tuning frequency.

No idea how much I could rely on transfer to bring up the bottom.

The plan was to make the box as big as I can up to 2.0 or so ft3. I don't know if I can achieve that, but I think it is well within reason. I will definitely try to build in the ability to change port length for tuning. In any case, I would rather get more output and EQ down if needed.


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## Orion525iT (Mar 6, 2011)

BowDown said:


> I ran a front 12" sub in my F350. I created a center console replacement and fired the sub off the dash. Worked great!
> 
> My current install has a 10" sub in place of the dash center console piece.. it's firing off the windshield. This too works great. It's a high eff 10" old school sub. Doesn't take much power to move it.
> 
> ...


Ok, so firing up to the windshield with great results, but still recommending down firing? I assume that this is because placing the sub further away will lessen the chance of hearing noise/artifacts. Is there any other reason? Are you saying that given full freedom with your install, you would choose down firing over the current install?

Its a low (6mm) excursion, carbon cone, high eff sub.

BTW, I looked at your install multiple times in the past for ideas.


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## nubz69 (Aug 27, 2005)

Down firing will give you the best sound imo. When I was an installer this was what I found time and again. When you downfire a sub enclosure you gain two benefits. One, you usually get a little loading on the woofer which helps improve it's coupling with the cabin airspace, this will increase output a bit. Two, when you downfire, the higher order harmonics are absorbed a bit by the floor. This makes your sub sound a little bit cleaner.


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## Orion525iT (Mar 6, 2011)

nubz69 said:


> Down firing will give you the best sound imo. When I was an installer this was what I found time and again. When you downfire a sub enclosure you gain two benefits. One, you usually get a little loading on the woofer which helps improve it's coupling with the cabin airspace, this will increase output a bit. Two, when you downfire, the higher order harmonics are absorbed a bit by the floor. This makes your sub sound a little bit cleaner.


Thank you for lending your experience. I was leaning towards the down fire. The disadvantage with down fire is that the install will not be as straight forward and I will need to do a more radical move the evap core and heater core so I can still have functioning HVAC. I also might loose some volume as I will need air space under the cone. But the down fire will allow the sub coil to be on the same plane as the coils on the mids. I was also having some clearance issues between the woofer basket and the firewall cross member when trying to fire into the windshield. I do think that the benefits of down firing will be worth the additional effort with the HVAC.


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## CulinaryGod (Jun 5, 2008)

Old thread, I know. But is there a common knowledge of how much height should be held from the woofer to the floor? I'm currently considering building a downfire enclosure for home use and cannot find where anyone states the distance between the woofers surface or box and the floor. I have 4 stainless steel legs that are 3-3/4" tall and was hoping they'd work well for this build. If I surface mounted the woofer it would be about 3" between it and the floor. Does this jive with you guys or is it too much? Any input is appreciated

Thanks,
Steven


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## minbari (Mar 3, 2011)

1/4 speaker diameter or more


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## CulinaryGod (Jun 5, 2008)

So, 1/4 the diameter of the speaker is the distance that should be held from the floor? So for 12" it's 3" from floor, 10" it's 2.5", and 15 it's 3.75?

So my 3-3/4" tall legs will work for my 12" subwoofer? Do you have any links that provide the 1/4 diameter+ theory that you stated or is this just an assumption?


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## minbari (Mar 3, 2011)

just experience

you can wait and see if other chime in, but if you goggle it 1/4 of diameter is pretty standard.


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## bobduch (Jul 22, 2005)

My 18" downfiring home Velodyne has 3". Your legs are fine.


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