# Decrease sub box volume?



## Tegguy92 (Mar 13, 2011)

I am in the process of building my sub box and due to the size I am filling the interior volume is too big. I have about 1.8 cu ft per sub and the sub wants 1-1.2 What is the best/easiest way to decrease the interior volume? I've heard 2x4's and 4x4's I'm curious if there are any other ways? This will be a fiberglass front box.

Thanks in advance


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## Horsemanwill (Jun 1, 2008)

sand


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## qwertydude (Dec 22, 2008)

Is this a sealed box or ported? If sealed, manufacturer recommendations usually run a little on the small side and you'll likely get better low end extension on a sealed box running higher than manufacturer spec.

If this is ported, than the easiest way to take up space is to get large hard foam blocks, available at art stores like Michael's and glue them inside.


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## Tegguy92 (Mar 13, 2011)

Sorry I forgot to mention that it is a sealed enclosure. I'd like to decrease the volume to about 1.2 cu ft


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## 9-3Pilot (Mar 13, 2009)

What subs are you using? It often gives better frequency response to run a larger than manufacturer spec box. 

If you are set on decreasing the box volume, I agree with quertydude on the foam blocks, just measure .6 cubic feet of foam blocks and glue them in(make sure to test the glue first to make sure it won't melt the foam).

Edit: I like foam because it's not heavy for the amount of space it takes up.


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## Tegguy92 (Mar 13, 2011)

I'm using Arc Audio Black 12" subs.

Where is a good place to get the foam blocks that are being mentioned? (Online and local)


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## qwertydude (Dec 22, 2008)

3" Thick White EPP (1.3#) 24"x36", 1 sheet

EPP foam is probably the most durable foam and is safe to glue together with super glue. It doesn't crumble like styrofoam. But Michael's has a large selection of different foam blocks, just pick which one feels toughest.


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## 9-3Pilot (Mar 13, 2009)

This will get you what you need:

Shop Insulfoam 1-in x 2-ft x 4-ft Expanded Polystyrene Insulated Sheathing at Lowes.com


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## Tegguy92 (Mar 13, 2011)

9-3Pilot said:


> This will get you what you need:
> 
> Shop Insulfoam 1-in x 2-ft x 4-ft Expanded Polystyrene Insulated Sheathing at Lowes.com


Do you know if you can glue multiple pieces together?


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## 9-3Pilot (Mar 13, 2009)

Yeah, Gorrilla Glue will work well, wood glue might work as well. Don't use superglue or contact cement as those will melt polystyrene.


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## Tegguy92 (Mar 13, 2011)

Ok I need sand paper anyways so I guess it will be a single trip


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## BuickGN (May 29, 2009)

You're making a mistake. Try it without decreasing volume first. It will likely sound "quicker", dig deeper, and require less power in a larger box. All you're doing by reducing volume is making them more inefficient and the frequency response peaky.


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## Tegguy92 (Mar 13, 2011)

BuickGN said:


> You're making a mistake. Try it without decreasing volume first. It will likely sound "quicker", dig deeper, and require less power in a larger box. All you're doing by reducing volume is making them more inefficient and the frequency response peaky.


Won't this dig deeper but decease the "tightness" of the bass? I'm looking for sound quality over volume and have read multiple reports going either way.


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## BuickGN (May 29, 2009)

Tegguy92 said:


> Won't this dig deeper but decease the "tightness" of the bass? I'm looking for sound quality over volume and have read multiple reports going either way.


No. A larger box gives both. The boomy and "slow" bass comes from too small of a box. Every sub I've tried both ways has sounded better in a larger box. I've run a 12W6 from the factory size of 1.25' to 1.7' and eventually infinite baffle which is about 20'. Most subs sound better in larger boxes and as a bonus they will require less power.


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## Tegguy92 (Mar 13, 2011)

BuickGN said:


> No. A larger box gives both. The boomy and "slow" bass comes from too small of a box. Every sub I've tried both ways has sounded better in a larger box. I've run a 12W6 from the factory size of 1.25' to 1.7' and eventually infinite baffle which is about 20'. Most subs sound better in larger boxes and as a bonus they will require less power.


If they require less power to operate is there a chance of overpowering the sub? Sorry if it's a stupid question but I'm new the to the whole box thing.


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## ZAKOH (Nov 26, 2010)

I am honestly surprised that you're willing to waste about 1.5 cu ft of space, no one which will be available to either subs or for cargo. I would have bought/built a new box instead of having one that's too big. Regarding the "best" box size, I prefer to load the parameters into WinISD, let it choose the sealed box size for a perfect qtc. If I am not happy with box size, I play with it as long as qtc stays in 0.6-0.8 range. Some subs have perfect qtc in 1.8 cu ft box, but still only about 0.8 in a 1cu ft box, so I wouldn't take it as granted that the manufacturer recommendation is always wrong.


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## Tegguy92 (Mar 13, 2011)

ZAKOH said:


> I am honestly surprised that you're willing to waste about 1.5 cu ft of space, no one which will be available to either subs or for cargo. I would have bought/built a new box instead of having one that's too big. Regarding the "best" box size, I prefer to load the parameters into WinISD, let it choose the sealed box size for a perfect qtc. If I am not happy with box size, I play with it as long as qtc stays in 0.6-0.8 range. Some subs have perfect qtc in 1.8 cu ft box, but still only about 0.8 in a 1cu ft box, so I wouldn't take it as granted that the manufacturer recommendation is always wrong.


The "wasted" space isn't an issue this is going in my 1972 Chevelle and I don't plan to carry much in the trunk. I am fine with where it is sitting and either way I would have left the face of it sitting where it is so there would have still be wasted space behind the box.

I'll check out WinISD and see what it tells me (If I can figure out how to use it)


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## Nicks84 (Jun 30, 2010)

I have the same sub and it seems my Fosgate sub I had before sounded louder, smoother, and tighter, which I know shouldn't be the case. So I think I need a smaller box as well. The sub does not sound bad by any means. But I 'think' a smaller box is needed ? My question was "Do I really want to use foam or similar material" ? I only ask that because its pourus and not hard.


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## Tegguy92 (Mar 13, 2011)

Nicks84 said:


> I have the same sub and it seems my Fosgate sub I had before sounded louder, smoother, and tighter, which I know shouldn't be the case. So I think I need a smaller box as well. The sub does not sound bad by any means. But I 'think' a smaller box is needed ? My question was "Do I really want to use foam or similar material" ? I only ask that because its pourus and not hard.


Do you know what box size you have?


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## BuickGN (May 29, 2009)

Nicks84 said:


> I have the same sub and it seems my Fosgate sub I had before sounded louder, smoother, and tighter, which I know shouldn't be the case. So I think I need a smaller box as well. The sub does not sound bad by any means. But I 'think' a smaller box is needed ? My question was "Do I really want to use foam or similar material" ? I only ask that because its pourus and not hard.


If its "boomy" and "slow" chances are you need a larger box.


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## BuickGN (May 29, 2009)

Tegguy92 said:


> If they require less power to operate is there a chance of overpowering the sub? Sorry if it's a stupid question but I'm new the to the whole box thing.


Yes and no. The air spring of the box makes the sub less efficient and at the same time reduces cone control. Most manufacurers call for a small sealed box so that the thermal limits of the sub are reached before you bottom it mechanically. Put it in a larger box and you raise efficiency and gain cone control which will sound better. SPL is determined by excursion so if the sub in the large box can only take half the power before bottoming out, thats a good thing. Power doesn't determine output, excursion does so the less power required to hit full excursion the better. I can model it for you when I get home to prove what I'm saying.


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## donnieL72 (Jun 20, 2012)

In a small sealed box, there is more resistance for cone movement. When the cone moves into the box, the air pressure wants to push it back out. When the cone moves outward, the negative pressure in the box wants to pull it back in. This causes the speaker to be less efficient. In a large box, the speaker has less resistance to movement. The speaker is more efficient and can move faster, producing smoother and tighter bass all the while needing less power. An IB setup in reality is a sealed enclosure with a huge box. Very efficient with a lot less power requirement.

Buick, you beat me to it.


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## Tegguy92 (Mar 13, 2011)

So although I will gain efficiency I run the risk of mechanically bottoming out the sub and damaging it? I'm will be running the RMS recommended wattage for the subs.


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## donnieL72 (Jun 20, 2012)

Turn the gain down on the amp. Your amp will run cooler and it will be easier on your car's electrical system.


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## minbari (Mar 3, 2011)

Tegguy92 said:


> So although I will gain efficiency I run the risk of mechanically bottoming out the sub and damaging it? I'm will be running the RMS recommended wattage for the subs.


yes, that is true. but in a small sealed box you, although you wont mechanically damage it as easily, you will run a high risk of thermally damaging it. only problem with thermal damage is you dont know it is happening until the sub just quits. mechanical limits are VERY audible and you will know when you pushed it too hard.


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## Tegguy92 (Mar 13, 2011)

minbari said:


> yes, that is true. but in a small sealed box you, although you wont mechanically damage it as easily, you will run a high risk of thermally damaging it. only problem with thermal damage is you dont know it is happening until the sub just quits. mechanical limits are VERY audible and you will know when you pushed it too hard.


Where as if I ran a box at the recommended or maybe 25% over recommended it would be a little bit of the best of both worlds?


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## minbari (Mar 3, 2011)

sure, you could definitely find a happy medium between mechanical and thermal handling and still have it sound good and be relatively efficient.


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## BuickGN (May 29, 2009)

Tegguy92 said:


> So although I will gain efficiency I run the risk of mechanically bottoming out the sub and damaging it? I'm will be running the RMS recommended wattage for the subs.


Lower the power.


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## BuickGN (May 29, 2009)

Tegguy92 said:


> Where as if I ran a box at the recommended or maybe 25% over recommended it would be a little bit of the best of both worlds?


Nope. What do you mean the best of both worlds? Your powerhandling is going down at the same rate your efficiency is going up. The sub is requiring less power for the same output. Why would you want to make it less efficient instead of turning the gains down on the amp for the same output? Less power has several benefits.

Output will be the same in a small box or large box. The only difference is the larger box will sound better and require less power for the same output. You're wanting to drive efficiency down just so you can supply it with more power which makes no sense. Less power for the same output is the best of all worlds. 

For example, my current setup in a very large box gets much louder on 500w than my old small sealed box did on 1,300w. I can't brag to people about how much power I'm running but I can brag about how much it does on so little power. Most people go with tiny inefficient enclosures because they have to. You have the space which is something most people don't have. Take advantage of it.


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## Tegguy92 (Mar 13, 2011)

BuickGN said:


> Nope. What do you mean the best of both worlds?


Getting slightly higher output for less power while still playing it safe but not making it as easy to hit the subs mechanical limit




> For example, my current setup in a very large box gets much louder on 500w than my old small sealed box did on 1,300w. I can't brag to people about how much power I'm running but I can brag about how much it does on so little power. Most people go with tiny inefficient enclosures because they have to. You have the space which is something most people don't have. Take advantage of it.


Once again I don't care how loud it gets.


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## BuickGN (May 29, 2009)

Tegguy92 said:


> Getting slightly higher output for less power while still playing it safe but not making it as easy to hit the subs mechanical limit
> 
> 
> 
> Once again I don't care how loud it gets.


Again, making it easy to hit the subs mechanical limit is a good thing. Set the gains accordingly and enjoy the efficiency. Its not going to be this massive difference with the box you have where you're going to feed it 50w and its going to bottom out. You might have to reduce power by 15% to 20% and you would only have to worry about bottoming on the lowest of frequencies. If your amp matches the sub's rms power rating chances are you don't have enough power to hurt it even in the larger box. If you don't care how loud it gets you will probably never get close to its limits. If you meant that last comment as you think the sub will get louder in the large box, it can't since excursion determines output and it only has so much. What I'm saying is the sub has the exact same output potential in the large box but it will require less power for the same output.


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## Tegguy92 (Mar 13, 2011)

BuickGN said:


> Again, making it easy to hit the subs mechanical limit is a good thing. Set the gains accordingly and enjoy the efficiency. Its not going to be this massive difference with the box you have where you're going to feed it 50w and its going to bottom out. You might have to reduce power by 15% to 20% and you would only have to worry about bottoming on the lowest of frequencies. If your amp matches the sub's rms power rating chances are you don't have enough power to hurt it even in the larger box. If you don't care how loud it gets you will probably never get close to its limits. If you meant that last comment as you think the sub will get louder in the large box, it can't since excursion determines output and it only has so much. What I'm saying is the sub has the exact same output potential in the large box but it will require less power for the same output.


I get what your saying now with your previous comment it seemed like a larger box will make it louder(I must has misread it) I'm just worried about damaging the subs. I'm running the Arc KS1200.1 Amp


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## donnieL72 (Jun 20, 2012)

Turn the gain down on the amp. You don't have to use all the power. 

Turn the gain way down on the amp. Turn up the head unit until about 75% volume. Turn up the gain on the sub amp until you hear some distortion on the kind of music you usually listen to. Turn the gain back down some until said distortion is gone and then a little bit more for safe measure. After that, don't turn your volume up past where you set it at and you should be fine.


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## Tegguy92 (Mar 13, 2011)

donnieL72 said:


> Turn the gain down on the amp. You don't have to use all the power.
> 
> Turn the gain way down on the amp. Turn up the head unit until about 75% volume. Turn up the gain on the sub amp until you hear some distortion on the kind of music you usually listen to. Turn the gain back down some until said distortion is gone and then a little bit more for safe measure. After that, don't turn your volume up past where you set it at and you should be fine.


I might try this the problem is I listen to all different types of music. Also I forgot to mention I'm going to running the BitONE sound processor is this going to have an effect on how I do stuff on the amp? (Allow me to reiterate NEWB)


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## BuickGN (May 29, 2009)

I'm going to model this sub in both boxes when I get home. That will probably ease your mind (or make it worse lol). I really think you will be happier with the sound of the larger box.


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## Tegguy92 (Mar 13, 2011)

BuickGN said:


> I'm going to model this sub in both boxes when I get home. That will probably ease your mind (or make it worse lol). I really think you will be happier with the sound of the larger box.


Thanks


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## Tegguy92 (Mar 13, 2011)

Buick I hate to ask because your doing me such a huge favor but I was curious if you had a chance to model this?


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## BuickGN (May 29, 2009)

Tegguy92 said:


> Buick I hate to ask because your doing me such a huge favor but I was curious if you had a chance to model this?


I literally just got home and remembered I forgot yesterday. Give me 30 minutes...


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## BuickGN (May 29, 2009)

This sub shows very little difference from 1.2 to 1.8'. It shows a little more low end in the 1.8' but not enough to hear. On 500w it hits xmax at 25hz in the 1.2 and at 30hz in the 1.8. Excursion never gets high enough to damage the sub in either enclosure at 20hz. I would leave it as is, you probably won't notice a difference in either size. If you're more comfortable with less volume, go for it.


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## Tegguy92 (Mar 13, 2011)

BuickGN said:


> This sub shows very little difference from 1.2 to 1.8'. It shows a little more low end in the 1.8' but not enough to hear. On 500w it hits xmax at 25hz in the 1.2 and at 30hz in the 1.8. Excursion never gets high enough to damage the sub in either enclosure at 20hz. I would leave it as is, you probably won't notice a difference in either size. If you're more comfortable with less volume, go for it.


Thanks Buick I was seeing the same thing in WinISD but I had never used it before so I wasn't sure if I was reading it right or not. I'll probably leave it as it right now and decrease it later if I need to.

Next challenge is to do the fiberglass and figure out how to program the BitONE.


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