DD 3515G SQ box

[Volvo_S80]

The box I have now is my first attempt at a slot port I know it's not perfect but I did learn some things.

It's 32x 23.5x 14.5 I used a port calculator somewhere online and have it tuned to ~30hz I roughly compensated for sub displacement and bracing.

It get pretty loud. It has good sound when I have my bass knob in the middle but when I max it

out It just doesn't sound as good.

I can probably get 1 more inch out of the Height if I mount the sub differently I have it mounted on the top now. I plan to use birch. I like the stained wood look.

Here's my current box

So should I go a little bigger/smaller? What should I tune it to? I'm looking for the best SQ. I don't think I'll loose too much output considering I never max it out anyway.

The sub is DD 3515g the amp is DD M2C (2400)

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[mrpep]

Nice box . I've always wanted 2 big *** 15"s in my conversion van - something about it .....

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[Volvo_S80]

Thanks. I like the 15 but I might switch it to one or 2 12's in the spring.

Anyone have a good suggestion on box size tune and port area?

 

[LosIsATool 5,000+ posts]

You need to get it firing back or walled off forward. Firing up is killing it in a trunk.

5 cubes with 75sq inches of port at 32-35hz.

 

[Jeffdachef 5,000+ posts]

Thanks. I like the 15 but I might switch it to one or 2 12's in the spring.
Anyone have a good suggestion on box size tune and port area?

Yes, dont go with slot, Go with a round port. Get some 6" pvc or an 8 inch sonotube instead. You dont need as much port area which saves a lot on airspace. With the sub facing back same direction as the port, you'll get better low end response so you dont have to tune as low. Any kind of upfiring in the trunk reduces a lot of low frequency response.

 

[mrpep]

I'd love to hear a well tuned 15" - I've been itching for one for. A while

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[Falcons 5,000+ posts]

I'd love to hear a well tuned 15" - I've been itching for one for. A while

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It sounds amazing.

 

[Volvo_S80]

I'll go with back firing Is one 8 inch sonotube enough? or should I go with more? to get 75sq inches of port it looks like I need 3

 

[LosIsATool 5,000+ posts]

I'll go with back firing Is one 8 inch sonotube enough? or should I go with more? to get 75sq inches of port it looks like I need 3

You need less with round ports.

 

[Jeffdachef 5,000+ posts]

I'll go with back firing Is one 8 inch sonotube enough? or should I go with more? to get 75sq inches of port it looks like I need 3

75 is what he meant with slot ports. You dont need nearly as much with aeroports.

 

[Massive spl]

I've heard plenty of sub up port back in trunks and they all slammed. Maybe your hearing distortions when cranking the bass knob?

 

[Volvo_S80]

I'm going to take a trip down to the plumbing supply house near me to get a price on some 8 inch PVC compare it to sonotube and go from there. I'm thinking I'll do the sub to the left and the port resting in the bottom right of the box for ease of keeping it secure. I won't flare it I'll just make it flush with the box. I'm also going to need a 15 inch Sub woofer grill

I don't think it distortion because I have a clipping light on the bass knob and it doesn't seem to be clipping. I set the gain with a DMM on a 50 hz tone with the bass knob a hair lower than max. (don't know if that's the right way or not) It get's loud and it does sound ok I just think it can sound better. I'm sure it doesn't help that my front stage can't keep up. But I think a better box is needed. Plus I have to ship my MS-8 in again so I'll be without sound for a couple weeks. I figured now is the perfect time to build another box.

 

[Volvo_S80]

$78 for 8 inch PVC. I'll pass.

I'm still going to try the aero port design It will be easier to change tuning and 8 inch sonotube it is.

After looking up some info I see that my port resting on the bottom right is restrictive so I'll center it in the space between the sub and the edge of the box.

Would it be better to build with MDF and add like a 1/8 th or 1/4 inch piece of wood on the outside for the stained look I want? Or does it really not matter?

I was also thinking if Birch plywood or Oak plywood wasn't dense enough I could add a layer of fiberglass on the inside of the box.

 

[Buck 5,000+ posts]

2.5 cubes per 3512, do less port area with a slot. A 8" round tube will sound great.

I've done subs up port back in a trunk and broke a rear deck from the lows (AB HD 12's). I've done a lot of 15's up firing as well. Most of the sound comes out of the port, so the whole up firing thing not being as loud is a bad rule of thumb. It's vehicle dependent. Hell, I've even done all up firing in certain cars and been loud, like crown vics.

 

[supra1987]

Would it be better to build with MDF and add like a 1/8 th or 1/4 inch piece of wood on the outside for the stained look I want? Or does it really not matter?

I was also thinking if Birch plywood or Oak plywood wasn't dense enough I could add a layer of fiberglass on the inside of the box.

just use the birch from the get go.better than mdf in my opinion.I think if the box is done right you shouldn't need a layer of fiberglass on the inside.but that being said I'm not sure if fiberglassing improves sound or not.