A newbie's first design

[Terrum]

As mentioned in a few other threads, I'm looking to go from a single SA-12 D2 Classic (750W) to dual SA-12 V.2 D4s (2x1000W). I've got the amp (SALT-2), waiting for the subs to be delivered, and now I just need to get a design and box built.

My current SA-12 Classic's box was designed by Buck but unfortunately due to his inability to design currently I've had to resort to doing my own or find someone else to do one for me (or get help from this lovely forum). I decided to spend the day measuring my trunk to figure out the absolute maximum I can comfortably fit in there for an enclosure that I will be able to take out at ease when I need to carry luggage.

It was a huge pain having to measure a perfect rectangle whilst taking into consideration the dimensions of the door frame, parcelshelf and the slant of the seats, but now I have dimensions of a box that I threw together on subbox.pro that I can comfortably fit into my trunk: https://subbox.pro/en/b/6faST67qs I took 0.75" off the depth to allow for a double baffle during the actual build.

My current box is tuned to 30Hz but I wanted to tune the new box slightly higher this time (32Hz) so that's what I've set the box to on the link above. I'm not entirely sure what I should have set the 'Port Area' to. Sundown's site recommends 26 sq in so I just doubled it because there's two subs, although I'm sure that's wrong.

I'm just looking for someone who can check it all over for me to make sure it's fine, or anyone that can offer opinions/tips/discussions etc to help me get the best out of my box, or if someone can recommend a designer that has lots of experience building boxes for Sundown subs and can help me achieve the best output etc.

Thank you for reading and I look forward to any replies

 

[Buck]

Yeah I wish I could design it for you. My health is just garbage, and I’m in constant pain

If you’re going to do 32 hz, which tends to be a great daily tuning for most, then I’d just make sure you wind up at 3.5 cubes net. One option you may have is to side fire a 6” flared aero to keep the port situation easy, keeps the box smaller, if you think a side firing port could have enough clearance from a side wall. Sundown’s recommended port area per cube is about 14.9, and I’ve done anywhere from 12-16 per cube with those with square/slot ports for ported. If you truly have 2000w+ for amp power, you may wanna stick towards the 14-16 port area per cube.

One thing is your box will be a little smaller than 3.5 cubes net, if that program doesn’t take into account the sub displacement. If not, then you need to keep the port the same and just add some more chamber space; iirc it’s about .1 disp for each sub, so you’d want 3.7 in the chamber to wind up at 3.5 net, but keep the port the same as the box you have now. The box looks proper, otherwise, based on the numbers I’m seeing from it. I would recommend adding something like a 1.5-2” x 15.5” brace in between the subs, if it’s a single baffle, because that’ll keep the baffle from flexing and degrading over time.

The sub box you have designed, is it going to fire all to the rear?

 

[Terrum]

Yeah I wish I could design it for you. My health is just garbage, and I’m in constant pain

No worries man I just really hope you get better soon as it's never nice to have to deal with pain in general, let alone health-related pain.

If you’re going to do 32 hz, which tends to be a great daily tuning for most, then I’d just make sure you wind up at 3.5 cubes net. One option you may have is to side fire a 6” flared aero to keep the port situation easy, keeps the box smaller, if you think a side firing port could have enough clearance from a side wall. Sundown’s recommended port area per cube is about 14.9, and I’ve done anywhere from 12-16 per cube with those with square/slot ports for ported. If you truly have 2000w+ for amp power, you may wanna stick towards the 14-16 port area per cube.

The design shows a 'Net Internal Volume' of 3.51 cubic feet so I'd assume that is fine. I would go for an aero port but I think all the builders I know would only be willing to use a slot port, plus if I were to build it myself I would definitely not be confident in making an aero port As for power, that's on my to-do list as per another thread that I will soon update, where I am trying to find out the true amp power of my setup. The battery is 1850W so I'm hoping it's near enough that at least.

One thing is your box will be a little smaller than 3.5 cubes net, if that program doesn’t take into account the sub displacement. If not, then you need to keep the port the same and just add some more chamber space; iirc it’s about .1 disp for each sub, so you’d want 3.7 in the chamber to wind up at 3.5 net, but keep the port the same as the box you have now.

The site does offer an option for 'Woofer Displacement' in cubic feet but on Sundown's site the displacement section was empty so I wasn't sure what to put there. So you suggest I put 0.2 cubic feet into the 'Woofer Displacement' field of the design?

IMPORTANT EDIT: Going by a quick Google search someone had the same problem where they couldn't find the displacement.

https://www.reddit.com/r/CarAV/comments/gtd1xy

A response suggests 0.14 cubic feet (I assume per sub). Although I am curious how they got 'great lows but lacking punches'. I'm assuming by 'punch' they are referring to things like 'kicks'? Anyway, funnily enough, despite them calling those punches 'lacking' I'm actually trying to make my punches equal with the basslines as mentioned in my other post here. So I'm assuming with the 3.5 cubic feet box in this design I would get good lows but 'lacking punches' (still assume they mean the kicks), which is actually what I want to achieve They also mentioned that the displacement is going to make such a small difference to the internal volume that it would (probably) not matter. In my case the design is so tight to the trunk space I would worry about making it any bigger than the current design.

The box looks proper, otherwise, based on the numbers I’m seeing from it. I would recommend adding something like a 1.5-2” x 15.5” brace in between the subs, if it’s a single baffle, because that’ll keep the baffle from flexing and degrading over time.

Yes as per my OP "I took 0.75" off the depth to allow for a double baffle during the actual build." This will be added on top of the front rather than inside to save the internal volume.

The sub box you have designed, is it going to fire all to the rear?

Yes it's going to be positioned firing towards the trunk door (back of the car).

 

[audiobaun]

What vehicle is this going in? Curious

 

[Terrum]

What vehicle is this going in? Curious

It's a 2010 Renault Clio - nothing special Just incase, here are photos of the trunk and its dimensions (ignoring the amp as that's now gone and I plan to mount the new amp onto the box instead).

https://imgur.com/a/DhbO1aK

 

[Terrum]

So just to confirm, no one has any criticisms with the design? @Buck Should I consider adding wood to the corners like you did with my design? I'll also consider sanding down both ends of the port into a flare.

Of course if anyone else has any other tips or suggestions for what I can add to help me get the best out of the enclosure with its tuning and dimensions. I'm looking to finalize the design by the end of the week so I can get it to a builder for the weekend or potentially do it myself.

 

[Terrum]

Here's an update a month later:

https://imgur.com/a/hOrBx7Q

Got a sheet of MDF locally, put the cut list into CutList Optimizer and the shop was more than happy to cut it. I had almost no confidence I could do this, but despite installing the port slightly incorrectly (above the other port instead of to the side of it) I think it turned out great.

The left hole was cut too large but managed to work around it by screwing the driver in at an angle, the other driver is also at an angle just to make it look 'better' I guess. I made my own double-baffle too, all cut with a jigsaw with slightly bigger driver holes and the port. Stuck some gold-plated double-ended push-button terminals on, some handles, and carpeted myself.

Sounds fantastic too! Much louder than I anticipated. So much so that I need to work on dampening my trunk as that rattles more than I am comfortable with But I'll probably make a new post on that for advice.

Thanks so much again everyone for your help, and I look forward to any feedback!

 

[Glen Livet]

No worries man I just really hope you get better soon as it's never nice to have to deal with pain in general, let alone health-related pain.


The design shows a 'Net Internal Volume' of 3.51 cubic feet so I'd assume that is fine. I would go for an aero port but I think all the builders I know would only be willing to use a slot port, plus if I were to build it myself I would definitely not be confident in making an aero port As for power, that's on my to-do list as per another thread that I will soon update, where I am trying to find out the true amp power of my setup. The battery is 1850W so I'm hoping it's near enough that at least.


The site does offer an option for 'Woofer Displacement' in cubic feet but on Sundown's site the displacement section was empty so I wasn't sure what to put there. So you suggest I put 0.2 cubic feet into the 'Woofer Displacement' field of the design?

IMPORTANT EDIT: Going by a quick Google search someone had the same problem where they couldn't find the displacement.

https://www.reddit.com/r/CarAV/comments/gtd1xy

A response suggests 0.14 cubic feet (I assume per sub). Although I am curious how they got 'great lows but lacking punches'. I'm assuming by 'punch' they are referring to things like 'kicks'? Anyway, funnily enough, despite them calling those punches 'lacking' I'm actually trying to make my punches equal with the basslines as mentioned in my other post here. So I'm assuming with the 3.5 cubic feet box in this design I would get good lows but 'lacking punches' (still assume they mean the kicks), which is actually what I want to achieve They also mentioned that the displacement is going to make such a small difference to the internal volume that it would (probably) not matter. In my case the design is so tight to the trunk space I would worry about making it any bigger than the current design.


Yes as per my OP "I took 0.75" off the depth to allow for a double baffle during the actual build." This will be added on top of the front rather than inside to save the internal volume.


Yes it's going to be positioned firing towards the trunk door (back of the car).

I’ve heard on average.50 for displacement. Taking into account the speaker, bracing, etc. so if the box requires say 1.0 cubic foot. You build the box to 1.50 for everything involved.
As for your double baffle. I’d suggest putting it on the inside. It will give a much better look when you finish the outside. Makes everything flush.
As for the outside finish. I’d suggest using a router. Giving a rounded edge to the box. The side pieces. I’d router a groove around 1/4”. The side pieces will sit flush. Giving you a place to tuck carpet or the finish material into. Gives a cleaner looking box. In my opinion.

 

[Terrum]

I’ve heard on average.50 for displacement. Taking into account the speaker, bracing, etc. so if the box requires say 1.0 cubic foot. You build the box to 1.50 for everything involved.
As for your double baffle. I’d suggest putting it on the inside. It will give a much better look when you finish the outside. Makes everything flush.
As for the outside finish. I’d suggest using a router. Giving a rounded edge to the box. The side pieces. I’d router a groove around 1/4”. The side pieces will sit flush. Giving you a place to tuck carpet or the finish material into. Gives a cleaner looking box. In my opinion.

Thanks for your suggestions, but the box is already complete (see my last post). I chose to put the baffle on the outside to avoid losing internal volume.

I don't have a router unfortunately, nor would I have the experience to use one. Although I sanded down the corners and edges of the box and port as much as I could, I struggled to make a simple box as is and was lucky I didn't make any fatal mistakes

Feel free to check my last post to see the result and let me know what you think!

 

[Glen Livet]

Thanks for your suggestions, but the box is already complete (see my last post). I chose to put the baffle on the outside to avoid losing internal volume.

I don't have a router unfortunately, nor would I have the experience to use one. Although I sanded down the corners and edges of the box and port as much as I could, I struggled to make a simple box as is and was lucky I didn't make any fatal mistakes

Feel free to check my last post to see the result and let me know what you think!

The internal port wall on the right. Where it connects to the wall following the back of the box. I see a dark spot on the wood.
Is that a split where the screw went into the wood?

 

[Terrum]

The internal port wall on the right. Where it connects to the wall following the back of the box. I see a dark spot on the wood.
Is that a split where the screw went into the wood?

Yes that is a split, the port was the first join I made and I didn't make the pilot large enough, but I actually filled the split with some glue and it doesn't seem to have affected the sound at least.

Just one of many minor mistakes I made with this box

 

[shredder2]

I can't remember my 1st sub enclosure build, don't overthink the little things and keep learning.
Eventually you'll get way better and possibly help others.

Just keep it up, nobody knows everything and those who claim to learn something new everyday.