Plans for an SPL Box, optimum tuning frequency? Trying to pass 150dB

[akadj 10+ year member]

I have a Geo metro budget build

 

[RSDXzec 10+ year member]

If it were me I wouldn't tune it any higher then 43 hz. You vehicle is gonna peak in the low/mid 50hz range. I never tune any closer then 7-10 hz from vehicle peak resonance.. I do have a couple termlab meters (1 pending sale to mass car audio) so there is a lot of testing after my initial 7-10hz lower, but its a great starting point. I have honestly about 500 hours into the build I'm scrapping.

Alright, would you also recommend a smaller box like others in this thread have said?

And how much port area should I aim for?

 

[akadj 10+ year member]

Alright, would you also recommend a smaller box like others in this thread have said?And how much port area should I aim for?

4 - 15's.. 18-20 cubes before any displacement.. 250 square inch of port with a little length to bring down tuning to low/mid 40's hz

My box for my 2 atomic 15's is almost 11 cubes and 200 square inches with almost now real port length other then the multiple baffles.. but tuned high 55hz because its a wall and the vehicle peaks around 65-67hz

 

[RSDXzec 10+ year member]

4 - 15's.. 18-20 cubes before any displacement.. 250 square inch of port with a little length to bring down tuning to low/mid 40's hz
My box for my 2 atomic 15's is almost 11 cubes and 200 square inches with almost now real port length other then the multiple baffles.. but tuned high 55hz because its a wall and the vehicle peaks around 65-67hz

hmm so i was fairly close to begin with on port area and almost on volume, so would you say 14 cubes after port displacement?

and I think rather than reduce the height i'll reduce the length of the box so I have more room for the box to vent.

I'm also planning on having the port driver side, since the termlab goes on passenger side.

edit: I'm thinking based on all the recommendations so far I'm going to go with 14 cubes after displacements tuned to 44hz, kinda fits a few musical requirements I have as well.

Going on the larger side because I'll be running low power, and I did want a higher tune so 44 seems to fit.

another question I have is should I mount all four subwoofers as close as possible to the rear of the vehicle? or should I place 2 near the rear and 2 near the front? remember all subs will be facing up with the port back on driver side.

 

[akadj 10+ year member]

hmm so i was fairly close to begin with on port area and almost on volume, so would you say 14 cubes after port displacement?and I think rather than reduce the height i'll reduce the length of the box so I have more room for the box to vent.

I'm also planning on having the port driver side, since the termlab goes on passenger side.

edit: I'm thinking based on all the recommendations so far I'm going to go with 14 cubes after displacements tuned to 44hz, kinda fits a few musical requirements I have as well.

Going on the larger side because I'll be running low power, and I did want a higher tune so 44 seems to fit.

another question I have is should I mount all four subwoofers as close as possible to the rear of the vehicle? or should I place 2 near the rear and 2 near the front? remember all subs will be facing up with the port back on driver side.

Yes put all woofers on the same baffle and close together,.. keep them as far away from the port as possible. Keep the port as far to the driver side as you can and as far in the back of the vehicle

 

[RSDXzec 10+ year member]

Yes put all woofers on the same baffle and close together,.. keep them as far away from the port as possible. Keep the port as far to the driver side as you can and as far in the back of the vehicle

here's a basic model of where I plan to put everything, cutouts for subs and port in the rear.

remember I'm in australia, cars here are RHD so it is in fact on the drivers side.

 

[akadj 10+ year member]

here's a basic model of where I plan to put everything, cutouts for subs and port in the rear.remember I'm in australia, cars here are RHD so it is in fact on the drivers side.

Now that I see what your building I'm not sure that port is going to be the best way to do it.

I feel that the two woofers on the driver side will unload different because of the port placement.. Straight across the bottom would probably work a lot better

And your going to need at least 12" behind the port to the hatch of the car

 

[RSDXzec 10+ year member]

Now that I see what your building I'm not sure that port is going to be the best way to do it.
I feel that the two woofers on the driver side will unload different because of the port placement.. Straight across the bottom would probably work a lot better

And your going to need at least 12" behind the port to the hatch of the car

Alright sweet, this is how it looks.

Plans are to have 1" thick all around with 2" on the top, and probably some bracing in the centre spot there between all 4 subwoofers because that'd be the weak spot.

After bracing tuning would probably end up around 43hz, so it looks like that's the final design unless there's anything else that needs attention.

 

[akadj 10+ year member]

When are you.plans to start the build?

And are you planning on competing in db drags?

 

[RSDXzec 10+ year member]

When are you.plans to start the build?
And are you planning on competing in db drags?

No idea when, should be getting the subs in the mail this week or next, then getting a hold of wood I guess over the next few months. I'm in my last year of uni so study takes up a lot of my time but I will be trying to find time in between to make progress.

Yes this box will only be used for competition, it will only be in the car on the day of competitions so it will be set up the day before. This won't be used as a daily, that's why i was fine to go nuts on the tuning since music wouldn't be an issue, I have another box for daily use.

 

[akadj 10+ year member]

No idea when, should be getting the subs in the mail this week or next, then getting a hold of wood I guess over the next few months. I'm in my last year of uni so study takes up a lot of my time but I will be trying to find time in between to make progress.
Yes this box will only be used for competition, it will only be in the car on the day of competitions so it will be set up the day before. This won't be used as a daily, that's why i was fine to go nuts on the tuning since music wouldn't be an issue, I have another box for daily use.

You already have the amps?

I'm definitely interested to see how it works out, if I'm not on here send me an email with some results at danielknew@gmail.com

 

[RSDXzec 10+ year member]

You already have the amps?
I'm definitely interested to see how it works out, if I'm not on here send me an email with some results at danielknew@gmail.com

Yeah amps were bought a long time ago, except only 1 apsm-1500 will be connected until the battery is upgraded, then the second one is going in.

 

[VWBobby 10+ year member]

Here's a little hint that few guys seem to use here in the US, but is very popular in the UK....

Try to make as many hard surfaces inside of the cabin to reflect sound towards the meter. All these floppy panels, soft interiors, vinyl, rubber, etc ABSORB sound... The last thing you want to do is absorb sound for SPL. Fiberglass or hard door panels, hard dash, etc would all give you the max SPL compared to a floppy interior absorbing 5-10+++ DB... I have seen single sub setups that can push well over 150DB and not need nearly as much power as we use in the US. Efficiency is an easy way to win an SPL comp while using the same amount of power on tap.

 

[akadj 10+ year member]

Here's a little hint that few guys seem to use here in the US, but is very popular in the UK.... Try to make as many hard surfaces inside of the cabin to reflect sound towards the meter. All these floppy panels, soft interiors, vinyl, rubber, etc ABSORB sound... The last thing you want to do is absorb sound for SPL. Fiberglass or hard door panels, hard dash, etc would all give you the max SPL compared to a floppy interior absorbing 5-10+++ DB... I have seen single sub setups that can push well over 150DB and not need nearly as much power as we use in the US. Efficiency is an easy way to win an SPL comp while using the same amount of power on tap.

This is true, but you also have to stay within the rules of the db drags

 

[n8skow 10+ year member]

Your objective is to compete in dbDrag with this build?

Are you familiar with the class structure?