Sub needs a massive ported box?

[The_Grimy_One 10+ year member]

alright, for the record it is a hatchback so it's not a big car so feeling the bass shouldn't be hard to do. I definitely have room to go the full range between 1.25 to 3 if I need to. I probably will aim on the higher volume end of that to get the lower frequencies if I can feel them more. I'm not sure if max output means the most you can hear or the most bass you can feel, based on your statement I would assume that it's hear. I however am more interested in feeling the bass than hearing it

Max Output = Max SPL. Im not a very big fan of that kind of bass. The head hurting bass. I like the music to be more deep, and essentially "feel it" more in my chest.

 

[RSDXzec 10+ year member]

Max Output = Max SPL. Im not a very big fan of that kind of bass. The head hurting bass. I like the music to be more deep, and essentially "feel it" more in my chest.

great, I agree with you I prefer the same type of bass. That said, why did you say 2.25 as opposed to 2.5 or 3 cubic feet? Is there some sort of advantage to less volume inside the box?

Cheers.

 

[The_Grimy_One 10+ year member]

great, I agree with you I prefer the same type of bass. That said, why did you say 2.25 as opposed to 2.5 or 3 cubic feet? Is there some sort of advantage to less volume inside the box?
Cheers.

Well I dont think you want to sway totally to the SQ side... You are in 1 cube right now. 2.25 cubes is gonna be a HUGE difference.

 

[RSDXzec 10+ year member]

Well I dont think you want to sway totally to the SQ side... You are in 1 cube right now. 2.25 cubes is gonna be a HUGE difference.

alright then, good to know there is a huge difference between them. I only plan on making 1 box, I wont be testing out different sizes so I'm trying to get it the right size on the first go. Whichever size helps me feel the bass the most is what I'm going for.

Cheers.

edit: just checked the qtc on competing box sizes

1cuft - 1.075

2.25cuft - 0.8601

3cuft - 0.8103

 

[The_Grimy_One 10+ year member]

alright then, good to know there is a huge difference between them. I only plan on making 1 box, I wont be testing out different sizes so I'm trying to get it the right size on the first go. Whichever size helps me feel the bass the most is what I'm going for.
Cheers.

I mean, wait and see what some others say. I am deff not the most knowledgeable. And I dont know the sub that well. I just know some concepts of boxes... When going sealed, I usually sway towards the bigger box. You could try to use the max volume, but I think you would lose some SPL type bass that you will end up missing.

 

[duanebro 10+ year member]

A smaller box controls the cone better. So you can use more power. A larger box will give you more low end. I would go with a bigger box than what you have in any case.

As far as ported, you can do a ported box. But you should go with a different tuning than normal. I would say that a very low tune will help bring up your efficacy without many of the down sides that come with porting a high Q sub. If you want to go this route I'd use a PVC port because you can get a plug and try sealed also.

 

[hispls 5,000+ posts]

alright, for the record it is a hatchback so it's not a big car so feeling the bass shouldn't be hard to do. I definitely have room to go the full range between 1.25 to 3 if I need to. I probably will aim on the higher volume end of that to get the lower frequencies if I can feel them more. I'm not sure if max output means the most you can hear or the most bass you can feel, based on your statement I would assume that it's hear. I however am more interested in feeling the bass than hearing it

download winisd (freeware). Model some different sealed boxes and see what the response curve does as you make the box very large or very small. I would lean towards larger as well.

 

[RSDXzec 10+ year member]

download winisd (freeware). Model some different sealed boxes and see what the response curve does as you make the box very large or very small. I would lean towards larger as well.

oh wow thanks a lot! why didn't i hear of this program earlier, I did try looking for some but i would've had to pay for them. This software is great!

 

[RSDXzec 10+ year member]

got some response curves, measured at RMS power at 1 meter

I compared my previous sub to the new one in different sized boxes. I'm not sure what frequency I should really be looking to boost here. My lpf is set to 80hz so I know nothing higher than that matters, but around what frequency should i aim for the get the best "car shaking" bass.

edit:

A smaller box controls the cone better. So you can use more power. A larger box will give you more low end. I would go with a bigger box than what you have in any case.
As far as ported, you can do a ported box. But you should go with a different tuning than normal. I would say that a very low tune will help bring up your efficacy without many of the down sides that come with porting a high Q sub. If you want to go this route I'd use a PVC port because you can get a plug and try sealed also.

just checked out what a ported enclosure would be like, doesn't seem too bad to me

what do you guys think of this response curve?

only real downside it the delay is up to 30ms, whereas the sealed boxes have a delay of 6-7ms

 

[duanebro 10+ year member]

If you go to facebook and find their page, you can get the latest version.

What that doesn't show is the excursion in the different boxes. At 250 watts you will hit xmax with the 3 cf box. I would use a 2.5 cf box. Add a 3" PVC port 17" long. This should tune the box to about 21 Hz. You can find a plumbers test plug at the same place you get the PVC. This way you can switch between ported or sealed.

Btw, model that ported box in WinISD. See if you can figure out why I said to tune so low.

 

[RSDXzec 10+ year member]

If you go to facebook and find their page, you can get the latest version.
What that doesn't show is the excursion in the different boxes. At 250 watts you will hit xmax with the 3 cf box. I would use a 2.5 cf box. Add a 3" PVC port 17" long. This should tune the box to about 21 Hz. You can find a plumbers test plug at the same place you get the PVC. This way you can switch between ported or sealed.

Btw, model that ported box in WinISD. See if you can figure out why I said to tune so low.

ok I tried 26/23/21hz

21hz at 3" diameter is 14.7" long. I'm guessing you're saying to tune it low so it doesn't drop off at the end. But considering human hearing only goes down to 20hz would 23hz be good enough? I'm really liking the higher dbs I can get with a ported enclosure so I'm trying to get the optimum. ***** about the sub hitting xmax at 250wrms, tested that out and a 2.5cuft box with 350wrms is much better, do you think it would be able to handle up to 400wrms in a 2.5cuft box?

Also I definitely plan on getting a plug, considering 2.5cuft is near what I was going to go sealed anyway so it's a win-win situation for me right now. Either way ported/sealed I get what I want.

 

[duanebro 10+ year member]

ok I tried 26/23/21hz

21hz at 3" diameter is 14.7" long. I'm guessing you're saying to tune it low so it doesn't drop off at the end. But considering human hearing only goes down to 20hz would 23hz be good enough? I'm really liking the higher dbs I can get with a ported enclosure so I'm trying to get the optimum. ***** about the sub hitting xmax at 250wrms, tested that out and a 2.5cuft box with 350wrms is much better, do you think it would be able to handle up to 400wrms in a 2.5cuft box?

Also I definitely plan on getting a plug, considering 2.5cuft is near what I was going to go sealed anyway so it's a win-win situation for me right now. Either way ported/sealed I get what I want.

I went from memory on the port length, but you must calculate the volume displaced by the port. I think I modeled it at 2.25cf for the ported. Take a look at the group delay at the different tunings. The delay is higher around tuning. Phase shift does the same thing. One more detail, at tuning, the port air speed is really high. A bigger port is needed. But if you tune below where you will be using the sub then these issues are also moved down to where they don't matter.

 

[RSDXzec 10+ year member]

I went from memory on the port length, but you must calculate the volume displaced by the port. I think I modeled it at 2.25cf for the ported. Take a look at the group delay at the different tunings. The delay is higher around tuning. Phase shift does the same thing. One more detail, at tuning, the port air speed is really high. A bigger port is needed. But if you tune below where you will be using the sub then these issues are also moved down to where they don't matter.

Ok that's good, looking at the delay if I tune to 20hz the highest delay at 20hz is 21ms and at 22hz its 27ms. Is it ok to tune subs this low? I don't want to cause any damage to it. Also what kind of delay is ok for maximum at 20hz? I'm trying to get good spl too and the lower I tune it the less spl I get.

Considering the length of the port, in order to hold it in place would it be a good idea to have it near the wall of the box and drill a couple of holes into the pipe and the box, then use a nut and bolt to secure it in place as well as adding the glue on the outside edge of the port (on the 3/4" length contact around the pipe touching the wall of the box)? I think if done well this would be a good method to secure the port and reduce "port noise" but I'm not sure if it would introduce any leaks.

edit: here are the graphs of spl and group delay showing sealed vs 21/22/23 hz

I'm really liking 22hz, it seems to have the "flattest" response (if I'm using the terminology correctly) and the group delay isn't too high i guess.

spl

group delay

I also downloaded the latest version of winisd and I'm unable to get an xmax graph based on the information I have available to me.

 

[duanebro 10+ year member]

Ok I will try to clear up a few things, and post some graphs of this also. Please do remember that your car plays a big part of the response – and WinISD does not model that.

I used 10.7” for Dd. This might not be correct, I guessed based off of other drivers I’ve modeled.

Let me post a few graphs:

Black line is 1cf sealed (400 watts)

Purple is 2.5cf sealed (300 watts)

Red is 2.4cf ported @ 23hz (400 watts)

I reduced the power on the bigger sealed box because of excursion:

I didn’t include Group delay or phase shift because all the models are about the same above 30hz. I don’t expect this sub to be used below 30 hz very often, and if you do, I’d guess port noise will be the biggest concern. Speaking of port noise, don’t drill any holes in the port. Just make a brace at the end to hold it. Just like the side of the box where it ends. Use SCH-40 pipe, it will be very stiff. If you have a router rounding over the ends of the port will be a good idea. With the 23hz tuning your 3” port will only be 12.75” long and should take up less than .1cf.

Tuning a sub really low will not hurt the sub unless excursion is to high above tuning, It should be fine even with 400 watts in this case. It is rare to see subs tuned this low in car audio, but with your sub I think it is the best way to get the most SPL while retaining SQ.

 

[its_bacon12 10+ year member]

That high of a Qts is suited more for IB, which is why you're getting huge box requirements

Try something with a Qts under .3 and Fs above 30 for a decently sized ported box.