TC Sounds LMS-R 12" sub with a Sundown 1200D amp (help me build my box) - AVS Forum

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EndersShadow's Avatar EndersShadow
06:21 AM Liked: 547
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10-14-2012 | Posts: 3,595
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So I had another thread a LONG time ago (here) about building a box for my Jetta.

I am needing to actually do that now. I am open to just about any suggestions within reason. I am planning on building a box that is ported, tuned to ~30 hz to give me the flattest response (looking for a musical sub here, not SPL driven ONLY). I want to keep port noise under 20-30 m/s peak. I am looking to build a box about 1.75 cubic feet. My trunk is about 36" wide x 39" long x 20" tall. I would take ~2 inches off each measurement just to make sure it fits in though so lets call the trunk 34" x 37" x 18"

Right now the outer dimensions I am thinking of are 28" W x 16" H x 12" L. The interior dimensions would actually be 26 x 14 x 9 as I plan on using 1" think pressure treated MDF and making the baffle double to hold the weight of the woofer.

My main trouble is using those dimensions to come up with a port that isnt longer than the box. Any help would be appreciated

Comments?
tundrSQ's Avatar tundrSQ
06:45 AM Liked: 12
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Slot port or round port?

1" mdf is overkill...i would use 3/4 and then double baffle...and use the slot port to help brace the box.
EndersShadow's Avatar EndersShadow
06:47 AM Liked: 547
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Can do either, preference on the slot port as I have somewhat basic woodworking skills and I think a slotted port would be easier.
tundrSQ's Avatar tundrSQ
07:39 AM Liked: 12
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i agree slot port is the way to go...are you thinking something like this? And just need the proper dimensions? slot port.jpeg 71k .jpeg file
Attached: slot port.jpeg (71.3 KB) 
EndersShadow's Avatar EndersShadow
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Quote:
Originally Posted by tundrSQ View Post

i agree slot port is the way to go...are you thinking something like this? And just need the proper dimensions? slot port.jpeg 71k .jpeg file

Kinda like that, but with the 12" off to the right side. The more I think about it, the more I want to make it stretch as wide as I can, as tall as I can and then make it as shallow as possible (need at least 7 1/2 inches for the sub alone). I would then take the amps mounted at the back of the seat and mount them on the inside the slot port to the woofer. The amps are 12" and 13 1/2" tall and each is 10" wide and 3 1/2" deep. So I need about 36" wide to fit all that. The hope is that I could make the box so that the amps end up mounting flush, so the woofer section would stick out another 4 inches than the rest of the box? So the box would kinda look like a capitol L. That making any kind of sense?


Kinda like this (forgive my rudimentary modeling skills


box.txt 1k .txt file
Attached: box.txt (669 Bytes) 
cubdenno's Avatar cubdenno
10:45 AM Liked: 63
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30 hertz tune is not going to give a flat in car response. Due to cabin gain/transfer function with that sub, you are going to get a pretty huge bump of low end. For flat response, tuning lower is required to get the flat response or sealed. Do you have winisd? I would model your sub with an input of 800-900 watts to find the compromise of port vs port velocity that is doable. At that power amount try to be as close as possible to 20 m/s as possible. Even with that amp wired for a one ohm dcr due to box rise the power produced will be around 2/3s of rated.

The small enclosure size is going to make it difficult to keep low tuning and port size manageable.

I wil have to look at my computer when I get home and I will see if I have any designs that fit your criteria.
tundrSQ's Avatar tundrSQ
10:54 AM Liked: 12
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Quote:
Originally Posted by cubdenno View Post

30 hertz tune is not going to give a flat in car response. Due to cabin gain/transfer function with that sub, you are going to get a pretty huge bump of low end. For flat response, tuning lower is required to get the flat response or sealed. Do you have winisd? I would model your sub with an input of 800-900 watts to find the compromise of port vs port velocity that is doable. At that power amount try to be as close as possible to 20 m/s as possible. Even with that amp wired for a one ohm dcr due to box rise the power produced will be around 2/3s of rated.
The small enclosure size is going to make it difficult to keep low tuning and port size manageable.
I wil have to look at my computer when I get home and I will see if I have any designs that fit your criteria.

why would he want a flat response? In fact if anything i would suggest tuning HIGHER not lower...and let the cabin gain make up the difference. I think i would shoot for a 38 or 41 hz tune...but thats just me.

Go over to DIYMA and search thru the threads to find a tune point for a trunk mounted sub in a car like yours.
cubdenno's Avatar cubdenno
11:46 AM Liked: 63
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In his first post he said flat response.
Tuning higher will make it harder to blend the mid bass to the subs.

The higher you tune, the closer to the vehicle resonance you are. You then end up with a one note wonder/ fartbox. Great for spl not so much for sq which again, in his first post he said he was wanting.

As for diyma, they would not say tune higher for sq. been there for almost 6 years. In fact the true main guys who have not just joined in the last,three years would explain in great detail why tuning higher is going to suck for sq.

Car audio.com would agree with tuning higher. But that site is a sewer of bad info.
Give a look at mobilesoundscience.com. The guys who were with the original founder NP Dang (diyma ) started that site after Ant made diyma another car audio.com after he bought it.
tundrSQ's Avatar tundrSQ
01:24 PM Liked: 12
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i think its possible to achieve SQ.....without striving for a flat freq response in the low end. I am not trying to get him to the point where he is a spl burp machine by any means....and maybe i am not used to people wanting their sub to play flat.... especially in this case where he has chosen to use a beastly sub and amp combination and a ported box.

Occasionally ...people don't say what they mean....and personally i would still do my search i suggested and see whats working for people.
EndersShadow's Avatar EndersShadow
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On my iPhone so will keep it short. Outer dimensions might be 36 wide x 17 tall x 14 deep on the woofer and 10 deep on the rest. I believe it will be approximately 2.5 cubes. Need to actually model it and will post later.

Thoughts?
EndersShadow's Avatar EndersShadow
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Also this might be helpful:

http://tcsounds.com/product/drivers/lms-r-driver/
cubdenno's Avatar cubdenno
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The nice thing is, if you have an eq, any peaks can be eq'd down. Otherwise, I would model a bit to at least get you an idea. JBL had a graph of the cabin gain of a bunch of vehicles. Look for that and you can have an idea of what you will see in car.
EndersShadow's Avatar EndersShadow
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Quote:
Originally Posted by cubdenno View Post

The nice thing is, if you have an eq, any peaks can be eq'd down. Otherwise, I would model a bit to at least get you an idea. JBL had a graph of the cabin gain of a bunch of vehicles. Look for that and you can have an idea of what you will see in car.

My Kenwood KDC-X794 has a 5 band PEQ as well as programmable crossovers and slopes.

I still plan to model it in WinISD when I get home and post how that looks. Can anyone tell me if the TC Sounds specs for the small ported box will work decent in my car?
cubdenno's Avatar cubdenno
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The 1.8 cu ft enclosure would work fine. Tuned low though. Just model a higher tuning point. I fell the port may be undersized especially with the power you will be running, but again modeling should show what's going to happen. Tuning higher will help that port length.
EndersShadow's Avatar EndersShadow
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Quote:
Originally Posted by cubdenno View Post

The 1.8 cu ft enclosure would work fine. Tuned low though. Just model a higher tuning point. I fell the port may be undersized especially with the power you will be running, but again modeling should show what's going to happen. Tuning higher will help that port length.

So you would go with the large ported 1.8 cubic feet tuned to 20 hz with a 70" port over the small ported 2.5 cubic foot tuned to 30 hz with a 31 inch port? Is the because you think it will give me a better frequency response than the 30 hz box?
cubdenno's Avatar cubdenno
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They have the box sizes swapped. It should be 1.8 tuned to 30 is the small box. Just check the port length for tuning.
cubdenno's Avatar cubdenno
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10-15-2012 | Posts: 1,495
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how good are you at taking a design and adding/subtracting to make it work for you?

I have a truck design for a center console sub. Rear firing. Ported. for a 12.

1.85 cubic foot. I believe the tuning is higher for max thump. I honestly can't remember and my work PC does not run WinISD for some reason. Gobs of port area.

to adequately suit you, changing woofer location and adding a side to increase port length to lower tuning might have to be done. Let me know if you are interested.
EndersShadow's Avatar EndersShadow
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Quote:
Originally Posted by cubdenno View Post

how good are you at taking a design and adding/subtracting to make it work for you?
I have a truck design for a center console sub. Rear firing. Ported. for a 12.
1.85 cubic foot. I believe the tuning is higher for max thump. I honestly can't remember and my work PC does not run WinISD for some reason. Gobs of port area.
to adequately suit you, changing woofer location and adding a side to increase port length to lower tuning might have to be done. Let me know if you are interested.

Sure I am good to a point with that kinda stuff...
cubdenno's Avatar cubdenno
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Pm me an email address. I will send it tomorrow from work
EndersShadow's Avatar EndersShadow
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Quote:
Originally Posted by cubdenno View Post

Pm me an email address. I will send it tomorrow from work

PM sent
cubdenno's Avatar cubdenno
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Did you get the design?

Understand my quick sketch?
EndersShadow's Avatar EndersShadow
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Quote:
Originally Posted by cubdenno View Post

Did you get the design?
Understand my quick sketch?

I got it and it makes sense. Just need to tweak the back of the box since my trunk is angled.
cubdenno's Avatar cubdenno
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Ooof. That may cause some unforeseen effects.

Changing the geometry other than just port length will change a whole lot on the response of the sub and enclosure.

Just a heads up.

If you are needing a trapezoidal-ish enclosure than running round ports would be the way to go about that. Or order a design from Pete for your woofer.
EndersShadow's Avatar EndersShadow
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Quote:
Originally Posted by cubdenno View Post

Ooof. That may cause some unforeseen effects.
Changing the geometry other than just port length will change a whole lot on the response of the sub and enclosure.
Just a heads up.
If you are needing a trapezoidal-ish enclosure than running round ports would be the way to go about that. Or order a design from Pete for your woofer.

Yeah I figured that frown.gif. I will take a look and I might just order a design myself. Depends on a couple different factors.
EndersShadow's Avatar EndersShadow
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post #25 of 25
10-24-2012 | Posts: 3,595
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As happens, things change. In this case this entire project has been scrapped and I now need to sell the Sundown 1200D.
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