Planning a box for car sub - Home Theater Forum and Systems - HomeTheaterShack.com

 
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post #1 of 6 Old 07-08-09, 01:57 PM Thread Starter
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Planning a box for car sub

I've read several posts dealing with this sort of retrofit (car sub in HT application). Like many others I have a mildly used 12" car sub in my closet waiting to be put to some use.
I have entered the TS parameters of my Alpine Type R dual 2Ω sub into WinISD (great program by the way) and have done many itterations with port size, tuning, and box volume. I have to keep the box sized to meet with the expectations of my significant other (no larger than an endtable). I am hoping to put together a sonosub build cause they look the best in my opinion.
Currently I have no home theater in my house. The TV speakers are driving me crazy with their tinny sound and low volume so I'll be looking into a receiver and speakers as well... but that is another topic.
Since I'm new to HT and to WinISD I just want to be sure I have the general proceedures down. So here's what I did:
Obviously I already have a sub; I found the TS parameters for the sub and entered them into WinISD.
I want as low of a response as possible but understand I am limited by the 12" sub and my available box size.
Examining cone excursion, SPL curve, and port air speed I came up with a 5CF (net) volume with a 6" circular port, tuned to 22hz.
However, due to cone excursion and an attempt to flatten out the response curve several signal attenuations were needed. I set a highpass filter at 18hz, a lowpass at 120hz, and a parametric EQ gain of 4db at 34hz.
I plan to run between 200 and 250 watts to the sub.
My questions stem from my proceedures. Are they sound? Are the EQ settings available in amplifier or will I have to use a separate EQ for this sort of signal modification?

On a side note; my buddy asked me how my subs could be tuned to 22hz when the spec sheet indicates a response of 25-400hz. I told him that tuning can be accomplished to lower the frequency response of a sub with an oversized box and properly sized ports. Just wanted to verify my reasoning.

Thanks for any input.
Nate
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post #2 of 6 Old 07-08-09, 02:42 PM
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Re: Planning a box for car sub

First of manufacturer FR response ranges for subs are basically worthless. Don't worry about it. It's mostly related to the enclosure, tuning and SPL level needed anyway.

I don't have the specs for the Type R 12 in Winisd but just make sure that your basice response is fairly smooth and has a slight roll-off down towards the tune before rolling off drastically from there. After that get as much port area as you can on it without making the port crazy long, which will lower your port resonance down into a range that may color the sound in the upper register of the subs range. 36" is a general rule of thumb.
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post #3 of 6 Old 07-08-09, 02:48 PM
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Re: Planning a box for car sub

Quote:
My questions stem from my procedures. Are they sound?
Post the parameters so it can be verified.
Quote:
Are the EQ settings available in amplifier or will I have to use a separate EQ for this sort of signal modification?
Some plate amps have various boost and HPF setting by changing 2 resistors. Look at the Bash plate amps at Parts Express.

Quote:
I told him that tuning can be accomplished to lower the frequency response of a sub with an oversized box and properly sized ports. Just wanted to verify my reasoning.
Yes.




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post #4 of 6 Old 07-08-09, 03:07 PM Thread Starter
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Re: Planning a box for car sub

Thanks for the quick responses. I will post the specs for the sub and some graphs from WinISD tonight after work.

I'm not building a monster here, just wanted to do something with that sub.
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post #5 of 6 Old 07-08-09, 03:20 PM
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Re: Planning a box for car sub

Quote:
I'm not building a monster here, just wanted to do something with that sub.
But we're not done with you yet! Just kidding!




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post #6 of 6 Old 07-08-09, 04:01 PM Thread Starter
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Re: Planning a box for car sub

LOL yeah.

I have seen some awesome home theater rooms and some towering sonosub builds.
I dont quite have the $$ for what I want .... yet. But who really does?

I've built many boxes for cars, but they've all been sealed. Sounds great in car but for the larger HT environment got to go with ported.
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