Replacing a HT subwoofer with a car sub.
Jun 28, 2004 at 11:37 PM Thread Starter Post #1 of 89
skiguy411

skiguy411

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I have a cheap Awia 10 inch 150 watt Home Theatre sub. Instead of buying a whole new sub, I thought I might just change the speaker. I got the sub apart and pulled out it out. Would it be worth the extra 50 bucks to buy a new cone/driver and put it in the case with the home theatre amp?

Mods: Can I get this thread moved to DIY maybe?

Ok, update: Instead of replacing the the driver, I decided to build a brand new one from scratch. Dimensions are 17.25 x 17.25 x 17.5 with a 24.5 inch long 4 5/16th diameter port. New question is what is the next step to take in order to upgrade the sub.
 
Jun 29, 2004 at 1:06 AM Post #2 of 89
The box is half the battle. What kind of alignment is it and how much volume? I assume it's ported. gerG in particular can really give you some good advice. I would try winisd and run some simulations after you've figured out your box specs. Also beware the true power of your amp.
 
Jun 29, 2004 at 4:19 AM Post #3 of 89
Well, after thinking about it for awhile, I think im just gonna build my own sub. I believe I will use a rockford fosgate driver 12inch 150RMS (300MAX) with my current amp for now. Eventually I will upgrade the amp when I can get the money. Any problems with this plan?
 
Jun 29, 2004 at 6:11 AM Post #4 of 89
Any particular reason you chose the rockford fosgate driver? I don't know anything about it, but I'm surprised you chose a car audio driver, which people say are usually engineered for max SPL rather than high fidelity.
 
Jun 29, 2004 at 3:43 PM Post #7 of 89
Oh boy, subchat!

That Rockford sub is for a sealed enclosure (and probably a large one, given the high Qt). ooheadsoo is right, it will play loud but not very deep at all. They don't show F3 in the sealed alignment for a reason. It is probably 50 to 60 hz. It is also way too underdamped for a bass reflex alignment.

The Quatro seems pretty good for the price. It is a "tweener" design, half way between sealed and vented alignment. That makes it ok for either, but not optimized.

Some homework:

Is the cabinet sealed or ported?
What are the internal dimensions?
What is the woofer mounting hole diameter?
Can you tell the impedance of the original woofer? (Important for amp considerations).

Given the first 3 I can run simulations pretty easily. I have most woofers in the database, so I don't even have to type in T-S parameters.

Welcome to diy land.

gerG
 
Jun 29, 2004 at 10:20 PM Post #9 of 89
If you check out your local Circuit City, they might have an open-box/demo Alpine Type-R sub (mine had some, and MTX 8000s) and I got my 10" for 80 bucks, it's a pretty good sub and is an awesome deal for 80 dollars. I put it in a .7 cu ft box and it sounds great. It does go pretty low (I use that same amp) because I use it as my theater/music sub and watch a lot of LOTR: King and it play looow...lol. Anyway, have fun
tongue.gif
 
Jun 30, 2004 at 1:29 AM Post #11 of 89
Hey D-EJ915, have you ever loaded up winisd's signal generator just to do an impromptu informal test of your sub's extension? I'm interested in your sub's performance. In sealed configuration, by ear, my sub starts rolling off at 33-34hz or so and still makes a tiny bit of rumble at sub 30hz but not significant. That's with my sub's balance set to match my speakers for music. If I bump the gain for movies, I can get plenty of response at 30hz and a bit below. My box is pretty big though (105 liters or so.)

skiguy411, the sub you have planned on paper looks good to me...Might get a little wooly as it approaches 30hz, but some people claim that it's negligible. Hopefully gerG will give a thumbs up on it. Seems like a nice project. Might be easier to mount the amp in the same chamber though. As for the vent, I think the most important thing is for it to not be facing the wall. Putting it on a side wall should be OK. I'm not sure about it "interfering with the backwave" and stuff like that, but as some other people have said, "the friggin magnet and motor structure are behind the cone obstructing the backwave already."
 
Jun 30, 2004 at 2:22 AM Post #13 of 89
ok, first cut. It just dawned on me that have not tried posting this type of output before, so here goes:

Quatro.jpg


If it worked, the red trace should be the cabinet that ski sent me. It is about 2 ft^3 internal, and tuned to 28 hz. I wanted more deep bass, so I kicked the cabinet up to 4 ft^3, and tuned down to 25 (blue curve). I also have excursion plots, but not too interesting. At 100 watts we are within limits down to below 20 hz.


gerG
 
Jun 30, 2004 at 2:41 AM Post #15 of 89
I prefer front porting. It eliminates a lot of problems, with no down side other than you have to make the port look nice. I have a great trick for that one. Cut the port hole to the ID of the port tube. You can then use a roundover bit in a router to radius the exit. Looks much nicer than cutting to the OD of the port and having to deal with the end of the PVC/ABS pipe.

I would never consider mounting an amp to a subwoofer again. I got tired of resoldering joints. My personal bias from my own experience, but vibrations will take a long term effect.

The braces look nice. What are the dimensions? Usually the challenge in subs are the panel flexures. Braces that connect opposite sides are quite effective in eliminating these.


gerG
 
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