experienced in car audio, no clue for an HT sub

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Hi -
I recently built a 12" slot ported enclosure for my car which turned out to be pretty impressive. It's driven with 700w rms and blends pretty well with my 6.5" component speakers up front seeing 360w rms.
It sounds good and can get "hearing loss" loud without audible distortion when I'm in that kind of mood.

As for my HT set up...
I have a Technics 100x5 receiver, sony 5-1/4 bookshelf fronts, I built the center speaker with twin 4" drivers and a 1" tweeter - all Boston Acoustics, the rear speakers are some cheap jensens, and a 5-1/4 30w jensen sub.

I assume most of you are lauging at this point, but to be perfectly honest it's ALMOST satisfying. The room is small (~17'x11') and it doesn't make a bad little set up, especially considering I only have about $500 in it.

The glaring need IMO is low end.
I have two 12's sitting in the basement collecting dust. Both car subs, but both model pretty well. One is the same as the one in my car - it has an f3 of ~26 in 2.7cf, the other ~29 in 5.2. With the small room I don't want to take up much (any) floor space so I'm thinking a shallow box under the couch.
I doubt I can get 5.2 with my space constraints, but 2.7 seems doable.
Should I consider a 4th order BP in an attempt to keep the sub from drowning everything out at 100hz+?

Anything bad in general about using a car sub that I might not be considering?

Now, my real question - power. This is a sub capable of handling several hundred watts. I don't want to spend hundreds on an amp only to have it drown everything else out then spend hundreds more to catch up. Can I get 30-40hz with only 100w, 200w?
Or am I just an idiot and need to scrap the whole thing?
Watts have nothing to do with how low you can go. I got down to a useable 18 Hz with a 12" adire shiva in an extended bass shelf (EBS) ported sonotube alignment. I may have been pushing 50 - 100W (from a 130W amplifier) into it in a small room. Your experience may vary depending on the efficiency and specs. of your driver.

If you haven't already, determine the T/S specs of your sub and model it in WinISD. Choose the alignment depending on what you are trying to achieve, ... eg. an EBS for low, low bass, lacking a bit in punch, .. or tune it higher to 25 - 30 Hz for more punch. Porting is probably your best bet for HT effects.

There's no reason car subwoofer drivers shouldn't work in home, apart from the fact that some of them are overpriced for what they are. In short, it depends on the sub.

I'd suggest you buy a plate amplifier first, .. and then try your car sub in home, to get a bearing on what your situation is. Look for something around 200 W - 300 W . MCM has a 300W ampifier for $89 right now.
they've both been modeled in winISD, that's how I came up with my F3's.

When I first built my car enclosure I tested it on my home receiver with only 100w, and the other, slightly higher Fs sub (350w rms). In this smaller than ideal enclosure it began to roll off at a much higher frequency than I would like for the home, but the sub I plan to use would be much lower, and hopefully about what I'm looking for.
It would be tuned ~26, which is the ideal plot from winISD. Showing basically flat response down to about 30, rolling off pretty sharply with an f3 at 24.5 and f6 around 22. That's with the 2.7cf volume which I believe I can work with.

What about port location. I thought it might be helpful to have the sub at one end and the port at the other to help keep from localizing the bass. I don't know if that would help or hurt things overall though.

Where's this MCM?

It lists for higher, ..but call them and ask, it should go for $89 according to an email -promo I got a couple of days ago.

Port location shouldn't matter too much IN GENERAL, .. but with the benefit of hindsight,

1. if you use a port tube, try not to have it point directly at the pole piece of the speaker, .. motor noise becomes more obvious

2. port closer to the floor might get you a bit more bass reinforcement, . depending on the situation.

3. port and driver on the same face give you a bit more flexibility in placement (don't have to worry about a wall blocking off the port)

4. also take into account room gain. In other words, a sub that models flat anechoically can get boomy in the wrong room.

Other more knowledgable folks can give you specific reccomendations.

Hope that helps.
Consider buying a "pro" stereo amp; this is generally the highest watts per dollar value. Try music stores, pawn shops, eBay (for local sellers). The influx of "made in China" amps seems to have driven prices down a lot.

Also, consider just using a stereo integrated amp or receiver as a power amp, if you have one lying around or can pick one up very cheap.
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