turning car subs into home theater

[KILURV8]

Hey All, I have 2 15 inch infinity subs that I have been trying to sell for a while, and I just can't find any takers. Anyways, I am temped to try to set at least one of them up to be a powered home theater sub by using a car amp. Now how in the heck do I take the 120 V AC and convert it to 12V DC so the amp will work. I know I need a converter and a bunch of fuse blocks, but where can I find a converer like that? Any help is appreciated.

Honda Killer Forever

[91TSIAWD_Mark]

A converter for that will run hundereds of dollars, like $300-700 depending on the size of your amp. They'd be at industrial supply stores.

2 other, and possibly better ideas, are:

Get a new amp or 2 like a Marantz MA500 and build a x-over and hook it up

Get a new sub amp from partsexpress.com like this one http://www.partsexpress.com/pe/showdetl.cfm?&DID=7&Product_ID=9390&CATID=43

Both of these run off AC. The Marantz sounds great and is THX certified.

[4G63Rydah]

I doubt that car speakers will perform well as a home theater piece. Car speakers are designed to run in relatively small air enclosures....even the free-air speakers have a "box" (ur car). Home theater speakers are designed to run in large open rooms.....I might be wrong, but I've tried it before and it didn't work out too well.

[sab4you]

Yeah:
1. dont bother hooking up car amp to home outlet. If your that desperate, just hook up car subs to home stereo.

2. car subs wont really sound so hot in room - they are meant for smaller areas. You might wanna try building a box and face it against the wall, about 1/2 foot away - this may make it sound louder.

Definately get a crossover. Remember that the car speaker is most likely 4 ohms, while home stereos drive 8 ohms - so this means it will drive 2x the power into your speaker and possible heat up/damage your stereo unless you wire it series with another 4 ohm speaker.

[90GSTforME]

My friend and I had a lot of time one day, so this is what we did:
Built a tower to hold a car battery, cd player, an amp mount, and a battery charger.
What you do is run your equiptment off the battery and then recharge it. If you get a large battery, you can thump for at least a couple hours.
NEVER run an amp right off the battery charger, it is dirty unregulated power output. The battery acts as a smoothing buffer for the power supply.
With a dual post battery i supose you could charge the battery as you listen.
Yes, this was all basically pointless but its cool.
It was built mainly to test 12v equiptment without tearing up a car for power supply.
Anyway, subs do ok in medium and smaller rooms as far as loudness goes.

[1.8L_2slow_lol]

One of the kids I go to college with has 2 12" subs built into his couch. I have no clue how he did it, but you can't stand to sit on the thing! He probably has $10,000 easy into his home theater system. He's a total audio nut, you can hear him pull into the parking lot every morning from inside the college. His system is easily worth twice what the car is worth, typical ricer.

[welderx]

do you have any of the information that came with your infinity subs? there are what's called theil-small paramaters that describe the mechanical and electrical charactaristics of the speaker. this is the data that all box builders use to develop enclosures of the proper size and type. the easiest route would probably be to contact infinity. the other posters have mentioned that using car speakers in the home have given less than satisfing results. this is probably due to the enclousure. cars have a huge "transfer function" that is, when you put an enclosure in a car it makes big bass easy. the car acts as a secondary enclosure and car sub boxes are designed with this in mind. putting the same enclosure in a big space yeilds poor results.
the amp can be set up to run on 120v a/c with no trouble, you just need a power supply. i met a guy 15 years ago who did the very project you propose...too bad i don't know where he is. the converting of voltages on equipment is pretty common though, you just need a competent tech. a lot of iasca competitors used to do this in reverse, running pro audio equipment in their cars. go to the audio asylum, on this news board you will find guys who design and build their own audio systems ask around in the general asylum.
http://www.audioasylum.com greg

[Josh95TSiAWD]

Build a square box with the sub facing down toward the floor. Put four legs about the height of a pop can or so.
You don't have to put legs on if you don't want, just face the sub forward.
Radio Shack sells a frequency cap (not sure if that is what it is called and about a $1 or so and small)you can hook to one of the speaker wires(usually positive).Get one that cuts out anyting above 120Hz - 150Hz Then just hook it to your home audio system. No conversions needed.



[Edited by Josh95TSiAWD on 01-08-2001 at 10:02 PM]

[Lotito1]

If you hook it to your home system be carefull what ohm level your at. I am pretty sure that home systems usually are only stable at 8 ohms. If you wire your speaker for a lower load you might jack up your amp... Just a warning...

Good Luck ~

[Johnny]

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Definately get a crossover. Remember that the car speaker is most likely 4 ohms,
while home stereos drive 8 ohms - so this means it will drive 2x the power into your
speaker and possible heat up/damage your stereo unless you wire it series with
another 4 ohm speaker.
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Actually the more Ohms a speaker has the less power the amp
requires to run the speaker. Because it doesn't put as much
of a load on the the amp. Now if he went and hooked up a 1 ohm subwoofer to his home stereo he'd definatly have a problem, because the amplifier probabnly has't been designed to be 1-ohm stable. So he will definatly short out a driver transistor. and just because you lower the ohms doesn't mean you increase power output 2x. If you hook a four ohm speaker to a mono amp at 125 watts. When you put a 2 ohm speaker to it you most likely will not see more than 145-175 watts depending on the size of the amp.

Well thats about it for this post. Figured I'd help out so you all don't embarrass yourselfs next time you go into a car stereo shop.

Johnny
91 Plymouth Laser RS
91 Eagle Talon TSI

[Johnny]

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the amp can be set up to run on 120v a/c with no trouble, you just need a power
supply. i met a guy 15 years ago who did the very project you propose...too bad i
don't know where he is. the converting of voltages on equipment is pretty common
though, you just need a competent tech. a lot of iasca competitors used to do this
in reverse, running pro audio equipment in their cars. go to the audio asylum, on this
news board you will find guys who design and build their own audio systems ask
around in the general asylum.
http://www.audioasylum.com greg
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Ok heres some info on that. Its not really that hard to convert Home audio equipment to run on 12 volts. After the "home" equipment has been plugged into the wall 110-120 volts of Ac current gets fed into hopefully a line filter (to reduce noise coming into the equipment) than from the line filter it probably goes through a fuse and than into what is called a Full Wave bridge Rectifier. What the Rectifier does is change the waveform coming into the equipment. It does it using Diodes basically it chops the bottom half of the AC waveform off. Than the output from the rectifier goes into a series of caps and smooths out the waveform so it can used as a DC source. (most circuit boards run off of DC, although AC can be present also in circuit but thats another story) So after it gets through the filter stage what your left with is DC. DC like AC has voltages. Most Household Electronic equipment thats powered by AC runs on 12volt DC. So basically what you need to do is instead of running the voltage through the rectifier you hook it up onto the output terminals of the rectifier. ITs pretty simple actually. And if the voltage on the cirucit board is lets say 9voltsDC you can either set up a series of Resistors or by a step down transformer to lower the voltage. Well thats about it for this. Hope you all learned something. OH incase you all are jumping around thinking you can hook your tv up to your 12volt system without an inverter, that would be a big NO. T.V.'s require actually the full 120 volt AC input to run.

Johnny
91 Plymouth Laser RS
91 Eagle Talon TSI