classybum Posted February 2, 2001 Share Posted February 2, 2001 so i'm going to build myself a ported sub box, 2.5 cu. ft. with a 12" woofer. One problem that remains is amplification.. i am pulling hte sub out of my car.. so i do have the car amp, and was just going to buy an ac to dc power inverter. But, then i remembered that some people are able to hook up their subs to the main(?) speakers for bass output? does this work without amplifying the sub? if noone knows about that.. can anyone tell me how many amps of current a car battery puts out so that i can buy the right power supply? thanks for any info Quote Link to comment Share on other sites More sharing options...
RossVTaylor Posted February 3, 2001 Share Posted February 3, 2001 CB, A passive sub is traditionally powered by the amplifier's front channel speaker lines. Those speaker lines run to the inputs on a passive crossover network (usually on the subwoofer) where the bass "separated" and fed to the subwoofer driver. The filtered midrange and upper frequencies are then sent out of the passive crossover to the front left/right speakers. So, in other words, the speaker wires run from your amp or receiver to the sub, then from there to each speaker. In this setup, the amp or receiver is supplying all the power for all three speakers (Left/Right/Sub). I've had a couple of passive subs over the years and was never really impressed with their performance. Using a separate amp for the sub frees your main amp up from the need to drive the bass woofer. Then the main amp only drives the left and right speakers. I don't think you'll find many supporters of your idea to use a car amp. But hey, I've done my share of weird experiments in my day! A car battery "puts out" as much current as is drawn from it, up the the limits of the battery and the wire. What you need to find out, in order to size your power supply correctly, is the ampere draw of your amplifier. It should state that somewhere in your manual or on the amp. If not, check the fuse holder that came on the amp - it may give you an idea of the max current they designed it for. If it says, say, "5 amps" then you would need a 12-volt power supply capable of supplying at least 60 watts. Volts times Amps equals Watts. That 60 watt power supply, however, won't have the capacity to supply the spikes your amplifier might draw momentarily. In practice, I'd actually suggest a much bigger power supply but I don't know enough about car amps to make an informed recommendation. Instead of spending 50-60 bucks on a 12 volt power supply, you might want to save that money towards a used stereo amplifier that you'll be much happier with. Best of luck to you, Ross Quote Link to comment Share on other sites More sharing options...
Steve Phillips Posted February 3, 2001 Share Posted February 3, 2001 A seperate stereo amp would be much better than trying to use a car amp and power supply.The power supply would most likely emit some"noise"into the system and a good poer supply would cost enough to get a used amp. Quote Link to comment Share on other sites More sharing options...
oosting Posted February 3, 2001 Share Posted February 3, 2001 Check out places like the Salvation Army Thrift store. I found an old Sansui 100W receiver there for $8. You'd be amazed what you can find. Ed Quote Link to comment Share on other sites More sharing options...
classybum Posted February 3, 2001 Author Share Posted February 3, 2001 hmm, ok, perhaps i'll just go the regular amp route then. But this leads to another problem.. where do i find an apropriate amp? i've already got my reciever, any suggestions about where to find a good sub amp? i've seen those super expensive mono-block amps or something, does anyone make decent cheaper priced ones? DAH!! i just found sub amps at partsexpress.com and budget restraints tell me i want the 160watt into 4 ohm amp.. would that probably be enough power? eh.. probably. i'm so pumped to get started now that i've found partsexpress.com. thanks for the input though Quote Link to comment Share on other sites More sharing options...
Steve Phillips Posted February 4, 2001 Share Posted February 4, 2001 160 should be good if you don't crank really hard.I had a stereo amp driving my Kicker Comps that had 190 rms to each sub.I also had a watt meter on it and noticed one day it was highting the 200 light.These meters are slow so no telling what was really there. Now using a Carver 400 X 2 into at 4ohms and noticed something was missing.Distortion. I had very good luck using one side of my Denon amp at about 300 going to each sub.Also great job.Better too much than too little.An underpowered speaker will die faster than an over powered one,using in moderation,that is.Too little power will drive the amp to clipping,causing death. Sure you can cook a speaker driving it way too hard with excesive power. Quote Link to comment Share on other sites More sharing options...
Steve Phillips Posted February 5, 2001 Share Posted February 5, 2001 Found what you need at Sears.It will cut a perfict round hole and you could even use it to flush mount the sub. ROTOZIP SpiraCut saw.#27745 on sale for $89.99.Kinda like a router. Comes with a case,circle cutting guide,bits. Quote Link to comment Share on other sites More sharing options...
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