How do you hook up an amp or preamp(are those the same thing?) ?

masch · 11-17-2003, 10:05 AM

Hola

So due to problems with my head unit, (http://www.mp3car.com/vbulletin/show...t=17372&page=1)
I think I will be disposing of it tomorrow. Now, I just got this idea about a head unit-less setup. I think I may have read that somewhere on this site or another about almost a year ago. Anyway I searched for "amps" and it turned out 20 pages worth of stuff and I dont think I can find the old posts, especially not since I'm using a gprs connection atm and I get charged by the kb's.

Will this setup work?

Epia C3 800 built-in sound (stereo) - homemade stereo to RCA male cable - preamp - RCA cable - 2 channel amp - speaker cable - crossover connectors - speakers/tweeters.

I was told that I cant use 4 speakers on my 2 channel amp if I get the amp because the amp will burn if I do that. Does this happen often?

Will this generate a lot of noise signal (like engine noise)?

Where should a ground loop isolator go if I intend to get one?

Can I use the homemade stereo plug - RCA male cable or do I need a special one to connect the sound card to the preamp?

Which wire length should I minimize if I intend to minimize noise? Can I put the preamp at the dash and the amp at the trunk? At which stage is it most susceptible to noise?

Also, if I were to open my head unit, where should I look for for the built-in amp or preamp just in case I wanna fool around with it? I looked but not much make sense for me.. there arent any legible labels or anything.

I guess this should cover all the n00bie questions about getting sound in the car. Perhaps in the future someone can direct similar questions to this thread.

btw, excuse me for my english. I'm not a native speaker.

THanks in advance. Disposing my head unit was an idea from dodgecummins and sunglassesron. =P

DodgeCummins · 11-17-2003, 04:21 PM

I would look at the Amps hook up manual. Look at the ohms for output, check your speaker ohms.

The basic answer is this. Lets say your Amp can handle from 2 to 8 ohm speaker setups.

Now someone help me if I screw up the math.

If you have 2 8ohm speakers and hook them in series (assuming the same wattage speakers) You will have 16 ohms on the speakers...outside the range for the amp.

Lets say you hook them up in parallel...(both speaker + to the + on the amp, both speaker - to the - on the amp)

now some math 1/((1/8)+(1/8))=1/(.125+.125)=1/.25=4

So with 8 ohm speakers in parallel, you are at 4 ohms...That matches the amp.

Now if your speakers are 2 ohm, then you cannot run them in parallel, but mathmatically you could run them in series...I don't know if that is a good idea or not.

For the rest of your questions...it depends. But the cables you want the shortest are the line level outputs from the computer to the amp/preamp. The speaker wires can be very long.

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