Dumb question about amplifiers

hd1080 · 02-01-2006, 01:49 PM

I'm in the planning stages of a car PC which will be used solely to play MP3's. I'm considering going from the line out of my sound card straight to the speaker inputs. I know this is a stupid question, but do I need an amplifier? If I do, what are some good ways to do this for cheap? Thanks.

3onDubs · 02-01-2006, 02:08 PM

I don't know if it is possible to do it without an amplifier, but I do know that it makes it a heck of a lot easier because you simply plug in the RCA's from the sound card into the amplifier. If you want a cheap amp, I have a couple for sale.....PM me if your interested.

DavC · 02-01-2006, 02:10 PM

Yes you do.

Your choices: http://indashpc.org/new/docs/Car%20C...TO%20final.htm

hd1080 · 02-01-2006, 02:29 PM

Alright, so an amp is needed...

Another question if people are up for it: I'd like to be able to select between 2 or 3 inputs for the speakers. One of these would be the stock car stereo. The other would be the PC, and the third (if possible) would be a pair of RCA jacks. I'd use the basic components of a selector from radio shack to do the job, but would it work to have the speaker out on the stereo go in as one input, the PC (followed by the amp) to another input, and then the RCA jacks to another? I'm guessing the RCA jacks are going to need an amp too, huh? Also, how could pan & front/back selectivity work? Maybe I need to think this through some more...

DarquePervert · 02-01-2006, 02:36 PM

Yeah, you do need to think this through a bit more.
If you want to select between different audio inputs, you can get selector switches for that very purpose.

If you have a headunit with AUX-in, why don't you just run the audio form the PC through the headunit? Then you don't need an amplifier. Seems like a more cost-effective way to go.
You can still use the audio selector witht he oputput going into the headunit and the various audio sources as inputs to the selector.
Then you select the AUX on your headunit and you'll get audio from whatever source you have selected.

3onDubs · 02-01-2006, 02:39 PM

Quote: Originally Posted by hd1080

Alright, so an amp is needed...

Another question if people are up for it: I'd like to be able to select between 2 or 3 inputs for the speakers. One of these would be the stock car stereo. The other would be the PC, and the third (if possible) would be a pair of RCA jacks. I'd use the basic components of a selector from radio shack to do the job, but would it work to have the speaker out on the stereo go in as one input, the PC (followed by the amp) to another input, and then the RCA jacks to another? I'm guessing the RCA jacks are going to need an amp too, huh? Also, how could pan & front/back selectivity work? Maybe I need to think this through some more...

Why do you need 3 inputs? If you can stick with two inputs (head unit and pc), than you can use the aux in on your head unit to connect your pc audio. Then you can run one set of RCA's from your head unit to your amplifier. If your head unit is a stock car head unit, than it might not have the aux in location on the back of it. In that case, I would suggest either ditching the head unit completely, or upgrading to an aftermarket head unit that has aux in terminals.

You do not want to use an audio selector before your amplifier. This will introduce noise into your system and is definitely overkill. As far as the fade/balance settings goes...if you have a four channel amplifer, than you will dedicate one channel to each of your 4 car speakers. Then you can still use your head unit to control the fade and balance. If you go with a two channel amp, than you have to sacrifice either fade or balance. Most people would rather sacrifice the balance since you always want both sides playing evenly.

Hope that helped a little.

3onDubs · 02-01-2006, 02:41 PM

Quote: Originally Posted by DarquePervert

Yeah, you do need to think this through a bit more.
If you want to select between different audio inputs, you can get selector switches for that very purpose.

If you have a headunit with AUX-in, why don't you just run the audio form the PC through the headunit? Then you don't need an amplifier. Seems like a more cost-effective way to go.
You can still use the audio selector witht he oputput going into the headunit and the various audio sources as inputs to the selector.
Then you select the AUX on your headunit and you'll get audio from whatever source you have selected.

Good point....if you have aux in on your head unit, then you don't even need an amplifier

hd1080 · 02-01-2006, 02:51 PM

Thanks for the input guys; this has been helpful. Unfortunately my car stereo does not have an AUX input. :-/ While it seems it would be easiest to buy one, I'm hesitant to, mostly because of cost. Plus that would void my reasoning to build a car PC. Although I suppose an amp would be up there in costs too...

gnomad · 02-01-2006, 03:46 PM

Quote: Originally Posted by hd1080

I'm in the planning stages of a car PC which will be used solely to play MP3's.

Then why bother with the trouble and expense of a PC when an iPod will do the job just as well?

Quote: Originally Posted by hd1080

I'm considering going from the line out of my sound card straight to the speaker inputs. I know this is a stupid question, but do I need an amplifier?

If you want to be able to hear anything, yes.

-g.

hd1080 · 02-01-2006, 03:57 PM

Mainly because it's just not as much fun. I want the challenge of building my own. Plus, with a car PC I can customize the interface, and there's room for expandability, like ODB-II if I ever go that route.

I did just remember that I have a very old but high end head unit with an aux input. I'll see if I can't tuck that in the back and use it as a makeshift amp for the PC... I don't want to use it as the main head unit because the interface is shot, but the electronics inside all seem to work decently.

DavC · 02-01-2006, 04:20 PM

Why don't you run the HU through the PC (link it to a line-in on the sound card) if you are not using its internal amp.

RawsonDR · 02-01-2006, 10:19 PM

Quote: Originally Posted by DavC

Why don't you run the HU through the PC (link it to a line-in on the sound card) if you are not using its internal amp.

If he has no amp, then the headunit must be doing it. The RCA jacks, though, could go into the computer assuming he wanted them available for mp3 players and other line level audio sources. Whether or not noise is introduced, I dunno.

billmee · 02-02-2006, 09:12 AM

Quote: Originally Posted by hd1080

Thanks for the input guys; this has been helpful. Unfortunately my car stereo does not have an AUX input. :-/

Is it a stock HU ?

You can get an adapter for a lot of different stock HUs that pretend to be a cd changer. This would allow you to use your HU as an amp and retain fade/balance control.

Check Crutchfield.

hd1080 · 02-02-2006, 12:22 PM

It is a stock HU and this does seem like the ideal solution. There is such an adapter at Crutchfield, but it seems to suggest that you need an AUX button on the radio. I'll look into this some more though.

hd1080 · 02-02-2006, 12:30 PM

Oh man, these boxes look pricey... Is there a way to hack the wiring to send a signal straight to the HU?

(I've got a 1997 Saturn SL2, by the way)

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