CarPC sound through car speakers without a headunit?, how?

**raypsaliga** · 05-16-2004, 07:12 PM

Originally Posted by hifiguy

although i didn't start this thread, i am planning to have a HUless system.

I will be using an external usb soundcard, M-Audio's Sonica Theater, to directly feed audio into two amplifiers. The first amp will be a JL Audio 450/4 that will accept stereo front and rear inputs, and a Jl Audio 500/1 amp that will accept the .1 channel from the souncard (using 1/8" to rca to y-spliter in order to turn the mono signal into 2 mono signal since the amp preferes 2 identifcal mono feeds). The great thing is that the soundcard software will downmix the 7.1 to 4.1 and lets you define the crossover frequencies. Both the amps also have crossovers built in for even more adjustment.

But turning on the amps still remains cloudy. Yes, both amps accept +12V for the remote trigger but I wonder if I can hook up both amps in series (the remote signal that is) so that only 1 on/off switch is needed instead of two.

I will be using a Lilliput screen to control the volume up front. Any of this make any sense?

do you want a manual on off switch, or for the amps to only be on when the pc is? if you want them to be on/off with the pc you could run the on/off wires from the amp into a molex connector from the computer psu, (yellow is 12v, the black is gnd, red is 5v), because they are only powered while the computer is on, therefore the amps will know when to be on and off. this way you are doing exactly what the HU would do, the amp won't know the difference. catch my drift?

**hifiguy** · 05-17-2004, 12:19 AM

yep, i know what you are saying. i talked to a car audio friend and his only warning for hooking up the amps and pc to turn on together was the following: make sure the pc is on before the amps turn on. reason being that if the amps are on, and then they receive a signal telling them to turn on again, the sound will be distorted.

any thoughts on this? wire a seperate on/off switch?

**thepogcbr900rr** · 05-18-2004, 06:02 PM

Originally Posted by raypsaliga

you could wire the on/off line of the amp to the 12v rail of the computer psu, that way it shuts down with the computer.

Im going to use

for my rca outs.

What if you are using a laptop as your carputer, then where and how would you hook up the blue remote wire from the amp??

Since im going to leave my carputer on with constant power going it, and in hybernation mode when im not in my car....

Maybe find a way to have the amp turn on when the car is turned on with something that only comes on when the car is on.

What about wiring it to where the acc in the radio is?

Any suggestions?

After

i found out that you can just wire the blue remote wire to a acc wire ( yellow ) in the car that would be for the HU, just make sure that the carputer gets powered on BEFORE the amp gets the power so it wont make a loud pop from the soundcard.

Being that my laptop will have a constant power from the dc adapter, I just have to make sure that its powered up before i turn the car on. OR just leave it always in hybernate mode, and it will always be one before the amps are.

**Scouse Monkey** · 05-18-2004, 06:26 PM

Couple of ideas, dunno if they are any good - people who know more please comment:

Can't you just use the ACC line for turning on the amp (but not powering it)??

And for laptop could you use a small relay to switch 12v from the car triggered by something that turns on with the laptop - eg serial port 5v or unused pc card power ????

**raypsaliga** · 05-18-2004, 08:08 PM

Originally Posted by Scouse Monkey

Couple of ideas, dunno if they are any good - people who know more please comment:

Can't you just use the ACC line for turning on the amp (but not powering it)??

And for laptop could you use a small relay to switch 12v from the car triggered by something that turns on with the laptop - eg serial port 5v or unused pc card power ????

I'm not too sure on this one either. but what about cranking, if the acc line drops below 12v during cranking, will the amp register this as an off? and will this be a big deal if it does? the amp might go off and then back on when the power comes back up. this might happen if you are listening to music with the car off, and then turn it on. I'm guessing it wouldn't matter. Monkey has a good idea though. Also, the acc line I've read can hit up to 18v during normal operation, how will this effect the amp?

**raypsaliga** · 05-18-2004, 08:12 PM

Originally Posted by hifiguy

yep, i know what you are saying. i talked to a car audio friend and his only warning for hooking up the amps and pc to turn on together was the following: make sure the pc is on before the amps turn on. reason being that if the amps are on, and then they receive a signal telling them to turn on again, the sound will be distorted.

any thoughts on this? wire a seperate on/off switch?

sorry about the no responsiveness. i've been busy... well your friend probably knows better than I do, so I'd listen to him over me. If what you discribed happens, will it damage the amps? if not, you could always try your setup to see, if so, take the safe route and do a seperate switch..

ray

**hifiguy** · 05-18-2004, 11:32 PM

Originally Posted by raypsaliga

sorry about the no responsiveness...take the safe route and do a seperate switch..
ray

no worries, yeah think i will do a seperate switch. this will also be a summer project so i'll post updates as it comes along.

**fraganic** · 05-19-2004, 03:59 AM

Originally Posted by thepogcbr900rr

Im going to use

for my rca outs.

Ummmm, what is this?

**thepogcbr900rr** · 05-19-2004, 04:10 AM

Originally Posted by fraganic

Ummmm, what is this?

Its a usb soundcard allowing you to put your sound from the computer to a external amp for speakers and a sub

**Mears** · 05-25-2004, 02:20 PM

If you use a minijack y-splitter from radio shack to get two RCA plugs, how would you achieve stereo sound? Wouldn't it just be mono?

Also, what if your sound card used digital out? Would you need to buy a standalone DAC? I thought that was one of the benefits of using a HU.