Input to Amp question *Newbie Alert*

**Danger Powers** · 02-20-2002, 11:49 PM

Hi,

I'm putting together a system at the moment, all second hand parts. I have a sharp laptop with a 5gig drive, Win ME (stripped down), and a custom MP3 player I programmed in Delphi. This will be powered by a custom dc/dc convertor. I already have a clarion head unit (no aux in, but line level outs) and have purchased a couple of amps (one for the mains and one bridged for the subwoofer I'm going to squeeze into the parcel shelf on my MX5 - Miata).

Ok all this I planned out and its going pretty well so far (nice cheap laptop with broken screen - and blown mobo fuse fixed in a few minutes) but I didn't think about how I'm going to mix the MP3 sounds and CD Header sounds to the inputs on my amps. The Annhilator is only a 2 channel but high powered and supposed to be excellent (I'm going to use this to drive the sub) I haven't recieved the 2nd amp yet, bought spur of the moment from an auction site) but I think this is 4 channel - I presume this means 4 output channels? So how do I mix the signals without damaging either head or laptop - does it matter at line level? Or do I need to put some diodes or something in the lines?

Sorry about this huge novel, but I thought I'd try and introduce myself, I've been lurking for a few weeks, since I decided I needed more tunes in my car (for the sunny days when the tops down).

Thanks in anticipation

**Aaron Cake** · 02-21-2002, 08:15 AM

First, search. This question has been answerd once a week for the past three years.

Second, connect the computer to the Aux inputs on your headunit. If you do not have Aux inputs, you will either need to get another head unit or go some other way (FM modulator, FM transmitter, etc.)

**Danger Powers** · 02-21-2002, 02:33 PM

Hi Aaron,

I did search, as you know the search function was down because it needed to be indexed.

No aux inputs, either I didn't explain properly or you've misunderstood. I don't want to run the laptop through the head unit. I want to run both the headunit and laptop through the amps. I don't want to induce more noise by running through the headunit or using an FM modulator. Therefore I need a mixing unit of some kind? Perhaps I'll dig my Op Amp books out and make something.

Thanks

**g60** · 02-21-2002, 03:58 PM

Just use a 2-1 rca wire, and turn down the headunit when you use the laptop. You can find them at radioshack.

**Danger Powers** · 02-21-2002, 04:20 PM

Thanks mate, just wanted to be sure that line level voltages from the laptop wouldn't damage the output on the headunit and vice versa..... minimal voltage but thought I'd check.

**MP3DUB** · 02-21-2002, 09:26 PM

this is entirely off topic, but your icon looks veeeery familiar g60

**g60** · 02-21-2002, 11:46 PM

Originally posted by MP3DUB
this is entirely off topic, but your icon looks veeeery familiar g60

Haha

I'm so original, aren't I

**Danger Powers** · 02-22-2002, 02:47 AM

Hey! Stop stealing my thread

**Aaron Cake** · 02-23-2002, 03:07 PM

A Y cable would work fine, but there are passive mixer boxes available that will do a much better job of it. But the voltages are compatible regardless.

Oh, and the search should be working now.

**Danger Powers** · 02-23-2002, 03:18 PM

Thanks, I got a couple of adapters yesterday and the second amp. Amp no.2 is a sony 4 channel in 4 channel out pre-xplod though and quite small, although its supposed to be 20 Watts RMS per channel - I think I'll probably bridge this for the subs and use the Annihilator for the mains (this amp weighs about 2 tonne and is the size of a large suitcase)...

Still needed for the project is a DC/DC convertor that will supply 22 volts at 3 amps, a LCD 8 x 20 serial (the laptop has no parallel or serial ports but I've just picked up a usb-serial convertor cheaply) and a v.small keypad - its got to fit under my ashtray, my car is a softtop and the top is nearly always down, I don't want to give any thieves the idea anything special is in the car. I suppose a remote is the other way but I'm hopeless at losing things!

Thanks
Danger