REVscene Automotive Forum - **NEW** Car audio FAQ !

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**NEW** Car audio FAQ !

Well, this is a new, updated car audio FAQ. The old one was filled with dead links and dated info. If you can't find it here a quick SEARCH will most likely net you a good answer.

REVSCENE CAR AUDIO FAQ version 2.0

ohms

Quote:

An Ohm is a measure of resistance and impedance, which tells you how much a device will resist the flow of current in a circuit. For example, if the same signal at the same voltage is sent into two speakers - one of which is nominally rated at 4 ohms of impedance, the other at 8 ohms impedance - twice as much current will flow through the 4 ohm speaker as the 8 ohm speaker, which requires twice as much power, since power is proportional to current.

Basically 2 ohms puts out twice as much power as 4 ohms assuming you have the same amp and assuming the amp can handle 2 ohms.

A good website for looking how to wire up an amplifier to your subs:

http://mobile.jlaudio.com/support_pages.php?page_id=145

Channels

Quote:

If you only have one line-level set of outputs available, and wish to power two sets of speakers from a single amplifier, you may be able to save money by purchasing a two channel amplifier which is stable to two ohms rather than spending the extra money for a four channel amp. If you do this, however, you will be unable to fade between the two sets of speakers (without additional hardware), and the damping factor of the amplifier will effectively be cut in half. Also, the amp may run hot and require fans to prevent overheating. If you have the money, a four channel amp would be a better choice. You would need to add a dual-amp balancer in order to maintain fader capability, however, but it is more efficient than building a fader for a two channel amp. If you wish to power a subwoofer or additional speakers as well, you may want to purchase a five or six channel amp.

What size speakers fit in my car? This is one of the better fitment sites out there:

http://www.mobiletoys.com/partners/jbl/index.asp

Where can I get carpet/vinyl

Most car audio stores carry carpet and alot carry vinyl too. Fannys Fabric also carries Vinyl and Carpet and will be alot cheaper to buy. Quality varies alongside price so don't cheap out if you want it to look amazing.

Setting Gains [list=1][*]Disconnect all signal inputs to the amp [*]Turn all sensitivity adjustments as low as possible [*]Turn head unit on to around 90% volume (not 100% or else you'll have head unit distortion in there - unless you've got a good head unit) with some music with which you're familiar, and with EQ controls set to normal listening positions [*]Plug in one channel's input to the amp [*]Slowly turn that channel's gain up until you just start to notice distortion on the output [*]Turn it down just a wee little bit [*]Disconnect current input [*]Repeat steps 4-7 with each input on your amp[*]Turn off head unit [*]Plug in all amp inputs, and you're done [/list=1]

If by some chance you do have an oscilloscope (and preferably a test disc), you do essentially the same thing as above, except that you stop turning the gains up when you see clipping on the outputs of the amplifier.

Note that if you are paralleling multiple speakers on a single amp output, you need to set the gains with all of the speakers in place, since they will be affecting the power and distortion characteristics of the channel as a whole.

Power Wire Sizes

This site has a chart of the size of power wire you should use.

http://www.the12volt.com/info/recwirsz.asp

How do I wire my subs? - As posted by Akdiplomats

Subwoofer wiring help

Installing a Capacitor

Quote:

Originally posted by orgasm_donor
Charging is the key here. You will need a resistor to charge it so you don't weld/blow sh!t up/catch yerself on fire. You can also use a 12 volt test light instead. I would also suggest a voltmeter to monitor your charging.

Connect your optional voltage meter to the pos + neg of the cap. Hook up ground. Now, instead of hooking up the positive directly to the battery, you will need to put a resisitor in between (or test light). When you connest this, the test light will light up bright and the voltmeter will start counting up from 1 v, climbing in .02-.04 increments. As the voltage climbs, the light on the tester will dim.

Now, if you don't have a voltmeter, just watch the test light dim until it goes right out - that'll be fine. With the voltmeter, I just wait until it gets above 12 volts so it will be safe to connect directly.

Connections. POS to the battery (fused) and NEG to ground or ground distribution block. When I connect my amps, I go NEG fromthe amp to NEG from the cap and I go POS from the amp to POS from the cap. I generally fuse this last connection for safety. There are other ways you can connect a cap as well. BTW, make sure the distance from cap to amp is as short as possible.

A great FREE site that gives you wiring colours for alarms:

www.bulldogsecurity.com

Misc. Links
Kick Panel Tutorial

Simple Fiberglass Sub Box Tutorial

Subwoofer and Enclosure tutorials

Some installation techniques

Please post other current links for installs, tutorials and other misc. stuff below.

OD, what is damping factor?

quote:
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If you only have one line-level set of outputs available, and wish to power two sets of speakers from a single amplifier, you may be able to save money by purchasing a two channel amplifier which is stable to two ohms rather than spending the extra money for a four channel amp. If you do this, however, you will be unable to fade between the two sets of speakers (without additional hardware), and the damping factor of the amplifier will effectively be cut in half. Also, the amp may run hot and require fans to prevent overheating. If you have the money, a four channel amp would be a better choice. You would need to add a dual-amp balancer in order to maintain fader capability, however, but it is more efficient than building a fader for a two channel amp. If you wish to power a subwoofer or additional speakers as well, you may want to purchase a five or six channel amp.
--------------------------------------------------------------------------------

Quote:

Originally posted by Soundy
Another amp wiring tip!

Okay, it goes for wiring up just about anything in your car: if you're wiring something inside the passenger compartment directly to the battery, always, ALWAYS put a fuse in the line AT OR NEAR the battery... or more specifically, before the wire goes through the firewall.

Within 18" of the battery is the rule of thumb and IASCA regulation as well.

Quote:

Originally posted by orgasm_donor
Within 18" of the battery is the rule of thumb and IASCA regulation as well.

if it's going to be that long, make sure there's some sort of mechanical serurement for that 18" length of wire (ie. zip tie it). if the wire somehow falls out of the fuse holder then lands on the chassis, it could pass hundreds of amps until the wire or the battery melts

http://en.wikipedia.org/wiki/Damping_factor

Quote:

Originally Posted by Guy_LikeWhoa (Post 3912600)

thats a lot of help thx

Is there anyone know who can fix/replace electronic component in a car amp? I have well setup an amp running but no output. I suspect it's a power issue. Anyone play around with transistor, cap or resistor component definitely know how to fix it.

Hi this car is very nice. It's very comfortable while driving.

Quote:

Originally Posted by jasongrover (Post 8293479)

Hi this car is very nice. It's very comfortable while driving.

Cool story bro
But does it come in interesting?

Does Soundsgood still do a trade in program? I have a sub and amp i want to trade for a credit for a single din deck.

Quote:

Originally Posted by maxx (Post 8657377)

Does Soundsgood still do a trade in program? I have a sub and amp i want to trade for a credit for a single din deck.

We can hook you up in our Coquitlam facility. Ask for Mike