Frequently Asked Car Audio Questions - Audio & Electronics Forum

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Frequently Asked Car Audio Questions
Wednesday, February 15, 2006 8:07 AM
Subwoofers

Let's start with the basics. Subwoofers play low notes. Subwoofers have what's called voice coils. Voice coils cause a magnetic field when energised, hence moving the cone. You can have a sub with a few different configurations, typically SVC and DVC. Voice coils will have an impedence, such as 4 ohm and two ohm. For some specialty speakers, they'll have 6 ohm voice coils.

Ohms Ohms are a measurement of resistance. For amplifiers, when you put more of a load, the distortion increases. Keep that in mind.

SVC stands for Single Voice Coil.

DVC stands for Dual Voice coil. Dual voice coils MUST have both voice coils wired up, either in series or parallel.

Parallel: Both positive leads are wired together, both negative leads are wired together, and leads go out to your amp or another speaker like so:



You'll notice that the speaker is a dual 4 ohm voice coil sub, and wired in parallel. When wiring voice coils in parallel, take the impedance of the voice coils, these being 4, and divide it by 2. That'll give you your impedence. For this example, your impedence will be 2 ohm.

Series: Positive from Coil A is jumpered to the Negative of Coil B. The negative from Coil A and Positive of Coil B go out to your amp or another speaker like so:



You'll notice that the speaker is a dual 4 ohm voice coil sub, and wired in series. When wiring voice coils in series, take the impedance of the voice coils, these being 4, and double it. That'll give you your impedence. For this example, your impedence will be 8 ohm.

The most common dual voice configurations are dual 4 ohm and dual 2 ohm. A single dual 4 ohm sub can be wired to 8 ohm or 2 ohms. A single dual 2 ohm sub can be wired to 4 ohm or 1 ohm. Two dual 4 ohm subs can be wired to 4 ohm or 1 ohm, and two dual 2 ohm subs can be wired to 2 ohm or 1/2 ohm.

Amplifiers

Amplifiers come in many shapes, sizes, colors, makes and brands. We'll do the most common ones. There are a few types. Class A/B amps are usually good for 2 ohm stereo or 1 ohm mono. Class D, X, Digital, etc... Are usually monoblocks and good for 2 ohms or less.

MAKE SURE TO CHECK WITH YOUR AMPLIFIER MANUFACTURER TO SEE WHAT LOADS YOU CAN OR CANNOT PUT ONTO YOUR AMP AND PROPER WIRING

Monoblock: Monoblocks are a 1 channel amp. Sometimes they have 2 sets of RCA's in, sometimes only one. Monoblocks are used primarily for subwoofers. These are your Class D, X, Digital, etc... amps. Most are good to 2 ohm. Some are good to 1 ohm, and very few are good to 1/4 amp. Some monoblocks are called High Current. They'll play with higher voltages to them, usually 14.4 volts.

Two Channel Amps: These are a stereo amps, a left and a right channel. Most stereo amps are good for 2 ohms stereo, and most two channel amps can be bridged to play a subwoofer, and are usually good to 4 ohm.

Four Channel Amps: Four channel amps are used to run 4 sets of speakers, usually front/rear. They have independent gains on the front and rear. Some 4 channel amps can be bridged to 3 channels or 2 channels. Some can do 2 ohm stereo, and those that can be bridged to 3 or 2 channels can usually run a 4 ohms.



Tuning your amps

The simplest and easiest way to get your amps tuned is to follow these simple instructions. Grab your digital multimeter and a calculator.

output = square root (watts * ohms)

First, take your amp's wattage at load. For example, let's say your amp does 300 watts rms at 4 ohm. That would be 1200. Take the square root of that and you'll get 34.64101615137755, so let's say 34.64. Take your multimeter and set it to AC volts. Disconnect your speakers from the amplifier. Grab this file here - http://www.realmofexcursion.com/audio/testtones/20Hz_to_120Hz.mp3 - and burn it to a cd. Turn your eq's off, turn your volume to 3/4 of the way up, hook up your multimeter to the + and - of the speaker outputs and play the sine wave. Your peak voltage should hit at the beginning of the cd - adjust your gain till it reads the voltage you figured out earlier, then leave it. Hook your speakers back up, and your gain is set. Don't turn your volume up above this volume or else you'll clip.


Clipping Since your speaker outs are AC voltage, you have an AC wave, with a peak and a valley, usually symmetrical. When your signal is clipped, you'll have an extreme valley or peak, deadly for speakers.

Storage devices/Energy makers

Capacitors Everyone gets the wrong idea about capacitors. THEY ARE NOT A BATTERY. They do store energy, but for car audio, they're used to fill valleys and level out peaks when you have a long bass note. They are used to clean the signal only.

Battery Batteries, without them, your car won't start. Yellow top optimas and deep-cycle batteries are wonderful for car audio. They have higher storage than regular batteries, and they can be discharged and recharged safely. They are also a closed battery, and can safely be put inside a trunk without having fumes.

Alternator Our stock alternator puts out around 75 amps at an idle and 120 at around 2000 rpm. They do make higher output alternators but MAKE SURE YOU CHECK and see what it puts out at an idle. Some will put out stock at an idle and make max at 3000 or 4000 rpm. Make sure the amperage is higher at an idle or else you could cook your alternator, battery, or both.

The BIG 3

This post here - http://www.j-body.org/forums/read.php?f=4&i=117446&t=113629#117446 - written by Wysiwig, is a wonderful resource on the Big 3. You'll notice less dim when the bass hits, quicker starting, and less strain on electrical devices.

This sums it up. If you should have any technical questions, myself, Wysiwig, Soundsgood, Lash, n8ball2013, cavi sedan ls, cavi in kc, unholysavage, and sweetnloud can help you out. If I forgot anything or anyone, I apologise.




Re: Frequently Asked Car Audio Questions
Wednesday, February 15, 2006 5:08 PM
nice job!




Re: Frequently Asked Car Audio Questions
Wednesday, February 15, 2006 5:51 PM
Thanks brother, it's getting old having the same questions asked over and over again, so I simplified things, and of course mentioned you brother



Re: Frequently Asked Car Audio Questions
Thursday, February 23, 2006 7:40 AM
nice


--------------------------------------------------------------
Offical dealer for the following-

SOUNDSTREAM
DB LINK
DB DRIVE
PANASONIC
GARMIN
ROSEN
SCOSCHE
XE DESIGNS
SOUNDGATE
PAC
LITEGLOW

Re: Frequently Asked Car Audio Questions
Sunday, February 26, 2006 8:16 AM
Subwoofer Enclosures:

As there are different types and shapes of subwoofers, there are different enclosures.

Sealed: - Your sealed box is probably the easiest (and most forgiving type of box) to create. This enclosure is totally sealed.


Ported: - A ported box has a port either round, square, or a vent. If built properly, the low-end response is greater than a sealed box. Downfall with this box is a much larger size than a sealed box.


Bandpass: - Those pre-fab bandpass boxes that you see at your local audio shop are utter crap. They are WAY too small for a proper bandpass. A 4th order Bandpass has the rear section of the subwoofer sealed, and the front area of the subwoofer ported. A 6th order Bandpass has the front and rear area ported. Like ported boxes, bandpass boxes are large. Bandpass boxes are wonderful since you can set the response curve with them, and you also gain db's, just like a ported box.


Isobaric: Isobaric boxes feature subwoofers that are front to back of each other. One advantage of them are they can use a smaller box than a conventional box using both drivers. However, they aren't nearly as loud as a traditional ported, sealed, or bandpass box.






Re: Frequently Asked Car Audio Questions
Sunday, February 26, 2006 6:20 PM
glad this got stickied.. good info



Re: Frequently Asked Car Audio Questions
Tuesday, February 28, 2006 4:15 PM
Thanks brother, now if people will read it, maybe our lives will be easier.



Re: Frequently Asked Car Audio Questions
Tuesday, February 28, 2006 4:26 PM
a wider selection of test tones all of them are recorded at 0db
http://kan3.freeservers.com/





Re: Frequently Asked Car Audio Questions
Wednesday, March 01, 2006 2:01 PM
okay i have a 2001 cavalier and i need to know what all the wires that go into my factory amp are i am trying to bypass the amp and hook the rear speakers up that way any feed back would be very much appreciated
Re: Frequently Asked Car Audio Questions
Wednesday, March 01, 2006 4:49 PM
I would like to thank John Lenko for the wiring colors and polarities.

Radio Wiring

Off the radio harness:

Left front +: Tan wire, pin A8 (to E2 on amplifier)
Left front -: Gray, pin A9 (E3)
Right front +: Light Green, pin B11 (F1)
Right front -: Dark Green, pin B10 (E1)
Left rear +: Brown, pin B8 (E6)
Left rear -: Yellow, pin B9 (E7)
Right rear +: Dark Blue, pin A11 (E5)
Right rear -: Light Blue, pin A10 (E4)

On the amplifier harness:
(inputs are as noted above), outputs:

Left front tweeter +: Black wire, pin E13
Left front tweeter -: Yellow, pin E14
Left front speaker +: Dark blue, pin E15
Left front tweeter -: Light blue, pin E16
Right front tweeter +: Light green, pin F2
Right front tweeter -: Purple, pin F3
Right front speaker +: Orange, pin F7
Right front speaker -: Dark green, pin F6
Left rear tweeter +: Tan, pin F15
Left rear tweeter -: White, pin F16
Left rear subwoofer +: Dark blue/white, pin F5
Left rear subwoofer -: Light green/black, pin F4
Right rear tweeter +: Red, pin F14
Right rear tweeter -: Tan, pin F13
Right rear subwoofer +: Light blue/black, pin F11
Right rear subwoofer -: Dark green, pin F10

Note that that includes RPO radio code U85.. which is the Monsoon radio I think.. so.. if you don't have that.. you won't see ALL those wires on the amplifier.. you'll just have wires from the radio straight to the speakers (esp. in the front)... sure fire way to check - look at the colours of the wires to the speakers themselves.

------------------------------------------------------------------------------------------------------------------------



Bypassing the factory amp

Let's say you got yourself a new shiny headunit and you have the Monsoon system, or that factory Monsoon doesn't put out enough oomph for your new speakers. Let's get a hacking on that harness, shall we?


To bypass the factory Monsoon amp using an aftermarket radio

NOTE: To be able to replace the factory amp and radio at a later date, be sure to leave some slack on your harness

Using the wiring chart up top, match up both of the outputs for each speaker to the input of the amp. For example, for the left front +, you'd wire the tan wire from the input side of the amp to the black AND the dark blue of the output of the amp. Confusing? Thought so. Most people replace the stock speakers anyways, so off to plan B.

Bypassing the factory amp using an aftermarket deck AND aftermarket speakers to the Monsoon system
Aftermarket speakers, they love you long time. Wire a set of output speaker wires to the corresponding input speaker wires. For example, I'd want to use the tan input wire for the left + speaker, and wire it to the dark blue, so it would correspond with the left + side.

Adding an aftermarket 4 channel amp to the Monsoon system
Most of your 4 channel amps will have low level and high level inputs. Wire the inputs up top to the corresponding inputs on your 4 channel amp. READ the instruction manual to which wire on your amp matches with the INPUT wire mentioned up top. As for wiring it to speakers, see Bypassing the factory amp or Bypassing the factory amp using an aftermarket deck AND aftermarket speakers to the Monsoon system.

WARNING WARNING WARNING WARNING WARNING WARNING
If you do NOT understand any of this, print this out and take it to a PROFESSIONAL (note - Barf Buy and Circus City are NOT professionals) to get installed



Re: Frequently Asked Car Audio Questions
Thursday, March 02, 2006 1:04 PM
I thought this would be a good place to put this.



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--------------------------------------------------------------
Offical dealer for the following-

SOUNDSTREAM
DB LINK
DB DRIVE
PANASONIC
GARMIN
ROSEN
SCOSCHE
XE DESIGNS
SOUNDGATE
PAC
LITEGLOW


Re: Frequently Asked Car Audio Questions
Sunday, March 05, 2006 4:03 PM
Diamond Audio

Sorry just had to add that I didn't see it.





Re: Frequently Asked Car Audio Questions
Thursday, March 30, 2006 9:03 AM
Materials for building a Fiberglass Box

I'm pulling this from another post I just made.


I get my fiberglass materials from US Composites. They are reasonably priced, and have great quality materials. Their shipping is top notch. I believe everything I've always ordered was received within 3 days of the order (most of the time my card hadn't even been billed yet).

There are of course other places to get your materials from. I don't have experience with anything other than what I have listed here and Bondo brand. I'd stay away from Bondo. For a few pennies more, you'll get much better supplies from US Composites.

You'll want a few things if you'll be doing a fiberglass and MDF box. Here's a suggested shopping list:


Home Depot/SLowes

* 3/4 in. Medium Density Fiberboard. 1 Sheet should be plenty.
* Wood Glue. I'd go with the Urethane glue (the name scapes me at the moment)
* Two 1 lb. boxes of 1 1/4 in. screws. You may not need both, but forking over $3 more initially means you don't have to make a second trip just in case.
* Professional Respirator. It's the 3rd from the bottom in that link. Don't cheap out here. Buy yourself a good respirator, the one with a cartridge on either side of the mask (makes you look like Darth Vader... wait did I just reference Star Wars... I've only seen one movie. God help me!) You're lungs will thank you in the end
* Latex Gloves. Fiberglass resin is a bitch to get off your hands.
* Acetone. If you want to clean your brushes. I prefer to get throwaway brushes and toss them out after I've laid down some resin. It's up to you.
* Tee nuts and screws to go with them (with Allen style heads). This is for security. Most break-ins that result in stolen subs are due to the fact that the person used a regular Phillips head screw. $5 is nothing to protect your $100 subs.
* Drill Bits. Get the size you need for your screws. PREDRILL MDF and your life will be a lot easier. Get at least 2-4 bits that you need in your size. It's too easy to break small bits.
* Counter Sink. This is so your screws will sit flush with your box. It's a wonderful little tool that costs very little, and if you ever do any woodworking at all, you'll be glad you have it in your tool box.

US Composites

* Fiberglass (polyester) resin. I usually get the B-440 , but the 435 would work for stereo enclosures. This stuff has a shelf life, so don't buy the 5 gallon barrel if you only need one for now.
* Fiberglass Cloth or Fiberglass Mat. Chopped Strand Mat is usually enough for stereo enclosures.
* MKEP. This is what reacts with the resin and causes it to cure. If you don't have much experience with fiberglass, go ahead and pick up some extra MKEP b/c you will likely go through that bottle they supply with your resin.
* Brushes. They have lots of brushes in their supplies section. I'd buy a box or two.
* Fillers. You'll at least want the a good chopped strand filler (Duraglass) as well as a plastic filler (feather-rite). You may also want to consider the glazing putty (Evercoat).

Good luck






Re: Frequently Asked Car Audio Questions
Thursday, March 30, 2006 9:10 AM
I forgot to add (edit button please):

You'll need tools obviously:
Palm/Orbital Sander, Circular or Table Saw, Jig Saw, and a Drill. You'll also need sandpaper to sand the fiberglass down, and fleece or other stretchy cloth. For the Fillers, you'll want spreaders to spread the stuff and tounge depressers/popsicle sticks work to mix it.

I'm sure I'll find more to add later






Re: Frequently Asked Car Audio Questions
Thursday, April 06, 2006 9:28 AM
I have a question about RCA wires... are the real expensive sets for say like $60 much better then a cheap set for $20??



Re: Frequently Asked Car Audio Questions
Thursday, April 06, 2006 3:58 PM
Blake Matthews wrote:

I have a question about RCA wires... are the real expensive sets for say like $60 much better then a cheap set for $20??

not usually


--------------------------------------------------------------
Offical dealer for the following-

SOUNDSTREAM
DB LINK
DB DRIVE
PANASONIC
GARMIN
ROSEN
SCOSCHE
XE DESIGNS
SOUNDGATE
PAC
LITEGLOW

Re: Frequently Asked Car Audio Questions
Thursday, April 20, 2006 4:30 PM
Ok...when setting your amps and you say I need to take my watts x ohms and square root of that....do you mean the RMS watts? Because I don't wanna see some guy setting them thinkin he should take the max rating of his amp...unless im wrong and hes suppose to...but ya...please clarify for me, im pretty noob...

Another thing, does that freq sweep work with speakers too? because i have a HPF set at 125htz for my speakers, so should i turn that off when setting their amp? and with the eqs...do i level them out and leave them leveled out after all the tuning is done too?...

I think I have more questions, just can't remember them right now so ill post em when i remember, but if someone could look after those ones for now...thx

wysiwyg wrote:

i would say they bang, they don't really pound so much. but if
you want to bump, then they will bump and hit real hard and a lot good.

LOL
Re: Frequently Asked Car Audio Questions
Wednesday, May 17, 2006 8:24 AM
Misc helpful Car Audio sites:
These sites contain great info ranging from how to hook up a headunit to more advanced topics such as building your own subwoofer. These are the sites I go to when I can't figure out how to do something or if I want to learn something new. Anyway here ya go:

Basic Car Audio Electronics

MTX's Car Audio Education

Do.It.Yourself. Subwoofers

Soundstream's Enclosure Tips and Guides

Rockford Fosgate's Subwoofer Wiring Guide

General Audio Electronics Calculators

The 12 Volt (Great site with info for installers)

D.I.Y. Car Audio aka The InstallDr

Great forums for newbies (Flaming for newb questions are usu. kept to a minimum) - caraudio.com

Termpro - Home of DB Drag - Great forums with advanced topics - Beware of harsh gang flaming

Understanding Thiele-Small Parameters aka T/S Parameters

Installer Tech

Subwoofer Design Theories

Test Tones for Download

Kicker's Tech Tips Manual - Warning PDF file!!!

Basic Speaker Motor Design

Car Stereo.com's Library of Car Audio Articles

Basically ALL Mobile Electronics - This site has a nice chunk of info

Car Audio FAQ

Mobile Works USA - Has general car audio and guides on how to disassemble the dash of just about every car

Caraudio.com's Car Audio Definitions

Newbie Guide to Custom Kickpanels - Caraudio.com

Speaker FAQ - Caraudio.com

Proper Door Sound Deadening - Car Audio.com

Caraudio.com's Bass Track Thread

SPL Questions Answered - Caraudio.com

Termpro's Fav CD's and Bass Tracks

Tempe's Car Audio Bible

Termpro's List of Audio FAQ's

Hearing Damage and You

Termpro's Old School Car Audio Discussion

Termpro's Sound Quality Forum - A good place to start for SQ Purposes

ICIX Woofer Comparison 2005

Tips on how to keep your car safe from thieves

Carstereos.org ak formerly known as SiN forums - Home of the Official Forums of Resonant Engineering among others.

Sounddomain.com

If I find or remember more sites I will update the list.



Re: Frequently Asked Car Audio Questions
Friday, June 23, 2006 7:21 PM
Lanman31337 wrote:

WARNING WARNING WARNING WARNING WARNING WARNING
If you do NOT understand any of this, print this out and take it to a PROFESSIONAL (note - Barf Buy and Circus City are NOT professionals) to get installed


Also,
DO NOT EVER, EVER, EVER, EVER Cut a factory wiring harness out of your car for ANY reason. Spend the $8 on a wiring harness to plug into your car.






^CLICK ME TO SEE HOW I BUILT EVERYTHING^ How To in Interior Forum
Re: Frequently Asked Car Audio Questions
Monday, June 26, 2006 7:13 PM
Another good point brother. Hack and chop = headaches.



Re: Frequently Asked Car Audio Questions
Sunday, July 16, 2006 2:26 PM
can someone post how to take apart the dash of a 95-99 cavalier thanks in advance

Re: Frequently Asked Car Audio Questions
Wednesday, July 19, 2006 12:15 PM
Re: Frequently Asked Car Audio Questions
Monday, July 24, 2006 3:34 PM
Lanman31337 wrote:

Subwoofers

Tuning your amps

The simplest and easiest way to get your amps tuned is to follow these simple instructions. Grab your digital multimeter and a calculator.

output = square root (watts * ohms)

First, take your amp's wattage at load. For example, let's say your amp does 300 watts rms at 4 ohm. That would be 1200. Take the square root of that and you'll get 34.64101615137755, so let's say 34.64. Take your multimeter and set it to AC volts. Disconnect your speakers from the amplifier. Grab this file here - http://www.realmofexcursion.com/audio/testtones/20Hz_to_120Hz.mp3 - and burn it to a cd. Turn your eq's off, turn your volume to 3/4 of the way up, hook up your multimeter to the + and - of the speaker outputs and play the sine wave. Your peak voltage should hit at the beginning of the cd - adjust your gain till it reads the voltage you figured out earlier, then leave it. Hook your speakers back up, and your gain is set. Don't turn your volume up above this volume or else you'll clip.


Before I do this, is this for a single channel amp? If you have a mult-channel (mines a 4) do you pick the RMS for the individual channel and then do the calculation? (This seems logical but I do not want to blow my speakers)




Re: Frequently Asked Car Audio Questions
Monday, July 24, 2006 5:29 PM
yeah i believe so, but on an amp used for speakers i think you gotta use a different frequency sweep to determine when clipping will occur if you arnt going to be playing low notes through them...i have yet to hear what sweep to use...so if someone could help out with that id appreciate it


wysiwyg wrote:

i would say they bang, they don't really pound so much. but if
you want to bump, then they will bump and hit real hard and a lot good.

LOL
Re: Frequently Asked Car Audio Questions
Wednesday, July 26, 2006 3:38 AM
Y ou do use the RMS of each channel for a 4 channel amp. If your amp is 75x4 rms, you'd use that. Next, you'll take a peek on your amp and see where the high pass crossover is set at - usually around 100 hz or so. Grab the test tone from http://www.realmofexcursion.com/downloads.htm - and play that note. If your high pass is set at 120, grab the 120 hertz test tone. I'll see if I can whip up a sweep on there from 100 to 10000 on there, it's created, should show up within a day or two.



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