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BigCProductions99 12-28-2009 12:47 AM

General Car Audio Help And Advice
I'll Start Off With A Detailed Description Of Setting The Gains On Your Amplifier(s), Without The Use Of An Oscilloscope, But With A DMM. I Will Be Posting More Information Later On, Such As Wiring Diagrams, Vehicle Specific Wiring Help, And Just Answering Some Of Your Questions As Best I Can, The Credit Goes To One Of My Fellow SSA Members For This Write-up.

Most audio equipment dies for one simple reason. Most people push their equipment beyond its limits. Whether it is the amplifier, subwoofer or full range speakers, clipping is the number one cause of failure. To prevent clipping, use this tutorial.

To figure out what voltage you should set the gains to, multiply the RMS power of the amplifiers output by the impedance of the speaker, then find the square root of that number. If you are using an amplifier that has an RMS rating of more than your speaker(s) can handle/rated for, then use the RMS rating of the speaker (instead of the RMS of the amplifier) to determine the voltage to set your amp to. This is also referred to as gaining down.

Gain Setting Equation
Voltage of the output = sqrt(RMS Power X impedance of the speaker)
Say the amp provides 100WRMS into a 4 ohm speaker:

Voltage = sqrt(100W X 4 ohms)
Voltage = sqrt(400W*ohms)
Voltage = 20V

Again, that was only an example, use the ratings of your amp to figure that out.Setting the Gain(s)
To set the gain(s), you need two things:
1. A DMM (digital multi-meter) that is capable of measuring AC voltage (needs to be able to measure up to a range of 200V).
2. A test tone CD to use to set the gains at the correct setting.Now, to set the gain(s):
1. Start the vehicle, and pop the test tone CD in the head unit.
2. DO NOT hook up the sub(s) or speaker(s) to the amplifier while doing this, just leave the outputs unused at this time.
3. Now, time to set up the head unit.
a. If the loudest you listen to your music at on a regular basis is 22/35 with bass @ +3 and treble @ 0 with MX (or any other sound processor) on, use those settings. NEVER turn the headunit above 3/4 of the maximum volume.
b. Remember to have the car turned on.
c. If you want to use bass boost on a sub amp, set it prior to setting the gains on the amp and use the center frequency of the bass boost (45 Hz for most amps) as your test tone. <--- I NEVER Run Bass Boost, It's Just A Marketing Ploy That Destroys Equipment.
d. Please remember that if you have a subwoofer volume control on the headunit and/or a bass knob for the amplifier, set it to the maximum before you set the gains on the sub amp.4. Take the leads from the DMM and but them on the outputs from the amp.
5. Set the gain so that the outputs of the amplifier equal the voltage you found above. This is a MUST.

I Personally Use A 50hz Tone For Subwoofer Amps, And A 1khz Tone For Full-Range/Component Amps.

Tones Here: Realm of Excursion - Audio Downloads

You Will Need The 50hz Sine Wave And 1khz Sine Wave Tones.

This Is A Good Way To Set Your Gains, But The Best Option Is With An Oscilloscope, Because You Can See The Threshold Of Clipping.

BigCProductions99 12-28-2009 01:11 AM

Brief Explanation On The Big 3. The Big 3 Is Nothing More Than Upgrading Three Wires, That Tremendously Boost Your Voltage And Efficiency Of Your Vehicle's Electrical System. (This Is Not Just For Car Audio Guys, If You Are Running Alot Of Auxillary Power Items, Winches, Lights, Etc, You Need To Do This.)

I Prefer 1/0 Gauge Wire.

The Big 3 Are:
1. negative battery wire to ground - just replace the negative batt. terminal and wire and ground it to the factory location
2. engine block to ground - replace the ground wire from the engine block to the chassis with a bigger wire
3. alternator to batt - add a fused wire from the postive post on you alternator (the one coming from the battery) to the postive terminal on your battery. Make sure it is fused to the rating of the wire of at least the factory fuse.

Note on #2- Some cars have a batt-engine block connection instead of chassis to engine block...

Wire Here: KnuKonceptz - view products for category Power Wire

BigCProductions99 12-28-2009 01:30 AM

Wiring Diagrams:

For Front Stage, If You Were To Run Pro Sound Components That Are 8 Ohm:

s3nt3nc3d 12-28-2009 01:51 AM

Great thread! Thanks for posting! Mods, any way we could get this stickied?

BigCProductions99 12-28-2009 05:25 PM

Damn, Already? Lol, Thanks Bro.

1992wranglersahara 12-28-2009 06:23 PM

Thanks, man. I hope to put all this to good use someday soon!

BigCProductions99 12-28-2009 09:48 PM

Just Some More Basic Information, I'm Going To Keep It Simple For Now.

Co-axial vs Components

What's the difference?

Co-axials are speakers that have the tweeter permanently mounted in the middle of the midwoofer. Co-axials typically do not have external passive crossovers.....only a capacitor in-line with the tweeter to highpass the tweeter. They are generally much cheaper than components, and will work well off of headunit power (but will perform well off of external amplification aswell).

Components have separate midwoofers and tweeters as well as an external passive crossover. The midwoofers and tweeters are separated for a number of reasons.....for example, to allow optimal speaker placement. The passive crossovers are usually quite complex (for more advanced than what's used for co-axials) and are designed to optimize the performance of the speakers (by way of crossover points, crossover slopes, tweeter attenuation, tweeter protection, impedence compensation [zobel network], etc etc). The speakers used in component sets are typically of much higher quality and better performance that those used in co-axials. Typically components are best used with external amplification only.

2-Way vs. 3-Way

In a perfect world, we'd have a single speaker that could reproduce all frequencies perfectly, 20hz to 20khz. Unfortunately for us, such speaker does not exist…, we need to break the frequency spectrum down and play it through multiple speakers (mids, tweeters, subs, etc). This is where we get "2-ways, 3-ways, 5-ways, etc" from.

In co-axials, a 2-way speaker is a speaker that contains only a midwoofer and a tweeter…..the midwoofer playing the lower frequencies (down to around 80hz or so), the tweeter playing the higher frequencies (around 3khz or 4khz and up). 3-way co-axials typically have a midwoofer, tweeter and "supertweeter", with the supertweeter being designated to handle the very, very high frequencies only. Co-axials can go as high as 5-way (midwoofer, midrange, smaller midrange, tweeter and supertweeter). For all intents and purposes, anything more than 2-way in co-axials is a marketing gimmick. Going with 3-way co-axials or higher usually does not increase performance much, if at all.

For component speakers, a 3-way system includes a dedicated midbass (generally plays around 60hz-350hz), a dedicated midrange (generally plays around 350hz-6500hz or so), and a tweeter (generally 6500hz and up). Whereas a 2-way system is only a midwoofer (playing around 60hz-4000hz or so) and a tweeter (4000hz and up). Ideally, for a 3-way system, you'd want to put the midbass in your door, and have kicks built for the midrange & tweeter. For a 2-way component set, kickpanels or door mounting will suffice with generally good results.

General advantages of a 3-way component set:

1) There isn't a crossover point in the middle of the midrange frequencies (which are generally the most important to imaging and tonality), and they aren't being split up between drivers like they sometimes are in a 2-way setup. In a 3-way, they will be played by mainly one speaker, which is the dedicated midrange.

2) In a lot of cars, the mids will need to be flipped out of phase to help correct some midrange frequency phasing problems. In a 2-way system where one speaker plays midrange & midbass, running one of them out of phase will decrease the midbass impact. By running a 3-way, the midrange can be flipped out of phase and it has no effect on the midbass since it is being played by a separate driver.

3) The midrange and midbass frequencies in a 3-way may sound "cleaner" since each speaker has more of a limited bandwidth to play.

Disadvantages of a 3-way component set:

1) Tuning and aiming the speakers can be a much bigger pain in the ass with 3-ways. Installation, tuning, phasing and aiming speakers will be much easier/quicker to perfect with 2-ways.

2) Room. It can be much more difficult find the room to fit all of the speakers. In some cars, kickpanels are simply out of the question.

3) Money. 3-ways are normally considerably more expensive than 2-ways

lonniedivers 11-24-2010 02:50 AM

I recently purchased a 99 Ford F150 XL Extended Cab. It has the factory stereo in it currently. I installed a pair of Boston SL80 6x8 speakers in the rear doors that I had purchased for another car and would not fit. It sounds a lot better but need more upgrades. wanted to get some more experienced comments or suggestions before I proceed.

ydgp 09-02-2011 01:48 PM

Sorry if I'm posting in the wrong thread . . . but here goes. Put a Pioneer stereo in my YJ about a year ago. Everything was working great. Made a sound bar out of wood and stuck some old speakers in it and attached it to the roll bars overhead. (Pretty crappy, but so what?) Replaced the factory dash speakers with some used ones laying around also. Like I said, everything was working great. Rain. Bad weather. Stereo won't power on. . . Unhooked all the speakers. Checked all fuses under dash (especially dome, etc.) - checked all relays under the hood. Checked and replaced (just for good measure) the stereo fuse. Checked all wiring caps to make sure there were good connections. Made sure the harness was firmly seated in the stereo. Still nada. Did I fry it somehow???????? Obviously, I'm no stereo installer, although I do pretty well with home electronics. Please help. I'm tired of driving around without sound. (Although the wind sounds pretty good)

lsimons123 07-16-2012 11:39 AM

I just purchased a 2005 wrangler sport and this is the first time in the forum. One of the sound wedges is loose and I can't seem to find out how to tighten it up. I can see where it goes into the cross bar but I don't see a bolt or nut. The outside bolts on the outside rails are secure. Any help!!! when the speaker is on it makes a rattling noise.

wirth315 04-14-2013 06:14 PM

12 volts postive.

alaska_av8r 05-21-2013 07:17 PM

The above link did not work for me but here is the updated link for the tones:
Realm of Excursion

alaska_av8r 05-21-2013 09:15 PM

I realize this is an old thread but I am confused on what amplifier output I need to use for the formula. My amp is an Alpine MRX V70 and here are the specs:

Per channel into 4 Ohms: 60W RMS x 4 + 250W RMS x 1 (14.4V at <1% THD+N)

This amp has 3 total gains, one for the sub, and one for channel 1+2, another for channel 3+4.

So in computing the total RMS, would I use 60 watts x 4 channels = 240 watts total output, now 240 watts X 4 ohms = 960, however instead of getting the square root of 960, shouldn't I divide by 2 since I have two gains, (one for channels 1+2, and another for channels 3+4)?

That would give me 480 and the square root of 480 = 21.9V that I should be looking for on the meter as I adjust the gains.

The sub I assume would work like this:
250w X 4 ohm = 1000, square root of 1000 = 31.6V

Dlm2980 09-01-2016 01:43 PM

98 wrangler tj radio hard wire
2 Attachment(s)
So I bought the jeep with no radio in it and finally tried installing a radio that was giving to me .. But can't quite figure it out .. I uploaded the diagram of both the radio im trying to install and the color diagram of the wires from the jeep.. Now I got all the speakers hooked up right .and none of the fuses are blown .. And I also know that the speakers do work .. But I don't know what wires connect to what as far as acc constant etc .. Any help would be appreciated on this subject ...

islandmonkey 09-21-2016 06:57 PM

Speaker sizes, and water resistant Brand
All my console and sound bar speakers soaked in storm, and died.. Any suggestions on brand and size please?

dean4537 10-18-2016 11:06 PM

hey thanks for this audio help thread.
i want to jeepbeef up my sounds in my jeep so i went and bought this sub from amazon and currently have these in the sound bar also might buy this amp

so my question is what else do i need? do i need all new wiring or can i use the stock speaker wiring? ive tried to learn how to do this myself but always keep reading different things and ways to do it :/

Jerry Bransford 10-20-2016 12:37 PM


Originally Posted by islandmonkey (Post 27467993)
All my console and sound bar speakers soaked in storm, and died.. Any suggestions on brand and size please?

Most automotive speaker cones are made from mylar, polypropylene, etc. which is waterproof. I would just make sure any replacement speakers you buy have cones made from materials like those and not paper.

Polk DB series speakers would be a great choice, they work well with standard head units that don't have big aux amplifiers. They don't require a lot of power to drive so they will put out plenty of volume for all but 16-20 year old who is out to damage his ear drums. polk Audio | Car Audio Speakers

5.25" is what came in your sound bar but 6.5" speakers fit directly without modification.

Your front OE speakers are 4x6 oval speakers but it's an easy thing to convert them to round 5.25" which will sound better.

You can easily get adapter plates to convert your front 4x6 opening to hold a 5.25" speaker like this...

dean4537 11-11-2016 04:12 PM


Originally Posted by dean4537 (Post 27754233)
hey thanks for this audio help thread.
i want to jeepbeef up my sounds in my jeep so i went and bought this sub from amazon and currently have these in the sound bar also might buy this amp

so my question is what else do i need? do i need all new wiring or can i use the stock speaker wiring? ive tried to learn how to do this myself but always keep reading different things and ways to do it :/

Bump any help with this?

Jerry Bransford 11-14-2016 06:14 PM

Unless you plan to drive those speakers at full-blast continually which would cause deafness or at least tinnitus in short order, the stock speaker wiring will be fine. The power a speaker CAN handle and the power an amplifier CAN put out is nowhere near what power is actually being used even fairly loud listening levels.

99GoldenSahara 12-21-2016 12:37 PM

Sorry to butt in, but Mr. Bransford, many of us miss you over on the TJ Tech and General Discussion forum. Hope you come back someday!

Jerry Bransford 12-21-2016 09:21 PM


Originally Posted by 99GoldenSahara (Post 28384641)
Sorry to butt in, but Mr. Bransford, many of us miss you over on the TJ Tech and General Discussion forum. Hope you come back someday!

Thank you, that was much appreciated. The moderators know why I decided to stop participating there. However, it was made abundantly clear to me they didn't care enough to fix the problem reported multiple times over several years.

99GoldenSahara 12-22-2016 02:50 PM

Personally I hope you change your mind. For many of us, the information we received from your experience and others (like Water Dog) not only was invaluable but also made working on our Jeeps more fun and purposeful.

I totally understand your frustration as I was reading one of the threads where a certain subscriber chose to "not play nice" and was not only rude but should have been removed from the forum. He's still mouthing off, but most folks realize he's just a bag of air and offers little to nothing in terms of assistance and insight to the conversations. The administrators dropped the ball on that.

Anyway, I told Dennis (Water Dog) I'd give it a try. I for one would love to hear from you again and see more pictures of the amazing places you wheel your Jeep into and out of! I miss your knowledge and experience which has helped me out immensely on more than one occasion.

Have a blessed Christmas.


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