Understanding the multimeter on preamp

I don't understand how exactly I am to interpret the multimeter readout when trying to determine my preamp output voltage.  I know to stick the postive to the inside and the negative to the outside.  Also, I understand that it could prove fatal to the health of the preamp output for the inside to make contact to the outside.  If anyone would be interested in explaining how I might go about making a wire that could conect to the RCA on one end and the split off into two separate wires, one being positive and the other being negative, I would be most appreciative.

Back to the multimeter...
My headunit's top volume is 35 and the preamp output is 4 volts.  It is the Alpine CDA-9833.  It read .363 at volume level 33 and up.  It read .202 at 28.  It read .015 at 21.  How do those numbers equate to 4 volts?  Is the 4 volts a max output voltage or RMS?  Would the RMS rating have changed since the CEA 2006 compliance deal?

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...typically, I just run whatever I randomly pick up off the floor.
1995 Ford Ranger Supercab
MECA member
Team CSS

1.  You can use alligator clip leads on your meter for safer connecting to the RCA.  Or

2.  You can have the RCAs connected to the amplifier, turn the gains down to minimum, and read the voltage across the speaker terminals of the amp.  See the well-know JL tutorial that shows this.

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Build the box so that it performs well in the worst case scenario and, in return, it will reward you at all times.

sorry man...forgot to mention all the details...it was set to AC.  That I already knew to do, I just don't understand the readout.  How should I interpret it?  What does the .363 mean?  I thought I should be looking for 2, 3, or 4 volts.  Also, I don't really get why we set the meter to AC...I could've sworn that the CD Player sends out a DC signal and that when the DC signal crashes into the DC power inside of the amplifier, it created the amplified signal.  A note on stripping the wire back...I'll do it again, but I couldn't figure out what it was I was looking at.  I know there is suppose to be a wire shield surrounding the outer edge of the cable and that it is suppose to be negative and then there is a wire in the center that is the positive wire that actually sends the signal.  I'll sit down with the wire tomorrow.  I got lab reports to write up tonight.  I appreciate any and all input.

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...typically, I just run whatever I randomly pick up off the floor.
1995 Ford Ranger Supercab
MECA member
Team CSS

I guess I could give a little more background as to why I'm looking into this.  I'm going to press the "Front End Defeat" button on my MB Quart RAA1000 amplifier so that I can use my FMOD crossovers and be confident about the crossover points.  I set my gains at just below 1/4 volume like Crutchfield told me to, they said that would be set to recieve around the 4 volts that my headunit should put out at full volume, but when I press the "Front End Defeat" button, the music volume increases.  I determined two things after playing around with things.  One, the "Front End Defeat" button set the gain to a smaller voltage, which meant that I could no longer turn my headunit up to the point of maximum voltage output because it is already that loud at a lower volume level.  Two, the gain was no longer adjustable, which means that I am stuck with the lower voltage input point...life sucks.  Oh, and, by the way, I have ADHD which makes it difficult for me to put information down in an understandable manner because of the way it is processed in my head.  Just yell at me about whatever it is that doesn't make sense and I will clarify.  Thanks for the help!

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...typically, I just run whatever I randomly pick up off the floor.
1995 Ford Ranger Supercab
MECA member
Team CSS

Use a test tone sine wave for a steady signal.  Read V AC on the 20 scale of the meter...displays in whole numbers from 20 volts down.  Voltage will vary depending on frequency.

You said, "I set my gains at just below 1/4 volume like Crutchfield told me to...".  You will not get this system set up correctly using such a plan as that.  Make your test tone CD, read the threads found in a forum search for "gain", and set you amp gains correctly.  You will be listening for clipping;  knowledge of the deck's voltage output is not a requirement.  Here is a thread to help you get started:  https://www.the12volt.com/installbay/forum_posts.asp?tid=75001&PN=1

And by the way, your post was very clear and you explain yourself better than most do. 

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Build the box so that it performs well in the worst case scenario and, in return, it will reward you at all times.

To "nouseforaname"...I finally took a look at your name...thats great...lol.  I knew about the speaker end of things being AC, I'm just still surprised about the preamp outputs being AC.  I thought that a DC preamp output collided with the power from the charging system within' the amplifier causing the signal to become both ampilifed and AC, however, it appears that an AC signal collides with a DC power source and creates an amplified AC speaker signal.  If I'm wrong, then just throw a few rocks and I'll get the picture.  I'm trying to put two and two together on how all this equipment works so that I can be of better help to my friends when they need help.

To "stevdart"...I only set the gain the way they told me to so that I could get an idea of what things sound like the way their people think. I mentioned it only to give some background for comparison to the whole "Front End Defeat" thing.  It was all just for clarity.

Thanks for setting me a little straighter you two.  If you don't mind though, want did the .363 stand for?  Was it just a crazy, off the wall reading that I got because of a wrong setting or is there some formula that I need for it to make sense?  I appreciate all the help and advice.

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...typically, I just run whatever I randomly pick up off the floor.
1995 Ford Ranger Supercab
MECA member
Team CSS

If you had the meter set correctly, it stood for slightly more than 1/3 volt.

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Build the box so that it performs well in the worst case scenario and, in return, it will reward you at all times.

So, I need to be in the 200mA position.  I just set it to the AC volt spot, but there is an AC section that has numbers with a mA listed beside each number.  I figured those were intended to read amperage.  I do have a range button on here, but I'll have to go hunt down my manual to understand exactly how it works.

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...typically, I just run whatever I randomly pick up off the floor.
1995 Ford Ranger Supercab
MECA member
Team CSS

No, you're first assumption was right- mA is for current (amperage).  You're reading should be in ac voltage, as Steve said.

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My ex once told me I have a perfect face for radio.

I played with it in AC voltage and figured out that there is a range button on there.  I played with my friend's multimeter as well and figured out which range was 200.  I used both of our meters on my setup and read .202 volts at volume 28.  That reading was taken out of the subwoofer output.  I checked the settings and made sure that the subwoofer level was turned up.  I still want to check the other preamp outputs to see if that one might be bad, I just haven't gotten around to it.  Also, I think that it might be reading so low because I have 80 Hz turned all the way down.  I'll try turning 80 Hz  back to flat and see what happens.  I tried my meter on a friend of mine's headunit and it read 1.5 volts so I'm pretty sure that my meter is working, especially being as how my friend's meter gave all the same readings.

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...typically, I just run whatever I randomly pick up off the floor.
1995 Ford Ranger Supercab
MECA member
Team CSS