dc amps different on different wires

Hey guys. I've been having issues with an install and need some advice. I have a 2011 Hyundai Genesis coupe with the premium audio. Needless to say, the audio was not that premium. So I have replaced the stock speakers with Infinity Kappas and a Boston Acoustics 5 channel amp. I am not going for audiophile so please dont give me grief for keeping it on a budget. So I have the stock headunit (nav, BT, voice activation, XM) going to the stock amp to an audiocontrol LC7i LOC with bass restoration because the stock headunit stops increasing the bass at a certain point to protect the stock sub, which is out.

I have a cheap DMM and I was checking the DC amps on the terminals to the LOC. I might be doing this wrong, but I got some strange numbers. I put the neg lead on the LF- and the positive to the LF+ and the reading was like -50. Did the same to the RF and the reading was 0. The LR was around -40 and the RR was 110. The left and right sub channels were nearly equal around 40. And of course these numbers change with volume and with what is playing. These numbers were taken with relatively low volume and in quick succession. So obviously the weird ones are the RF and RR. Does it seem like something is miswired? I have full fade and balance control with no obvious problems. I think I need to rewire the whole thing. Is there a way I can find out exactly which wire is which?

I know that if I buy a new headunit and run RCAs, that would eliminate all of my problems. But I dont like the dash kit for my car and dont want to spend another $700 for a comparable headunit.

Any help that anyone can offer would be greatly appreciated.

Let me add something to the info which may be pertinent:

The DMM was on DC amps 20. The readings all had a negative sign on them except the sub channels. One sub was pos and one was neg. The readings on the front and rears looked something like -0.50, except the RF was -0.01 and the RR was -1.10.

okay...GO! (please)

What DC amps are you trying to read? If you are looking at speaker output, then you would want to read AC, and you'll get more useful information reading voltage not amps.

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I do not know if the amperage or voltage for that matter should be equal to all of the speakers from the stock amplifier. If I put it on DC volts, it usually reads 0.01 or something low like that. I would expect that all of the signals be equal or inverse opposites. See, I had to rewire the stock amp harness because like a rookie, I cut the wires too close. I am also somewhat color blind so browns and greens look very similar, same with blue and purp. So hooking the right wires back to the right place might be off. I am trying to find a way to track them back to their home.

I have to ask what should I be looking for to tell if I have it wired correctly? I think the speakers sound a bit tinny or out of phase even. If you tell me voltage, resistance or amp and tell me what to measure across I will do it without question. Wiring is not my strong suit.

So to refresh, I have the stock head unit sending speaker levels to a stock amp, the stock amp speaker level outs to a LOC, the LOC obviously sends RCA to the aftermarket amp.

Please keep the ideas coming and thank you for responding!

You want to read AC volts, not DC volts. Audio is AC. But reading voltage will only tell you if there is a signal it will tell you nothing about speaker polarity if that's what you think may be wrong. You must verify that each + speaker terminal is wired to each + speaker output on your amp, and you must verify that each + speaker wire from your HU is wired to each + speaker input on the LOC.

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Lucky the amp wasn't blown... connecting outputs to a dead short.
Line outs will be more tolerant.

DYohn, ya that's what I need to do. Any tip on how to do this easily with basic tools? I know I can pull a pair of wires and hook them up to a speaker and fade and balance my way to get some sort of speaker location. probably not the best idea. Is there a way to tell if a wire from the head unit is pos or neg?

Oldspark, I am not sure the dead short you are referring to. I may have explained my situation improperly. Or I did and I got away with making a big electrical mistake.

Thanks for your input guys!

You got away with making a big electrical mistake if you connected an amp meter across the terminals of an operating amplifier. Don't do that. :)

You should be able to identify POS and NEG speaker wires from your head unit by using the vehicle wire color codes. Check the wiring database using the links to the left. As far as the connections to your speakers, you should know what that is if you installed them, but if not you can check with a D-cell or 9-volt battery if you can see the speaker cones. Disconnect the speaker wires from your amplifier. Hold the speaker wires to the battery terminals and watch the woofer cone. If it moves "out" toward you, then the wire on the battery POS is connected to speaker POS. If it moves "in," then the wire on battery POS is connected to speaker NEG.

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Hmm, I don't know if I tested across the amp terminal or not. On the LOC it has phoenix type connections. The "L" shaped 4 port thingy with screws on each wire. I was touching the screws that hold the wires down.
Unfortunately, there is not a wiring guide for a 2011 Hyundai genesis coupe listed. I checked on gencoupe.com and I see a diagram for the stock amp harness, but it just has numbers in the AMP block, no colors listed.
I did some searching and people are saying that when using the DMM, put the red probe on what I think is pos and the black on what I think is neg. I should get a positive number if I have the right wires. If it was a negative shift, then the wires are crossed. Would you agree with that? Almost all of the readings I get are negative, which would make me think everything is wrong. It could be wrong going into the stock amp from the HU. But that should output proper polarity to the LOC where I am reading these odd negative numbers. I think I have a big project this weekend...
The wires from the aftermarket amp to the speakers are correct. I ran them all fresh from the amp all the way to the speakers. No stock wiring from amp to speaker.
Thanks again.

As was said, amp/speaker outputs are AC so I too fail to see how you can get a + or - reading. It sounds like you researched caraudio forums which I have found often contain incredulous information (like the correct answer is often the opposite to what they say!).

A common test for speaker polarity is to use a 1.5V battery and see which way the cone deflects. (1.5V should be fine for any speaker of 3W and higher for 1 Ohm speaker impedance and above.)

Obviously I am not too savvy on even basic wiring so I might be measuring across the wrong points. But if I put the positive lead from the DMM to the positive wire and the neg lead to the neg wire, I get a negative number when I have DCA 20 selected. I am not too concerned with the polarity from amp to speaker, more so from the stock head unit to the stock amp. I think I have some wires crossed somewhere and it is giving me poor sound. I ran wires straight from my aftermarket amp to each speaker, no breaks or splices. So those should be right. I get the negative DCamps from my stock amp to my LOC. So I think I have the wrong wires from the stock amp to the LOC. Otherwise the stock amp should put out the proper polarity regardless the input to the amp. I did shift all the sound to the front right speaker and all of the reading across the wires from amp to LOC read the same as if all channels were driven evenly.

Again, thank you for your insight!

STOP TRYING TO READ AMPS. You do not want to read amps at all. Plus, audio is AC not DC so any reading you get with a meter selected to DC is meaningless. Just stop trying to use that meter until you know how to use it.

What's the DVM make and model?

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I have a small red DVM. It is made by CEN-TECH item #90899. It may have cost $5 at harbor freight. Since I dont do alot of electrical stuff, I figured I did not need a $50 DMM. Kinda kicking myself now. Please hold the laughing. It has DCV, ACV, DCA, continuity, resistance, hFE, 10A.

The reason I was measuring with the DCA 20m setting was I was not getting a measurable number in DCV, so I assumed amps were the way to go. So I should be in AC volts?

I am sorry if I frustrate you, its just anything I find online is either for complete dummies or electrical engineers. I like to think i am in the middle somewhere.

Thank you!

OK so I reread the whole post. First off, thank you guys for trying to steer me in the right direction. I think I was so set on finding my solution that I did not listen to you guys. I am going to try AC volts tonight and see what readings I get. I just cant tell if I have a very strange situation to start off with or if I made it strange.

Stupid question but here goes...If I take the meter and put the black probe on a good chasis ground then take the red probe to a speaker wire would that tell me polarity or just cause a short? I have a feeling it is a short.

You cannot determine speaker polarity with a meter. I gave you a method in an earlier post.

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fair enough. thank you for all of your help.

And by the way, to measure the voltage output of an audio amplifier you would use the ACV setting. To measure the voltage from your car's electrical system, you would use the DCV setting. You cannot measure amps (the "A" settings) by placing the meter leads from pos to neg. I recommend you do not attempt to measure amps in any case.

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Hey Dyohn, I tried the AC volt setting and I didnt get much of a reading. Maybe I did it wrong, maybe the meter wont measure that low of a value. The voltage output of an amplifier would be a positive number right? Unless I had some wires crossed. I will search how to measure the output of an amp.I guess the reason I was measuring DC amps was that they were the only thing that showed any numerical value on my meter.

Thank you for all of your help and especially your patience.

Here's the formula: Power = (voltage times voltage) divided by resistance. So, a 50 watt amplifier when it's at max output, assuming a 4-ohm speaker, will equal about 14 volts AC. A 10-watt amp (such as a vehicle head unit) will give you about 6 volts. Disconnect the HU speaker wires from the LOC, play some music, turn the HU up and measure the voltage across the speaker wires.

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I appreciate the formula and info. So to clarify, I would use VAC, touch the pos lead to the pos wire and the neg lead to the neg wire and should get a reading of some sorts? Will it be a positive or negative value? Will it be the same value to all pairs of wires (so long as fade and balance are centered)?

Thank you! Have a great Friday!

adurm] wrote:

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I appreciate the formula and info. So to clarify, I would use VAC, touch the pos lead to the pos wire and the neg lead to the neg wire and should get a reading of some sorts? Will it be a positive or negative value? Will it be the same value to all pairs of wires (so long as fade and balance are centered)?

Thank you! Have a great Friday!

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With AC there is no polarity so there should be no pos or neg displayed and it really doesn't matter which lead goes to which wire. The only way you would get the same value on all channels is if you are playing a test tone. Music signals jump all over the place and are difficult to read.

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