Stereo Expert advice needed

[TX82FIAT]

folks, I decided to put a nice stereo in the car with some nice speakers and a mini amp. The head unit is nothing special as I don't want to draw to much attention to the car. The mini amp is 300 Watt. 4 channel 75 Watt each channel with 45 RMS. The speakers are 200Watt 40 RMS per pair. I ran the RCA cable and wired everything up before mounting speakers in the pannels. After about 15 seconds of wondering if i hooked something up wrong the sound came out of all four speakers for each channel on the amp. sounded great. played it for about 10 minutes as i programmed all the radio station in. Not sure why the 15 second delay. plugged the speakers into the panels and buttoned everyting up and did one more test and speakers all worked. They sounded great and I finally have a Spider with a good stereo. Smile and a beer as i pat myself on the back for a nice system build inexpensively.

Now the interesting part. Later in the day my wife asked me to start the car she wanted to hear this new stereo system that only cost about $130 dollars in materials. So I turned the stereo on and ..... nothing. The amp is powered up, the radio is powered up, the speakers are dead silent. I can't get the stereo to play!

I did not play the volume at a level even close to high enough to damage the speakers. I have power at the radio with an antenna signal and power at the amp. I would think I have a signal issue or an interference issue that took a little time to emmerge. However, i could have some wierd electrical issue. I know the ground is good as i tested it and in the trunk you have the unique ability to hook the ground direcly to the negative terminat for the best ground possible.

help??

So, tonight i'm going to test for current across the speakers and see if i have another speaker around the house with RCA inpute to test the signal from the head unit. Any other thoughts about what to look at? Also, the amp is secured direclyt to the metal trunk wall. I read earlier today thet an amp should not be mounted on a metal surface even though i see it done that way all the time. thoughts?

Thanks, Ray

[RRoller123]

Does the system have any kind of "mute" control?

[maytag]

is the head unit a digital tuner? Many digital tuners will send NO signal to speakers if it can't find a sufficiently strong stereo signal to reproduce.
Have you tried playing a CD in it?

[Texasbull]

And to add to the obvious, did you hook the antenna back up?

[TX82FIAT]

The head unit does have a mute funtion. However, i do not have the mute on. the display shows "MUTE" when on. The antenna is hooked up and the head unit has a nice function where you can see the variations of the music on an equalizer on the display. The music is playing as I can see the equalized on the head unit bouncing around. So the signal from the antenna is making it to the head unit.

Unfortunately i choose a head unit with no CD player. it has the AM/FM bands and has aux inputs and a USB drive. A few years back I digitized my entire music collection and sold over 500 CD's. The head unit is shorter in depth because it does not have a CD player and as we all know there is limited room behind the console. I'll try the aux in with a hook up to my I-pod tonight when I get home. I do think you may be on to something with the signals being transmitted into the head unit. I just don't get why it worked fine and then stopped. That points me in the direction of some type of interference or signal loss.

I guess I could test resitance/current across the speakers and then place a 12 volt battery across the + - terminals on the speakers to see if I get a pop or gurgle to ensure the speakers are still good. if I can get a speaker to work from the RCA jacks before the head unit and i can verify the speakers work then it would seem the issue would be with the mini amp.

All thoughts and testing procsesses welcome.

[maytag]

you're certain the amp has power? most are fuse-protected.

[dmwhiteoak]

On most amps there is a blue wire that must be connected to the receiver. That is where the delay comes in to play. You will get no output from the amp until that blue wire gets it's signal. It is to protect your speakers from a hard hit.

[dmwhiteoak]

You should also have a blue wire in the reciever harness.

[adrians]

Blue signal wire enables the AMP signal processor, so a power light on the AMP only means the AMP has power - not signal to switch on the audio signals - so recheck the blue wire.

Regards

[TX82FIAT]

I do have a blue wire. The blue wire on the head unit is the amp power on switch that turns the amp on when the radio is turned on. If I don't turn on the radio the amp has no power. The audio signal is carried to the amp from the RCA cables. The amp does not have a blue wire. The amp has 4 input channels for RCA in. Wires on the AMP wiring harness are:

4 sets of speaker wires + and -
1 Red power wire
1 Black ground wire
1 orange head unit signal wire that turns on the amp - this is the wire hooked to the blue wire on the head unit.

All wires accounted for. When I hit power on the radio the amp green light comes on so i know part of that function works. I guess i will have to determine if that same wire is not only turning on the amp but simultaneously turning on the signal to be recieved. I guess this is to be expected from a $40 mini amp. the model is a Nitro Bmw-x43 300 Watt 4 Channel Car Amplifier. The idea was to amplify enough for listening when cruising down the highway top down and create in essence an independent circuit away from the ignition drawing power. I'll post some pick tonight if i can not get the signal from the ipod to work when I get home.

[dmwhiteoak]

Check for A good connection orange to blue.

[124JOE]

you can use a battery to test each speaker AA,AAA,C,D all will make a speaker thump just a bit
as you tap the wire on the pos end batt while holding the other ground side on
FYI

[TX82FIAT]

OK, I have signal from the head unit. Used a random battery powered speaker with an RCA input and it worked. The speakers gave a little pop (all four) when applying a small battery to them. This leads me to believe the problem is in the $30 AMP. On the box the amp came in it did not say how many ohms the amp could push. Purchased on e-bay and could have swore the description said 4 ohm amp. However, after some research on the intranet last night the amp is a 2 ohm 75 watt per channel 45 RMS. So, I think what is happening is the speakers are producing too much resistance for the little $40 2 Ohm amp. I'm looking at another little Rockford Fosgate mini amp that is 4 Ohms. Options at this point are a better amp or 4 two ohm speakers.

[124JOE]

go for a bigger amp

[digitech]

I don't doubt that your "little e-bay amp" is the problem , in fact I'm betting on it but it has nothing to do with it being rated for a 2 ohm load vs a 4 ohm load. If the spec supplied is on the up & up, it's actually better that it can handle a 2 ohm load. The problem is, I suspect, it's a cheap little off-shore knockoff that has questionable quality and dubious specs. Pay a little more and get a quality brand name amp.