Hi, all,

Strange situation:

If I turn on the sound system, then the car, the HU and sub amp come on normally after a few seconds, but the amp for the front speakers goes into protect. Sometimes it comes out of protect. If I start the car first, wait about a minute, then turn on the sound system, it seems OK, though I have not tried more than a couple of times...

Installer blames amp, but this amp came from a SoCal S2K friend and I saw and heard the amp the day I bought it from him. No problems.

Shorting to ground somewhere, maybe? Why would order of operation make a diff??

He did an otherwise great install, including a great sounding Laurent box and sub in trunk

Edit: I've read about ground issues and gain being too high on amp....one of these maybe?

Thanks! Mike

 

U got pm

-Art

 

i hope you own a multi-meter. if not, buying one to troubleshoot this might be a good idea.


first thing you need to do is this:

set the meter to resistance and set the range for whatever is less than 10 ohms. disconnect all wires going to the amp and measure the resistance of each wire going into the amp except the power wire (with 1 lead on the wire and one on a ground bolt in the car). write down what those are, and report them back here.
the ground should be 0, the speakers should all be infinite.

 

Yeah protect is usually because you have a lower OHM load than the amp can handle.

Example, a 4Ohm DVC sub can either be wired to 4 Ohm or 2 Ohm. If your amp can only go to 4Ohm and you have wired to 2Ohm your amp will go into protect mode.

 

What is the amp make and model?

I have seen some amps do some strange things when they are on and then the car is started.

Could be a short on one of the front speakers and I have also seen some strange protect things happen if the amps power lead or ground was not solid (due to the current sag/spike when the car is started).

 

oops.. it should be 8 Ohms (in series) and 2 Ohms (in Parallel) assuming its 4 ohms PER coil

 

Hi, William!

It's a Memphis Audio 16MC2004 (50 x 4). I bought it from a SoCal forum member (great guy) and I saw it working perfectly in his S, so I do not agree with the installer, who blames the amp.

It is the amp for the front speakers (Infinity Kappa Perfects). No impedance issues there.

Also, the amp powers down when I eject a CD, then goes into Protect upon inserting the CD again. Sub amp (single channel 250W Memphis) and HU seem fine during this time.

I see two ground wires going into the ground input on the amp...I wonder if he is grounding the sub amp to this one????

Another SoCal member owned an Al & Ed's Autosound and has a great tech that I am going to bring it to. I'll update as I know more......

Thanks for the responses!

Mike

 

2 grounding wires? That is interesting....who did the install?

John

 

John at USA Window Tinting in Westminster (They have been doing audio installs for about 6 years now). He did a nice install for the member that I bought the amp from....

I am also wondering if he is grounding to chassis or not....

 

I just can not believe that they let you leave without fixing the problem. Sounds kinda arrogant to blame it on the amp to defend the install.

I would be interested to know where they are grounding the amps to. Sounds like they are daisy chaining the ground from one amp to the other to ground.