I was trying to troubleshoot my left front comps today and ran into somethign with my amp that scared me. Soundstream 4 channel amp being run in 3 channel mode.

The front left speakers sounded much softer and very rolled off since i installed my cleansweep so today i decided to measure the gains with a DMM and found my "by ear" setting to be off enough to cause the left to be softer...but did not explain the rather severe rolloff i was hearing....

The problem arose when i was metering the speaker wires at the amp while fading from left to right...i ran into 2 problems that confused me....one may be normal..the other i am not so sure about. I don't remember the exact reading so i will explain in simple terms. And the reading may be irrelavant anyway...i am no expert.

1. After adjusting the gains with a DMM and making sure left and right were all balanced perfect all the way into the amplifier i could still hear the left side sound really softer and rolled off when fading all the way to the left. so i measured the Ohms of the speakers and they were both reading 3.6 at the crossover.

BUT...when i attached the speaker leads to the amp and measured them while playing pink noise i noticed that the right speaker measured say .56 went the balance was dead center and so did the left....well maybe .54.

BUt and i am finally getting to the problem...fading ALL the way to the RIght...and the ohms reading stayed at .56 or close....but fading all the way to the left and the left speaker dropped off to like .25....

Agains i have never put an ohm meter on the speaker leads while they were connect to the amp and whith a signal being played...i did this right at the amp ....and this leads me to my second concern...

Probing the left speaker leads at the amp...would actually lower the sound out put for the left channel....as would moving the speaker wire around....leading me to believe something might be wrong with my amp?

I moved the front comps over to the ba side of the 4 channel amp and that problem went away...

i was able to get balanced sound finally...even though the ohms still dropped when fading all the way to the left...maybe me wonder if this is normal...

could someone fade their system all the way to the left and to the right and see if they have the same thing happen to them?

 

First off using a normal off the shelf DMM is not the correct or even an item to use to do what you are talking about.

DMM are set up to measure correctly at 50HZ-60HZ only. Using them to measure Pink Noise or any ohter frequency will give you major errors and it will nor read the same even with the slightest difference in voltage from one side to anohter. You really need to use an AUDIO capable (i.e. audio spectrum decible meter) that will give you the proper readings at frequencies from 10HZ to 25,000 HZ or more.

As for measureing the impedance (ohms) it can not be done while any audio is playing as the DMM puts out its own voltage to use as a measuring standard. Any other voltage introduced will cause the meter to reach in unstable inaccurate ways.

So in conclusion all the testing you did gives you no usable information.

But the part you mentioned about moving the wires around giving you changes in sound level did make a lot of sense and yes you probably do have something wrong with the amp if you can move the wires and the sound level changes. It sounds as if there is a bad solder connection on the board or wire connecting the amp to the output connector.

 

what about moving the balance control left and right? Just do me a favor next time you are driving and tell me what you hear when you move the balance control all the way to the left compared to all the way to the right.