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Measuring Output Voltage on Amps?

Printed From: the12volt.com
Forum Name: Car Audio
Forum Discription: Car Stereos, Amplifiers, Crossovers, Processors, Speakers, Subwoofers, etc.
URL: https://www.the12volt.com/installbay/forum_posts.asp?tid=46077
Printed Date: July 05, 2025 at 7:49 PM


Topic: Measuring Output Voltage on Amps?

Posted By: bbusbee
Subject: Measuring Output Voltage on Amps?
Date Posted: December 26, 2004 at 9:32 PM

Problem: I just installed my new amplifier yesterday and I don't get any sound.  I know the speakers and wiring are good because they were hooked up before to my RF amp.  I am now adding this new amplifier to drive these speakers for the high range 3 way configuration on the Alpine 9833 HU that I have installed.  To be clear I had the speakers hooked up to the mid range jacks on the same HU before this new addition.  I tried checking the voltage on the RCA wires coming to the amp from the HU and I'm getting 1.5 volts, first am I thinking straight by doing this and second, does this sound like the correct voltage?  I think the preamp jacks on the HU are rated at 4 volts. When I checked the voltage coming out of the amp on the speaker wires I got .007 and 2.8 volts, I think.  Again, I'm not sure I'm doing the right thing.  So far from my novice trouble shooting atempt I think I may have a defective Amp.  What do you guys think? 



Replies:

Posted By: stevdart
Date Posted: December 26, 2004 at 11:31 PM
Don't do voltage measurements.  Start your troubleshooting like this:  first read the amp manual cover to cover;  verify power connection and clean ground on the amp;  RCA's connected from head unit output to amp input;  speaker wires connected properly to the amp;  fuses good and in place; remote turn on wire connected properly from deck to amp.  Make sure the deck is on and a source is playing. Now, is the amp on and showing a power light, and if so is it also showing a shutoff indicator?  If the amp lights are correct, then you can connect a test speaker (any old 4 ohm or 8 ohm speaker) to a set of speaker output terminals on the amp.  Does the test speaker play the music?  If not, look at the head unit for a setting adjustment.

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Posted By: DYohn
Date Posted: December 27, 2004 at 9:29 AM
I agree with the above first steps.  Like stevdart said, does it power on?  Does it stay on?  Is there +12V on the power cable?  Did you use the same power/ground/remote as your previous amp?  Did you setup your input gain?  What is the new amp?

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Posted By: bbusbee
Date Posted: December 27, 2004 at 11:23 AM

Hey guys,

I figured out what the problem was, operator head space and timing, meaning I'm an idiot! 

I am driving a set of component speakers with this amp (Kenwood KAC 7201) and the one speaker I was listening to, the front left tweeter, was not working.  As I was trouble shooting I came close enough to the left mid-range speaker to hear sound coming out.  I have the tweeter and the mid-range separated by about 2 feet, the tweeter is installed in the front door and the mid-range is installed in the rear door, don't ask why.  When I realized the problem I simply adjusted the gain to bring out the sound, yes I had previously tried adjusting the gain but I didn't hear anything the first time.  Now all I have left to do is figure out why that front left tweeter is not working, should be simple, and they check the HU for volume adjustments for the high-range speaker jack. 

Lessons learned?  Listen to more than one speaker when trouble shooting. 

I do have another question if you don't mind.  Which unit should be used to adjust the crossover's, the HU or the amp?  All three amps coming off of the HU have crossover ajustments as well as the HU, is there a preference?

Thanks again.

BBusbee






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