Somethings not right?? Help

[disturbed471985 5,000+ posts]

Amp and speakers are in my sig. The problem I am having is when the amp is turned off and I check to see what ohm each channel has on it I get the correct reading of 2.1 -2.4 load per channel. Once I turn the amp on the loads are all over the place. 8-20 ohm per channel and they just dance?? I have check the coils on the speakers and all read as they should around 4 ohm. So the vc's all seem to be ok but as soon as I turn on the amp and check the load at the terminals the ohms are just crazy?? Any ideas??

Click to read more...

 

[Kangaroux 5,000+ posts]

Is that when music is playing or when the amp is idling?

 

[disturbed471985 5,000+ posts]

that i will go check right now

 

[bubbagumper6 5,000+ posts]

Better question is, why are you trying to measure the resistance of the speaker while the amplifier is on?

 

[disturbed471985 5,000+ posts]

ohms go crazy as soon as amp is turned on no matter if playing music or not..

 

[disturbed471985 5,000+ posts]

Wanting to make sure all my connections are correct as each channel has 2 4ohm speakers wired to each and wanted to verify amp is seeing a 2ohm load. The main reason I checked was because I almost have no output. I mean there is sound but no where near what it should be.

 

[Z1NONLY 10+ year member]

I have to take load readings often in my line of work. It's never a good idea to try and read the load when it's connected to the amp. (The amp has it's own resistance that you are throwing in the mix when you try to get a reading with the amp connected.)

Even worse, reading the load (resistance) while the amp is powered up could damage your meter. If you have an analog meter, you could actually watch the needle "dance" to the music...before the meter dies.

The bottom line is that you are reading more than just your speakers when you put your leads on the amp's terminals. (or the speaker terminals when they are still connected to the amp)

 

[maylar 10+ year member]

The amp puts out a very small amount of voltage due to offsets at the output stage. It will be a few millivolts, maybe a tenth of a volt, and will drift a bit with time and temperature. This is perfectly normal.

This voltage will drive your ohmmeter nuts. The measurement you're getting is meaningless.

 

[disturbed471985 5,000+ posts]

Bahhh well before amp is turned on the ohms are correct so I guess I will just have to take to a shop cause I have double checked everything 20times in the past week and I just have no output I mean stock radios get 5 times louder then mine so something is not tight.

 

[Z1NONLY 10+ year member]

You could play a test tone and read the AC voltage at the terminals.

That will at least let you calculate the power output you are getting.

 

[CRXBMPN 5,000+ posts]

so we have determined your impedence is correct, and now you have an output problem. discuss that with us before you bring it to a shop. do you have a coil backwards and causing cancellation?

 

[disturbed471985 5,000+ posts]

ac voltage at the power terminals is 30.4.. if u meant speaker terminal then 0.

 

[disturbed471985 5,000+ posts]

so we have determined your impedence is correct, and now you have an output problem. discuss that with us before you bring it to a shop. do you have a coil backwards and causing cancellation?

what do u need to know? I am sitting in the front seat of my car so I can tell u anything.

 

[disturbed471985 5,000+ posts]

ideas? thoughts? info needed?

 

[Z1NONLY 10+ year member]

How are your speakers configured? If you can run one speaker alone and it sounds good you may just have a polarity issue.