P2D4-10 showing 5ohms per Coil

[Kinnonholt21]

Ok guys, I searched and couldn't find a topic with the same issue I have so here goes. I have two Fosgate P2D4-10's. I wired them in parallel to my Fosgate P500.1bd expecting them to be 1ohm. After a day of riding around I decided it wasn't as loud as it should be (all my gains are properly set etc..). So I picked up a new multi-meter to check my ohms. And what i found doesn't seem possible. According to my multi-meter the two subs, each wired parallel and then wired parallel together, are providing 2 ohms of resistance to the Amp. So I took everything apart to check my wiring and do some investigating. I found that each voice coil is reading 5 ohms, when wired together the ohms, at the terminal on the box, measures at 3.5-3.6. Then with the terminals wired together to go to the amp it gets down to 2 ohms. I am not exactly new to car audio but I am definitely not a pro. Any help would be awesome. So here are a few questions...

1. Has anyone ever seen/had this happen?

2. How is this possible?

3. What am I doing wrong?

4. Do I need a new multi-meter?

5. Could the terminal be causing the extra resistance?

[Joe X]

Check your probes, you should get 0 a ohm reading when the probes are in direct contact with each other.

[Kinnonholt21]

That may have solved the problem right there. With the two leads together the meter reads 1.4-1.6 which is about exactly how much it seems off in my truck. I guess I will be getting a new/better meter tomorrow to make sure! Thanks for the quick response and quick fix.

[Seymore]

Don't be that embarrassed, I'm pretty sure almost all of us have done something similar to that (I'm no exception)

[xxgokouxx]

I custom build my dripping atomizers for my vaporizer, and, like you I use the ohm load. For future reference, I believe to fix the ohm offset, you can measure your ohm load at x-amount by touching the probes. Take that # and subtract it from your ohm load readings. That should give you direct ohm load on the sub's final impedence.

Hope this helps!

[timc31610]

I custom build my dripping atomizers for my vaporizer, and, like you I use the ohm load. For future reference, I believe to fix the ohm offset, you can measure your ohm load at x-amount by touching the probes. Take that # and subtract it from your ohm load readings. That should give you direct ohm load on the sub's final impedence.

Hope this helps!

I wouldn't suggest going that route. Something either in the meter or in the leads is causing the resistance to be abnormal. While this may stay a constant there is a possibility that it will not and cause you to read the wrong resistance and could damage something. When you touch the leads together there should be zero resistance if the meter and the leads are functioning correctly. Anything above zero indicates a problem which will lead to inacurate readings.

[xxgokouxx]

Ahh, gotcha.... I guess it's different for car audio .

I figured the only reason why the readings were off (as on my cheap multimeter) was the calibrations were off on it. In the PCB board inside, there's a knob that you can tweak and tune to adjust readings.

I'm no pro with audio stuff so I can't say.... Just got back into it since 5-10 years so forgive me if I'm wrong.

[timc31610]

Ahh, gotcha.... I guess it's different for car audio .

I figured the only reason why the readings were off (as on my cheap multimeter) was the calibrations were off on it. In the PCB board inside, there's a knob that you can tweak and tune to adjust readings.

I'm no pro with audio stuff so I can't say.... Just got back into it since 5-10 years so forgive me if I'm wrong.

Im not saying that you are wrong, just that I wouldn't trust a meter that was off.