# How to measure impedance amp is seeing from sub with DMM

• 12-07-2012
How to measure impedance amp is seeing from sub with DMM
The title says it all. Is there a way to do this? I have a True RMS multimeter on hand
• 12-07-2012
neo_styles
Re: How to measure impedance amp is seeing from sub with DMM
This is stickied in the Help 101 tab at the top of the forum. You know Ohm's Law?
• 12-07-2012
Julian
Re: How to measure impedance amp is seeing from sub with DMM
No not while it's playing... you can measure DCR of the subs. Unless you're burping there is no reason to find out because impedance curve will be different based on the frequency being played.
• 12-07-2012
dragnix
Re: How to measure impedance amp is seeing from sub with DMM
Just put ur dmm to the sub n get an idea of "baseline" resistance
• 12-07-2012
Re: How to measure impedance amp is seeing from sub with DMM
Quote:

Originally Posted by neo_styles
This is stickied in the Help 101 tab at the top of the forum. You know Ohm's Law?

Ok i will check that out. Thanks!
• 12-11-2012
vector
Re: How to measure impedance amp is seeing from sub with DMM
Just measuring the impedance of the speaker will usually give you a good idea.

Are you wanting to know worst case scenario? Sometimes for fun I will use Winisd (LinearTeam) to model the speaker and box that I have. I take the lowest point in the models impedance curve and play that frequency through my system while clamping (https://www.youtube.com/watch?v=oTvE9KyQstg) the amplifier. With this result you can calculate out the lowest actual impedance your amp should see at any frequency.
• 12-11-2012
keep_hope_alive
Re: How to measure impedance amp is seeing from sub with DMM
measuring impedance curves is what the DATS or WT-3 is for.

Dayton Audio DATS Dayton Audio Test System 390-806

using Ohms law to measure impedance requires you know two of the four parameters + know what frequency you are playing. Voltage is easy and a given. Current is the next option, and fine for low volume testing.