Impedance measurements - Ref input level low

Dear all

I am new to REW and impedance measurements. First of all, i am blown away with how great REW is! Very impressive software John!

I have made my very first T/S measurements based on the added mass method, but i am trying to create myself a workflow that generates trustworthy measurements.
I followed the documentation for REW, and is using a Win10 machine + Focusrite 2i2 soundadapter. 100R reference resistor measuring 99,32ohm.

I am able to repeat measurements well, but have noticed the message "The input level on the reference input is very low". I have tried using both headphones output on the Focusrite, and an external amplifier, and still get that message.

I would be happy to learn what i am doing wrong here

Thanks

BR
Thomas

Levels adjusted with open terminals, channels are adjusted to same level, just before clipping


The message when presing "Check levels"


After sweep performed, it says Level OK


An example of my measurements

Does a DCR measurement of your speaker (using a meter that say measured your 99.32 ohm ref) match the REW measurement at say 10Hz (circa 3.5 ohm) ?

The message is a bug which occurs if the ref output (not used for impedance measurements) is not the same as the measurement output as the test signal is incorrectly being sent to the ref output. I have fixed it for the next beta build.

trobbins said:

Does a DCR measurement of your speaker (using a meter that say measured your 99.32 ohm ref) match the REW measurement at say 10Hz (circa 3.5 ohm) ?

Click to expand...

At 3Hz, REW measures 3,266 ohm - My lab calibrated Agilent DMM measures 3,28 ohm. That is quite precise

John Mulcahy said:

The message is a bug which occurs if the ref output (not used for impedance measurements) is not the same as the measurement output as the test signal is incorrectly being sent to the ref output. I have fixed it for the next beta build.

Click to expand...

Thanks for sharing John! Amazing work you are doing!

Best regards