Loopback Accuracy Distance Measurment

[Sonder]

Hello, I am just wondering how accurate should the readings be from speaker to microphone, mine always seem to be out by 5 are 6 cm, is this OK?
Below is the readout but the actual distance from mic to speaker is 20cm

Delay 0.7016 ms (241 mm, 9.47 in)
relative to Loopback with no timing offset

 

[John Mulcahy]

There may be additional delays in the replay chain accounting for the extra time taken for the signal to arrive at the mic.

 

[EarlK]

That (@2" ) differential is about right ( for a small speaker ).

The "Time of Flight" will always include the delaying effects of any crossover ( specifically inductors ) as well as the drivers voice-coil inductance ( which is another coil in series with the Low-Pass inductor ) .

These coils add their inductance together to produce measurable delay to the signal being propagated ( created ).

That means the measured acoustic signal will just about always emanate from somewhere behind a drivers diaphragm ( and sometimes even behind the voice-coil if it's really large diameter ).

 

[Sonder]

Many thanks for the answers, helps a lot in understanding the physics.