Audix TR40 / TR40a comparison

Over the last few years, I’ve acquired (3) Audix TR40 mics and most recently an Audix TR40a (newer model) for use when my Earthworks mics might be damaged or stolen. I was curious to see what differences there are between the two models (if any).

Using a QSC KW122 speaker on a stand for my DUT, I tested each mic in the same position, one at a time. What you will notice is that TR40-1,2,3 are very close in frequency response and phase response.

Here is a trace of the (3) TR40 mics.

Audix TR40 (3) mic comparison

Here there TR40a is added to the overlay list.

Audix TR40 & TR40a comparison

You will note that the TR40a is roughly 3.5db less sensitive than the TR40s. The amount it takes to match the mics. Of special interest is the discrepancy in phase between all 3 TR40 compared with the TR40a.

Audix TR40 & TR40a with offset

Looking at the impulse response between two of the TR40 and the TR40a, they are very different even though the measurement rig is the same. Same speaker, same position, same mic position (+/- 1/4″), same everything. Someone who knows microphone design might immediately know why the TR40a has a phase response that is so different from the other mics.

Audix TR40 & TR40a IR with text

Here is the information I can find on the specs of the TR40 and TR40a.