nonidentity of the two compression drivers

[Flaesh]

I bought a pair on sale (cheaply).
I was not expecting a miracle for $ 60, although the difference of the resonance frequencies of 130 Hz seems to be too big.
but the difference in the graphs of 2kHz I do not understand. What causes this?

 

[ZilchLab]

You likely need to open them, inspect, and clean the gaps, also verifying that the diaphragms are the same.

Then, measure them on a horn or waveguide, with proper loading....

 

[Flaesh]

I have no 1" horn\wg now. may be tomorrow..
FR with corresponding difference at 2kHz:

 

[Pano]

Get then on a horn, then the measurements will mean something. But don't expect them to match too closely.