Same mic, same speakers, different results!

Evening all,

I'm pulling my hair out trying to figure out what has happened here and hopefully somebody here knows?!

In 2020 I bought a calibrated omnitronic flat frequency response mm 1c mic and measured my speakers really just to check the crossover caps were still good etc; B&W CM9 combined, high, and low as attached. Fairly linear for the expected range and no weird spikes etc pretty flat. I tested with and without the rear bass port plugged etc and they are flattest with the least THD plugged with the B&W provided foam.

Recently I got the itch and added PV1 subwoofers to each side (it is a fairly large room and one unvented 500w sub wouldn't really do it alone).

Now I wanted to retest combined with subs, subs alone, etc primarily to set the crossovers on the subs such that I am not duplicating frequencies or leaving gaps; I know what my ears think it should be about 35hz but it is nice to confirm.

Now the actual problem; I cranked the crossovers to max and I loaded REW on the same laptop with the same mic and the same speakers as 2020 then I get a completely different graph! This is shown in the attached file marked .

I have checked the xlr squid interface calibration file used is the same as it was in 2020 (and it's actually pretty similar without).

Is my mic dead? Did I screw up some setting? I have no idea what is happening iirc this mic was always pretty linear no cal file needed etc.

I hope I have included the relevant details and any suggestions as to exactly how I'm being an idiot and screwing something up here would be appreciated!

Thanks for reading, Alex

Did you forget to turn on phantom power? RTA is an easy way to verify the mic is working.

I tried it with both 12v and 48v phantom power at the switch on the preamp, my recollection is that it wants 48v and that is what it was set to.

I have another old phantom power preamp somewhere I can see if that still works and report back.

I will try RTA and replay again; although I presume it will show the same big S curve?

Just tested with newer and old phantom power supplies, getting the exact same readings with the phantom power switch on and I am with it off... so I guess you're right that it's getting no phantom power but not because I have forgotten.

Is it going to be the mic in some way given that it is the same on both phantom power supplies? Or both power supplies are dead? Is it a common failure? I'm way out of my depth with all this.

RTA attached; not really sure what I'm looking for here?

I would check that you have your audio input and output correctly configured in REW's settings. Measurement info shows that you have just "default device" selected in the settings, so REW will just use whatever input and output device windows is configured to use, which may not be your audio interface.

Thank you so much for the help.