Regarding the BOB-19389
I previously used the BOB-18011.
However, the BOB-18011 is no longer in production.
Therefore, I am currently reviewing the BOB-19389.
I received many questions and answers via Spartkfun’s chat.
This made me even more curious.
Except for the main IC, all circuits of the BOB-18011 and BOB-19389 are perfectly identical. (I previously drove the BOB-18011 at 1.8V.)
However, the voltage input range of the BOB-18011 is 1.6V to 3.6V,
and the voltage input range of the BOB-19389 is 2.3V to 3.6V.
I initially thought the input range was due to differences in the main IC, but
The input range of the SPH8878LR5H-1 main IC in the BOB-19389 is 2.3V to 3.6V, while the low voltage range is 1.6V to 1.9V. This suggests that it should be possible to operate at 1.8V as well.
I request official verification and testing from Spartkfun.
We haven’t tested this configuration previously but we will tomorrow and should have an answer for ya 
Thank you. I have also placed an order for testing. The sensitivity and overall performance may be somewhat reduced, but I expect it to function properly. I look forward to seeing the results of your testing. I hope it will operate reliably at 1.8 V.
Well suddenly now we are out of stock! Ha
I do expect it to work fine, my guess if the engineer just went with the first spec table in the datasheet and never saw the low-power mode page…feel free to report your findings back here after testing 
I am currently in the process of ordering the parts, and it appears that delivery will take approximately two weeks. I will share the results once they are available.
I would also appreciate it if you could share your findings when you have them.
I will post an update after the parts arrive. Thank you.
Hello,
I was able to test the product (BOB-19389) earlier than expected because it arrived sooner than anticipated. This allowed me to perform a comparison test with the remaining BOB-18011 unit.
Please note that the input voltage was 1.8 V. After applying power and exposing both devices to a continuous sound source, I verified with an oscilloscope that the peak-to-peak output voltage of the BOB-19389 was at a level very similar to that of the BOB-18011.
This was the result I had expected. At this point, I would appreciate it if you could also test the BOB-19389 on your side and share your findings.
If I have the opportunity, I will upload the comparison waveforms as well.
I look forward to seeing your test results.
Best regards,
Awesome - we’ll test when we have more stock come in!