First of all, the metal fan protection is removed, secondly - it somehow works. I mean temperature drops by ~ 2 degrees and noise drops ~6 dB.
I actually bought it on ebay for another Antminer.
I dont really understand thermodynamics and all but is true that your ambiance temp is below 20c ?, this kind of extension modification not working for tropical climate (ambient above 25c), it only make it hotter (by 2-3 or more in celcius, on s9)
As for the noice reduction, isn it because of projected sound ? The longer the cone will make lower noise but if you measure it on the projection area (in front of the cone) its the same db produced
Anyone tried to put additional exhaust fan on z9 mini ?
Anything that redirects or alters airflow will warm it up slowly over a period of time. ambient temperatures and airflow is a strange beast. even the silver grill on the rear that area added up is blocking that intake..i have thought of removing that silver grill and getting more clean air in.. just my thoughts if it helps..