Subsequent to the analysis I did in the link above, I’ve obtained a more sensitive microphone and have conducted further testing. Using the excellent REW (Room EQ Wizard) with a lower noise floor UMIK2 from MiniDSP, I can repeatedly show the frequency and amplitude of the noise from my Mac Studio Max.
The below graph is the net change in db over frequency with the Studio off vs. on. There is a 24db net change in sound pressure at 2.6kHz and a lower amplitude change of 15.5db at 400Hz. The 400Hz appears to be the normal ”whooshing” that we don’t mind, whereas the 2.6Khz is the irritating “whistle” or “whine” that we despise.
As mentioned before, I have two Studio Max in two different cities and both exhibit the noise, so I haven’t bothered to try for a return with Apple. I think I’ve passed the one year mark now anyways so I’ve learned to live with it.
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