As strange as it sounds, I believe the problem I describe here is a result of installing the recent Security Update 2007-007 on my 17" SR MBP.
After the update, the following problem occurred and was consistently reproducible. When recording audio (voice) via USB microphone, lots of extreme static when running on battery power only. Amount of battery charge doesn't affect the static level. However, when running on A/C power, clean recording. I tried four different microphones of quality varying from low-end to semi-professional grade, using GarageBand, Audio Hijack Pro, and Adobe Soundbooth CS3. Extreme static (only when on battery power) in all cases.
I thought I had a hardware issue on my hands UNTIL I tried recording in Windows running under VMWare Fusion on battery power. Perfectly clean recording in this case. But back to OS X = static again. It then seemed I was dealing with a software issue, so I did a complete re-install of OS X 10.4.9.
Under 10.4.9, slight static when recording under the above conditions, but noticeably less than before. Updated to 10.4.10 but with no other updates and got perfectly clean recordings consistently, on both battery power and A/C power.
I then installed each recommended update, one at a time, and ran my audio tests after each update. No problems until right after installing Security Update 2007-007, at which point the original extreme level of static returned.
This only seems to affect the SR models. I subsequently ran these audio tests on my C2D (non-SR) 15" MBP as well as my CD white MacBook. No issues either before or after the update.
It all seemed really strange until I read in the "fine print" that Security Update 2007-007 included changes to Core Audio. Since I'm not a developer, I don't know how significant that is, but there is definitely a positive correlation between the update and the static on my system.
This post is FYI for other SR owners.
After the update, the following problem occurred and was consistently reproducible. When recording audio (voice) via USB microphone, lots of extreme static when running on battery power only. Amount of battery charge doesn't affect the static level. However, when running on A/C power, clean recording. I tried four different microphones of quality varying from low-end to semi-professional grade, using GarageBand, Audio Hijack Pro, and Adobe Soundbooth CS3. Extreme static (only when on battery power) in all cases.
I thought I had a hardware issue on my hands UNTIL I tried recording in Windows running under VMWare Fusion on battery power. Perfectly clean recording in this case. But back to OS X = static again. It then seemed I was dealing with a software issue, so I did a complete re-install of OS X 10.4.9.
Under 10.4.9, slight static when recording under the above conditions, but noticeably less than before. Updated to 10.4.10 but with no other updates and got perfectly clean recordings consistently, on both battery power and A/C power.
I then installed each recommended update, one at a time, and ran my audio tests after each update. No problems until right after installing Security Update 2007-007, at which point the original extreme level of static returned.
This only seems to affect the SR models. I subsequently ran these audio tests on my C2D (non-SR) 15" MBP as well as my CD white MacBook. No issues either before or after the update.
It all seemed really strange until I read in the "fine print" that Security Update 2007-007 included changes to Core Audio. Since I'm not a developer, I don't know how significant that is, but there is definitely a positive correlation between the update and the static on my system.
This post is FYI for other SR owners.