Topic: H120 noise

[westkc3]

Recorded Larry Coryell Trio last night.  As I was driving home I listened to the recording and it sounded pretty good until I got to an acoustic track when I heard a strange noise, over the road noise no less.  When I got home, I transferred the file to my PC and listened thru my Sony VD - 900 cans.  Ouch!  On the acoustic track it stands out like fingernails on a chalk board.  Why would this be? 
 
Equipment/settings;
AT 853 sub-cards
CA ST 9100 (Not positive of the setting as this was a stealth job and I set according to meter levels, I'd guess it was only at around 10 o'clock)
H120 (Rockboxed) line in gain @ +10, AGC Safety on
 
I checked the battery in the pre with a voltmeter and it's still fully charged.  I checked the recording screen and the AGC knocked the gain down to +9.5.  All connections were double checked prior to beginning the recording. 
 
Is this the H120s pre, HDD the ST 9100?

[Arni99]

It doesn´t sound like the known noise we all know from preamps. It´s more kind of electrical-noise. Never had this issue with my H120, but mine is CF-card-modded and it could be that the spinning harddisk causes this noise which can only be heard at silent tracks.

[westkc3]

Upon futher listening the noise first appears between tracks 3 & 4.  I do notice from the very start of the recording what sounds like a hush of air.  Is it possible this could all be from HVAC?

[boojum]

HVAC is always a problem, especially with mic's that can hear down low.