PD150 Audio Tests submitted by David Cherniack
The Companion notes: With over twenty-five years of experience in television and film production, David Cherniak has worked with and around cameras for most of his professional career. He has interviewed such notable figures as Alan Ginsberg and Stephen Hawking, and currently works for the Canadian Broadcasting Company. With these credentials, it can be safely said that David knows good audio when he hears it. What follows is a description of his audio tests of the Sony PD150's Automatic Gain Control circuit, along with an audio file in .wav format which you can download and listen to. From there, you can draw your own conclusions. David describes his procedure:
Here's a cut down file of a new test that's designed to accurately compare AGC and manual gain on the Sony PD150. This is how it was done...
It uses the line-in jacks to record a generated -14db tone which alternates with an interval of silence. This is sent through a mixer, to the line-in audio inputs on the PD150.
The tone and silence is first recorded with AGC switched on, and the level adjusted at the mixer to read -14db on the PD150. Then, the manual gain is turned on and adjusted so that the tone peaks at -14db. The playback output from the camera
is then digitized in the computer and converted to a .wav file.
The file is about 500kb, in two sections. First, you'll hear the manual gain... silence, and then tone. Following that is the AGC, silence and then tone.
The hiss on AGC is clearly less... about -64db to -52db.
PD150test.wav (493 kb)
Written by David Cherniack
Thrown together by Chris Hurd