On 6 Dec 2002 09:25:04 -0800, rtbond@optonline.net (Rob) wrote:

>Does anyone know if using the "Ext Mic" input on the SONY TRV-840
>camcorder routes the audio signal (from the external mic) through an
>automatic gain control (AGC) circuit?

Yes, it does... And there is no manual gain-adjust.

>If so, can it be disabled? (my guess would be no) I'm considering
>whether using quality external mics to record live music is worth the
>effort. I've heard AGC circuits can sometimes be problematic (e.g.,
>boosting the level of unwanted audio noise that might couple into the
>mic input, especially during quiet portions of the music.)

The Sony AGC design is quite good, with little of
the "swelling" of low-level noise in quiet passages,
or "level-diving" with loud passages. If the mic is
well-matched for sensitivity and the music dynamic
range is not TOO great, the effects of the AGC,
compared with older systems, can be excellent and
barely audible in operation (similar to manual
gain-riding, likely necessary without the AGC...).