Re: turn off AGC

mv@xxxxxxxxxxxxxxxxxx wrote:
In message <1143805585.304897.289310@xxxxxxxxxxxxxxxxxxxxxxxxxxxx>, Oleg Kaizerman <KAIZERO1@xxxxxxxxx> writes
pd150 or 170 do not have automatic level control
they have fixed input stage with hard limiter around-1 dbfs
common mistake .
alc its wrong term only
the Panasonic 100 also has the same structure but without fixed input
stage m the limiter kicks at -6 dbfs till -4.5 (ganged)


Oleg dear chap, you're being pedantic to a fault. Of course the PD's have, for all practical purposes, automatic audio level response with options for 0db limiter/cut off.

Nevertheless the issue is one of using an external mixer, such as an SQN, as a means of over riding, to a significant degree, the cameras auto level response using the cameras proportional responsiveness to such an input.

There is a significant difference. ALC is exactly what it says: Automatic Level Control. IOW, it raises the gain for quiet inputs, and lowers it for louder signals...leaving everything squashed within a narrow dynamic range. A hard limiter does nothing at all to the signal until it reaches a preset level, then chokes it off (in a usually unfriendly fashion).

However, given that the it does nothing until then, it's only a matter of keeping the input below that threshold to get decent recorded dynamics. That can be done with a mixer or even a simple level control between the mic and camera. Some experimentation is in order to stay below the threshold, but overall, it's good news for the OP.

A 'sort of' ALC can be achieved with a limiter by raising the gain of the mic to the point that almost any audible sound will hit the limiter threshold; but it's not true ALC, which is variable.

jak
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Relevant Pages

  • Re: turn off AGC
    ... they have fixed input stage with hard limiter around-1 dbfs ... ALC is exactly what it says: ... A hard limiter does nothing at all to the signal until it reaches a preset level, then chokes it off. ...
    (rec.video.production)
  • Re: turn off AGC
    ... they have fixed input stage with hard limiter around-1 dbfs ... ALC is exactly what it says: ... That can be done with a mixer or even a simple level control between the mic and camera. ... A 'sort of' ALC can be achieved with a limiter by raising the gain of the mic to the point that almost any audible sound will hit the limiter threshold; but it's not true ALC, ...
    (rec.video.production)
  • Re: turn off AGC
    ... they have fixed input stage with hard limiter around-1 dbfs ... the Panasonic 100 also has the same structure but without fixed input ...
    (rec.video.production)