Posted by Rick Merrill on 03/31/06 20:59

jakdedert wrote:
> mv@movingvision.co.uk wrote:
>
>> In message <1143805585.304897.289310@u72g2000cwu.googlegroups.com>,
>> Oleg Kaizerman <KAIZERO1@gmail.com> 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

Suppose one were to raise the gain of Just One Channel (e.g. the right channel of a stereo input) - would that force the ALC (I'm unclear on the diff. from AGC) to be a constant?

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