compressor threshold setting when recording into a computer

[Daniel]

If I set my RNC compressor's threshold knob to 0db, and use the
fastest attack, fastest release and highest ratio of 25:1 (in regular
mode), I notice that on my computer's soundcard meter (delta 44 set at
+4dbu input sensitivity) the signal gets limited to approximately
-12db.. This seems to indicate that if I bypass the compressor and set
the preamp gain so that the signal to the point where it just misses
clipping my soundcards input and then insert the compressor, the
compressor will probably have an input signal level which is way
higher than what it considers 0db...

Will this degrade the compressors performance? Should I concentrate on
providing a signal level to the compressor which is close to what the
compressor considers 0db, and then set the compressor's output gain to
a high value like +10 db or whatever gain it is needed for the
soundcard to show a signal level closer to its own 0db mark?

I wonder if the RNC supernice mode is dependant on signal level that
it receives and if the compressor receives a signal much greater than
what the compressor considers 0db the super nice algorithms would
provide unexpected results...

[Scott Dorsey]

Daniel > wrote:
>If I set my RNC compressor's threshold knob to 0db, and use the
>fastest attack, fastest release and highest ratio of 25:1 (in regular
>mode), I notice that on my computer's soundcard meter (delta 44 set at
>+4dbu input sensitivity) the signal gets limited to approximately
>-12db.. This seems to indicate that if I bypass the compressor and set
>the preamp gain so that the signal to the point where it just misses
>clipping my soundcards input and then insert the compressor, the
>compressor will probably have an input signal level which is way
>higher than what it considers 0db...

Makes sense.

>Will this degrade the compressors performance? Should I concentrate on
>providing a signal level to the compressor which is close to what the
>compressor considers 0db, and then set the compressor's output gain to
>a high value like +10 db or whatever gain it is needed for the
>soundcard to show a signal level closer to its own 0db mark?

If it clips, it will degrade the performance. If it doesn't clip (and the
RNC has reasonable headroom), it won't.

>I wonder if the RNC supernice mode is dependant on signal level that
>it receives and if the compressor receives a signal much greater than
>what the compressor considers 0db the super nice algorithms would
>provide unexpected results...

No, the knee on the supernice mode is pretty smooth, there isn't an abrupt
transition anywhere. In fact, the supernice mode has a smoother knee than
the default mode. But you can still clip the input stage.

The whole point of a slow, soft-knee gainriding compressor is that it makes
it possible for you to be more sloppy about input levels. That's one of the
main reasons it's used.
--scott
--
"C'est un Nagra. C'est suisse, et tres, tres precis."

[Scott Dorsey]

Daniel > wrote:
>If I set my RNC compressor's threshold knob to 0db, and use the
>fastest attack, fastest release and highest ratio of 25:1 (in regular
>mode), I notice that on my computer's soundcard meter (delta 44 set at
>+4dbu input sensitivity) the signal gets limited to approximately
>-12db.. This seems to indicate that if I bypass the compressor and set
>the preamp gain so that the signal to the point where it just misses
>clipping my soundcards input and then insert the compressor, the
>compressor will probably have an input signal level which is way
>higher than what it considers 0db...

Makes sense.

>Will this degrade the compressors performance? Should I concentrate on
>providing a signal level to the compressor which is close to what the
>compressor considers 0db, and then set the compressor's output gain to
>a high value like +10 db or whatever gain it is needed for the
>soundcard to show a signal level closer to its own 0db mark?

If it clips, it will degrade the performance. If it doesn't clip (and the
RNC has reasonable headroom), it won't.

>I wonder if the RNC supernice mode is dependant on signal level that
>it receives and if the compressor receives a signal much greater than
>what the compressor considers 0db the super nice algorithms would
>provide unexpected results...

No, the knee on the supernice mode is pretty smooth, there isn't an abrupt
transition anywhere. In fact, the supernice mode has a smoother knee than
the default mode. But you can still clip the input stage.

The whole point of a slow, soft-knee gainriding compressor is that it makes
it possible for you to be more sloppy about input levels. That's one of the
main reasons it's used.
--scott
--
"C'est un Nagra. C'est suisse, et tres, tres precis."

[EricK]

Daniel wrote:
> If I set my RNC compressor's threshold knob to 0db, and use the
> fastest attack, fastest release and highest ratio of 25:1 (in regular
> mode), I notice that on my computer's soundcard meter (delta 44 set at
> +4dbu input sensitivity) the signal gets limited to approximately
> -12db.. This seems to indicate that if I bypass the compressor and set
> the preamp gain so that the signal to the point where it just misses
> clipping my soundcards input and then insert the compressor, the
> compressor will probably have an input signal level which is way
> higher than what it considers 0db...

What you are discovering is that 0db on your sound card is different
that 0db on the RNC. This would be typical with any piece of gear that
uses VU style metering. 0db on digital gear is the maximum signal that
can be recorded before distortion. 0db on an analog piece of gear refers
to the Nominal level, not the maximum level.

What your findings tell me is that your Delta card provides you with
12db of headroom above +4dBu.


--
Eric

Practice Your Mixing Skills
Multi-Track Masters on CD-ROM
www.Raw-Tracks.com

[EricK]

Daniel wrote:
> If I set my RNC compressor's threshold knob to 0db, and use the
> fastest attack, fastest release and highest ratio of 25:1 (in regular
> mode), I notice that on my computer's soundcard meter (delta 44 set at
> +4dbu input sensitivity) the signal gets limited to approximately
> -12db.. This seems to indicate that if I bypass the compressor and set
> the preamp gain so that the signal to the point where it just misses
> clipping my soundcards input and then insert the compressor, the
> compressor will probably have an input signal level which is way
> higher than what it considers 0db...

What you are discovering is that 0db on your sound card is different
that 0db on the RNC. This would be typical with any piece of gear that
uses VU style metering. 0db on digital gear is the maximum signal that
can be recorded before distortion. 0db on an analog piece of gear refers
to the Nominal level, not the maximum level.

What your findings tell me is that your Delta card provides you with
12db of headroom above +4dBu.


--
Eric

Practice Your Mixing Skills
Multi-Track Masters on CD-ROM
www.Raw-Tracks.com