Reversing comprerssed dynamic range

[paul]

I have a recording of a piano recital taken from VHF radio.
The basic sound quality is excellent, and there is no intrusive
background noise. Everything is fine when the pianist is
playing quietly or even moderately loudly. It is just during
the climaxes where it feels as though an invisible hand has
turned the volume down, robbing the music of its impact and
sense of immediacy. My subjective feeling is that the
compression used is not linear; i.e. the radio station allows
the volume to reach a certain threshold level before switching
on the compression.

Can someone suggest how I could use DC 6 to reverse this
dynamic range compression? I realise that some trial and error
will be necessary, so if somebody who has actually done such a
thing could give a starting point for experimentation, that
would be very welcome.

[Craig Maier]

I would try using the Punch and Crunch in Expander mode with modest settings of the "ratio" control. Then, I would adjust each bands threshold so that the expansion only occurs on the crescendos or transient peaks of the material. This will be indicated by the horizontal bar graph movement (located below each band) at the correct times in the music. Trial and error in conjunction with these meters will help find the correct threshold(s).

It is important not to use too large a value of ratio in order to maintain a natural sound, in my opinion. I keep the ratio control under 2.0 when attempting to do what you are describing.