Ashdown Engineering PRO FX Manual Del Usuario página 5

ASHDOWN ENGINEERING - PRO FX
AN INTRODUCTION TO COMPRESSION
Compressors are widely used for Levelling the Audio signal , Limiting to prevent unwanted distortion, and for
dynamic range preservation and finally as an effect . Most compressors have a single Threshold adjustment above
which the signal is compressed and below which the signal is passed through with no modification.
As the threshold is lowered and compression takes place the output signal level drops so a Gain control is usually
provided so that the original uncompressed signal level can be recovered. Usually a Ratio control is included to
enable the user to set the amount of compression , generally from 1:1 to 1: infinity.
The later ratio is usually used in Limiter applications. In addition to the above mentioned controls there is also ad-
justments for Attack and Decay on commercial compressors and since all of these controls are interactive to some
degree they are all difficult to set up and use.
The Ashdown range of compressors all feature a smooth transition from the uncompressed
to compressed portions of the signal, giving an effect similar to a compressor having multiple thresholds ,in effect
the compressor gradually squeezes the signal harder and harder as the overall level increases without the abrupt
changes in compression that are sonically undesirable.
There are many types of compressors available but the Pro bass player will only realistically need small selection to
perform specific function. The first of these is the Compressor limiter , used to prevent clipping and consequent
distortion in the main amplifier. In general this type of compression if being used correctly should really only be
noticeable to the player and imperceptible those listening to the performance.
USER GUIDE ASHDOWN ENGINEERING - PRO FX
The Studio Comp is an example of such a compressor suitable for this purpose The SC has controls for "Threshold"
which sets the level at which the unit starts to limit the signal, "RATIO" which sets the amount of compression and
an overall "GAIN" control which allows the signal level to adjusted . The SC features optimised settings for attack
and release so no adjustment is required in respect of these.
In use the compressor is placed between the pre amplifier and power amplifier, or instrument and amplifier and
adjusted accordingly, Once stage volume has been determined the compressor is adjusted so that with excessive
playing the amplifier cannot be overloaded, when adjusted correctly the SC will allow players to achieve higher
overall average volume output without distortion and help protect the speakers.
Of course the SC may also be used as a general compressor rather than a limiter.
Thanks for reading,
Dave Green
Chief Engineer
USER GUIDE