Drawmer DF330 Universal Noise Filter - Manual (Page 10)

DF330 OPERATOR’S MANUAL 8
reaches the threshold level, the filter will stop tracking and start to shut as the level
drops.
It should not be inferred that the Auto setting will always produce the best results
regardless of the type of programme material being processed. It is most suitable for
programme material that varies drastically in level but where the low level sections still
contain wanted high frequencies. However, if the programme contains significantly more
low frequency content than high, then the Manual mode is likely to give better results.
If in doubt, try both Manual and Auto settings and decide which is best for the material
being processed.
Once both expander and filter sections have been set up, they should both be switched
into circuit and their effect evaluated, comparing with the un-treated signal using the
bypass switch.