User Manual

DF330 OPERATOR’S MANUAL

OPERATION

The unit should be connected in line with the signal to be processed, preferably via the

console's insert points. See the section 'INSTALLATION' for details.

Setting up is identical for mono or stereo operation, the only proviso being that for stereo

use, the Stereo Link switch must be on and both sets of controls should be set similarly.

The expander is best set up independently of the filter, so at this point, the filter should

be switched out. Now the user must decide whether a sharp or progressive action is

required. For a sharp gate-like action, a high ratio and high degree of attenuation should

be chosen, together with a fast release time. If, on the other hand, a less obtrusive

action is called for, a lower ratio combined with the minimum attenuation setting and a

slower release time will allow the threshold level to be increased slightly so that dynamic

range expansion can be implemented on low level signals. This choice depends entirely

on the nature of the material being processed, so a period of experimentation is

recommended which will enable the user to become familiar with the operation of the

DF330 and obtain the best possible results from it.

It is essential that the expander should only affect low level signals close to the noise

floor and so careful setting of the threshold is essential.

The attack time of the expander is completely automatic, adjusting itself to suit the

attack characteristic of the signal being processed, regardless of frequency. This will be

of particular value when cleaning up a vocal track. Once the expander is set for optimum

performance, it should be switched out and the filter switched in. The filter can be used

in either Manual or Auto mode, depending on the type of material being processed.

In the Manual mode, the threshold should be set so that moderate to loud sounds cause

the filter display to show the full 20kHz and this will probably fall to 10 or 12kHz between

beats in the case of pop music. The next step is to play a quieter part of the programme

and check that the filter action is having a beneficial effect on the noise content. This

may be checked by switching the bypass switch and comparing the treated and

untreated signals.

If the noise is still too obtrusive, a higher threshold level may be set, but if on the other

hand there is a noticeable lack of high frequencies and noise is not a problem, then the

threshold level may be reduced. On very noisy programme material, the setting up

procedure is a matter of choosing an acceptable compromise between background noise

and some loss of high frequency definition.

In Auto mode, the Threshold control should be set up with only background noise being

fed into the unit; in the case of a recording, this might be a section of blank tape before

the programme starts. The filter Threshold should be turned clockwise until the filter just

starts to open in response to the noise and then it should be backed off slightly so that

it is once again closed. This will be evident by watching the filter frequency display. At

this stage, the programme material may be introduced and operation should be

completely automatic.

Signal above the threshold is analyzed for frequency content and the filter is in turn

controlled so that it tracks the upper frequency limit of the programme. Because the filter

response is extremely fast, sudden changes in the spectral content can be

accommodated, and, because the signal level has little effect on the filter action, the

filter will track the frequency of the input even through fades. When the signal level