EZ Impulse Filter

[Craig Maier]

The EZ Impulse Filter combines the noise rejection characteristics of the more user controllable performance of the “Expert-Impulse” Filter with some automation (adaptive elements) and the resultant ease of use. The purpose of this filter is the attenuation of record clicks, ticks, crackle, and pops. It can also be used to reduce radio static interference and can be used to remove some high frequency “buzz” related to the power line frequency. It has only three controls that need to be set by the user. One control determines the aggressiveness of the EZ-Impulse Filter’s response to large scratches or impulses. A second control affects its response to “crackle” which is another term for smaller and densely populated impulses. The “Narrow Crackle” control affects its response to smaller impulsive events. Three bar graphs provide the user with visual feedback as to the effect that each of the controls has on the signal. A tally of “Total Clicks Fixed” is also provided for use as a relative reference and an operational aid. Before using the EZ Impulse Filter, the file should be Gain Normalized to -3 dB first for optimum results. Use the Normalized Gain Scaling feature found under the CD Prep menu to accomplish this task. Set it for -3 dB.

The following is a listing of the EZ-Impulse Filters controls:


EZ Impulse- Powerful and Easy To Use!

• Scratch

This control sets the threshold for the detection and interpolation of large clicks, pops and scratches. Low numbers are less aggressive, while large numbers are more aggressive. The normalized range for this control is 0 to 100.00

• Crackle

This control sets the threshold for the detection and interpolation of small clicks, crackle, impulses and high frequency “buzz”. Like the Scratch control, low numbers are least aggressive, while large numbers provide a more aggressive response. The normalized range for this control is also 0 to 100.00

• Narrow Crackle

This control sets the sensitivity of the system to narrow pulse width crackle. Like the other controls, increased values represent increased sensitivity to this type of noise. The normalized range for this control is 0 to 100.00 with a good place to start being around 50.

• Big Clicks Checkbox

This feature enables a “Big Click Filter” having a fixed ratio setting of 1.4. For details pertaining to the functionality of a “Big Click Filter”, please refer to the section of this User’s Manual having that name.

• Bar Graphs

All three filter controls have their own “Clicks per Second” bar graph having a range of display of 0 up to 400. These three graphs are useful for setting their respective controls. Indications that are too low may mean that the system is not sensitive enough to pick up the impulses (or there are none or not many), while indications that are too high may indicate that the Wave file is being damaged by overreaction of the filter(s). Using these graphs, in conjunction with the “Preview” mode makes the setting of the EZ Impulse Filter very simple and effective. The slider control green zones are good places to start with. Most of the time, you will find the best result to be within that zone; rarely, the control(s) will have to be set higher or lower than those zones.

• Total Fixed

The Total Fixed accumulator counts the total number of impulsive events repaired by the system. It responds to the Scratches and Crackles, but not to the Narrow Crackle function. It is interesting to compare these data from one recording to another. It is somewhat of a litmus test for the grade of the recording that you are working with.

• Bypass

This control allows you to hear the unprocessed signal for comparison purposes. It can be used “on-the-fly” during Preview and slider adjustments. Do not forget to uncheck “bypass” before running the filter after you have satisfied yourself with the slider control adjustments.

• Solo/Brass

Choose this setting when brass instrument solos or up-front vocal solos are causing distortion when using the EZ Impulse filter. This feature will suppress distortion produced by those instruments or strong lead vocals. It should not be used on material that does not contain up-front brass or up front vocals as the filters performance will be compromised under those circumstances.