Tech Works IC-52B, Руководство по эксплуатации и установке, Страница: 19 / 26

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Notch Filter Setup: Do after initial adjustments
Notch Filters can greatly reduce feedback; however they cannot make up for
poor acoustic isolation
When shipped from the factory the Notch Filters not used.
The Notch Filter Configuration Jumpers must be moved to the appropriate channel first
The factory settings are: LO, fully CCW, HI, Fully CW; the Notch Filters are essentially disabled
There are two methods to adjust the Notch Filters; both entail forcing a feedback condition
The one below is required if access to the jumpers is unavailable
If the covers are off the IC-52B, the second method may be easier; see next page
Method 1:
Move Speaker wires
The
Notch Filters are adjusted by moving the Speaker wires so the channel with the
Notch Filters is temporarily connected to the Room Speaker with the microphone
To induce feedback
There are two distinct primary resonance modes in most installations. One is room resonance;
usually one mode is most prevalent, such as floor to ceiling resonance. This frequency is
usually on the order of a few hundred cycles. The second mode is the distance of the
microphone from a near object. This frequency is much higher near 1000Hz. The IC-52B
incorporates two filters in tandem, one a low Band Filter 250Hz to 1000Hz, and the other a High
band Filter 750Hz to 3000Hz.Adjust the Notch Filters one at a time. Increase the Speaker Level
Control until feedback occurs.
Make a rough determination of the frequency (or measure the frequency with a counter).
If the feedback is below ~800Hz, adjust the ‘Lo Notch’ until feedback ceases. If the feedback is
above ~800Hz, adjust the ‘Hi Notch’ until feedback ceases. (This is a 20-turn pot so it is best to
start from one extreme, and slowly turn the pot in the other direction
Increase the Speaker Level Control until feedback occurs again, if it is at the same frequency;
try finely adjusting the same filter to see if the feedback can be eliminated. If the frequency is
different, and in the other range not already tuned, repeat the steps above
If only one Notch Filter is required, the other filter should be set at the extreme of its range.
Fully CCW (lowest frequency) for the LO filter, and fully CW (highest frequency) for the HI filter.
After the Notch Filters are adjusted, move the speaker wires and redo the initial adjustments.
Note:
Before making any adjustments assure there are audio Inputs and Outputs
All the associated indicators must be lighted green