Rolls RPQ160b quick start Operation, OPERATION Cont

OPERATION

The two shelving filters are designed to roll off the frequency response of the Signal; the Low Shelf cuts the frequencies 3 dB at the control’s indicated setting and rolls off below, and the High Shelf cuts the frequencies 3 dB at the indicated setting and rolls of above. The Low Shelf Sweep Diagram shows the response curve of the Low Self filter at its minimum and maximum setting.

Set at 16Hz O dB

Set at 500 Hz

2040 80 160 320 640 12k 16k 20k Frequency (Hz)

LOW SHELF SWEEP DIAGRAM

The High Shelf Sweep Diagram shows the response curve of the High Self filter at its minimum and maximum setting.

O dB Set at 30 kHz

Set at 1 kHz

2040 80 160 320 640 12k 20k 40k Frequency (Hz)

HIGH SHELF SWEEP DIAGRAM

Please note that when the Low Shelf is set fully counterclockwise (16 Hz), the filter is essentially bypassed. Similarly, when the High Self control is set fully clockwise (30 kHz), that filter is essentially bypassed.

The Level control has a detente at the center (0 dB) position. if the Clip LED is lighting, the Level control may be turned counterclockwise to reduce the gain of the RPQ160, thereby reducing the clipping. If a weak signal is present, the Level control may be turned up (clockwise) to increase the gain. To achieve the maximum signal to noise ratio, the Level should be set 3 dB below the clipping level. This is done by adjusting the Level control with a normal signal present until the Clip LED lights, then turning the Level down to just below the point when the LED goes out.

OPERATION Cont.

Shown below is the typical symmetrical response curve of a swept parametric band filter with the Frequency control set at 1 kHz, the Level set at +15 and -15 dB, and the Octave control set at .3, .5, 1, and 3. These curves remain consistent over the frequency spectrum, they simply shift to whatever frequency setting is indicated by the Frequency control.

The shape is most narrow when the OCT control is set at .3, and is widest at the 3 setting.

	20
	15
	10
dB/division5	5
	- 5
Amplitude,	-10
	-15
	-20	100	200	600	1k	2k	6k	10k	20k
	50

Frequency (Hz)

APPLICATIONS

The RPQ160’s precise equalization has many applications including school or church gymnasiums, home or professional recording studios, live sound, or musical instruments.

When coupled with a spectrum analyzer, the RPQ160 can match exactly the properties of typical acoustic resonances and reflections, and make immediate improvements to any installed system’s amplitude and phase response.

Live applications include equalizing trouble spots where a mix may be muddy, too harsh, flat, and even eliminate feedback precisely without affecting the flavor of the overall sound.

Recording studios benefit from the RPQ160’s precise equalization in notching out trouble frequencies that need to be removed, or by re-equalizing a final mix.