Symetrix 628 - Page 12

628
10
knob a slow turn until you feel a single click. The MASTER numeric display will show the current
bandwidth setting in the program for the frequency selected. Continued rotation of the knob will
change the bandwidth and the display will show the value in octaves.
Note: The 628s bandwidth control has a logarithmic taper. You will notice a greater
change in value with each click as the ratio increases.
Bandwidth defines the width of the cut or boost centered at the equalization frequency. When
applying a boost, the bandwidth (in octaves) is measured between the points on the curve where
the signal drops 3 dB below the boost applied at the center frequency. When a cut is applied to a
signal, the bandwidth (in octaves) is measured between the points on the curve where the signal
drops 3 dB from flat response.
When you need to notch out an offending hum or buzz, use a narrow bandwidth setting of .3
octaves (0.30 oct.), to suppress only the offending frequency. To boost a wide range of frequen-
cies use a broad bandwidth setting of 3 octaves (3.00 oct.), for a smoother response. Push the
SAVE button and the MASTER display will show the flashing letters Sto(Store). Push the SAVE
button again and the 628 will record your new bandwidth setting. This edits the program and
permanently records the change.
The amount of cut, or boost, determines the amount of change made at the equalizer center
frequency. Turn the CUT/BOOST knob slowly until one click is felt. The MASTER numeric
display will show the cut, or boost, (in decibels, dB) currently used in the processing preset.
Turning the knob further will change the cut, or boost, and the new value will show in the LCD
display. Push the SAVE button once and the MASTER display will show the flashing letters Sto
(Store). Push the SAVE button again and the 628 will change the program and record the new
amount of cut or boost.
An example ...
Lets run through an example of making an equalization change to make sure that everyone is with
the program. We will add a 4 dB boost at 125 Hz with a bandwidth of 3 octaves on program #10.
1.) Start by rotating the PRESET NUMBER knob until the MASTER display reads 10.
2.) Momentarily push the LOAD button.
3.) Now select the LOW equalization band by repeatedly pushing the Band Select
button to the left of the FREQUENCY knob until the LOW LED lights.
4.) Turn the FREQUENCY knob until the MASTER numeric display shows a
frequency of 125 Hz (.125 kHz).
5.) Next, turn the BANDWIDTH knob until the MASTER numeric display indicates
3 octaves (3.00 oct.).
6.) Rotate the CUT/BOOST control until a 4 dB boost is indicated (+4.0 dB).
7.) Finally, push the SAVE button. Note that the MASTER display shows the Sto
message. Push the SAVE button a second time.
Thats it! Youve changed the equalization and modified program #10.
Note: You can find more advice on equalizer theory and adjustments in Chapter 4.
The Compressor ...
Now weve graduated from equalization school and its time to move on to compressor college.
The COMPRESSOR section of the 628 operates the same way as the equalizer. When you move
any of the knobs one click, the MASTER display identifies the current value. Moving the knob
further than one click changes the value of the function. Make sure that the COMPRESSOR
section is active by momentarily pushing the Operate/Bypass button to the right of the RELEASE
control until the ACTIVE LED comes on.