Ashly GQX-3101 User Manual download pdf (Page 9)

Operating Manual - GQX 3102, GQX 3101, and GQX 1502 Graphic Equalizer

In designing a graphic equalizer, a selection of

filter sharpness must be made. More sharpness (higher

Q) produces less filter overlap and tighter control over an

individual band, but also causes “ripple” in the frequency

response when many filters are boost or cut together to

produce a flat response. We feel that the graphic

equalizer’s primary use is for “voicing” and tone control,

and have set our filter sharpness to produce a maximum

of 1dB ripple.

The summing system in a graphic equalizer is

also important. Since there are a number of filters which

combine to produce the overall response, it is important

that the filters not interact (they WILL overlap, but the

response of one filter should not modify the response of

another). Ashly uses an “interleaved” summing system

where every other filter uses the same summing ampli-

fier so that adjacent filters never share the same drive

and feedback signals. This allows the filters to maintain

their natural response.

10 100 1K 10K 100K

-20

dB 0

+20

+10

-10

Frequency (Hz)

10 100 1K 10K 100K

-20

dB 0

+20

+10

-10

Frequency (Hz)

On most graphic equalizers, frequency response ripple is produced by

overly sharp filters. (15-band equalizer, all bands boosted 15dB)

Ashly's GQX graphic equalizers use slightly

broader filters producing less ripple.

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Ashly GQX-3101 User Manual Page 9