TOPIC:

Hi,

How do accomplish this filter. -1 db/Oct, 10 db across 20 hz to 20kh.

Thanks
Lito

The easiest way would be to program three shelving filters with center frequencies of 63Hz, 632Hz, 6324Hz, each with a 3.3db gain and Q=0.5. That will yield a "tilt"ed response across the full audio band just as you have specified.

There are other solutions as well, but that's easiest.

Dave.

Nice trick Dave! We didn't think of that one..

DevTeam

Thanks, would it be possible to explain how you have calculated this?

rup40 wrote:

Thanks, would it be possible to explain how you have calculated this?

Do you mean the frequencies?

In miniDSP programming, the shelving filters are defined using the center of the two cutoff frequencies. (F1 & F2)
Center frequency = SQRT (F1 * F2)
The audio range is composed of three decades (20-200, 200-2000, 2000-20000) so this yields center frequencies of 632, 632, and 6324 Hz. (Shelving filters set to Q=0.5, which is equivalent to first-order.)

In the OP's case, he was asking for a 10db level change across the audio range, so that's where the 3.3db (for each) gain setting comes from.

Dave.