KVR Audio

declassified · Post by **declassified** » Thu Oct 27, 2005 3:28 pm

I need a very steep notch filter that goes down to -infinite at the center frequency and doesn't affect the other frequencies too much. All notch filters I've tried only go down to -12 or maximum -36dB.

FreEq is good (I own it), but I can't choose an exact frequency to cut off because it only has a "step" every 80Hz or so.
I'd like to enter the frequency value (or turn a knob) and be able to lower that particular frequency to -infinite dB.

robenestobenz · Post by **robenestobenz** » Thu Oct 27, 2005 6:53 pm

AFAIK, a notch filter has to totally reject its center frequency or it isn't a notch filter.

You could use one band of the freeware Posihfopit EQ to achieve this, anyway. Plpareq1 can do this as well, although with considerably more CPU cost.

red_giant · Post by **red_giant** » Thu Oct 27, 2005 7:00 pm

you can use phasetone by tritone digital to do that. make Q as steep as possible (to 0.01, or maby thats the widest), set the blend to 50% (50% inverted + 50% origional = cancled) and then select your frequency

red_giant · Post by **red_giant** » Thu Oct 27, 2005 7:01 pm

oh yeah, i mentiond that one because it's free

red_giant · Post by **red_giant** » Thu Oct 27, 2005 7:04 pm

ha, shoulda wrote this all at once,
i just used exactally that technique to remove some substantial tape hiss from some old recordings, worked like a charm

JonnySun 2.0 · Post by **JonnySun 2.0** » Thu Oct 27, 2005 8:06 pm

Eqium can also do that

declassified · Post by **declassified** » Thu Oct 27, 2005 9:12 pm

Ok, thanks a lot. I tried phasetone and Plpareq1 on a sine wave, and phasetone did a better job of lowering the volume, although it didn't get down to -infinite.

robenestobenz · Post by **robenestobenz** » Thu Oct 27, 2005 9:31 pm

Try posihfopit next.

Space Boy · Post by **Space Boy** » Fri Oct 28, 2005 4:23 pm

declassified wrote:FreEq is good (I own it), but I can't choose an exact frequency to cut off because it only has a "step" every 80Hz or so.

The smallest step should be about 11 Hz. Did you try using the ASCII import option? You can define your notch filter in a text file and import it into FreEq Boy.

polyslax · Post by **polyslax** » Fri Oct 28, 2005 6:01 pm

Wave Arts Trackplug has 2 brickwall filters which you could set on either side of the desired frequency.

diverdee · Post by **diverdee** » Fri Oct 28, 2005 6:50 pm

yeah for free posihfopit has a 'true' notch filter I believe.

ouroboros · Post by **ouroboros** » Fri Oct 28, 2005 7:02 pm

I think it's possible with Bugpass, as well: no resonance, but if the controls are inverted; brickwall on either side of freq, as well

brok landers · Post by **brok landers** » Sat Oct 29, 2005 1:28 pm

robenestobenz wrote:AFAIK, a notch filter has to totally reject its center frequency or it isn't a notch filter.

correct, thats why it is sometimes also called "band reject filter". everything else is just a one band bell eq, which is only able to reduce the centerfrequency with a certain amount.
some notchfilters allow you to change the slope stepless though, which i find most missing in many notchfilters.

Notch filter that goes down to -infinite