What exactly does low cut filter work

I thought I understood what the low-cut filter in cubase does but now I’m not so sure. if I set it for say 130 Hz. Shouldn’t it cut out everything below 130 Hz? Strangely it does not. There’s still plenty of content in that frequency range even with the filter on and the area showing red over the waveform… It seems the only way I can actually filter that content out is with one of the four eq. bands using a low shelf or a low cut. can someone explain to me exactly what that low-cut filter does? Thanks.

The filter has steepness settings, 6dB/oct, 12dB/oct, 18dB/oct, 24dB/oct, etc.
Try different settings and see if it helps.

Maybe you must turn the filter on, not only adjust the frequency.

The low cut filter in the pre section sits earlier in the signal chain compared to the channel EQ, hence you’re getting different results.

thanks. Can you expand on that?

There are various points in the signal flow where you can make a low (or high) cut. This covers one method:

A square wave cut that chops out everything below a chosen point would be highly unmusical – maybe even sound distorted so low cuts always have a curve that reduces frequencies below the chosen cut off point - they don’t simply remove all content below the cut off point. As Vinnie_Lee noted above you can choose more subtle or more extreme versions of the curve. Low cuts turn down the amplitude of frequenices below the cut off point-- they don’t just chop off and remove them completely. In reality if you want to reduce more content you will want to make your cut a little higher than 130Hz with a steeper curve which will have more of an effect on the frequencies below that.

If you want to read more about filters then there is plenty out there on the Net. I found this by Googling ‘how do filters work in a DAW?’

If you are meaning what Timo told you, it is the fact that the filters (low cut and high cut) belong to the pre section, together with pre-gain and polarity switch. This section is ALWAYS at the beginning of the processing chain in the channel and you can not change that. The channel strip is at the end of the chain and the four band channel eq belongs to the channel strip. That is, you will get different results if you filter with one or another, depending on plug-ins you have in the inserts and possibly other processing in the channel strip. You can move the channel strip from post inserts to pre inserts, but that will be after the pre section, never before.

And you must consider what wildschwein told you too: you can’t expect that you will eliminate the WHOLE content below the frequency you adjust in the filter. The filter has a curve with a slope, so that keeps attenuating more and more with descending frequency, but not with gain -inf.

1 Like

The signal will hit the pre section first, then the inserts, and then the channel strip EQ. So, if you, for example, have an insert that adds low frequency information (e.g. reverbs can do that), you can cut low frequencies all you want in the pre, but will need to do so again to get rid of the ones that an insert might add (if that’s what you want).

This article has more info on signal flow in Cubase:

This is configurable BTW, but I’m describing the default setup.

1 Like

Wow I never even thought about that. Ok thank you for explaining

1 Like