Why changes a highpass the distorted sound?

[crazyfiltertweaker]

I made a kickdrum and distort it just above 180Hz. I made a highpass at 25 Hz and with this the sound changes, without not.. Without distortion, the sound is the same, but with distortion, all the punch is gone and the timbre is COMPLETELY DIFFERENT ! But why? I thought everything below 25 Hz is not audible?? And the distortion is JUST ABOVE 180 Hz..

So what is the reason for this behaviour???

[vegaron]

I don't I comprehend your problem entirely but one thing you seem to miss: no frequency dependent effect or action has a sharp cut, where you could say: "above/below this frequency my effect does not happen".
Your distortion does affect your kick drum below 180Hz, but its influence decreases, the lower you go with the frequency.

[crazyfiltertweaker]

I try explain better:
I make a lowcut to generate more headroom below 25 Hz. In theory the sound shouldnt change. But after cutting, the punch and the timbre of the kickdrum changes completely but the frequencies of it start at 40 Hz and the distortion starts at 180 hz. but the punch at 50 Hz is gone, the timbre between 180Hz-280 Hz of the distortion is completely different witht the lowcut at 25 Hz. But why???

[Harry_HH]

This other recent Kvr thread may be helpful.
I don't know your case but HPF always changes the harmony content - does it explain you case, dunno, but most likely relation to the following:

viewtopic.php?f=62&t=470923&p=6585350#p6585350

[thecontrolcentre]

Are you high passing just the kick drum, or the whole track?

[sinkmusic]

In theory the sound shouldnt change.

Not really : because your ears in theory can not hear below 25hz doesn't mean that the sound doesn't change.
Hipassing can change the phase (among others), and changes the spectral balance as well as the harmonic content. Therefore, if you apply further fx after the HP in your chain, it's an expected behaviour to have your sound sound different.

Also, think about a compressor with internal side-chain : due to the amount of compression applied, using a 150hz side-chain may very well make change the way you hear the high freq range, even if the side-chain is applied to the bass range (and it doesn't even mess with the phase). Does it make sense ?

[Harry_HH]

In theory the sound shouldnt change.

Not really : because your ears in theory can not hear below 25hz doesn't mean that the sound doesn't change.
Hipassing can change the phase (among others), and changes the spectral balance as well as the harmonic content. Therefore, if you apply further fx after the HP in your chain, it's an expected behaviour to have your sound sound different...

That's what the above link hints - for all who care to read.

[.jon]

I try explain better:
I make a lowcut to generate more headroom below 25 Hz. In theory the sound shouldnt change.

In theory the sound has to change. No such thing exists as a clear cut at 25Hz or any frequency.

All filters affect a range of frequencies around the cutoff frequency, the exact curve depending on the filter design- yet it's always a curve centered on the cutoff freq. Furthermore the freqs below (for a hipass) the cutoff point are attenuated according to the filter slope, not cut off completely. Many hipass filters have gentle slopes like 6dB/octave to avoid issues like dramatic phase changes and strong resonance humps above the cutoff point. This can often be changed to something steeper in many plugins, which may or may not sound better, and you can always use another EQ band to correct some of the issues hipassing causes to the sound.

[sinkmusic]

I try explain better: I make a lowcut to generate more headroom below 25 Hz. In theory the sound shouldnt change.

No. By definition, if you apply a processing to a sound, it will change it : processing a sound IS changing a sound. Now, the processing could be expected not to be audible, but that is a different story (as expectations are not science, and "not being audible" doesn't mean it doesn't change).

Yes, removing frequencies *should* make a sound less loud, but we know that quite often, removing low frequency content will make the sound louder (you can google that, you will find plenty explanations). Or check the videos posted above.
After all, with the trend of noise-canelling headphones, we should all know that adding sound to a sound can create silence instead of a louder signal, don't we ?

[MogwaiBoy]

Possibly a 'resonant peak' right around or just above the centre frequency of the cut-off filter. What EQ are you using? If it's a real analog/character type emulation EQ... ditch it and try something cleaner.

[Yacc]

not sure if the op will read this but always do the lowcut after distortion because distortion will produce new low frequencies.

why it has this behaviour? because distortion creates harmonics based on the present frequencies, the signal is there, no matter if you can hear it or not, its a signal which will be processed.

btw a little experiment:
make a sine bass, cut all audible frequencys away until you hear nothing, you will still feel something if you got a subwoofer or good headphones. its there even if you cant hear it
you also can go a step further an put extreme distortion on this not audible signal and you will again hear something because distortion creates new harmonics also in the high frequency spectrum (but it will sound like a motor or something and horrible if you arent into noise )