Page 2 of 2
Posted: Thu Dec 08, 2005 12:52 pm
by Machinate
blastique wrote:Clearscreen wrote:if i ran two eq4's as steep low pass filters in serial (ie one after another..) and controlled the frequency on both with one knob does that make it a 24db resonant filter? would 4 in a row be a 48db filter? would 8 be (other than insane) a 96db filter?
hmmmm....
low pass or do you mean low shelf?
I'm no expert, but I don't think combining several of the same slopes would cause the slope to get steeper, rather you would be cutting more at the same frequency points with less movement of the knob. ie with a low shelf that has a 12db slope, by turning your knob all the way to the left, because of live's -15db -> 15db range limit, that would optimally cause a 15db drop at that range. Combining 2 eq4s doing the same thing, controlled by the same knob *should* knock off 30db when you turn all the way. While that's a fair bit to cut, I wouldn't do it because the slope would still be pretty tame and the whole point is to get a steep steep slope carving out a nice chunk of the low end with ease.
afaik, using two 12db filters in series *is* the way to do a 24db filter in many cases. Let's say that a filter is cutting 12db/octave, well, what happens when you have -12 and subtract another 12? You get -24! pretty simple, in my head at least.
Can anyone clarify this?
Posted: Thu Dec 08, 2005 1:21 pm
by Sinjin
thems the facts mate. its called stacking, last i checked.
Posted: Thu Dec 08, 2005 2:48 pm
by Machinate
...and stackin' keeps the tired man from slackin'!
Posted: Thu Dec 08, 2005 11:11 pm
by blastique
blastique wrote:Clearscreen wrote:if i ran two eq4's as steep low pass filters in serial (ie one after another..) and controlled the frequency on both with one knob does that make it a 24db resonant filter? would 4 in a row be a 48db filter? would 8 be (other than insane) a 96db filter?
hmmmm....
low pass or do you mean low shelf?
I'm no expert, but I don't think combining several of the same slopes would cause the slope to get steeper, rather you would be cutting more at the same frequency points with less movement of the knob. ie with a low shelf that has a 12db slope, by turning your knob all the way to the left, because of live's -15db -> 15db range limit, that would optimally cause a 15db drop at that range. Combining 2 eq4s doing the same thing, controlled by the same knob *should* knock off 30db when you turn all the way. While that's a fair bit to cut, I wouldn't do it because the slope would still be pretty tame and the whole point is to get a steep steep slope carving out a nice chunk of the low end with ease.
God, what am I going on about? This isn't right!!!
I was never here... This post never happened.
My past lecturers would literally kill me for this pack-of-poop I wrote.
Thanks for pointing this out guys.
of course the slope would be steeper combining 2 shelves, the db roll-off per octave would increase while the frequency points would remain the same.
shoot me now
Posted: Thu Dec 08, 2005 11:31 pm
by Clearscreen
thanks for the replys, good to know that if i ever need to make a 96db (or higher!!) resonant filter i can.
i tried two EQ4's in a row at about the time i asked the question and i have to say it sounded pretty good over a synth bassline with a bit of saturator for luck.