Filter Help

Silas · Joined: Apr 27, 2008 Posts: 23 Location: Denmark

Hey, I need to put a filter on a mixer so I have the mid and high on one output and the bass in its own.. Am i looking for a Passband filter or am I way off ?

To clearify, I need the filter to split the mid and high range from the bass..

Help me out please, THANKS..

bubblechamber · Posted: Tue Sep 23, 2008 5:59 pm Post subject:

it seems like you could do this with a high pass, for the mids and highs. and a low pass for the bass.this would give you 2 output.
3 band passes would work too, and that might give you more control in the long run. but would require 3 outputs.
david

urbanscallywag · Joined: Nov 30, 2007 Posts: 317 Location: sometimes

A state-variable filter would be cool since it has simultaneous low pass and high pass outputs (with a single cutoff frequency).

Silas · Joined: Apr 27, 2008 Posts: 23 Location: Denmark

Hmm, both suggestions sounds just fine... Problem is I've spent the last hour looking at filters and I don't understand much.. Certanly none of the calculations.. whoa.. Really I guess i just wan't to be spoon fed, can you link me to somewhere theres schematics that also tells me what the values of the components ?

Looking at the state-variable filter, I'm guessing it's no problem having the mid and high on one output and the low on it's own?

Also, I have no internet at my place so I have to commute 30 min, to get to some internet, so I would really apriciate if you could help me out in one go..

THANK YOU VERY MUCH!

Scott Stites · Posted: Wed Sep 24, 2008 7:48 am Post subject:

Buchla 194 sounds like a good start for what you're shooting for.

Marjan Urekar's redraw is here:

http://members.tripod.com/urekarm/synth/download.html

An SDIY thread about it is here:

http://dropmix.xs4all.nl/pipermail/synth-diy/2008-April/006679.html

It may fit the bill. I've got one on perf, pretty cool.

Cheerios,
Scott

Dave Kendall · Posted: Wed Sep 24, 2008 10:51 am Post subject:

Just a thought - is it for a DJ-type use, or for a P.A. crossover use?
If it's for DJ use, you might want to look at a type of filter, or pair of filters (lowpass and highpass), that can have the frequency swept via a pot or control voltage.
To filter out all but the "real" bass, you will often need a relatively low cutoff frequency, around 100Hz or lower, and need to tweak the cutoff frequency according to the track you're playing through it. The same holds for the mid-high frequencies.

The steepness of roll-off (sharpness at the cutoff point) is probably an issue too. For example, a 6dB/octave filter will sound very different to a 24 dB filter in this application....

In the end, just use your ears to decide what filter type to go for - if it sounds good, it *is* good. Smile

just my .02 pence worth....

cheers,
Dave