[sdiy] Graphic EQs? and Mort

[Peter Grenader]

I have never done tests on the actual bandwidth of each filter but have
wondered this myself.  Is the first filter some sort of a low pass and last
some sort of a high pass filter?

I will tell ya a cute graphic EQ trick though I used to do back in the days
of (gasp!) control tracks in electronic music.  Subotnick used to be big on
these, mainly because he didn't have enough modules or recording tracks
availible to do what he needed to otherwise.  He would end up using four
tracks of an Ampex eight track deck for control tracks (which contianed the
timing, amplitude and spacial location control information)  and the last
four tracks for the audio information which we would end up hearing.

Well, it got to the point where four control tracks weren't good enough.  So
what we ended up doing is putting two totally independant control tracks on
each Ampex track at different frequencies. One at about as high as the
Buchla followers would respond to that corrosponed to a band filter CF, one
at the lowest.  We would run the output of these tracks threw the Buchla's
10 band comb filter and vwah-lah...

We could demultiplex two control tracks per channel with absolutely no
crosstalk. Worked like a charm.

-P


> 
> 
> Edu Silva wrote:
> 
>> Use an EQ to narrow the freq response from 40Hz to 15kHz.
> 
> I've seen several different graphic EQ's, but never really needed to
> use one, so never really gave them much thought.
> 
> My one question at this point is as follows;  what happens to the
> audio that is above and below the highest and lowest (respectively)
> bands of the EQ?  Are the 'end-point' bands set to attenuate all
> frequencies beyond them, or do the ultra, and sub sonic frequencies go
> through untouched?
> 
> thanks all.
> 
> -ben