[music-dsp] brute force convolution emulation of Sontec EQ
citizenchunk at gmail.com
Wed Feb 23 22:59:42 EST 2005
perhaps this is a dumb experiment; perhaps futile. nonetheless...
so here's the deal: at work, i have access to this really sweet Sontec
EQ--for lack of the model#, it's the vinyl mastering one (with A/B
settings) with 3 peaking and hi/lo shelves per side. i believe its the
MES-430. if you're familiar with the one i'm talking about, you know
that it's just "pure buttah." anyway, after messing around with some
commercial plugin EQ's and getting dissatisfying results, i've come up
with this little thought experiment that might be a good exercise for
me in convolution.
the Sontec uses all stepped pots, so the range of possible settings,
although many, are quantifyable. one can also reduce this number by
narrowing the range of certain parameters to "sane values." so, if one
were to outline a set of possible settings (knob combinations), one
could feed it a delta value and record the impulse response for that
setting, thereby capturing the TOTAL sound (including its input/output
transformers). if one were to put these impulse responses into a vast
lookup table, one could accurately emulate the Sontec, through
convolution, for any given setting.
now, that's just what i am ASSUMING. (note the doubt in my voice.) in
practice, i'm not quite certain that this is an accurate emulation.
after all, feeding it a delta only creates an impulse response for a
given input level. maybe the circuitry reacts differently to different
input levels. i don't know much about analog electronics, but i do
know how crazy and unpredictable it can get.
i'm curious to hear the opinions of the experts here; especially those
who are familiar with analog electronics, and in particular, the
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