hello list,

last weekend i made some tests with the a155,
using it as a graphic vco. bakis told me, that
i should post the results here, maybe they are
of interest for anybody.

as all of you may know, the a155 is dc-coupled
and outputs only positive voltages. so if you use
the a155 as a graphic vco, the audio waveform will
be positive as well and not alternating around
zero as usual. not a big deal, as there is no real
audible difference between dc and ac, but if you
use the waveform in the middle of a patch, the
differences can be huge, for example when using
the a155 output as a modulator for exponential fm
with an a110 or a111 vco. so sometimes you may
want to transform the dc voltage of the a155
into an ac voltage in certain cases.

here is a list of a100 modules which do this:

all vcf's without exception
a109 vca part
a114 ringmod
a119 external input
a125 phaser
a126 frequency shifter
a128 fixed filter bank
the old a130 and a131 vca's (with cem chips)
a135 vc mixer


now the modules where the a155 output remains dc:

the new a131 vca (with ca3080 chips)
a132 vca
a133 polarizer
a138a, a138b, a138c mixers
a170, a171 slew limiters


sorry if some modules are missing, but i couldn't
test them all during the weekend.

i hope this info is of use for anyone :-)


best wishes

ingo