Signal subtraction – Erica Synths EDU DIY Dual VCA Eurorack Module Kit User Manual
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SIGNAL SUBTRACTION
Valid point – but here’s the twist.
If we take our inverted twin signals and subtract
them from each other, the result will be a signal without any DC o
ff
set
. Why? Well,
since both original signals have the same o
ff
set, they’ll cross each other exactly at their
respective mid-points.
For this example, we’ll assume that this would be right on the 6 V line. Now if we subtract
6 V from 6 V, we get 0 V. From here, the two signals will diverge, which means that their
di
ff
erence increases. At the waves’ respective peak and valley, that di
ff
erence is at its
most extreme: 7 V versus 5 V. Subtract those numbers, and we get a 2 V peak for our
new, centered oscillation. Move half a wavecycle ahead, and the same is true in the other
direction, giving us a -2 V valley.
And the best thing about this is that it works
regardless of what the exact DC o
ff
set is – as long as it’s the same for both original
signals
. Okay, but how do you subtract two signals from each other? Simple: with
You can try this chapter’s circuit in a simulator. I’ve already set it up for you right her
you can change all values by double clicking on components.
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