I am a software engineer, and just learning digital signal processing formally, though I've hacked around before a fair amount.
I'm implementing a delay audio VST and I'm trying to wrap my head around how one creates equations of the output given a system diagram. I'm not used to circuit diagrams (they're weirdly parallel to me), so I'm trying to figure out how one goes from this system diagram:
to an equation. As best I can tell, the equation for this is:
y[t] = x[t] + y[t - T] * gain
x[t] is the input on the far left,
y[t] is the output on the far right, and the delay time in samples is
Is this correct?
I don't fully see how the system diagram implies the second term is
y[t - T] rather than
x[t - T], but intuitively, I know it must be, because an audio delay unit can't really incorporate feedback if the original signal delay only happens once (feedback must enable the ever-decaying ringing with time). Otherwise we'd get just a shifted version of the original, added to the original. This would be boring.