The SID has audio-in that can be summed with internally-synthesized sounds and routed through the on-chip filters before going back out.
I found this pinout in the programmer's reference guide and tinkered with it a bit as a kid, but I didn't really know what I was doing, so it never went beyond a novelty. Who knew, forty years later, that it'd get proper treatment as an effects generator!
Thanks for explaining - I had no idea there were audio in pins, and was searching the page for how they managed to route audio to the SID without any modification.
Warning to the curious: it is very easy to fry your SID connecting directly to the audio in (don't ask how I know this). Make sure of your levels before you connect, and don't plug this in with the power on in case there's a short.
Is this still the case with recent audio hardware? I was under the impression that a typical instrument's output levels are far too low to cause any damage and that all inputs would be surge protected.
In my defense, I was like 9 at the time and didn't know about AC-coupling for audio signals yet. That smoked SID is still down in my basement somewhere, I wonder how much of it still works.
That's a pretty good article. Also, the classic one-volt-or-so voltage limiter is a pair of antiparallel silicon diodes. You can put them in series for a bigger limit.
This is fantastic, but I wonder how could I miss it in the old days. I had the full C64 reference manual and all I found was an audio in that could only turn on and off the incoming signal, which of course was a lot less fun than letting it through the SID filters; was it a different input? I'm not sure I used the DIN connector though, I probably interfaced to the user port; can't remember.
One thing to note about a wah-wah pedal[1] if you ever want to simulate it in software is that if I understand it correctly it’s a parametric equalizer and when you wobble the peddle you are affecting the Q (bandwidth) of the equalization. You can hear this for yourself if you use a normal mixing desk, just play something, set a reasonable boost to some mid frequency on the parametric eq and wobble the Q backwards and forwards. You basically get the effect of the pedal.
All true, but Wikipedia is just a reference, not an authority, right? “Wah” and “Wah Wah” are both fine. I assume the “Wha-Wha” spelling you used is autocorrect or accident?
The SID has audio-in that can be summed with internally-synthesized sounds and routed through the on-chip filters before going back out.
I found this pinout in the programmer's reference guide and tinkered with it a bit as a kid, but I didn't really know what I was doing, so it never went beyond a novelty. Who knew, forty years later, that it'd get proper treatment as an effects generator!