This is something I've wanted to re-visit for a while, I was never happy with my original layout - you couldn't use the proper op-amp in it and it was a bit crappy looking too.
I have added 2 parts to this build, neither affect the sound - they protect the circuit from the wrong polarity supplies which is necessary if you use the original RC3403 op-amp because it costs a fortune.
you can of course use a jellybean quad op-amp like a TL074 or LM324
