MIDI Works, I made the audio test cable described elsewhere on this forum and was able to:
play notes and hear this at point 1,
play notes and hear this at point 2.
play notes and not hear anything but crackle and noise on point 3. ( pin 1 of TL074p ‘middle’ chip )
all subsequent audio path test points hiss/noise/crackle.
sound only comes out of the ‘input’ socket so this might be a short between point 2 and 3 ( TL072 pin 1 to TL074p pin 1 )
When I built this over Christmas I had soldered 220ks in place of 10ks all around the filter section so had to order metal film resistors wait weeks and finally this week got around to replacing them. While doing this I damaged a tantalum cap on audio path 4 and replaced it with a ceramic 1nf cap which is probably gonna cause other issues but for now I think getting poles 1/2 up is my immediate goal.
How can I check the path between point 2 and point 3 ( TL074 pin 1 to TL074P pin 1 ) ?
Can I bridge the TL072 pin 2 output directly to pin 1 of the TL074p safely with some breadboard wire ?