I was looking at the spark plug PDF and followed the Barberelectronics link which has really inspired me to try the whole OPamp stacking a go. Do you know what other chips could possibly be stacked... like a PT2399? Has anyone every tried to stack a BBD/delay chip and if it can be done what would the outcomes be? Thanks!
Out of curiosity, I just tried stacking PT2399s. Definitely doesn't work. All I got was nasty static and no delay or even clean signal.
Op amps with the same pinout will work. EDIT: I think some LM chips are an exception.
Given the circuitry needed to sub two 3008s for 3005s, you definitely cannot stack BBD chips.
Stacking op amps will increase noise. Just FYI. YMMV. TTFN.
You can often stack buffer ICs to bring the output impedance of an amplifier down. Not usually necessary for guitar pedals, but can help in hifi situations like headphone amps.
Thanks for taking the leap of faith on the PT2399! also for the great info