SAD512D Projects?

[TeleCrunch]

I found an old Ensoniq synth pcb board in my junk pile with 4 SAD512D chips waiting to be pulled and tested—along with a bunch of NEC 4558s I'm not sure I can test these outside of a project. Any ideas for a decent DIY project that I can use at least one of the BBDs, and maybe all four if they're all good? Can a SAD512D simply replace other BBDs like MN3017, MN3019, MN3007, MN3009 in projects?

[Zerro]

Generally, 4558 are twin opamps with the same structure as TL072 or JRC4580 - both low noise opamps - I would use here 4580s. SAD 512 are analog delay lines "shorter" than SAD1024 and they all are little higher noise ones. You can substitute them with modern dealy lines of course, but pins and clock settings will be different, so you must build accomodating sister pcb. You can raise clock freq while the same delay time, but better circumstances for higher freqs, playing around low pass filters at input and output. And power supply source.