That's the issue I came across with the Sewer Pipes. It wouldn't let me use anything less than 560R. When I would turn it on, I would get a small double-pop and then only the OP Amps would be working. I don't think I even hand anything coming out of the mod/demod sections. Even just setting up the chip for a normal datasheet delay yielded the same results. I swapped in other PT's and got the same thing, then I tried the ones from different source and they worked fine with the 100R.
The ones that don't like short delays are the ones I got from Tayda, but they are different than the first one I got from them. The 2 I originally used are from Steve (smallbear), and the first one I got from Tayda, and they have no problems with the 100R at all. The one from Steve have a nicer case, while the ones from Tayda look more like National chips... square, boxy, dull case. If I get a hankerin, I'll post pics of the different ones. Just gotta get into a case for a pic of one of them.