The bias resistor can be split into two resistors with their common node bypassed to gnd with a cap. This maintains bias stability while removing negative signal feedback. ;)
Chris
Put an Ammeter in line with the primary. With inductance that low I expect to see excessively high current ... especially if you shunt that 1 Ohm resistor.
Chris
Bob brings up a good point. I'm not a musician but I believe the input impedance of many instrument amps are hi Z, so the drivers that feed them expect same.
Chris
The OpAmp circuit you posted is identical to the Data-Sheet's test circuit, so there's nothing wrong there. Since you want to detect a momentary loss of a pulse train try Googling "555 Missing Pulse Detector".
Chris
Your Transformer model appears to be modeled as Coupled Inductors. Does LT Spice provide a Transformer model also? Transformer models are modeled in terms of turns ratio,coupling (k) coefficient, Rprim, Rsec.
Chris
That xfmr indicates Pri= 50uH, Sec: 400uH. I don't think so and may be why LT Spice is upchucking without the 1Ω in the primary. The input current will be in the ozone without it.
Chris