Hello, I am making a simple OP amp circuit based off of MXR's Distortion Plus guitar pedal in LTSpice and I am running into this issue when running a transient simulation. When I run this simulation the program freezes and when I stop the simulation, these convergence errors pop up.

This is the schematic that I am simulating below




What could be the issue here? Any help is greatly appreciated.

 

Please post your file.
I don't know why but I would start by removing (.include "lm741.lib") and replacing it with an op-amp from the list.
You might also try replacing the 1N34a.

 

Hard to tell.

1Meg input and feedback resistors are too large for the typical input bias current of a 741.

Why are you putting two resistors in series?
For simulation purposes one resistor, equal to the sum of the two, will work the same

You can remove R5 since it is shorted.

C1 serves no purpose since V2 is an AC short.

Post your .asc file for the circuit.

 

Please post your file.
I don't know why but I would start by removing (.include "lm741.lib") and replacing it with an op-amp from the list.
You might also try replacing the 1N34a.

The lm741 OP amp is a library that I downloaded from TI since it is not included in LTspice. Even with other OP amps that I have tried, there is a similar convergence error. Same with the germanium diode, I make a .LIB file for the diode to emulate it's characteristics.

 

Hard to tell.

1Meg input and feedback resistors are too large for the typical input bias current of a 741.

Why are you putting two resistors in series?
For simulation purposes one resistor, equal to the sum of the two, will work the same

You can remove R5 since it is shorted.

C1 serves no purpose since V2 is an AC short.

Post your .asc file for the circuit.

I know it seems very unorthodox, but that is what is in the guitar pedal circuit. It's supposed to create a good bit of distortion. The two series resistors are emulating a potentiometer, so I can change the two values to visualize the different waveforms from these. I attached the circuit diagram below.

 

The lm741 OP amp is a library that I downloaded from TI since it is not included in LTspice.

I tried different parts for the op-amp and for the diodes and it runs for me.

 

I tried different parts for the op-amp and for the diodes and it runs for me.
View attachment 342400

Interesting, when I ran different components it still did not work for me, glad that it worked for you. Weird how the libraries are causing so many issues. What could be going wrong with the libraries?

 

Unfortunately, spice models and libraries do not come with any sort of provenance or certificate of authenticity. The usual convergence problems arise from steep edges, requiring "small" timesteps and derivatives that are not "smooth". You have to build your confidence level with your tools and pieces parts one step at a time especially when merging "old models" with "new" simulation algorithms.

 

You need to add some resistance between V2 and C1, or set the internal resistance of V2 to some nonzero value.

 

I tried different parts for the op-amp and for the diodes and it runs for me.
View attachment 342400

For simulation purposes, Use LTspice builtin UniversalOpamp3b.

 

For simulation purposes, Use LTspice builtin UniversalOpamp3b.

View attachment 342403

Thank you so much! I see with the programmable values for slew rate, etc. that I can tailor it to the LM741.

 

Thank you everyone for the really great advice. It helped out a ton and now I'm getting no errors on my output.