Quick transistor question.

[JWStewart]

I'm building an MXR GT OD and the input buffer calls for an MPSA14. I only have MPSA13s. Will the different transistor affect the sound of the pedal? If so I will source some 14s. Thanks.

[Silver Blues]

As a general rule, no. You should be fine with the MPSA13. The Darlington is just used there because even though an ideal buffer amplifier has unity gain, the real system obviously has some non-idealities and the high gain in the transistor allows your signal to come out closer to unity (let's say 0.97). You've got tens of thousands of hFe in either transistor so I don't expect there to be much difference.