I’m new so this might be a silly question…
In order to do what you want you need to use the drum sampler, not the synth sampler engine.
The OP-1 doesn’t actually chop samples, but instead assigns a section of the sample to a specific key (drum engine). Look closely at the waveform. There will be a larger waveform that corresponds to the section of the sample assigned to that specific key on the keyboard and a much smaller waveform at the top of the screen that will indicate which section of the entire sample you are at.
Using the green and white encoders, you can define which section of the sample you want on which key. Using the blue encoder will change pitch (this is for drum sampler only).
Hello. It sounds like you sampled in synth mode which places the same sample chromatically on the keyboard. Try using the drum sampler and it will allow you to slice different parts of the sample over the keyboard.
Cheers and congrats on the OP!
Thanks very much!